Why do mudflows and landslides occur? Collapse - what is it? Causes and consequences of collapses

Introduction.

Definition and essence of the phenomenon.

Causes of occurrence.

Classification of the phenomenon being studied and/or its place in a higher level classification.

Varieties.

Distribution and scale of manifestation.

Dynamics.

History of the study.

Forecasting (including folk signs).

Environmental consequences and influence on human economic activity.

Human influence and control ability.

Myths, legends, beliefs, folklore.

Conclusion.

Used literature and sources.

Applications.

Introduction.

The topic of my essay is such a common phenomenon in many coastal areas as landslides.

The purpose of the essay is to familiarize yourself with the essence of this phenomenon, to identify the causes of its occurrence, to establish the environmental consequences and influences on human economic activity, as well as possible measures to combat or manage this phenomenon.

Landslides, i.e. large displacement of earth masses is associated with the activity of ground and surface waters and other factors. They develop on steep coastal slopes of ravines, river valleys, lakes and seas.

Since landslides not only change the shape of the relief, but also cause irreparable harm national economy and human life, they need more in-depth study to eliminate negative consequences.

Definition and essence of the phenomenon.

“Landslides are the sliding displacement of masses rocks down the slope under the influence of gravity. The impetus for the beginning of such a displacement is usually the loss of unusually heavy rains or the rapid melting of snow cover, causing an excess flow of water into permeable strata, as well as seismic tremors.»

In the mountains, landslide processes occur when loose sediments lying on steep slopes become waterlogged. On the plains, the formation of landslides is caused by the presence of clayey aquifer layers located obliquely towards a river valley, a deep ravine or towards a steep seashore. This occurrence of rocks creates mechanically nonequilibrium conditions for soil masses located above the waterproof layer. The surface of this layer, when excessively moistened, becomes slippery, the adhesion strength of the waterproof surface and the overlying soil layer weakens and at the moment when the adhesion force of the aquifer with the overlying layer becomes less strength the gravity of this thickness, individual blocks of soil begin to slide along the inclined surface of the aquitard.

Large landslides with deep displacement of rocks cause significant changes in the contours of coastal slopes and give them special shapes. The simplest case of a landslide slope is presented in Figure 1 (Appendix 2). The dotted line indicates the original position of the steep coastal slope. After the landslide, it took on a completely different shape, represented by a solid line. In any landslide slope, individual main elements can be identified.

“The sliding surface often shows polishing or shading marks caused by rocks rubbing against each other as they slide. This polishing is often called sliding mirrors. The displaced rocks located in the lower part of the slope are called landslide accumulations, or landslide body. The upper, steeper part of the slope, located above the landslide body, is called the post-landslide scarp. A landslide body in cross section is usually expressed in the form of a terrace-like step, often thrown back towards the undisturbed remaining part of the slope and called a landslide terrace. The surface of such a terrace is most often irregularly lumpy, but sometimes more or less leveled. The junction of the landslide body with the supra-landslide scarp, sometimes expressed by a depression in the relief, is called the rear suture of the landslide. It can be located at different levels depending on the composition of the rocks composing the slope and the nature of landslide displacements. In most cases, it is located at the bottom of the slope, sometimes above it, but in some places it drops significantly lower, even going under the water level of a river or sea.

Often a landslide body is a series of blocks that have slipped down under the influence of own weight(Figure 2 - Appendix 2). In this case, the sequence of layers is preserved in the blocks and only their tilting towards the undisturbed part of the slope is observed. This, according to A.P. Pavlov, is the delapsive part of the landslide, which occurred under the influence of gravity of rocks (Latin delapsus - fall, sliding). In the lower part of such a landslide, the displaced rocks are strongly crushed and crushed under the pressure of the overlying blocks. This is the detrusive part of the landslide, which arose as a result of the pushing of blocks that came off from above (Latin detrusio - collision). Sometimes the pressure of landslide masses is so significant that in front of them there appear mounds of bulging rocks that make up the base of the slope. In such large landslides, landslide friction breccias are formed along the sliding surfaces. In a number of landslide areas, complex landslides consisting of many individual blocks are observed. Such complex landslides usually combine delusive (in the upper part of the slope) and detrusive (in the lower part of the slope) types of displacement.

Large landslide displacements form huge circuses, or rather half-circles, protruding deeply into the shore. They alternate with more stable sections of the slope, which are like capes, called inter-landslide ridges.”

Causes of occurrence.

For the formation of landslides on slopes, the following factors are necessary: the presence of a water layer and its slope towards the slope, the presence of an aquifer and groundwater.

The movement of the thickness can be caused by various reasons: an earthquake, heavy rain, which increases its weight, erosion of the slope by a river or sea, and careless cutting by a person.

Studies of landslide areas have shown that landslides are a complex process that occurs under the influence of a complex of factors, including groundwater. These factors include:

1. Intensive erosion of the coast by a river or abrasion by the sea (destruction by the surf) in some cases are one of the main causes of landslides in the Volga region, on the Black Sea coast of the Caucasus and in other areas. When the bank is washed away by a river or abraded by the sea, the steepness of the slope and its stressed state increase, which ultimately leads to an imbalance of earth masses and their sliding.

2.Influence atmospheric precipitation affects the stability of earth masses. For example, it is noted that landslides in the gully network of the southern coast of the Caucasus occur mainly at the end of the rainy period (February - March), when maximum saturation of the soil with water is observed. In general, the degree of water content of rocks with both meteoric and groundwater is important.

3. Change in the consistency (condition) of clayey rocks on the slope as a result of the influence of ground or surface water and weathering processes. If the clay is exposed on the coastal slope, it is exposed to various external factors and weathers, gradually dries out, and cracks. This is especially helped by periodic exposure to water, during which alternating wetting and drying can completely disrupt its solidity. When saturated with water, such destroyed clay acquires a plastic or fluid state and begins to slide down the slope, dragging other rocks with it.

4. The formation of landslides is facilitated by the processes of suffosion (from the Latin suffosio - digging up, undermining), which consists in the removal of small clastic particles by filtering water through permeable sediments, as a result of which these deposits become less dense, and the soil masses obliquely lying above them begin to slide down the slope (Fig. 3 - Appendix 2). Under conditions of a leveled surface, suffusion leads to soil subsidence and the formation of shallow closed relief depressions. Such landforms, often found in steppe zone on the area where loess and loess-like deposits occur, known as steppe saucers, subsidence depressions, etc.

5.Hydrodynamic pressure created by groundwater near the exit to the surface of the slope. This is especially evident in the presence of a hydraulic connection between groundwater and the river. In this case, during floods, river waters feed underground waters (Fig. 3), as a result of which their level also rises. The decline in low water in the river occurs relatively quickly, and the decrease in the level of groundwater in the slope is relatively slow. It turns out that there is a gap between the levels of groundwater and river water, which creates additional hydrodynamic pressure in the slope. As a result, squeezing out of the slope part of the aquifer may occur, followed by sliding of the rocks located above. In this regard, in some cases there is an increase in landslides after floods.

