Experimental study on the dynamic pore pressure model of frozen-thawed soft clay for different degree of consolidation under dynamic loading

Abstract:

When freezing method is used in connecting passage in the subway, the structural of soft soil will be weaker because of freezing and thawing.And in the permafrost melting process, dissipation rate of pore water is so slower that leads to the soil has initial consolidation in the early subway operation,and then causing differential settlement by the long-term subway loading.In this paper, regarding the freezing temperature and the initial consolidation of the soil as influence factors.Through the dynamic triaxial test ,study the regular pattern of pore water pressure under subway cyclic loading . According experimental data, the established a model of dynamic pore pressure accumulation experimental which considers the freezing temperature and the initial consolidation . Study has shown that: freezing and thawing action will change the internal particle connection and pore structure of soil, and the dynamic pore water pressure accumulation rate of frozen-thawed soil becomes faster under cyclic loading; the lower the freezing temperature, the pore pressure of frozen-thawed soil develops faster with higher times of vibration , and the larger stable pore pressure value is in final; the initial consolidation of thawing soil has a greater impact on the pore water pressure, the higher the initial consolidation means the slower the development of pore water pressure and the smaller stable value;the coupling effect of freezing at low temperature and low initial degree of consolidation exacerbates accumulation of pore pressure of frozen-thawed soil , and it further soften the structure of soil.