基于蠕变本构的列车荷载下地基长期沉降计算
Long-term settlement of foundation subjected to moving train loads based on creep constitutive model
-
摘要: 推导了一种列车动荷载下基于蠕变本构方程的长期沉降计算方法。首先根据列车通过轨道时引起激振力,利用半无限空间Mindlin解求出轨道正下方任一点的列车移动荷载引起的动应力,其次采用波尔兹曼线性叠加原理和积分原理推导出动应力蠕变本构方程,然后将列车移动荷载引起的动应力代入动应力蠕变积分方程,推导出列车动荷载蠕变应力-应变积分方程,最后结合分层总和法计算出列车运行引起的长期沉降。并采用数值模拟和实测数据对本算法进行有效性验证,结果表明:推导的用于计算列车运行引起的长期沉降的半解析法计算结果与实测数据比较吻合,此半解析法忽略了间接作用轮对的影响,其计算结果相比于数值模拟结果偏小,但间接作用轮对长期沉降的影响很小,在工程上可以忽略不计。Abstract: A procedure for calculating the long-term settlement of foundation subjected to moving train loads is proposed on the basis of the creep constitutive model. The excited force associated with the moving train is converted to dynamic stresses on the infinite half-space by using the Mindlin solution. The creep constitutive equations are derived based on the Boltzmann principle of linear superposition, and the integral formation of the equations is then deduced. The long-term settlement of foundation can be calculated by using the proposed equations and the layer-wise summation method. The procedure is verified by the simulation and measured data. The results show that the predicted long-term settlement by the proposed method is in good agreement with the test data. The proposed method simplifies the moving train load, but the effect on predicting the long-term settlement is negligible.