6. Conditions of occurrence of rocks composing the slope, or, in other words, structural features. These include: the fall of rocks towards a river or sea, especially if among them there are layers of clay and aquifers on them; the presence of tectonic and other cracks falling in the same direction; significant degree of rock weathering.

7. Careless human activity, which sometimes leads to instability of the slope. This may be due to: artificial cutting of slopes, destruction of beaches (as sometimes happened during the construction of seaport facilities without taking into account the natural conditions for the formation of beaches and the direction of sediment movement), additional load on the slope, and incessant deforestation.

Classification of the phenomenon.

There are a large number of different classifications of landslides. They are usually divided into three groups - general, specific and regional classifications. “General classifications take into account the features of the landslide process based on a set of characteristics. Particular classifications are based on identifying more significant factors contributing to sliding.”

General and specific classifications are used to determine the applicability of various methods for calculating slope stability and selecting landslide prevention measures. Regional classifications are compiled for areas where landslides are widespread.

Of the general classifications, the classifications of A.P. Pavlov (1903), F.P. should be noted. Saverensky (1934), T.S. Zolotoreva (1963).

“Based on the structure of the landslide slope and the position of the sliding surface, according to F. P. Savarensky, the following landslides are distinguished: in homogeneous non-layered rocks with a curved sliding surface; landslides in which the displacement surface is predetermined by the geological structure; landslides, the sliding surface of which intersects layers of various rocks (Fig. 4).”

Table 1 (Appendix 3) shows the results of a comparison of the most fully developed classifications of landslides by type of their mechanism.

Of the private classifications, it is worth noting the classification of E. P. Emilyanova (1959), where the main factor is groundwater. Regional classifications distinguish landslides confined to certain stratographic horizons and slopes of different genesis (tertiary landslides, abrasion landslides, etc.)

In the higher level classification, for example, in the classification of slope movements by rock type, six types of landslides are given. refer to slope movements of rocky and semi-rocky rocks, which have high strength in the sample, low variability of strength under long-term, short-term and shock loads, a strong influence of fracturing and tectonic disturbances on the strength of the massif, and do not swell. This type of landslide manifests itself in the slow displacement of masses along the surface. They occur when the surfaces are flat and have little adhesion.

Thrust landslides occur in clayey rocks, which are characterized by low strength in the sample, a large difference in strength under short-term and long-term impact loads, and swelling. Moderate and slow movement occurs. The sliding surface passes at the bottom along the contacts between the layers, and at the top intersecting them.

This category also includes contact landslides And landslides of homogeneous rocks. The former are observed in the form of displacement along the contact layers and are characterized by the presence of contacts cut from below between the layers, and the latter are represented by cyclic sliding and a steep slope of loams.

Landslide-flows characterized by cyclic sliding and liquefaction and manifestation in silty rocks that have thixotropic properties (thixotropic liquefaction and soaking). Occurs when saturated with water to a moisture content above the yield point. This also includes seepage landslides, which are a cyclic collapse of sandy-clayey rocks above a sand slide, when the filtering and floating layers are below the layer of clayey rocks.

Varieties.

Depending on the volume of sliding masses, small (hundreds and thousands of m3), medium (tens of thousands of m3), large (hundreds of thousands) and very large (millions of m3) landslides are distinguished.

The main types of landslides on quarry side slopes (according to P. N. Panyukov) are shown in Fig. 5 (Appendix 2).

Dump landslides form an independent group of slope deformations in open-pit mining. Dump landslides are divided into simple and complex. Depending on the position of the sliding surface, S.I. Popov identified plantar, subplantar and supraplantar landslides. The main types of landslides on quarry side slopes (according to P.N. Panyukov) are given in Table 2 (Appendix 3).

Distribution and scale of manifestation.

“The geography of landslides is vast. They are developed in the Volga region: Nizhny Novgorod, Ulyanovsk, Volsk, Saratov, etc. Landslides occur on the banks of the Oka, Kama, Pechora, and on the Moscow River.”

“Landslides affect the banks of the Volga, the shores of the Black Sea near Odessa, the southern coast of Crimea and the Caucasian coast from Tuapse to Sukhumi, where they cause great destruction and require large expenses for strengthening.”

Dynamics.

The dynamics of landslide processes are characterized by certain patterns of their development over time. “First of all, one should distinguish between ancient and modern landslides. In accordance with this, I.V. Popov proposed a schematic diagram of the general patterns of the dynamics of landslide development (Table 3 - Appendix 3).”

If natural conditions are favorable and a situation is created for the implementation of shearing and shearing forces, preparations begin to disrupt the balance of rock masses. At this time, various phenomena may occur: “an increase in the weathering of rocks, a change in their humidity and physical state, a decrease in their strength, a change in slope steepness, plastic deformation (creep), including the phenomenon of deep creep in rocks.”

The kinetics of loss of slope stability taking creep into account was studied by G. N. Ter-stepanyan. “Creep is the slow deformation of rocks without the formation of a sliding surface, occurring at stresses significantly lower than the temporary shear strength. Depending on the magnitude of the stress, three forms of deformation are possible: 1-the increase in deformation stops at some point in time t1, having reached a constant value; 2-increasing quickly at first, then from moment t2 the deformation begins to occur at a constant rate; 3-at some moment t3 the deformation turns into shear.”

Slope rocks, depending on the stresses they experience at different points, can be in different phases of deformation: 1-stabilization, 2-creep, 3-shear.

There are four stages in the formation of landslides (according to E. P. Emelyanova):

“1. The stage of landslide preparation, during which the coefficient of stability of the slope decreases and the deformation of rocks increases, preceding their destruction.

2. The stage of the main displacement of the landslide, during which, following the destruction of rocks along the sliding surface, most of the landslide displacement occurs in a relatively short period of time.

3. The stage of secondary displacements is the period during which rocks that did not reach a stable state in the second stage are displaced in the body of the landslide.

4. Stage of stability (stabilization) - rocks do not experience deformation, the stability coefficient of the slope is constant or increasing.”

The duration of the first three stages varies. The first of them is the longest, although subsequent ones can take decades. Last stage can be interrupted when cutting a slope, earthquakes, etc.

The speed of landslides varies from fractions of a millimeter per day to several tens of meters per hour.

The size of landslides is significant. Thus, the landslide on the Zeravshan River (Tajikistan), which occurred on April 24, 1964, in terms of the volume of displaced rocks is more than 20 million m 3. It blocked the river and formed an embankment dam 150 m high. The reason was the abundance of atmospheric water, penetration through cracks, decreased adhesion of loose sediments, decreased adhesion of loose rocks to dense ones, and they moved.

