Study On Water Buoyancy Reduction And Drainage Decompression And Floating Resistance Of Underground Foundation Structures

Correct understanding of the buoyancy of underground structures and reasonable selection of anti-buoyancy measures are one of the important issues for vigorous development of underground space.The research shows that the existing anti-floating design is still conservative in calculating the buoyancy of clay foundation by Archimedes law,which increases the investment of anti-floating and causes waste of resources.At the same time,the existing anti-floating measures are uneconomical,difficult to construct and poor corrosion resistance.It is urgent to explore new anti-floating measures to promote the development of underground space.In this paper,the theory,experiment and numerical calculation of water buoyancy in clay foundation and drainage and decompression method in anti-floating measures are studied comprehensively.The main research contents and innovative achievements are as follows:Firstly,a simple and efficient experiment is designed.Through the stress analysis of the foundation model,the magnitude of water buoyancy in clay and its relationship with time are measured by the dichotomy method in mathematics.The experimental results show that the reduction coefficient of water buoyancy in saturated compact clay increases with time and finally stabilizes to a coefficient of 0.82.A pore pressure gauge is embedded in saturated compact clay,and the pore pressure gradually increases and finally stabilizes to 0.8 times the theoretical value by changing the water pressure step by step.Through the comparison of two experiments and the application of effective force principle,it is concluded that the fundamental reason for the reduction of water buoyancy in clay is that compact clay has a reduction effect on pore pressure.The anti-floating calculation of underground structures can bring considerable economic benefits by reducing the water buoyancy in clay under the condition of ensuring the anti-floating safety of underground structures.Then,the mechanism of drainage decompression and anti-floating is deeply analyzed and discussed.A model experiment of drainage decompression is designed,and various working conditions are analyzed,and the anti-floating effect of drainage decompression method is explored.Finally,based on the seepage theory of saturated soil and unsaturated soil,the finite element software is used to model and analyze the seepage.Under the action of variable groundwater level,the anti-floating design parameters and key points of a project are optimized and determined through seepage analysis and calculation under various working conditions.This paper studies the calculation of water buoyancy in saturated clay and the anti-floating effect of drainage decompression and anti-floating method,which has certain theoretical value and reference significance for the anti-floating design of underground structures.