Study On The Influence Of Deformation Settlement On Building Foundation Caused By The Rising Groundwater Level In Yinchuan City

The water level in the groundwater overdraft area in Yinchuan City has rebounded for many years after water resources management,and the rising groundwater level will cause changes in the mechanical properties of the powder clay layer in the foundation of Yinchuan City,thus triggering such hazards as foundation instability and uneven settlement of buildings and causing adverse effects on the engineering construction in the area.Therefore,it is important to carry out research on the mechanical properties of pulverized clay under rising water table and the effect of ground settlement after rising water table to maintain the normal use of buildings in the area.This paper takes powder clay soil in Yinchuan city as the research object,carries out the onedimensional consolidation compression and wetting test and triaxial wetting test of remodeled powder clay soil under different degree of wetting,explores the change law of compressibility,wetting and strength characteristics of powder clay soil with compaction degree and saturation degree,on the basis of obtaining the above mechanical property index,adopts GEO5 software and carries out finite element modeling combined with actual engineering to explore the influence law of rising groundwater level on the foundation humidification deformation settlement,the main research results of this paper are as follows:1)When the saturation is low,the reduction of the pore ratio of silty clay changes little,and the e-p curve is gentle.When the saturation is high,the e-p curve becomes steeper.For compacted silty clay,the compression modulus of soil gradually decreases with the increase of saturation,and finally tends to be stable.The greater the degree of compaction,the greater the reduction of the compression modulus.With the increase of compactness,the e-p curve flattens out,and the compression modulus increases with the increase of compactness when other conditions are the same.When the saturation is high(Sr=70%,85%),the compression modulus increment increases first and then gradually decreases with the increase of the degree of compaction,while when the saturation is low(Sr=40%,55%),the compression modulus has a positive linear relationship with the degree of compaction.2)At different compaction degrees,the collapse coefficient of silty clay decreases gradually with the increase of saturation,and the decline of the collapse coefficient increases with the increase of saturation.Under different saturation,the subsidence coefficient of silty clay decreases with the increase of compaction degree,and the decrease of subsidence coefficient decreases gradually with the increase of compaction degree.The influence of compaction degree on the subsidence coefficient is higher than that of saturation on the subsidence coefficient.3)Under low confining pressures(100 kPa,200 kPa),the stress-strain curves transition from softening type to hardening type with the increase of saturation,and the softening type becomes more significant with the increase of compaction degree.Under high confining pressures(300 kPa,400 kPa),the stress-strain curves always show a hardening type with the increase of saturation,and the specimens gradually transition from hardening type to softening type with the increase of compaction degree.Under the same compactness conditions,the internal friction angle and cohesion of silty clay shows different degrees of decrease with increasing saturation.Under the same saturation condition,the internal friction angle and cohesion of silty clay always increase with the increase of compactness.4)Based on the numerical simulation analysis,the settlement results calculated by the initial tangent modulus method and the compression modulus method are compared,and the prediction model of the humidification settlement of the foundation with rising water level is given,and the safety evaluation of the existing buildings is carried out.