新建道路下穿高铁桥梁对桥墩稳定性影响的数值模拟研究

Numerical simulation of the influence of new road underpassing high-speed railway bridge on pier stability

针对新建道路下穿高铁桥梁施工过程及运营过程(桩板式路基结构施工、路面施工以及交通荷载作用)对既有高铁桥梁桥墩稳定性以及安全性的影响进行了数值模拟研究,结果表明,新建道路施工以及运营过程对既有桥梁桥墩顶部产生的位移均满足规范中限值的要求,这说明规范化的道路施工过程对既有高铁桥梁安全性的影响较小。新建道路施工过程以及运营过程中,桥墩桩基础桩身轴力增量随着桩基础埋置深度的增加呈现先增大后减小的趋势,在距离桩顶0.65~0.75倍桩长处轴力增量出现最大值。桩板式路基结构施工和交通荷载作用时,不同桩基础桩侧摩阻力随着桩基础埋置深度的增加先减小后增大。桩板式路基结构施工阶段在距离桩顶0.50~0.70倍桩长处摩阻力由负值变为正值;交通荷载作用下在距离桩顶0.65~0.75倍桩长处摩阻力由负值变为正值。路面施工对不同位置桩基桩侧摩阻力的影响较小,并且路面施过程中桩基础不会受到负摩阻力。

A numerical simulation research is conducted on the influence of the construction process and the application process(pile slab subgrade construction,pavement construction and traffic load)of the new built road on the stability and safety of the existing high-speed railway bridge piers.The results show that the top displacement of the existing bridge piers during the construction and operation of the new road meets the requirements of the standard limit,which means the standardized road construction process has little impact on the safety of the existing high-speed railway bridges.During the construction and operation of period,the increment of axial force in pile foundation of bridge piers increases first and then decreases with the depth of the pile foundation.The maximum axial force increment is approached at the 0.65-0.75 times of the pile length from the pile top.During sheet pile construction and traffic loading,the pile shaft resistance of different pile foundations decreases first and then increases with the embedded depth.During the construction of sheet piles,the pile shaft resistance changes from negative to positive at the 0.50-0.70 times of the pile length from the top.Under traffic loading,the pile shaft resistance changes from negative to positive at the 0.65-0.75 times of the pile length from the top.Pavement construction has little effect on the pile friction,and causes little negative friction for pile foundation.