深埋曲线钢顶管受力特性现场监测试验研究

为了研究深埋曲线钢顶管施工过程中的力学特性,依托拱北隧道曲线顶管管幕工程,对曲线顶管管节轴向与环向应变进行了现场监测分析。实测数据结果表明,管节应变随顶进距离增大而略微增加,但基本保持在一定范围内。管节在顶进过程中应力曲线发生波动,停止顶进后逐渐趋于平稳。管节轴向应力主要受顶进力影响,而环向应力主要取决管节外侧环向荷载,曲线顶管管节弯曲内侧存在压应力集中。由于存在泊松效应,大埋深条件下管节顶部和底部轴向应力受环向变形控制。随着与机头距离增加,管节由轴向两侧受压逐渐转变为单侧受压,受压区位于管节弯曲内侧,应力集中更加显著。

Site monitoring of mechanical characteristics of pipes during steel curved pipe jacking under large buried depth

In order to study the mechanical characteristics of pipes during steel curved pipe jacking under large buried depth, the axial strain and hoop strain of curved pipe jacking are monitored and analyzed through site tests, based on the curved pipe jacking roof of Gongbei tunnel. The results show that the strain of pipe slightly increases with the increase of jacking distance, and maintains a certain range. The stress curve of pipe fluctuates in the process of jacking, but gradually restores stability after jacking stoppage. The axial stress of pipe is mainly affected by the jacking force, and the hoop stress mainly depends on the ring load out of pipe. Pressure stress concentration is located inside the pipe jacking curve. Under large buried depth, the axial stresses of pipe top and bottom are controlled by the circumference deformation because of Poisson effect. With the increasing distance between the pipe and the jacking machine head, the mechanical characteristics of pipe change from axial compression at both sides to one-side compression. The compression occurs inside the pipe bending with more obvious stress concentration.