A deep foundation pit in a soft soil region was discussed in this article. Its geological features include the sand flow and karst,which is actually the hidden karst region formed by covering the Ordovician limestone erosion surface directly with the fine sand. This foundation pit has adopted a variety of pit wall for the supporting method,such as row of piles and diaphragm wall,as well as the inner support combined with the three- axis mixing pile anti-water curtain. During the excavation process,an accident happened in the form of sand boiling in the pit bottom and also the ground collapse outside. According to the site geological conditions,surrounding environment,supporting structure and construction situation,combined with the geological data of excavation monitoring and scan result from the detection radar,this paper first analyzed the reasons of the accident,then proposed a method to relieve the danger by the method of anti-pressure with filter sand in the pit and external pressure grouting outside. Finally,this paper provide some recommendations to similar projects about survey and construction.
Journal of Water Resources Architectural Engineering
deep foundation pit
leaking stoppage under pressure
deep pit monitoring