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对于低路堤公路,合理地预测车辆荷载引起的地基塑性累积变形对于低路堤公路的设计有着重要的意义。从机制上讲,可将地基的塑性应变分为塑性体积应变和塑性剪切应变。其中对于塑性体积应变,提出采用不排水条件下的残余孔压模型与一维固结理论相耦合进行计算;对于塑性剪切应变,考虑了塑性体积应变引起的土体硬化,提出了修正的塑性剪切应变计算模型。然后基于所提模型,对萧山黏土的不排水与排水条件下的动三轴试验进行模拟,初步验证了所提模型的有效性。对于实际工程问题,首先运用数值的方法求得车辆荷载在地基中引起的附加应力,然后运用所提模型计算各土层的塑性应变,再结合分层总和的方法求得地基的累积塑性变形。以日本佐贺机场1号测点为例,说明了模型在工程边值问题中的有效性。
For low embankment highways, it is very important for the low-embankment highway to reasonably predict the plastic deformation of the foundation caused by vehicle load. Mechanically speaking, the plastic deformation of foundation can be divided into plastic volume strain and plastic shear strain. For the plastic volumetric strain, the model of residual pore pressure under undrained condition is proposed to be coupled with the one-dimensional consolidation theory. For the plastic shear strain, the soil hardening caused by plastic volumetric strain is considered and the modified plasticity Shear strain calculation model. Based on the proposed model, the dynamic and triaxial tests of Xiaoshan clay under undrained and drained conditions are simulated, and the validity of the proposed model is verified. For practical engineering problems, numerical stress method is used to calculate the additional stress caused by the vehicle load in the foundation. Then, the plastic strain of each soil layer is calculated by using the proposed model. The cumulative plastic deformation of the foundation is obtained by combining the stratified summation method. Taking the test point No.1 of Japan’s Saga Airport as an example, the validity of the model in the engineering boundary value problem is illustrated.