上覆高速桥梁对下穿顶管施工的力学响应

Mechanical Response of Overlying High-speed Bridge Subjected to Underlying Pipe-jacking Construction

以典型实例为背景,分析顶管掘进过程力学扰动机制,借助有限元软件建立顶管施工过程的三维精细计算模型,并通过理论分析验证其可靠性,而后揭示桥梁结构对顶管开挖的力学响应特征。研究表明,顶管通过监控点2倍的管径后,该位置地表沉降约完成总沉降量的75%。顶管施工力学扰动主要经历初始平衡、开挖扰动及注浆稳定三个阶段;顶管施工地表沉降满足Peck沉降槽分布,数值与理论计算规律吻合,说明三维模型具备合理性;顶管施工引起的桥梁结构附加变形与应力均远小于控制值,顶管实施方案总体可行,然而既有桥梁结构处于局部带裂缝状态,需加强施工监控。

Taking a practical example as the background, this paper analyzes the mechanical disturbance mechanism. The three-dimensional fine calculation model of pipe-jacking construction process is established with the help of the finite element software. Its reliability is verified through the theoretical analysis, and then the mechanical response characteristics of the bridge structure to the pipe-jacking excavation are revealed.The results show that the ground surface settlement at this position is about 75% of the total settlement after the pipe jacking goes through twice the diameter of monitoring point. The mechanical disturbance caused by the pipe-jacking construction mainly undergoes three stages of initial stress balance, excavation disturbance and grouting stability. The ground surface settlement caused by pipe-jacking construction satisfies the distribution of Peck settlement tank, and the numerical value is identical with the theoretical calculation rule.Therefore, the 3 D model is rational. The additional deformation and stress of bridge structure caused by the pipe-jacking construction are far less than the control values. The pipe-jacking implementation scheme is overall feasible. But the existing bridge structure is in the local fracture state. It is necessary to strengthen the construction monitoring.