顶管施工引起的土体垂直变形计算方法研究

对前人工作进行总结，将3个已有的经验公式合并成一个通用经验公式，该公式可以计算由土体损失引起的土体中任一点沉降。假定土体不排水，利用弹性力学的Mindlin解推导了顶管正面附加推力、掘进机和后续管道与土体之间的摩擦力引起的土体垂直变形计算公式。结合土体损失引起的土体变形计算公式，得到顶管施工引起的总的土体垂直变形计算公式，该方法适用于施工阶段。算例分析表明，正面附加推力引起开挖面前方地面隆起，后方地面沉降，以开挖面正上方为轴线呈反对称分布，在正常施工时产生的地面变形较小；掘进机和后续管道与土体之间的摩擦力引起的地面变形分布规律与正面附加推力相似，轴线分别位于掘进机中间部位和后续管道中间部位的正上方。

Study on calculating methods of soil vertical deformation induced by pipe jacking construction

Based on the previous study, general empirical formula to calculate settlement at any point is advanced by combining three existing empirical formulae. Assuming soil is not drained, the computing formulas of soil vertical deformation induced both by bulkhead additive thrust, force of friction between shield and soil, and force of friction between follow-up pipes and soil are derived from the Mindlin solution in elastic mechanics. Combining the formula of ground deformation induced by ground loss, the formula of total soil vertical deformation induced by pipe jacking construction is obtained. This method can be applied to the construction phase. As is shown in analytical calculation, bulkhead additive thrust will make the frontal soil of excavation face heave and the rear soil subside. Surface deformation induced by bulkhead additive thrust is small during normal construction; and the curves are anti-symmetry with~ axes of excavation face. For the surface deformation induced by force of friction between shield and soil and induced by force of friction between follow-up pipes and soil, both of their curve distributions are similar to that of bulkhead additive thrust with the axes at the middle of shield and at the middle of follow-up pipes respectively.