放坡开挖基坑变形及对邻近桥梁桩基影响模拟分析

Simulation Analysis of the Foundation Pit Deformation by Grading Excavation and Its Influence on the Pile Foundation of Adjacent Bridges

以成都市简州新城电力隧道二期一阶段朝阳路电力隧道工程为背景,针对放坡开挖基坑的稳定性及对周围桥梁桩基变形影响开展研究。结果表明:放坡开挖基坑水平变形主要集中在基坑两侧坡顶处,土体距基坑中心越远隆起量越小,基坑变形均在合理控制范围内。桥梁桩基整体位移形态为距离基坑较近一侧向上隆起,整体呈现倾斜状态。桩基与基坑间距越大,桩基位移响应就越小,土方开挖后应力释放产生的影响就越薄弱。土方开挖所产生的地应力影响范围约15 m,建议基坑施工过程中,应充分利用时空效应原理,分区、分层开挖,以减小应力释放对桩基产生的变形影响。

Based on the power tunnel project of Chaoyang Road in the second phase of the power tunnel in Jianzhou New City of Chengdu,this paper conducts a study on the stability of the foundation pit by grading excavation and its influence on the deformation of the surrounding bridge pile foundation.The results show that the horizontal deformation of grading excavation pit is mainly located at the top of the slope on both sides of the foundation pit.The farther the soil is from the center of the pit,the smaller the amount of the soil uplift is,and the deformation of the pit is within a reasonable control range.The overall displacement pattern of the bridge pile foundation is in the form of upward uplift on the side closer to the foundation pit,and the whole pile foundation shows the inclined state.The larger the distance between the pile foundation and the foundation pit,the smaller the displacement response of the pile foundation,and the weaker the influence produced by the stress release after excavation.The influence range of the ground stress generated by excavation is about 15 m.It is suggested that the foundation pit should make full use of the principle of the time-space effect and be excavated in separate zones and layers during the construction of the foundation pit so as to reduce the influence produced by stress release on the deformation of the pile foundation.