New method to compensate for membrane compliance in dynamic triaxial liquefaction tests on gravelly soils

The membrane compliance has a significant effect on the results of the triaxial liquefaction tests. The compensation method is one of the primary means to eliminate the impact of the membrane. The theoretical defects of the existing compensation methods are analyzed and verified in the comparison tests, and the new principle and method for the compensation of membrane compliance are proposed. Based on the large-scale dynamic triaxial liquefaction tests on the gravelly soils with various gravel contents and the measurement of membrane penetration volume, the feasibility and reliability of the new compensation method are verified by taking the modified pore pressure model, which can consider the membrane compliance as a reference. The research shows that the existing compensation principle will lead to inadequate compensation, which only uses the rebound water volume caused by the dynamic force as the total water supplement volume, and the new compensation principle is more scientific and reasonable, considering the effect of membrane distributary. In the dynamic triaxial liquefaction tests with different gravel contents and stresses, the results of the new method are consistent with the theoretical ones, and the variation law is uniform. Compared with the existing compensation method, the new method does not need repeated water replenishment and multiple approximations at a single compensation stage, and its operability is enhanced, and the compensation effect is superior. It is suitable for the dynamic triaxial liquefaction tests on gravelly soils and provides a new technical support for the dynamic characteristics tests on coarse-grained soils.