低矮路堤下膨胀土地基渗流与变形耦合研究

Analysis of coupled seepage and deformation of expansive soil foundation under low embankment

二维渗流与变形耦合控制方程是基于流体质量守恒、Darcy定律及膨胀土弹性本构方程得出的。结合云桂高速铁路低矮路堤下膨胀土地基现场浸水试验,并采用考虑耦合和不考虑耦合两种数值模拟方法,分析了低矮路堤下膨胀土地基的膨胀变形特性。研究结果表明,耦合情况下地基表面膨胀变形呈双曲线变化,非耦合情况下地基表面膨胀变形随时间的增加而逐渐增大,对同一时间而言,未考虑耦合效应数值模拟得到的膨胀变形落后于考虑耦合影响的膨胀变形;耦合与非耦合情况下地基的相对膨胀率沿深度方向呈衰减变化。数值计算结果与现场试验结果比较表明,不考虑耦合影响的数值模拟方法难以描述人工浸水条件下膨胀土地基的膨胀变形规律,而考虑耦合影响的数值模拟方法与现场实测值吻合较好。

Based on the mass conservation of fluid, Darcy law and elastic constitutive equation of expansive soil, two-dimensional equations of coupled seepage and deformation in expansive soil are obtained. Combined with the field soaking test on expansive soil foundation under low embankment of Yun-Gui high-speed railway, then both the numerical simulation considering coupling and that without considering coupling are used to analyze the swelling deformation characteristics of expansive soil foundation under low embankment. The study results indicate that the swelling deformation of ground surface can be fitted with hyperbola in the coupled case, but it increases gradually with time in the uncoupled case. The swelling deformation obtained from the numerical simulation which did not consider coupling is less than that obtained from the numerical simulation considering coupling at the same time. The relative expansion ratio decreases along the depth of foundation in the coupled and uncoupled case. In addition, the numerical calculated values are compared with test results in field. It is pointed out that the numerical simulation without considering the effects of coupling is difficult to describe the swelling deformation of expansive soil foundation under the artificial soaking condition. On the other hand, the results from the numerical simulation considering the impacts of coupling agree well with the measured results.