顶管施工中土体损失引起的沉降预测

Prediction of settlement induced by ground loss during pipe jacking construction

顶管施工过程中不可避免地会产生土体损失,进而引起地面沉降。对前人工作进行总结,提出一个可以计算土体中任一点沉降的通用经验公式。假定土体不排水,考虑土体泊松比以及采用椭圆形非等量径向土体移动模式,对Sagaseta公式进行了修正。算例分析表明,在开挖面后方较远处,修正Sagaseta公式与Peck公式和Loganathan公式的计算结果较吻合。修正Sagaseta公式与累积概率曲线的变形规律一致,开挖面上方地面沉降量都为最大地面沉降量的一半,但累积概率曲线的影响范围小、收敛速度快;该方法也适用于盾构法施工。

Ground loss is inevitably produced during pipe jgekiag construction; and ground settlement is brought consequently. Based on the previous study, general empirical formula to calculate settlement at any point is advanced. Assuming soil is not drained, the Sagaseta formula is modified by considering the Poisson＇s ratio of soil and adopting oval-shaped ground deformation pattern around tunnel section. It is shown in analytical calculation that, for the spot far from the rear of excavation face, the calculation results using the modified Sagaseta formula is quite accordant with that of the Peck formula and the Loganathan formula. The calculated deformation rule using the modified Sagaseta formula is accordant with that of the accumulated probability curves, Both ground settlement above the excavation face are half of the maximal ground settlement; but the accumulated probability curves own smaller effecting range and quicker convergence speed. These calculation methods also apply to shield construction,