Please help explain the meaning of several words in the first grade lesson 17. Urgent!

Mountains and peaks: Feng Luan

(1) continuous mountain peaks

Example 1: Mountain peaks fluctuate

Example 2: Overlapping peaks and mountains

(2) Small and sharp mountains

Omen: Hello.

[indicates; Signs before things happen.

Brightness: qιng yíng

[Explanation]: ① Describe the gentle and graceful movements and postures of women: light dance steps | How light it is to get off the bus, floating like plum blossoms. 2 refers to lightness and femininity: why rely on lightness. 3 relaxed and happy: chuckle.

[Synonym]: brisk (at a speed of ~)

[antonym]: heavy (~ panda)

[Proximity]: Light (~ Figure)

She walked lightly onto the stage.

Symmetry: yún chèn

Symmetry: even number; Harmonious proportion. (Excerpted from Modern Chinese Dictionary)

Fold:

[Chinese Pinyin]

[English] collapse; Collapse; Subsidence; Fall down; avalanche

[explanation] collapse

[Other detailed expansion]

First, the definition of collapse

Collapse (also known as caving, collapse or collapse) is a geological phenomenon that the rock and soil mass on the steep slope suddenly falls off the mountain and rolls and accumulates at the foot of the slope (or valley) under the action of gravity. Rock blocks (clods) of different sizes are piled up at the foot of the slope in a cone shape, which is called colluvium, which can also be called rock pile or rockfill pile.

Under the action of gravity, the rocks and soil on the steep slope suddenly fell sharply. Most of them occur on slopes greater than 60 ~ 70. A collapsed substance is called a collapsed body. If the collapse body is soil, it is called soil collapse; If the collapse body is rock, it is called falling rock; Large-scale falling rocks are called landslides. Collapse may occur in any zone, and landslides are limited to mountains and valleys. The separation interface between the collapse body and the slope body is called the collapse surface, and the collapse surface is often an interface with a large dip angle, such as joints, schistosity, cleavage, bedding plane and fracture zone. The movement mode of collapse body is dumping and caving. The debris of the collapse body rolls or jumps in the process of movement, and finally forms the accumulation landform-the rockfall cone at the foot of the slope. The cone structure of rockfill is loose, disordered, non-layered and porous; Due to the air tumbling effect caused by collapse, fine particles move farther, so they have certain sorting ability in the horizontal direction.

Second, the type of collapse.

1. According to the slope material composition.

(1) colluvium: Because of its loose texture, the existing debris and sand on the hillside can collapse again after being soaked in rain or shaken by earthquake.

(2) Surface weathering collapse: When groundwater flows along the bedrock surface at the lower part of the weathered layer, the weathered layer collapses along the bedrock surface.

(3) Sediment collapse: Some steep slopes composed of thick ice, impactor or pyroclastic materials collapse due to loose structure.

(4) Bedrock collapse: It often occurs along the joint plane, ground plane or fault plane on the hillside of bedrock.

2. According to the movement form and speed of the collapsed body.

(1) Collapse: Collapse often occurs on steep slopes where joints or faults develop, or steep slopes where soft and hard rocks alternate, or steep slopes composed of loose sediments.

(2) Sliding-type collapse: Collapse occurs along a certain sliding surface, sometimes the whole shape of the collapsed body is maintained, which is very similar to landslide, but the vertical movement distance is often greater than the horizontal movement distance.

(3) Slump: Loose debris, sand and clay, when wet with water, will cause slump. This collapse is very similar to debris flow. It is called collapse debris flow.

Third, the characteristics of collapse.

High speed (generally 5-200m/s);

Large-scale difference (less than 1m3— 108m3).

After the collapse, the relative positions of various parts of the collapse body are completely disrupted, and the sizes are mixed, forming a rockfill pile where huge stones roll out far away.

4. Internal conditions and external inducing factors of collapse.

1. The internal conditions of the crash are:

(1) Geotechnical type. Rock and soil are the material conditions for collapse. Different types of collapses have different scales. There are usually various types of magmatic rocks (also known as igneous rocks), metamorphic rocks, sedimentary rocks (also known as water rocks) and carbonate rocks (such as limestone and dolomite). ), timely sandstone, glutenite, rocky loess with initial diagenesis, loess with dense structure, etc. Large-scale landslides are formed, and interbedded rocks and loose soil layers such as shale and marl often collapse and fall.

