广花盆地地面塌陷成因与防治

GENESIS AND PREVENTIVE MEASURE OF SURFACE COLLAPSE IN GUANGHUA BASIN

广花盆地隐伏岩溶发育、上覆第四系砂砾层薄且无稳定的粘性土底板的特殊二元结构是产生地面塌陷的客观条件，地下水活动（以人为抽汲地下水为主）是引起地面塌陷的动力。抽汲地下水降低了地下水位，使上覆土层浮托力减小，水力坡度和流速增大，潜蚀作用加强。此外，抽汲地下水还使地下水紊动并带出大量泥沙，引起地面塌陷。根据广花盆地地面塌陷的成因特点，提出通过控制开采水位降深。

In Guanghua basin the well developed concealed karst, overlying thin Quaternary gravel layer and lack of steady clay footwall are the objective conditions for collapse formation, while artificially, induced groundwater activity is the motive force of collapse. Due to groundwater pumping the water level is lowered, the buoyancy in covering soil is decreased, the hydraulic gradient and flow velocity are increased, and the corrosion is enhanced. All these result in groundwater low turbulence, lots of silt and mud carried away and, eventually, collapse. According to the genetic characteristics of surface collapse, four preventive measures are put forward in the paper.