Deep Excavation The Numerical Simulation And Experimental Study

Based on the reviews of current research state for soil behaviors and deepexcavation,this dissertation valuates the characteristics and the application range ofsome common supportinng systems for deep excavation. The law of the active and passive soil pressure coefficient of Rankine and Coulomb varying with internal frictionangle and cohesion of soil is discussed.It is considered that the active and passive soilpressure are the limit state pressure and can not be keep for a long time in practicalearth,the coefficient of soil pressure at rest is suggested for calculationg the earthpressure behind the retaining wall when the excavation is deeper and bake a long time.The grey system theory is used to analyze the dependence between retaining wall S flexion and excavation area,depth of cut,thickness of retaining wass and otherfactors.The results shows that the wall's thickness and the period of time excavationtaken are the most importantfactors effect the the retaining wall's flexion.The concrete'screeping,shrinkage,the law of elastic modular growing with its age and rheologiccharacteristics of soft clay are studied.A nonlinear elastic-visco elastic constitutive modelfor concrete and visco elastic-visco plastic constitutive model for soft clay are established.A FEM program which can be used to both supporting system design and rheologicresearch is developed.As a example Yong Yin tower deep excavation project is caculatedfor design and two dimensional rheologic analyzed simulating practical work situation bythis program.The results are compared with the data obtained by site measurement.It isshoen that the horizontal flexion of retaining wall grows with the depth of cut and growsquickly when the depth of excavation is about to reach the final excavation level.The maximum point of wall's flexion is always near the excavation level.About thirtypercent of concrtet braceing pole s strain is creeping and shrinkage.Temperature has notable effect upon the concrtet braceing pole s axial force,but the vaule of effect isdiffcult to detemine.The distribution of braceing force is influenced by the cut program.The effect area of excavation is about two times of the depth of cut and the maximumpoint of earth's settlement bhind the wall is located 0.7 time of excavation depth from thewall.the maximum of settlement is about 0.7 time of excavation depth.The maximumof upheaval is 1.34 percent is l.34 percent of the excavation depth.The plastic zone lies mainly at theexcavation level and the earth's surface.