A very typical landslide on the seashore at Lyme Regis in England. The coast here is composed of white chalk, sandstones with flints and loose sand of the Cretaceous system, underlain by Jurassic clay, which is waterproof. The strata are inclined towards the sea, and groundwater flows down the clay, forming numerous springs and creating conditions for the sliding of the overlying strata. After rainy weather 1839, which saturated these strata with water and thereby increased their weight, on December 24 the entire coast began to move, broke into huge blocks, separated by crevices and ravines, and crawled towards the sea. The pressure of the masses pushed out from the bottom of the sea a ridge a kilometer long and 12 meters high, consisting of torn off blocks, covered with seaweed, shells, starfish, etc., and now forming a series of cliffs.

Near Odessa, the seashore consists on top of tertiary clays, underlain by limestone, which rests on blue clay; According to the latter, groundwater flows to the sea and causes periodic landslides. Large blocks break away from the shore, crawl, and capsize; the entire coastline is broken up by chasms and ravines, and shallows are squeezed out from the bottom of the sea. The size of landslides has increased since limestone began to be quarried here for urban buildings and extensive quarries provided access precipitation to the lower clay.

The southern coast of Crimea suffers from landslides along almost its entire length. Here, on the surface of strongly folded shales and sandstones of the Triassic and Lower Jurassic lies a thick layer of coarse colluvium, formed from the destruction and collapse of the overlying thick limestones of the Upper Jurassic that make up the cliffs of Yayla. Atmospheric precipitation and Yayla springs penetrate into this colluvium, and it slides along the steep slopes of shale along with buildings and gardens, is dissected by cracks, and destroys houses. The Black Sea coast from Tuapse to Sukhumi is also unstable; The immediate cause of landslides is often the erosion of the shore by the surf and its cutting off during the construction of railways and highways.

The right bank of the Volga in different places - in Ulnovsk, Volsk, Saratov, Syzran, Batraki, etc. - often slides because it consists of waterproof and aquiferous layers and is inclined towards the river.

History of the study.

Forecasting.

The forecast of landslide phenomena, depending on the stage of engineering-geological surveys, can be qualitative and quantitative.

“A qualitative assessment of the stability of slopes is based on the study, description and analysis of the engineering geological conditions of the slopes, their height and steepness, relief features, conditions of occurrence of rocks, their composition, physical state and properties; water cut, accompanying geological processes and phenomena.”

All this allows us to assess the stability of the slope in a descriptive form: the formation of a landslide is inevitable, perhaps doubtful, there is no reason to expect a landslide to occur.

Quantitative forecasts are based on rigorous, specific methods - modeling and calculations.

Typically, a harbinger of landslide displacements is the appearance of one or more cracks along the coastal slope (Fig. 6). These failure cracks gradually expand, and the detached part of the slope begins to slide down (Fig. 7 A, B). In addition to landforms created by landslide processes, improperly oriented trees on the surface of a landslide body are a good indicator. In the process of displacement, they are removed from their vertical position, acquire different slopes in certain areas, bend, and in places split, as was observed in Fili Park (Moscow), on the southern coast of Crimea and in other places.

Landslides can occur in the same area repeatedly from year to year. Slipped masses, if they are not carried away from the foot of the slope by river waters or sea waves, can prevent the further development of the landslide. Trees on landslide slopes become inclined and form a so-called “drunken forest.”

“To assess the possibility of a landslide, the slope stability coefficient is used, which shows the ratio of resistance forces to landslide displacement and active shear forces. Under various conditions it is equal to:

For a flat sliding surface - the ratio of the sums of projections of the above forces onto the sliding plane;

For a circular cylindrical sliding surface - the ratio of the sums of the moments of the corresponding forces relative to the axis of rotation;

For any type of displacement surface, the ratio of the total strength of rocks along this surface (for shear) to the sum of tangential forces along the same surface.

Landslides are possible when the slope stability coefficient (variable over time depending on various factors), decreasing, becomes equal to unity.”

To predict landslides, calculation methods are used based on determining the slope stability coefficient by comparing the stress in the slope with the strength of its constituent rocks, methods of taking into account the balance of earth masses, etc.

Regular observations of landslide phenomena are carried out in areas where these processes can cause damage to the national economy. “Observations are carried out using special benchmarks installed in the body of the landslide. Periodically, checking the instrumental survey, they monitor changes in the marks of the planned position of the benchmarks, which makes it possible to determine the speed of movement of landslides. At the same time, they monitor the regime of groundwater in wells, flow rates of springs, rock moisture, precipitation, water content of rivers, etc., and monitor the appearance of new cracks on the slopes or changes in the size of old ones.”

Environmental consequences and influence on human economic activity.

Landslides cause great harm to the national economy.

In some cities located along the banks of large rivers (in particular in the regions of the Middle and Southern Volga region), landslides create difficult situations, causing the destruction of residential and industrial buildings and communications.

Landslides occurring in the Odessa region are systematically reducing the area of the city's best dacha area, destroying gardens and destroying buildings.

Human influence and control ability.

Natural conditions conducive to landslides, for example, on the banks of the Volga, are aggravated by the carelessness of people who cut off the lower part of the slope to build streets, roads to piers and load the overlying slope with buildings that will inevitably collapse over time. The lack of sewerage in cities previously increased the amount of water penetrating into aquifers.

The western shore of Lake Baikal from the source of the Angara River to the Kultuk station is caused by a large fault that created a deep depression in the lake. This was not taken into account when constructing the railway; Numerous tunnels and cuttings cross the ends of the headlands between the valleys too close to the steep coastal slopes where the hard rocks are broken by cracks parallel to the main fault and are therefore unstable. Collapses of the walls of the excavations occur, bending the paths, and blocks fall out of the arches of the tunnels due to ongoing small movements near the fault.

“To successfully combat landslides, knowledge of the groundwater regime is necessary. Proper regulation of groundwater regime helps to stop landslides.”

“Measures to combat landslides include afforestation and bedding, strengthening slopes by covering them with turf with piles and stakes. The slope is more securely secured with concrete and stone walls. An even more reliable means is the installation of underground drainage (laying pipes) and surface drainage by installing concrete drainage ditches on the surface of the slope to collect atmospheric water.

In this way, for example, the steep slope of the right bank of the Moscow River on Vorobyovy Gory, where the ski jump rises, is strengthened.”

Myths, legends, beliefs, folklore.

Conclusion.

