Experimental study of pore pressure model of soft clay with different consolidation degrees under subway loading

The underlying soil possesses the nature of variation in consolidation degree before subway operation, which will result in the change of pore pressure as well as the differential settlement. Hangzhou saturated soft clay is tested by dynamic triaxial test system to find the effect of consolidation degree, consolidated stress and cyclic stress ratio on the development of pore pressure. A new pore water pressure model considering the initial consolidation degree and the threshold cyclic stress ratio is proposed on the basis of existing research findings. The results show that under cyclic loadings, the development of pore pressure undergoes higher regularity than that of shear strain. The higher the consolidation degree is, the slower the pore pressure increases. Furthermore, the pore pressure will be stabilized at a lower level with the increment of cyclic times. Taking pore pressure delaying into consideration will lead to more desirable results while predicting the pore pressure and long-term settlement of the tunnel. The obtained pore pressure model can well simulate the pore pressure development under subway loadings.