Collapse refers to the sudden and sharp falling movement of rocks and soil on steep slopes under the action of gravity. 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.
Formation condition
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, carbonate rocks of metamorphic rocks, sedimentary rocks with hard lithology, timely sandstone, glutenite, rocky loess with initial diagenesis, loess with dense structure and so on. Large-scale falling rocks, interbedded rocks such as shale and marl, loose soil layers, etc. are formed. , often mainly shedding and peeling.
2. Geological structure.
Various structural planes, such as joints, cracks, bedding planes, faults, etc. , cutting and separating the slope, providing boundary conditions for the formation of the collapse 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. the terrain.
The bank slopes of rivers, rivers, lakes (banks) and ditches, slopes of various hillsides, railways and highways, slopes of engineering buildings and artificial slopes are all landforms conducive to the formation of collapse. High and steep slopes with a slope greater than 45 degrees, isolated mountain mouths or concave steep slopes are all favorable landforms formed by collapse.
Geotechnical types, geological structures and landforms, also known as geological conditions, are the basic conditions for the formation of collapse.