Having studied this phenomenon as fully as possible, I can confidently say that landslides are not inferior to floods, earthquakes and other disasters on our planet in terms of destructiveness and unpredictability of consequences. Proof of this can be the recent landslide in the south of Kyrgyzstan, in the village of Budalyk. This happened on March 27, 2004. According to eyewitnesses, the volume of displaced rocks amounted to several million m3, 12 houses were wiped off the face of the earth and 33 people died. Similar phenomena have already occurred in this area before, but not on such a large scale. Studies have shown that the mountains are not dangerous and the possibility of new landslides is negligible. The cause of this landslide was an earthquake that occurred the night before the disaster. At the moment, experts say that there is a threat of new landslides.

This case makes it clear how imperfect the methods for studying, predicting and diagnosing landslides are. Therefore, it is necessary to continue studying this phenomenon as one of the dangerous phenomena.

Used literature and sources.

V. P. Bondarev “Geology”, lecture course, Moscow "Forum-hydra M" 2002.

G. V. Voitkevich “Handbook for the protection of the geological environment”, volume 1, Rostov-on-Don “Phoenix”, 1996

A. M. Galperin, V. S. Zaitsev “Hydrogeology and engineering geology”, Moscow “Nedra”, 1989.

G. P. Gorshkov, A. F. Yakusheva “General Geology”, Moscow University Publishing House, 1973.

V. V. Dobrovolsky “Geology”, textbook for universities, Moscow “Vlados” 2004.

I. A. Karlovich “Geology”, textbook for universities, Moscow “Academic project” 2004.

D. M. Kats “Fundamentals of geology and hydrogeology”, Moscow “Kolos”, 1981.

V. A. Obruchev “Entertaining Geology”, Moscow, Publishing House of the USSR Academy of Sciences, 1961.

M.P. Tolstoy, V.A. Malygin “Fundamentals of Geology and Hydrology”, Moscow “Nedra”, 1976.

Employees of the American aerospace agency NASA have made available the DRIP-SLIP software package, which makes it possible to monitor landslides around the world. The system scans satellite images and determines where a disaster could occur in the near future. /website/

The system is a collection of location maps updated every 24, 48 or 72 hours. This allows you to monitor the situation in real time. The capabilities of the complex are demonstrated using the example of a map of landslides that were recorded from 2007 to 2013.

“We are interested in quickly and accurately identifying unreported landslides to better understand the nature of their occurrence. This information will make it possible to clarify maps that depict the regions most prone to landslides and take measures to prevent them,” NASA experts noted.

Landslides often go unnoticed and unreported, resulting in a large number of casualties. "We know that a large number of Landslides occur during this time period in Nepal. Documenting them is very important to better understand why these events occur and what impact they have,” experts say.

Risk area - Nepal

Scientists pay special attention to Nepal, since landslides in this country are very current problem. Landslides occur here during the monsoon season and lead to the death of dozens and sometimes hundreds of people. One of the most destructive landslides occurred in this country last year after strong earthquake.

Due to hesitation earth's crust the mountain slopes collapsed and avalanches of mud rushed down the mountainsides and hills. The largest landslide occurred in the Miagdi region, about 140 kilometers from Nepal's capital Kathmandu. Landslides also occurred in other regions. People who survived devastating earthquake, died under layers of sliding earth.

Landslide record holder

Landslides occur quite frequently around the world. Largest landslide in modern history occurred on February 18, 1911 in the Pamirs in Tajikistan. After a strong earthquake, 2.2 billion cubic meters of loose material slid from the Muzkol ridge from a height of 5 thousand meters. The force of the impact of the collapsed mass caused a seismic wave that circled the entire globe several times.

The landslide covered the village of Usoy with all its residents, property and livestock, resulting in the death of 54 people. In addition, the descending mass blocked the Mugrab River, which is why Lake Sarez, 4–5 kilometers wide, was formed. Over time, the lake grew, flooding the villages of Sarez, Nisor-Dasht and Irkht. Currently, the lake still exists, its length and width are already 75 kilometers.

The lake still poses a danger to nearby settlements. This area is located in a seismically active zone, and weak tremors can trigger a breakthrough of Lake Sarez. In the event of a tragedy, a huge mass of water mudflow will pass almost to the Aral Sea. Potentially danger zone Home to about 6 million people.

The most destructive landslide

The most tragic in terms of the number of victims was a landslide that occurred in the Chinese province of Gansu in 1920. Most of the territory of this province is occupied by a loess plateau, which is a homogeneous soil mixed with lime, clay and sand. The soil here is fertile, so the area was densely populated. After the earthquake, the cohesion of the loess was disrupted, and the earthen mass rolled down in entire hills. She destroyed everything within a radius of 50 thousand square kilometers.

The situation was aggravated by the fact that everything happened winter night when all the people were in their houses. “The shocks followed one after another with an interval of several seconds and merged with the deafening roar of collapsing houses, the screams of people and the roar of animals that came from under the rubble of buildings,” recalled the miraculously surviving missionary.

One of the houses, moved by a mass of rocks, was moved almost a kilometer. However, the house remained undamaged. The man and child who were there were also not injured. Because of the darkness and noise, they did not even understand what had happened. Along with the house, the section of the road also moved. Now this place is called “Death Valley”. More than 200 thousand people are buried there.

Landslides in Russia

Scientists consider landslides to be the most dangerous natural disaster. The danger is that they can occur absolutely anywhere where there is a slope. Landslides are not associated with geographical location and can get off in any country, including Russia. Most often, residents have to deal with this natural phenomenon North Caucasus, Volga region, Primorye, Eastern Siberia and the Urals.

For example, in 2006, heavy snowfalls and continuous rains in the mountains caused severe landslides in Chechnya. The upper layers of rocks up to two meters thick rolled down the slopes, burying residential buildings in the villages of Shuani, Benoi, Zandak and others. In the village of Shuani alone, a landslide destroyed about 60 houses in one day. Residents left their homes, taking only documents with them.

The Russian Black Sea coast is also a risk zone. Mountain slopes built up with many infrastructure facilities create favorable conditions for landslides. The danger especially increases in the autumn-winter period, when the mountain slopes are washed away by rain. Active human activity, including construction and landscape impacts, are also additional risk factors.

Landslide is a downward sliding displacement of soil masses under the influence of gravity. Landslides occur on slopes when the stability of the soil or rocks on the slope is disrupted. The frictional forces that ensure adhesion of soils or rocks on slopes are less than the force of gravity, and the entire mass of soil (rock) begins to move.

It is known that most of the Earth's surface is slopes. Slopes include surface areas with inclination angles exceeding 1°. Slopes occupy at least 3/4 of the land area.

The steeper the slope, the greater the component of gravity, which tends to overcome the adhesion force of rock particles and move them down, creating a landslide.

The formation of landslides depends on the strength of the slope rocks, the alternation of soil layers of different compositions and their slope, and the presence of groundwater.

