富水软弱地层顶管施工土体扰动影响试验研究

Experimental Study on Soil Disturbance Effects Induced by Pipe Jacking in Soft and Water-rich Strata

  • 摘要: 为研究富水软弱地层中顶管施工扰动特性及参数设计问题,基于自主设计的模型试验系统,对顶管顶进过程中顶力、土体压力及地表竖向位移的变化规律进行分析。结果表明:顶力变化过程经历初始、过渡和稳定三个阶段,其变化速率受顶进速度与注浆压力的共同影响,较高的顶进速度有助于减缓顶力衰减,适当提高注浆压力可降低顶力并抑制其波动,但在高速顶进条件下难以有效控制土体扰动。土体压力在顶进过程中波动显著,其峰值位置随顶进速度增加向顶进方向推移,较大的注浆压力可降低压力峰值并缩短其出现距离。地表竖向位移主要表现为中轴线附近隆起,影响范围约为中轴线两侧约4倍顶管宽度的区域;注浆压力的增加显著抑制地表位移,而较高的顶进速度则导致更大的沉降,存在注浆压力与顶进速度的最优匹配值,使土体扰动程度降至最低。

     

    Abstract: To investigate the disturbance behavior and parameter design of pipe jacking in soft and water-rich strata, a series of physical model tests was conducted using a self-developed testing system. The variations in jacking force, soil pressure, and surface vertical displacement during the jacking process were analyzed. The results show that the evolution of jacking force consists of three stages: the initial stage, the transition stage, and the stable stage. Its variation rate is jointly influenced by jacking velocity and grouting pressure. A higher jacking velocity helps mitigate the decay of jacking force, whereas a moderate increase in grouting pressure can reduce the force magnitude and suppress fluctuations. However, under high jacking velocity, the mitigation of soil disturbance becomes limited. Soil pressure exhibits pronounced fluctuations, with the peak position shifting forward along the jacking direction as the jacking velocity increases. A higher grouting pressure can lower the peak magnitude and reduce the distance to its occurrence. Surface vertical displacement is primarily characterized by uplift near the centerline, with an affected range extending to approximately four times the pipe width on each side. Increasing grouting pressure significantly restrains surface displacement, while excessive jacking velocity exacerbates surface settlement. Moreover, there exists an optimal matching relationship between jacking velocity and grouting pressure that minimizes soil disturbance.

     

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