Study On The Test Error And Pore Pressure Influence Of Soil Dynamic Parameters

As one of the natural disasters, the damage caused by the earthquake is huge. In the study of soil dynamics, as the medium of seismic wave propagation and structural foundation, the dynamic performance of soil mass directly affects the safety of the structure, and the estimation of its dynamic parameters directly affects the cost of the project. Therefore, the study of soil dynamic parameters has important theoretical significance and engineering application value.In this paper, a single resonant column device was used to research the dynamic shear modulus ratio and experimental error problem of damping ratio. The differences and relations between the test and dispersion of different modulus ratio and damping ratio were analyzed. The purpose is to provide a basis for understanding the current level of the resonance column test and improving the technique of resonant column test, and to provide the basis for the seismic probability analysis of the engineering structure. Besides, in this paper, a new type of high precision dynamic three axis instrument was used to study the change of maximum shear modulus and ultimate shear stress with the change of pore water pressure. The more realistic formula for calculating the maximum shear modulus and ultimate shear stress was given. The calculation formula of the maximum shear modulus and ultimate shear stress with the increase of pore pressure is verified, and the basis for dynamic analysis of soil liquefaction reaction under consideration is provided.The main works of this paper are as follows:(1)Through the resonance column test data, two kinds of representative test group were designed to study the test error of the ratio of dynamic shear modulus and damping ratio of sand, clay and silt. What’s more, the distribution pattern and the basic law of the test error of the two test groups were given. The differences and relations between the test and dispersion of different modulus ratio and damping ratio were analyzed.(2)Based on the background of KiK-net network, two representative soil seismic response analysis methods both at home and aboard SHAKE2000 and LSSRLI-1 were studyed. According to the comparison results, select the appropriate calculation program for the analysis of the soil layer response. At the same time, it provides the necessary clues for the improvement of the seismic response analysis method of the soil layer.(3)For different types of venues,the effects of the dynamic shear modulus ratio and damping ratio of sand, clay and silt on the ground motion of two test groups were analyzed by using the selected soil response analysis program.(4)A new type of high precision dynamic three axis instrument was used to study the change of maximum shear modulus and ultimate shear stress with the change of pore water pressure. The more realistic formula for calculating the maximum shear modulus and ultimate shear stress was given. And the variation of maximum shear modulus and ultimate shear stress with pore water pressure were studied under different consolidation ratios.(5)The correction formula of the maximum dynamic shear modulus and ultimate shear stress in the growth of pore pressure proposed in this paper was applied to the effective stress analysis program. Besides, the calculated results of the effective stress analysis method were compared with the actual seismic record, which verifies the reliability of the effective stress analysis program of the improved soil layer seismic response.