Landslide in the Karmadon Gorge ( North Ossetia) came down unexpectedly on September 20, 2002 and filled a space of 5 km with ice-rock mass. More than 100 people have gone missing, including a film crew led by director Sergei Bodrov Jr.

Landslides in Crimea destroyed more than one settlement

Landslides can be caused by both natural and artificial causes associated with human activity.

Natural causes include: increasing slope steepness; the occurrence of clayey rocks on a slope, especially if they are heavily moistened; erosion of the base of slopes by sea and river waters, as well as seismic tremors (earthquakes).

Artificial causes include: destruction of slopes during road construction; deforestation; unreasonable behavior Agriculture on the slopes.

Landslides can occur on all slopes, starting with a steepness of at least 19°. However, on clay soils they occur at a slope steepness of 5-7°. Excessive moisture of the rocks is sufficient for this.

Landslides occur at any time of the year, but are especially intense in the spring or during summer rains. On the coasts of the seas, landslides develop after strong storms.

In Russia, landslides quite often occur in the Volga region - in the Saratov region, in the Volgograd area; on the banks of the Don, the Tsimlyansk reservoir, in the Kuban valley, in many regions of Siberia and the North Caucasus.

Landslides are large blocks of rock moving down a slope as a single body. The process of sliding is the sliding of a mass of soil over some surface. Therefore, for any landslide, a landslide body that moves and a sliding surface along which it moves are always distinguished.

In order for a landslide to form, several conditions are necessary, but the main one is the presence of water. Penetrating deep into rocks, especially clayey ones, water fills the pores between soil particles, reduces the adhesion of these particles and increases the weight of the rock. The balance between the adhesion forces and the force of gravity is disrupted, and the soil masses begin to slide down under the influence of gravity. Groundwater also affects clayey rocks in the same way. Sometimes they, by washing away loose deposits in such rocks, such as sand, lead to instability of the thickness of the rocks located above, and these rocks slide.

According to their scale, landslides are divided into large, medium and small-scale.

Major landslides, as a rule, are caused by natural causes and form along slopes for hundreds of meters. Their thickness reaches 10-200 m or more.

Average And small-scale landslides are less than 10 m in size, the cause of their occurrence is mainly related to human activity.

The following speeds of landslide movement are distinguished:

exceptionally fast - up to 3 m/s;
very fast - 0.3 m/min;
fast - 1.5 m/day;
moderate - 1.5 m/month;
very slow - 1.5 m/year;
exceptionally slow - 0.06 m/year.

When a significant mass of rock moves due to landslides, emergency situations can arise. Landslides can destroy individual objects and endanger entire settlements, destroy agricultural land, create danger during the operation of quarries, damage communications, tunnels, pipelines, telephone and Electricity of the net, lead to the death of people.

For example, on January 23, 1984, as a result of an earthquake in the Gissar region of Tajikistan, a landslide 400 m wide and 4.5 km long occurred. Huge masses of earth covered the village of Sharora. 50 houses were buried, 207 people died.

In 1989, landslides in Ingushetia led to destruction in 32 settlements, 2,518 houses were damaged.

In the spring of 1994, after an unusually snowy winter in Kyrgyzstan, huge landslides occurred in many areas, destroying hundreds of houses and causing casualties.

To organize the protection of the population from the consequences of landslides, control over landslides and their forecast is organized. It has been established that most potential landslides can be prevented if timely measures are taken at the initial stage of their development. Anti-landslide measures include: drainage of surface water flowing to the landslide area; removal of atmospheric water from the surface of the landslide area; planting trees and shrubs in combination with sowing perennial turf-forming grasses on the surface of landslide slopes.

To secure the banks of rivers, reservoirs and sea cliffs prone to landslide processes, slope coverings made of reinforced concrete slabs are used.

If a landslide cannot be prevented, the population is notified of the threat and evacuation is organized.

Study information about possible locations and approximate boundaries of landslides, remember warning signals about the threat of a landslide, as well as the procedure to follow when receiving this signal.

Signs of an impending landslide include jammed doors and windows of buildings and seepage of water on landslide slopes. If you see signs of an approaching landslide, notify the nearest landslide station, wait for information from there, and act depending on the situation.

If there is a threat of a landslide and time is available, early evacuation of the population, farm animals and property from threatening zones to safe places is organized.

When receiving signals about the threat of a landslide, turn off electrical appliances, gas appliances and the water supply network, and prepare for immediate evacuation.

Depending on the speed of landslide displacement detected by the landslide station, act in accordance with the threat.

If the landslide displacement rate is more than 1.5 m per day (rapid displacement), evacuate in accordance with a pre-drawn plan. When evacuating, take with you documents, valuables, and, depending on the situation and instructions from the administration, warm clothes and food.

Measures to prevent landslides: 1 - drainage of surface water flowing to the landslide area; 2 - removal of atmospheric water from the surface of the landslide area; 3 - planting tree and shrub vegetation in combination with sowing perennial turf-forming grasses; 4 - slope coverings made of reinforced concrete slabs for securing the banks of rivers, reservoirs and sea cliffs subject to landslide processes; 5 - warning the population about the threat of a landslide

If there is a threat of a landslide, you must: 1 - report to the nearest landslide station post or the unified rescue service about signs of a landslide (seepage, jamming of doors and windows of the building); 2 - evacuate your property and farm animals in advance

After the landslide has moved in the surviving buildings and structures, check the condition of the walls and ceilings, and identify damage to the electricity, gas and water supply lines. If you are not injured, then together with the rescuers, remove the victims from the rubble and provide assistance to them.

Collapses, their causes and consequences

Collapses- this is the separation and fall of large masses of rocks, their overturning, crushing and rolling down steep and steep slopes. Collapses natural origin observed in the mountains, on sea cliffs and cliffs of river valleys.

The formation of landslides in mountains is facilitated by the geological structure of the area. Landslides form in mountainous areas with highly dissected terrain, with steep, steep mountain slopes. The rocks are in an unstable state because they are cracked in these areas as a result of tectonic forces or weathering. The connections between individual blocks of rocks weaken and become fragile, and any, even minor, impact on them is enough for them to collapse down. Therefore, landslides most often form in the spring, during snowmelt, and in the summer, during heavy rains.

Collapses on sea shores and on the cliffs of river valleys occur due to the erosion and dissolution of coastal rocks of seas and rivers.

Landslides in mountains on the shores of the seas and in cliffs of river valleys are a common occurrence, but sometimes they lead to tragic consequences, creating emergency situations. Landslides can pose a threat to traffic safety railway trains and other ground transport. For example, Railway Tuapse - Sukhumi goes along the very coastal edge of the Black Sea. On the one hand, it is threatened by the occurrence of a landslide eroded by the waters of the sea, on the other hand, mountain cliffs hang over the railway track. In the Caucasus, after heavy thunderstorm rains, a road winding high in the mountains along the slopes of gorges is under the threat that part of the slope will collapse somewhere and make it impossible for vehicles to pass.