(2) Geological structure. Various structural planes, such as joints, cracks, bedding planes, faults, etc. Cut and separate the slope to provide boundary conditions for the formation of collapse from the body (mountain). The more cracks in the slope develop, the easier it is to collapse. The steep structural plane almost parallel to the extension direction of the slope is the most favorable for the formation of collapse.

(3) topography. The bank slopes of rivers, rivers, lakes (banks) and ditches, as well as slopes of various hillsides, railways and highways, slopes of engineering buildings and artificial slopes, are all landforms that are conducive to collapse. High and steep slopes with a slope greater than 45 degrees, isolated mountain mouths or concave steep slopes are all favorable landforms for collapse.

Geotechnical types, geological structures and landforms, also known as geological conditions, are the basic conditions for the formation of collapse.

2. There are many external factors that induce collapse, mainly including:

Earthquake (1). The earthquake bow l vibrates the slope, destroys the slope balance, and thus induces the slope collapse. Generally, earthquakes with intensity greater than 7 degrees will induce a large number of collapses.

(2) Snow melting and rainfall, especially heavy rain, heavy rain and long-term continuous rainfall, make surface water penetrate into the slope, soften the rock and soil and its weak surface, and generate pore water pressure to induce collapse.

(3) Surface water bodies such as surface scouring and soaking rivers constantly scour the side feet, which can also induce collapse.

(4) Unreasonable human activities, such as digging the toe of the slope, underground mining, reservoir water storage, water discharge and other human activities that change the original equilibrium state of the slope, will induce collapse activities.

There are also some other factors, such as frost heaving and temperature difference between day and night, which can also induce collapse.

Verb (abbreviation of verb) Determination of the boundary of collapse body

The characteristics of the boundary conditions of the collapse body play an important role in the scale of the collapse body. The determination of the collapse boundary is mainly based on the geological structure of the slope.

First of all, it is necessary to find out the extension direction, dip and dip angle, scale and development density of all developed joints, fractures, rock planes and faults in the slope, that is, the development characteristics of structural planes. Usually, the free surface of steep slope or parallel slope extension often forms a boundary on both sides of the collapse body; The bottom boundary of the collapse body is often composed of structural plane or weak zone inclined outside the slope, or it can be formed by cracks in the rock and soil itself.

Secondly, investigate the relationship, combination form, intersection characteristics and penetration between structural planes and whether they can cut or have cut the slope and separate it from the parent body (mountain).

Finally, according to the comprehensive analysis of the investigation results, it is found that those structural planes that cross each other and may or may have cut the slope away from its parent body are the boundary surfaces of the collapse body. Among them, the collapse body surrounded by well-connected structural planes (horizontal or vertical) is the most dangerous.

For example, on June 3 1980, a large area of Yuchihe phosphate mine in Yuan 'an County, Hubei Province collapsed. The boundary surface of the collapse body is composed of vertical cracks at the back, dolomite at the bottom and free surfaces in the other two directions.

For another example, the boundary surface of common loess collapse in the Loess Plateau is mostly composed of vertical joint surface, free surface and the interface of loess and other different lithology at 90 degrees in different directions. In addition, collapse bodies obviously controlled by fault planes are also common.

6. Time law of rock collapse

The time of rock collapse has the following laws:

(1) The rainfall process may be slightly delayed. The rainfall process mentioned here mainly refers to heavy rain, heavy rain and long-term continuous rainfall. This is the time when crashes happen the most.

(2) During a strong earthquake. It mainly refers to the collapse of the epicenter (mountain area) during a strong earthquake of magnitude 6 or above.

(3) During or after the excavation of slope toe. Due to the excavation of the toe of the slope during the construction of the project (or construction site), the stability of the upper rock (soil) is destroyed and often collapses. Some collapses are under construction, and most of them are small collapses. More collapses occurred within a period of time after construction.

