早白垩纪地层中形成岩溶塌陷,塌陷堆积区上部土层为第四纪正常沉积,下部为陷坑沉积--塌陷堆积。其形成机理是可溶性岩石在酸性地下水的作用下形成溶洞,当溶洞发展至顶板很薄时而塌陷,最后形成塌陷区上部的沉积。由于塌陷区第四纪土层太厚,采用端承桩工程造价高。对于低层建筑物,采用摩擦桩取得满意的效果。 The karst collapse was formed in the Early Cretaceous strata. The upper soil layer in the subsidence accumulation area was normal Quaternary sedimentation, while the lower part was deposition and collapse of the subsidence pits. The formation mechanism is that soluble rocks form caves under the action of acidic groundwater, collapse when the caves develop to a thin roof, and finally form the upper part of the subsidence area. As the Quaternary soil in the subsidence area is too thick, the use of end-bearing pile project cost is high. For low-rise buildings, using friction pile to obtain satisfactory results.