Karst, also known as karst, is a series of geological phenomena caused by surface water or groundwater dissolving soluble rocks. Such as ditches, caves and underground rivers.

It is a geological phenomenon that surface water and groundwater erode and scour the upper layer, resulting in cavities, cavity enlargement and surface subsidence.

Due to the interaction between karst and soil cave, a series of geological problems that are unfavorable to the project will be produced.

Such as the formation of cavities in rocks and soil; Destruction of rock structure; Sudden collapse of the surface; Groundwater circulation changes, etc. These phenomena have seriously affected the use and safety of construction sites.

The formation of karst is due to the dissolution of rock by water. Therefore, its formation condition is that it must have water-soluble and permeable rocks; At the same time, water flows and erodes in it. In other words, the material basis of karst has two aspects: rock mass and water quality. Water flows in the rock mass.

Karst and soil cave areas have great influence on the stability and safety of buildings.

When arranging buildings (structures), we should first investigate the location of karst and soil caves, and then take corresponding prevention measures according to the actual situation. When the location of the building (structure) can be shifted, in order to reduce the engineering quantity and ensure the safety of the building (structure), we should first try to avoid the threatened karst and soil cave areas, and then consider the treatment plan when it is really impossible to avoid them.

(1) Cut and fill

That is, the soft filler in the cave or soil hole is dug out, backfilled with gravel, stones or concrete, and compacted in layers to improve the foundation. A filter layer is set on the gravel backfilled in the earth cave to prevent the occurrence of undercurrent.

(2) Span cover

When the buried depth of the tunnel is large or the roof of the tunnel is unstable, the scheme of crossing the cover plate can be adopted. For example, long beam foundation, truss foundation or rigid large flat plate are used for crossing. However, the supporting point of beam and slab must be placed on a relatively complete rock or a reliable bearing layer, and attention should be paid to its bearing capacity and stability.

(3) perfusion

For karst caves or soil caves, when it is impossible to treat them by digging, filling and covering, cement or cement combined with mixed grouting can be used in the cracks of karst caves; For soil holes, holes can be drilled at the top of the hole to fill sand or gravel, and attention should be paid to filling and compaction.

(4) Drainage

The activity of water in the cave can dissolve, scour or corrode the wall and roof of the cave, leading to the expansion of cracks and caves or the collapse of the roof of the cave. Therefore, natural rainfall and production water infiltration should be prevented, and drainage measures should be taken to lead water to other places for drainage.

(5) Piling

When the buried depth of soil hole is large, pile foundation treatment can be adopted, such as concrete pile, wooden pile, sand pile or blasting pile. Its purpose is not only to improve the bearing capacity, but also to change the seepage conditions of groundwater by squeezing the soil layer with piles.

Karst and earth caves can be used to develop tourism, geological scientific investigation and treat diseases.

Rest and sleep in the cave can cure diseases. Speaking of caves, people often think of dark and humid scenes, but these caves full of hard rocks are a "natural sanatorium". The cave environment not only helps to treat some diseases, but also provides the best steam room for the spa service popular with women.

As a natural product, it is also a geological disaster, which should be rationally utilized and prevented.

Hey, I'm so tired. I finally finished. Let's see how it goes, shall we?