Study on Key Technologies for the Treatment of Deep and Large Foundation Pits with Complex Geology of Overlying Deep Silt and Underlying Karst Caves
High-rise buildings are widely built in China,and it is extremely difficult to deal with deep and large foundation pits in the complex geological environment of overlying deep silt and underlying karst caves.In this paper,the combined treatment technology of vacuum composite precipitation and pile foundation was proposed.Then,the influence of vacuum composite precipitation pumping time on pumping water volume was studied through field experiments;the finite element modeling of the rock-socketed pile construction process of karst foundation was conducted to determine the safe thickness of the roof of the karst cave,and the influence of karst cave size parameters on the load bearing capacity of the pile was analyzed.The results show that:(1)with the increase of pumping time,the pumping volume increases,and the vacuum composite precipitation efficiency is much greater than that of the atmospheric precipitation of tube wells;(2)with the increase of the thickness of the roof of the karst cave,the safety factor increases and the vertical displacement of the pile foundation decreases,and the safe thickness of the roof of the karst cave should be greater than 1.505 times the pile diameter;(3)with the increase of the diameter of the karst cave,the vertical displacement of the pile foundation also increases,while the height of the karst cave has little effect on the vertical displacement of the pile foundation.
deep siltkarst cavedeep and large foundation pitcombined treatment technologynumerical analysis
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