基于无限元边界的土-桥墩数值模型适用性研究

Applicability Study of Soil-pier Numerical Model Based on Infinite Element Boundary

为有效分析土-结构动力相互作用(SSI效应)对高墩桥梁地震响应的影响,采用有限元与无限元相结合的方式,建立了基于无限元边界的土-桥墩数值模型。通过对参考边界、截断边界及无限元边界3种模型边界条件下的位移、等效应力、加速度响应结果对比分析,验证无限元边界数值模型的有效性;在此基础上,进一步分析在SSI效应影响下,墩高对桥墩地震响应的影响规律。研究表明:无限元边界模型与参考边界模型的数值模拟结果较为接近,而截断边界模型与参考边界模型的数值模拟结果偏差较大,其中,参考边界模型的加速度峰值约为截断边界模型的1/3倍,因此无限元边界模型较截断边界模型精度高、适用性更好;当桥墩高度为9 m以上时,SSI效应对高墩地震响应的影响更加明显。

To effectively analyze the influence of soil-structure dynamic interaction(SSI effect)on seismic response of high pier bridges,a numerical model of soil-pier interaction based on infinite element boundary was established by combining finite element method with infinite element method.Based on the comparison and analysis of displacement,equivalent stress and acceleration response under three boundary conditions of reference boundary,truncated boundary and infinite element boundary,the validity of infinite element boundary numerical model was verified.On this basis,the influence law of pier height on pier seismic response under the influence of SSI effect was further analyzed.The results show that the numerical simulation results of the infinite element boundary model and the reference boundary model are close,but the numerical simulation results of the truncated boundary model and the reference boundary model are quite different.The peak acceleration of the truncated boundary model is about one third of that of the reference boundary model,so the accuracy and applicability of the infinite element boundary model are higher than that of the truncated boundary model.When the pier height is above 9 m,the influence of SSI effect on the seismic response of high piers is more obvious.