基于Hansbo渗流的理想砂井地基固结分析  

Consolidation of ground with ideal sand drains based on Hansbo's flow

作　　者：刘忠玉[1] 焦阳[1,2] 

机构地区：[1]郑州大学土木工程学院,河南郑州450001 [2]郑州大学综合设计研究院有限公司,河南郑州450002

出　　处：《岩土工程学报》2015年第5期792-801,共10页Chinese Journal of Geotechnical Engineering

基　　金：河南省教育厅自然科学研究计划项目(2010B560015)

摘　　要：室内试验和现场观测表明,许多饱和黏性土中的渗流在小水力梯度时不能用Darcy定律描述,这应该是导致基于Darcy渗流的传统砂井固结理论有时不能很好地解释某些砂井地基固结特性的原因。引入同时考虑低速渗流幂函数曲线段和较高速渗流直线段的Hansbo渗流方程描述非Darcy渗流,在自由竖向应变假定下修正了Barron的理想砂井地基固结方程,并给出了有限差分法数值求解格式。据此探讨了Hansbo渗流参数、地基厚度等对砂井地基固结进程的影响。计算结果表明:和Darcy渗流相比,Hansbo渗流延缓了砂井地基内的孔压消散速度,导致固结速度变慢,并且径向排水对孔压消散的作用会更显著。如将Hansbo渗流方程简化为幂函数形式,则往往会高估砂井地基的固结程度,特别是在固结的初期。最后对比了自由竖向应变假定和等竖向应变假定对计算结果的影响。A deviation of the pore water flow from the Darcian law is observed at small hydraulic gradients according to laboratory and field investigations on some saturated cohesive soils, which can account for that there are aspects of consolidation behaviour of ground with vertical drain system that cannot sometimes be explained on the basis of these conventional consolidation theories using the Darcian flow. In order to improve the computational accuracy of consolidation of vertical drains, the Hansbo's equation, described by the power function for lower seepage velocity and the linear function for higher seepage velocity, is introduced to describe the non-Darcian flow. Accordingly, the Barron's consolidation theory for clayey ground with vertical ideal sand drains is modified under the assumption that the vertical strains develop freely, and the numerical analysis is performed using the finite difference method. Then the effects of the parameters of Hansbo's flow and the ground thickness on the consolidation process of ground with vertical drains are investigated. The numerical results indicate that, compared with that of the Darcian flow, the behaviour of Hansbo's flow controls the dissipation of pore water pressure in clay ground, and thereby reduces the settlement rate of ground. In addition, the influence of radial drainage considering the Hansbo's flow has more influence on the dissipation of pore water pressure than that considering the Darcian flow. If the Hansbo's equation is simplified as the power function to describe the flow, the degree of consolidation of ground will be overestimated, especially in the preliminary stage of consolidation. Finally, the difference as regards the degree of consolidation obtained by assuming the equal strain theory or by assuming the free strain theory is investigated.

关 键 词：理想砂井 固结 Hansbo渗流 有限差分 固结度 

分 类 号：TU472[建筑科学—结构工程]