A landslide that came down from a slope blocked a mountain road

In mountainous areas, landslides can destroy and damage bridge supports, rail tracks, and coatings. highways, power lines.

To prevent this from happening, certain sections of roads, power lines and other objects can be moved from landslide-prone areas to a safe place. To prevent a collapse, engineering measures are being taken to strengthen the rocks. Rocks that threaten to collapse are reinforced with encircling steel hoops, cracks are filled with cement, and guide walls are created to change the direction of movement of the falling rocks. In some places, they organize the gradual collapse of rocks with low-power explosions.

If the threat of a collapse is known in advance, a unified state system of prevention and liquidation emergency situations(RSChS) organizes early evacuation of the population to safe places.

Test yourself

Why is it so important to check electrical wires and water pipes when entering buildings after a landslide has moved?
What is used to secure the banks of rivers, reservoirs and sea cliffs prone to landslide processes?

After lessons

Write down in your safety diary a definition of the natural phenomenon “landslide” with a detailed indication of the main reasons for its occurrence. Use the Internet to find examples of landslide displacement that had serious consequences for the population and the environment.
Discuss whether landslides are possible in your area. Why?
Who organizes the early evacuation of the population in the event of a collapse threat?

Workshop

Analyze possible consequences landslides and avalanches, create several situational personal safety tasks.
Develop a plan for your behavior in mountainous areas in the event of a landslide or avalanche.

The soil mass, especially its near-surface layers on the slope, experiences deformation even without the active development of the landslide process. This is due to the freezing and thawing of the upper horizons of the massif in the winter-spring period, their watering and drying out in the warm summer, with the forceful effect of filtering groundwater on the soil skeleton, with a change in the stress state in the massif due to an increase or decrease in the weight of soils when they are moistened - drying, the manifestation of the weighing effect of groundwater, the influence of local movements, the manifestation of individual cracks and man-made changes in the relief.

All of these factors can cause deformation of the surface cover in the direction of slope decline. This deformation can occur in the form of slow creep of soils (the phenomenon “ secular creep") with possible activations under abnormal influences of factors.

Occurrence of a landslide caused by an imbalance of the massif and deformation of the soil massif at a qualitatively different level. The landslide process is understood as an imbalance of the soil mass, its deformation under the influence of unbalanced forces, the separation of part of the mass by a tensile crack (potential or actual “failure wall”) and the movement of the formed landslide body along the sliding surface without loss of contact with the non-displaceable bed.

According to the nature of the imbalance of the soil massif, the characteristics of deformation, which are largely determined by the prevailing force influence and deformation mechanism, landslides can be divided into four main types.

The first type is block relatively deep compression landslides(according to other classifications - landslides of extrusion, crushing, subsidence, bulging). The imbalance of the massif and deformation during the formation of a landslide occur according to the compression pattern. Under compressive vertical pressure from the weight of the overlying layers, the horizon is deformed (crushed), the structural strength of the soils of which is less than the specified domestic pressure. Due to the deformation of the soils of the crushed horizon towards the slope, subsidence and deflection of the overlying massif occurs with the formation in the bending zone, first of a concentration of tensile stresses, and then of a pin crack (a lowered tensile crack). Further, along this crack, the landslide block separates and settles along a steep curved sliding surface. The sliding surface flattens out towards the slope and can be close to horizontal.

The most common are compression block landslides, the sliding surfaces of which are formed in clayey soils (Fig. 1. a, b). Landslides of this type affect the banks of rivers, seas, lakes, and form on the slopes of excavations, embankments, and on the sides of quarries. According to research results, deep block landslides also developed on the right bank of the Kama, in the area where the river crosses the Uzhgorod gas pipeline corridor.

Rice. 1. Schemes of landslide deformations based on the compression mechanism. a, b – compression landslide in clayey soils; c – subsidence and spreading of blocks of semi-rocky and rocky rocks; d – uplift of the valley bottom; e – gravitational folds: deep creep with S-shaped bending of layers; e – gravitational deformations of ridges.

Landslides of this type in semi-rocky and rocky soils are less known. They are found in mountainous and foothill regions. They are characterized by a slow development of deformation in the stage of preparation for displacement, lasting up to several hundred years (Fig. 1c-e).

IN The second type is shear landslides(according to other classifications - sliding landslides, shearing landslides, sliding landslides). In the pre-limit state, concentration of tangential shear stresses occurs in the corresponding zones of the soil mass: preparation of soil shears on steep sections of the slope during the formation of the angle of repose; creep of weathered near-surface slope deposits (cover landslides) with movement along an endless slope pattern; shift according to a predetermined geological structure weakening zone (in contact with the roof more than durable rocks, along the bedding plane). Deformation of a slope (slope) occurs in the form of a progressive shear with a drop in resistance as deformation occurs, a decrease in strength from the peak value to the residual value, and the gradual formation of a sliding surface (plane).

Rice. 2. Schemes of landslide deformations according to the shear mechanism. a – shear-cut; b – shift along bedding; c – shear-sliding of cover masses; d – shift (slide) of the soil (soil-vegetation) layer; e – bending of the heads of steeply dipping layers.

On steep ledges, the shift (sliding) of the sliding part of the massif occurs, as a rule, along a curved sliding surface extending to the base of the ledge or above it (Fig. 2a). Thus, a profile of an equally strong or equally stable slope is formed with displacement (often collapse) of softened soils. The sliding surface can be confined to inclined geological boundaries between layers. In this case, significant units of rocks can shift (Fig. 2b). The shear pattern along broken flat sliding surfaces is characteristic of the sliding of deluvial-eluvial slope accumulations along the inclined roof of bedrock (Fig. 2c). A frequent form of landslide manifestations is a shift (slide) of the soil and vegetation cover (Fig. 2d), revealed by a series of relatively short landslide cracks. Slow creep of the surface layer in the form of shear can be observed on relatively stable slopes with steeply dipping layers of strong rocks (Fig. 2e).

The third type is liquefaction landslides.(according to other classifications - flow landslides, drifts, slides, plastic, visco-plastic). Disturbance of the equilibrium of slope massifs in the form of liquefaction occurs due to the predominant force action of underground (ground) waters. The main mechanism of liquefaction, considered in soil mechanics as filtration deformation of the soil, is an increase in pore pressure (water pressure in the pores of the soil) and, as a consequence, a decrease in effective stresses. In a water-saturated soil mass, pore water, to one degree or another, can exert hydrostatic weighing and filtration pressure of different directions on the mineral skeleton of the soil, caused by filtration volumetric forces. The intensity and direction of these forces depend on external influences: static and dynamic loads on the slope, speed of filtration flows and fluctuations in groundwater levels, level regime in reservoirs and surface watercourses, intensity of precipitation, etc.