(4) The initial stage of reservoir impoundment and the peak period of rivers. At the initial stage of reservoir impoundment or the first peak of reservoir water level, the rock and soil on the reservoir bank are submerged (softened) for the first time, and the upper rock and soil are prone to instability, especially after water withdrawal.

(5) After strong mechanical vibration and large blasting.

Seven: the accumulation landform formed by collapse

1. A large number of stones, debris or soil falling from the collapse are piled up at the foot of steep cliffs or wide foothills, forming a rockfill pile.

2. The shape and scale of rockfill piles are different. The structure is loose, disordered, porous, different in size and not layered.

The shape and scale of rockfill depend on the height and steepness of the collapsed cliff and the slope at the foot of the slope.

Different from the development degree of rockfill piles. The base slope is steep, and it often accumulates into a cone-shaped rockfill pile under the steep cliff; The basement slope is gentle, and it is mostly a relatively open fan-shaped rockfill. Under deep valleys or large faults, due to the wide distribution of collapses, many rockfill piles are connected with each other, forming belt-shaped rockfill piles along the foot of steep cliffs.

Because the rockfill is a kind of dumping rapid accumulation, its structure is loose, messy, porous, different sizes and non-layered.

3. Three stages of the development of rockfill piles:

According to the collapse strength and later weathering and denudation degree, rockfill can be divided into three development stages:

① Develop rockfill piles: steep and fresh fracture surfaces and steep slopes.

(2) The rockfill tends to be stable: the contour is gentle, the rocks are weathered, and it is a concave slope with steep top and gentle bottom, and the surface debris is consolidated to some extent.

③ Stable rockfill: the slope is gentle, concave, compact in structure, partially cemented and covered with vegetation.

Rockfall piles are often encountered in engineering construction in high mountain and canyon areas, especially in road construction. Those unstable rockfill piles are easy to collapse, and the downward thrust is very large, which will cause serious consequences. Therefore, we must fully estimate the possible drastic changes in advance and take various effective measures.

Eight: identification method of collapsed body

The possible collapse is mainly identified according to the topography, geomorphology and geological structure characteristics of the slope. Generally, the possible slopes have the following macroscopic characteristics:

(1) The slope is greater than 45 degrees, and the height difference is large, or the slope is an isolated mountain mouth or a concave steep slope;

(2) The cracks in the slope are developed, especially the steep cracks vertical and parallel to the extension direction of the slope or the cracks along the slope or weak zone. Tension cracks have developed in the upper part of the slope, and the cracks and fissures that cut the slope are about to penetrate, separating it from the parent body (mountain).

(3) There is an open space in front of the slope, or there is a collapse, indicating that there has been a collapse and it may happen again in the future.

The slope with the above characteristics is likely to collapse, especially when the upper tension crack continues to expand and widen, the speed suddenly increases, and a small drop continues to appear, which indicates that collapse is about to happen and is in a state of explosive.

For example, Lianziya dangerous rock mass located on the right bank of Baojianxia exit of the Yangtze River is a famous collapse body. The limestone forming the slope formed a steep wall as high as 100 meters, which was deeply cut by numerous wide cracks, making the Linjiang cliff crumbling. It poses a great threat to the shipping of the Yangtze River. According to historical records, this area has occurred many times in the history of thousands of years, which shows that collapse has multiple characteristics and should be considered when predicting the possibility of collapse.

Nine. Human engineering economic activities may induce collapse.

After the basic conditions of collapse formation are met, the inducing factors become important. The time and intensity of inducing factors are related to collapse. There are many external factors that induce the collapse, among which human engineering economic activities are an important reason.

(1) Mining mineral resources. In the activities of mining mineral resources in China, there are many examples of collapse, both the slope collapse of open pit and the surface collapse caused by goaf formed by underground mining. More common, such as coal mine, iron mine, phosphate mine, gypsum mine, clay mine and so on.

(2) Road engineering excavation slope. When building railways and highways, the excavation slope cuts the soft stratum which inclines outward or gently. When blasting, the slope vibrates strongly, and sometimes the slope is cut too steeply, which may lead to collapse. There are many such examples.

(3) Reservoir impoundment and canal leakage. Here is mainly the infiltration and softening of water, and the hydrostatic pressure and hydrodynamic pressure of water in rock (soil) may lead to collapse.

