大直径深埋顶管施工对地表沉降的影响

Influence of large diameter deep buried pipe jacking construction on surface settlement

顶管施工因非开挖或少开挖而在城市建设中应用广泛,但顶管施工引起的地表沉降不容忽视。依托佛山市某电力隧道顶管工程,通过现场实测、数值模拟及Peck经验公式的方法研究了顶管施工引起的地表沉降规律,探讨了管-土摩擦、注浆压力及支护压力对地表沉降的影响。结果表明:顶管施工引起的横向地表沉降在距轴线约4倍管径范围内变化较大,管-土摩擦的改变对横向地表距轴线约3倍管径范围内的地表沉降影响较大,对纵向地表距开挖面约1倍管径范围内的地表沉降影响较小;注浆压力的增大能够抑制地表沉降;支护压力的改变对横向地表距轴线约2倍管径范围内的地表沉降影响较大。研究结果可为控制顶管施工引起地表沉降措施的制定提供参考;同时,实测值、模拟值及Peck经验公式所得到的地表沉降变化趋势和大小相近,验证了数值模拟及Peck经验公式在实际工程中预测地表沉降的可行性。

Pipe jacking construction is widely used in urban construction due to non-excavation or less excavation,but the surface settlement caused by pipe jacking construction cannot be ignored.Relying on a pipe jacking project of a power tunnel in Foshan City,the law of surface settlement caused by pipe jacking construction was studied through field measurements,numerical simulations and Peck empirical formulas,and the effects of pipe-soil friction,grouting pressure and supporting pressure on the ground settlement were discussed.The results show that the lateral surface settlement caused by pipe jacking construction changes greatly within the range of approximately four pipe diameters from the axis,and the change in pipe-soil friction has a greater impact on the surface settlement within the range of approximately three pipe diameters from the axis.It has little effect on the surface settlement within the range of approximately one pipe diameter from the longitudinal ground surface to the excavation surface;the increase in grouting pressure can restrain the settlement of the surface.The surface settlement has a greater impact,and the research results can provide references for measures to control surface settlement caused by pipe jacking construction.At the same time,the measured value,simulated value and Peck's empirical formula have similar ground settlement trends and magnitudes,verifying the feasibility of numerical simulation and Peck's empirical formula in predicting surface settlement in actual projects.