This mechanism of landslide formation is especially characteristic of dispersed soils with a weak structural skeleton and low filtration capacity. These include modern silts, water-saturated young clays and loams, quicksand, soils, peats, as well as clayey soils of various ages that have lost strength as a result of decompaction, weathering and hydration.

The action of the liquefaction mechanism is associated with the sliding of slopes of poorly cohesive soil during watering due to a change in the angle of repose from  =  to  = /2 (where  is the angle of internal friction of non-watered soil). At the point where groundwater emerges (discharges) to the surface of the slope, a landslide circus with a narrowed neck often forms (Fig. 3a). Liquefied soil masses (the product of the collapse of the stall wall and sides) in the form of a visco-plastic flow move from the neck to the slope with the formation of an alluvial cone at the foot. An increase in groundwater levels that occurs as a result of heavy rainfalls and heavy snow melting and, accordingly, ascending filtration forces can reduce internal friction in the soil to zero, and decompaction under low loads (surface layers) can lead to a loss of cohesion between mineral particles. In this case, liquefaction of sandy-clayey soil can occur even with small surface slopes (1:10 or less) (Fig. 3b). Often there are violations of the local stability of a slope section in places of excessive soil moisture and deformation in the form of sloughs (Fig. 3c).

Rice. 3. Schemes of landslide deformations based on the liquefaction mechanism. a – landslide circus with a narrow neck (groundwater unloading); b – landslide-flow; c – sludge.

Fourth type – tensile landslides with the separation of part of the rock mass (other names: landslides, collapse, complex landslide). Disequilibrium and predominant destruction occur under the influence of normal tensile stresses with separation of the mass along the fracture surface. Monolithic rocks can withstand significant tensile stresses (up to 30 MPa), as evidenced by the high steep slopes of the sides of many mountain valleys. When tensile stresses exceed the soil strength limit, unbalanced rock blocks separate from the rest of the massif, slide, and collapse (Fig. 4a). The separation of the massif can occur along discontinuous seismotectonic cracks with subsequent movement along the shear surface (Fig. 4b) or subsidence of the separated massif with deformation of the underlying stratum of clayey rocks (Fig. 4c). The presence of a steep prepared shear surface also promotes the formation of rupture cracks in the zone of tensile stress concentration (Fig. 4d).

Of all the types considered, deep block landslides pose the greatest danger to gas pipelines in the conditions of the Russian Platform (see Fig. 1). Combating deep block landslides is very difficult, especially when the landslide process gains momentum and becomes catastrophic, causing dangerous deformation and destructive accidents of gas pipelines.

In this section, 9 lines of the main gas pipeline are located in an old landslide circus formed by deep block landslides. Monitoring of the landslide process should be aimed at identifying deep movements and monitoring the state of a deep landslide.

Rice. 4. Schemes of landslide deformations according to the tensile mechanism with separation of part of the rock mass. a – separation and sliding with the collapse of rock blocks; b – rupture along a tectonic crack and sliding along the formed surface in a mountain massif; c – separation of the massif along a fault and subsidence of the rock block with deformation of the clayey strata; d – detachment at the place of concentration of tensile stresses and shear along a steep bedding surface.

Landslide- dangerous geological phenomenon, displacement of rock masses along a slope under the influence of its own weight and additional load due to erosion of the slope, waterlogging, seismic tremors and other processes. Landslides occur on the slopes of valleys or river banks, in the mountains, on the shores of the seas, and the largest ones occur at the bottom of the seas. Most often, landslides occur on slopes composed of alternating water-resistant and aquiferous rocks. The displacement of large masses of earth or rock along a slope or cliff is caused in most cases by wetting the soil with rainwater so that the soil mass becomes heavier and more mobile. It can also be caused by earthquakes or the destructive activity of the sea. The frictional forces that ensure the adhesion of soils or rocks on slopes are less than the force of gravity, and the entire mass of the rock begins to move.

Causes

The reason for the formation of landslides is an imbalance between the shearing force of gravity and the holding forces. It is called:

increasing slope steepness as a result of erosion by water;
weakening of the strength of rocks due to weathering or waterlogging by precipitation and groundwater;
exposure to seismic shocks;
construction and economic activities.

Landslides usually occur on slopes composed of alternating impermeable (clayey) and aquiferous rocks. The displacement of rock blocks with a volume of tens of m³ or more on steep slopes occurs as a result of wetting of the separation surfaces with groundwater.

Such natural disasters damage agricultural lands, businesses, settlements. To combat landslides, bank protection structures and planting of vegetation are used.

Classification

According to the power of the landslide process, that is, the involvement of rock masses in the movement, landslides are divided into small - up to 10 thousand m³, medium - 10-100 thousand m³, large - 100-1000 thousand m³, very large - over 1000 thousand. m³.

The surface along which the landslide breaks off and moves down is called the sliding or displacement surface; based on its steepness, it is distinguished:

Landslides are classified according to the depth of the sliding surface:

surface - no deeper than 1 m - slivers, alloys;
small - up to 5 m;
deep - up to 20 m;

very deep - deeper than 20 m.

Classification of landslides (according to Savarensky) according to the position of the displacement surface and the composition of the landslide body:

Asequential(in some sources they are indicated as sequential) - occur in homogeneous non-layered rock strata; the position of the curved sliding surface depends on friction and soil displacement;
Consequential(sliding) - occur when the slope is not uniform; displacement occurs along the interface between layers or crack;
Incidental- also occur when the slope is not uniformly composed, but the displacement surface intersects layers of different composition; a landslide cuts into horizontal or inclined layers.

Underwater landslides

Underwater landslides remained unexplored for a long time. Only their consequences - the tsunami - make themselves felt. They are formed when large masses of sedimentary rocks are removed at the edge of the shelf. Underwater landslides are much larger than above-water ones. For example, the Sturegga landslide on the slope of Norway has an area of about 3900 km², and the range of material movement in it reaches 500 km. The volume of just one such landslide is more than 300 times greater than the annual supply of sedimentary material to the World Ocean by all the rivers of the Earth. In Scotland, traces of the tsunami that followed the landslide were discovered at a distance of 80 km from the coast.

Security measures

Preventive measures

For warning in case of Study the information about possible locations and approximate boundaries of landslides, remember the warning signals about the threat of a landslide, as well as the procedure for giving this signal. Signs of an impending landslide include jammed doors and windows of buildings on the lower floors and seepage of water on landslide-prone slopes. If you see signs of an approaching landslide, report this to the nearest landslide station, wait for information from there, and act depending on the situation.

