任意干湿路径下非饱和土的水力耦合本构模型

HYDRO-MECHANICAL COUPLING CONSTITUTIVE MODEL OF UNSATURATED SOILS WITH ARBITRARY DRYING-WETTING PATHS

大量试验表明饱和土样经历脱湿过程进入吸湿阶段后,在高饱和度区域,残余气体会以封闭气泡的形式分布在土样孔隙中,此时土样呈现较大的压缩性,当吸湿过程结束基质吸力再为0 kPa时,土样并不会达到完全饱和状态。韦昌富等(2008)提出的非饱和土的本构模型没有考虑残余含气量的影响,认为土样在吸湿过程后仍能达到完全饱和状态,这与实际情况有一定偏差。为了更精确地模拟真实情况,基于考虑不同残余含气量的毛细滞回内变量理论和忽视残余含气量影响的非饱和土的水力耦合本构模型,提出了考虑不同残余含气量影响的非饱和土的修正本构模型。通过和实测数据的比较,修正模型可以较好地模拟任意干湿路径下的非饱和土力学特性。

A large number of tests have shown that after the saturated soil sample enters the hygroscopic stage in the dehumidification process, residual gas would be distributed in the pore of the soil sample in the form of closed bubbles in the high-saturation area. At this time, the soil sample shows great compressibility. When the matric suction is 0 kPa after the hygroscopic process, the soil sample would not reach full saturation state. Wei et al.(2008)put forward the constitutive model of unsaturated soil without considering the influence of the residual gas content, and considering the soil sample after moisture absorption process could still achieve fully saturated state, which has certain deviation with the actual situation. In order to simulate the real situation more accurately, this paper proposes a modified constitutive model for unsaturated soils with different residual gas contents. The modified model is based on the theory of capillary hysteresis internal variables and the hydraulic coupling constitutive model for unsaturated soils. The modified model is verified with the measured data and can well simulate the influence of any wet and dry path on the mechanical properties of unsaturated soil.