水平定向钻扩孔施工地表变形计算分析

Computational analysis of ground deformation caused by reaming in horizontal directional drilling

部分城市地下工程的管道埋深较浅(属半无限空间土体),上覆土压力较小,使用水平定向钻进行扩孔施工时常处于过压状态,易导致地表隆起变形,地面冒浆等情况发生。基于圆孔扩张理论和镜像法,推导出半无限空间土体下采用水平定向钻扩孔施工时地表位移的解析解,并以西安地铁十号线某穿越工程为例进行验证计算。结果表明:实测值与理论值变化趋势相一致,且平均误差仅为7%;增大扩孔级数、黏聚力和内摩擦角可以减小地表变形;强度理论效应对地表变形计算的影响不容忽视,计算时应根据土质选取合适的强度准则,避免使用D-P1和D-P3准则。分析结果可为水平定向钻技术的工程应用提供一定的理论技术参考。

The buried depth of pipelines in some urban underground projects is shallow(belonging to semi-infinite space soil),and the overlying soil pressure is small.Therefore,the horizontal directional drilling used in reaming construction is often in an over-pressure state,and can easily lead to surface uplift deformation and ground slurry.Based on the theory of circular cavity expansion and the mirror method,the analytical solution of surface displacement during the construction of horizontal directional drilling in semi-infinite space soil was derived,and a crossing project of Xi′an Metro Line 10 was taken as an example for verification calculation.The results showed that the measured values were consistent with the theoretical values,and the average error was only 7%.Increasing the number of reaming stages,cohesion and internal friction angle could reduce surface deformation.The effect of strength theory cannot be ignored,appropriate strength criterion should be selected according to the soil,and the D-P1 and D-P3 criteria should be avoided.The analysis results can provide some theoretical support and technical reference for the engineering application of horizontal directional drilling technology.