What to do in case of a landslide

When receiving signals about the threat of a landslide, turn off electrical appliances, gas appliances and the water supply network, and prepare for immediate evacuation according to pre-developed plans. Depending on the speed of landslide displacement detected by the landslide station, act in accordance with the threat. If the displacement rate is low (meters per month), act according to your capabilities (move buildings to a predetermined location, remove furniture, belongings, etc.). If the landslide displacement rate is more than 0.5-1.0 m per day, evacuate in accordance with a pre-worked plan. When evacuating, take with you documents, valuables, and, depending on the situation and instructions from the administration, warm clothes and food. Urgently evacuate to a safe place and, if necessary, help rescuers dig out, extract victims from the collapse and provide assistance to them.

Actions after landslide displacement

After the landslide has moved, the condition of the walls and ceilings in the surviving buildings and structures is checked, and damage to the electricity, gas, and water supply lines is identified. If you are not injured, then together with the rescuers, remove the victims from the rubble and provide first aid.

Largest landslides

The largest landslide in the Solar System was probably formed by Mount Euboea on Jupiter's moon Io. Its volume is estimated at approximately 25,000 km 3 .

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Notes

Literature

Landslides. Research and strengthening. M., 1981

Excerpt characterizing the Landslide

“Only Countess Elena Vasilievna, considering the company of some Bergs humiliating for herself, could have the cruelty to refuse such an invitation. - Berg explained so clearly why he wants to gather a small and good society, and why it will be pleasant for him, and why he spares money for cards and for something bad, but for good society ready to bear the expenses that Pierre could not refuse and promised to do.
- But it’s not too late, Count, if I dare to ask, then at 10 minutes to eight, I dare to ask. We will form a party, our general will be. He is very kind to me. Let's have dinner, Count. So do me a favor.
Contrary to his habit of being late, Pierre that day, instead of eight minutes to ten minutes, arrived at the Bergs at eight minutes to a quarter.
The Bergs, having stocked up what they needed for the evening, were already ready to receive guests.
In a new, clean, bright office, decorated with busts and pictures and new furniture, Berg sat with his wife. Berg, in a brand new, buttoned uniform, sat next to his wife, explaining to her that it is always possible and should have acquaintances with people who are higher than oneself, because only then can there be a pleasure from making acquaintances. - “If you take something, you can ask for something. Look how I lived from the first ranks (Berg considered his life not as years, but as the highest awards). My comrades are now nothing yet, and I am in the vacancy of a regimental commander, I have the happiness of being your husband (he stood up and kissed Vera’s hand, but on the way to her he turned back the corner of the rolled-up carpet). And how did I acquire all this? The main thing is the ability to choose your acquaintances. It goes without saying that one must be virtuous and careful.”
Berg smiled with the consciousness of his superiority over a weak woman and fell silent, thinking that after all this sweet wife of his was a weak woman who could not comprehend everything that constitutes the dignity of a man - ein Mann zu sein [to be a man]. Vera at the same time also smiled with the consciousness of her superiority over the virtuous, good husband, but who still erroneously, like all men, according to Vera’s concept, understood life. Berg, judging by his wife, considered all women weak and stupid. Vera, judging by her husband alone and spreading this remark, believed that all men attribute intelligence only to themselves, and at the same time they do not understand anything, are proud and selfish.
Berg stood up and, hugging his wife carefully so as not to wrinkle the lace cape for which he had paid dearly, kissed her in the middle of her lips.
“The only thing is that we don’t have children so soon,” he said, out of an unconscious filiation of ideas.
“Yes,” Vera answered, “I don’t want that at all.” We must live for society.
“This is exactly what Princess Yusupova was wearing,” said Berg, with a happy and kind smile, pointing to the cape.
At this time, the arrival of Count Bezukhy was reported. Both spouses looked at each other with a smug smile, each taking credit for the honor of this visit.
“This is what it means to be able to make acquaintances,” thought Berg, this is what it means to be able to hold oneself!
“Just please, when I am entertaining guests,” said Vera, “don’t interrupt me, because I know what to do with everyone, and in what society what should be said.”
Berg smiled too.
“You can’t: sometimes you have to have a man’s conversation with men,” he said.
Pierre was received in a brand new living room, in which it was impossible to sit anywhere without violating the symmetry, cleanliness and order, and therefore it was quite understandable and not strange that Berg generously offered to destroy the symmetry of an armchair or sofa for a dear guest, and apparently being in In this regard, in painful indecision, he proposed a solution to this issue to the choice of the guest. Pierre upset the symmetry by pulling up a chair for himself, and immediately Berg and Vera began the evening, interrupting each other and keeping the guest busy.
Vera, having decided in her mind that Pierre should be occupied with a conversation about the French embassy, immediately began this conversation. Berg, deciding that a man's conversation was also necessary, interrupted his wife's speech, touching on the question of the war with Austria and involuntarily jumped from the general conversation into personal considerations about the proposals that were made to him to participate in the Austrian campaign, and about the reasons why he didn't accept them. Despite the fact that the conversation was very awkward, and that Vera was angry for the interference of the male element, both spouses felt with pleasure that, despite the fact that there was only one guest, the evening had started very well, and that the evening was like two drops of water is like any other evening with conversations, tea and lit candles.
Soon Boris, Berg's old friend, arrived. He treated Berg and Vera with a certain shade of superiority and patronage. The lady and the colonel came for Boris, then the general himself, then the Rostovs, and the evening was absolutely, undoubtedly, like all evenings. Berg and Vera could not hold back a joyful smile at the sight of this movement around the living room, at the sound of this incoherent talking, the rustling of dresses and bows. Everything was like everyone else, the general was especially similar, praising the apartment, patting Berg on the shoulder, and with paternal arbitrariness he ordered the setting up of the Boston table. The general sat down next to Count Ilya Andreich, as if he were the most distinguished of the guests after himself. Old people with old people, young people with young people, the hostess at the tea table, on which there were exactly the same cookies in a silver basket that the Panins had at the evening, everything was exactly the same as the others.

Pierre, as one of the most honored guests, was to sit in Boston with Ilya Andreich, the general and colonel. Pierre had to sit opposite Natasha at the Boston table, and the strange change that had occurred in her since the day of the ball amazed him. Natasha was silent, and not only was she not as good-looking as she was at the ball, but she would have been bad if she had not looked so meek and indifferent to everything.
"What with her?" thought Pierre, looking at her. She sat next to her sister at the tea table and reluctantly, without looking at him, answered something to Boris, who sat down next to her. Having walked away the whole suit and taken five bribes to the satisfaction of his partner, Pierre, who heard the chatter of greetings and the sound of someone’s steps entering the room while collecting bribes, looked at her again.