格林函数表象积分对打桩排水的计算

在动力作用下饱和桩周土排水会对基桩工程性质产生很大影响，研究桩-土动力作用的排水计算很有必要。通过连续介质力学方法，利用两相饱和介质Biot动力方程固相与流相频域格林函数解答，结合排水状态Lamb表象积分，得到集中力作用下饱和土圆柱基桩排水量计算公式。按该公式计算了江苏省金坛市开发区联合中策橡胶项目基地在打桩施工中基桩的理论排水量，并与现场实测排水量对比，发现计算与实际测试的排水量相对误差较小，实际工程桩测试的平均每击排水量期望值为4.82 L，与计算排水量相对误差为34%。可以认为，该方法用于动力作用下饱和土基桩排水计算是合适的。但由于计算是在桩-土弹性系统的假定下进行的，没有考虑土的非线性变形影响，有待于进一步研究，使其更加符合实际。

Computation for drainage of pile driving via integral representation of Green functions

Usually water drainage in saturated sandy soil site occurs when a shock takes place. A similar phenomenon happens in pile driving and in vibroflotation for ground treatment. However, at present the simulation of water drainage cannot be performed in the context of conventional soil dynamics. Based on the Green functions in the frequency domain in the axisymmetric coordinates for a poroelastic medium, combining Lamb integral representation in drainage condition, equations for drainage of piles in saturated soils are performed. This paper reveals the comparative results of computational drainage and measured drainage at a project site in Jintan city, Jiangsu province, where some piles are driven. The expected value of average measured drainage is 4.82 L. The relative error between measured and computed drainages is 34%. Hence, the proposed method for drainage of pile in saturated soil is suitable in the view of conventional dynamic soil mechanics. And it may benefit further research on dynamic property of a pile driving in the saturated soil. The computation is under the pile-soil elastic system, without considering the nonlinear deformation of soil. So it needs further study to make it more realistic.