(4) Pile (abandon) slag filling. If the load, improper slag piling, waste slag and fill are located in the area where collapse may occur, the load of the possible collapse body will be increased, thus destroying the stability of the slope body and possibly inducing the collapse of the slope body.

(5) Strong mechanical vibration. Such as the vibration of trains and locomotives, and the vibration of forging machinery in factories, can all cause induction.

X. engineering measures to prevent and control collapse

Engineering measures to prevent collapse in China mainly include:

(1) occlusion. That is, the landslide covering the upper part of the slope. This measure is often used for the prevention and control of small and medium-sized collapses or artificial slope collapses. Usually, it is widely used in railway engineering by building adits, shed adits and other projects.

(2) interception. For areas where rockfall, spalling and small collapse only occur after rain, intercepting structures can be set at the foot of the slope or on the half slope. For example, set up a rockfall platform and rockfall trough to prevent the accumulation of collapsed objects, and build a stone retaining wall to prevent rockfall; These measures are also widely used in railway engineering, using waste rails, steel bars and steel wires to prepare rails or steel shed.

(3) stop. Build columns, retaining walls or support them with waste railings under boulders with protruding or unstable rocks.

(4) Retaining wall and slope protection. Retaining wall shall be built in the slope area prone to weathering and peeling, and the gentle slope shall be protected by cement. A general slope can be used.

(5) repair the gap. For cracks, joints and cavities in the slope, flaky can be used to fill the cavities and cement mortar cracks to prevent the further development of cracks, joints and cavities.

(6) Brush the edge slope. Brush slope technology is used to slow down the slope with dangerous rocks and boulders protruding at the mountain mouth and the slope in the weathered and broken section of the slope.

(7) Drainage. In areas with water activities, drainage structures are set up for interception and diversion.

Eleven: examples of collapse disasters:

For example, on June 3rd 1980, a huge rock collapse suddenly occurred in Yanchihe Phosphate Mine in Yuan 'an County, Hubei Province. During the landslide, some mountains of Eagle Mouth Cliff at an altitude of 830 meters dive from 700 meters to a valley at an altitude of 500 meters. The covered area of rocks in the valley is 560m long from north to south, 400m wide from east to west, 20m thick in earth and stone, and the collapse accumulation volume is * * *1100,000 cubic meters. The largest rock mass weighs 2700 tons. In an instant, a dam as high as 38 meters was built on the Yanchi River. Form a natural lake. The five-story building in the phosphate rock area was pushed down and buried by rocks. 307 people died. It also destroyed the equipment and property of the mine, and the losses were very heavy.

There are many reasons for the catastrophic collapse of Yanchihe Mountain. In addition to geological basic factors, the exploitation of underground phosphate rock is the most important human factor for the deformation and collapse of the upper model mountain. This is because: the phosphate rock layer exists in the lower part of the collapse body and is exposed at the bottom of the valley slope. The mine adopts room and pillar mining method and comprehensive open stope mining method. 1July, 979, the management method of pillar caving in large blasting room was adopted. Accelerated the deformation process of the upper mountain and the surface. There are ten surface cracks in the upper surface of goaf and collapsed mountain. The parts that produce cracks are all distributed at the junction of goaf and non-goaf. It shows that the formation of surface cracks is directly related to underground mining. Later, the cracks continued to develop, and under the stimulation of rainfall, a serious collapse disaster was finally formed.

After the discovery of mountain cracks, the mine has simply monitored the development of cracks. Although we have some actual data, we don't pay attention to the analysis of monitoring data and pay close attention to the development trend of cracks, so we can't predict them correctly and in time. This is also one of the main lessons that caused this catastrophic collapse.

Man: mí màn

1 full; Everywhere: Shan Ye filled with smog and yellow sand.

② Difficulties: The roads are diffuse.

Logo:

zhēngzhao

Signs revealed in advance; symbol

In a flash:

Word name: instant

Explanation of words: a short time, a moment, a moment. .

After a burst of thunder, it rained cats and dogs in an instant.

Gesture: Gesture: refers to various gestures. (zhétàI wàn qiān)

Impermanence: