Rational Use Of Soil`s Shear Strength Index In Excavation

This paper first analyzes several important factors affecting the soil’s shear strength parameters in pit engineering, selection of soil in pit side wall before and after pit precipitation and soil of pit after excavation,the direct shear apparatus and three triaxial shear strength test were carried out. According to the test results of soil samples, analysis of influence of precipitation, the excavation of pit,different test methods of shear strength index of soil mass in pit engineering;Then using the finite element software ABAQUS to simulate soil’s and supporting structure of pit’s deformation,which can not be achieved with the traditional theory. Finally, according to the different experimental groups calculate lateral earth pressure by using the calculation formula in the technical specification, using static theory calculate pile length and reinforcement of the retaining structure of pit, then analysis of different test results on the influence of pit retaining structure design.Through the above work to get the safety and stability of foundation engineering in different shear strength index selection.Get the following conclusions:(1)the pit engineering’s design calculation should adequately increase the cohesive force of the test result value which was taken rainfall measures using of pit soil samples tested before rainfall, otherwise it will cause unnecessary economic waste.(2)Shear strength indexes of pit by changing the confining pressure and the conventional used in pit’s design calculation almost get the same result;(3)the shear strength index showed a significant difference between the test and the three axle test,shear strength indexes three axis test value should be selected to design of pit under the premise of the three axis machine.