Study On Leakage And Improvement Method Of Waterproof Structure In Silty Layer

As the excavation is constructed in a deep silty layer with a high hydraulic conductivity,it is an economic way to construct a suspended waterproof by using cement mixing soil to prevent the groundwater seepage.However,due to construction depth,construction quality,and complex engineering-geological conditions,it is easy to cause local failure and the vulnerable spot(point,liner or area)of waterproof if its strength is not competent.Therefore,it is of great engineering significance to evaluate the seepage stability of the suspended waterproof during the process of excavation construction and to discuss engineering improvement measurement.In this thesis,combining with a practical project,lab tests,theoretical analysis and numerical simulation,the seepage prevention effect of suspended waterproof are investigated.The main research contents and achievements are as follows:(1)The physical mechanics and microstructure of solidified silt are investigated.This thesis analyzes the strength characteristics,deformation modulus,hydraulic conductivity and microstructure development of cement-silty solidified with different admixtures(cement,phosphogypsum,bentonite)and different mixing proportion,different curing age.Meanwhile,the strength development of solidified-silty under different variates is investigsted,aming to obtain the physical and mechanical parameters of solidified soil,and apply the parameters as improvement measurement.(2)The seepage prevention effect of suspended waterproof is investigated.Basing on the threedimensional seepage theory of groundwater and combining with numerical simulation,it discusses the effct of suspended waterproof with different variates,such as insertion ratio,dewatering depth and soil parameters.Furthermore,the assessment of suspended waterproof with local failure and the vulnerable spot(point,liner or area)is investigated.(3)The surrounding environment casused by waterproof leakage and improvement measurement of suspended waterproof are studied.Based on the field measurement data and finite element numerical simulation of excavation steps,the variation law of the ground settlement and the horizontal displacement of suspended waterproof that has leakage points,leakage area and its different location of suspended waterproof during excavation are analyzed.The results show that the leakage of the suspended waterproof has a serious threat to the safety of the excavation.Furthermore,the results of test parameters are used as an improvement measurement to evaluate the effect of advanced suspended waterproof.The results show that the measurement has a significant anti-seepage effect and an economic prospect of engineering application.