考虑指数渗流的砂井地基弹黏塑性固结分析

ELASTO-VISCOPLASTIC CONSOLIDATION ANALYSIS OF GROUND WITH SAND DRAINS CONSIDERING EXPONENTIAL FLOW

为深入探究饱和黏土地区砂井地基的固结机制,在Barron自由应变假定下,引入考虑时间效应的统一硬化(unified hardening,UH)模型描述土骨架的变形非线性关系,同时引入指数渗流方程代替Darcy定律,并考虑渗透系数变化及涂抹效应的影响,研究了土体非线性、施工扰动及外载荷等因素对砂井地基非线性固结过程的影响规律。结果表明:由于土体的黏滞效应,在加载前期,砂井地基不排水边界附近孔压出现升高现象,且考虑非Darcy渗流时上述现象更加明显,砂井地基固结速率也愈加缓慢。此外,涂抹区渗透系数的减小显著降低了砂井地基整体孔压消散速率,而外载荷的增大却加快了地基的固结进程。

For the deep investigation of the consolidation mechanism of sand well foundation in saturated clay region,this paper introduces the unified hardening model considering the time effect to describe the deformation nonlinear relationship of the soil skeleton under the assumption of Barron's free strain,meanwhile,the exponential seepage equation is introduced instead of Darcy's law,and the influences of permeability coefficient change and smearing effect are taken into account,the influence laws of soil nonlinearity,construction disturbance and external loading on the nonlinear consolidation process of sand well foundation are investigated.The results show that the viscous effect of soil causes the increase of pore pressure near the undrained boundary of the sand-drained ground in the early stage of loading.The non-Darcy characteristic of flow makes this phenomenon more obvious,and also significantly delays the consolidation rate of the sand-drained ground.In addition,the decrease of permeability coefficient in the smear zone can significantly reduce the dissipation rate of the overall pore pressure of sand-drained ground,while increasing the external load accelerates the consolidation process of the foundation.