非线性桩-土作用对车桥耦合振动的影响研究
STUDY ON INFLUENCE OF SOIL-PILE NONLINEAR INTERACTION ON VEHICLE-BRIDGE COUPLING VIBRATION
-
摘要: 该文基于文克尔地基梁理论,利用修正的P-Y曲线法和荷载传递双曲线法,建立了桩-土非线性作用模型。采用了桩和土相对刚度来计算水平方向桩-土相互作用的初始刚度。通过Mohr-Coulomb法则得到土的极限抗力,并结合Matlock P-Y曲线法对极限抗力的表达式进行了修正,从而充分考虑了土的极限抗力的深度效应。编制了桩-土非线性梁单元有限元程序,建立了考虑非线性桩-土相互作用的车桥耦合模型。结合工程实例,分析了非线性桩-土相互作用的桥梁模型对车桥耦合响应的影响,并与墩底固结模型进行了对比。结果表明:在车桥耦合振动过程中,考虑非线性的桩-土相互作用,桥梁的横向位移幅值显著增大,竖向位移幅值增大,桥梁加速度幅值降低。此结果对处于软弱基础的高速铁路桥梁的分析和设计提供了参数和依据。Abstract: Based on the beam on a Winkler foundation, a modified P-Y curve method and a load-transfer hyperbolic model are used to build the model of nonlinear pile-soil interactions. The relative stiffness of the pile and soil is adopted to calculate the horizontal initial stiffness of pile-soil interactions. The ultimate soil resistance is obtained by Mohr-Coulomb failure criterion. According to Matlock P-Y curve method, the expression of the ultimate soil resistance is improved, thusly the depth effect of the ultimate soil resistance is fully considered. The pile-soil nonlinear finite-beam element analysis program is compiled on the basis of these models. The vehicle-bridge coupling model considering nonlinear pile-soil interactions is built and applied to determine the behavior of a bridge in practice. The vehicle-bridge coupling vibration considering nonlinear pile-soil interactions is analyzed and compared with previous pier bottom consolidation models. The results show that the horizontal displacements of the bridge considering the nonlinearity of pile-soil interactions increase significantly in the process of a coupled vibration between a high speed railway bridge and a vehicle. The vertical displacements of the bridge increase. The accelerations of the bridge reduce. These results provide the parameters to the design of a high speed railway bridge located in soft ground with a high-pile cap foundation.