In the process of groundwater exploitation, the decrease of groundwater head causes the dissipation of pore water pressure, and the decrease part of pore water pressure will be transformed directly into effective stress, and the pore volume of soil will decrease continuously, resulting in the compression deformation of soil. This process can be summarized as follows:
Groundwater level drop-pore water pressure decrease-effective stress increase-soil compression deformation.
Because of the local variation of aquifer thickness, such as the abrupt change of the surface morphology of bedrock or the obvious difference of the thickness distribution of compressed soil, the differential compaction settlement of loose soil is caused. Tensile stress concentration in the area with the greatest difference in surface compaction settlement may lead to cracking and deformation. In urban areas located on the plain, subsidence basins are often produced by large-scale concentrated exploitation of groundwater. The outer margin of the basin is a tension stress zone, and a compressive stress zone is formed in the center of the basin. The tension and compression stress zone is formed between the two regions. The concentration of tensile stress will lead to the cracking and deformation of soil layer along the direction of tension. As a result, ground fissures often occur At the outer edge of the subsidence basin.
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