振冲碎石桩复合地基的等效渗透系数计算方法

振冲碎石桩法是水利工程常用的地基加固方法,其加固形成的复合地基涉及到桩体及其桩间土等多种材料及扰动挤密作用影响等,渗流特性复杂。对此,结合某水电站工程实际,依据振冲碎石桩布置及复合地基桩体和桩间土的特性和面积比例,考虑扰动挤密作用对渗透特性的影响,提出了振冲碎石桩复合地基的等效渗透系数计算方法,从渗透流量和位势分布等渗流要素,并采用三维有限元法,计算比较了真实模型(实际参数)、复合地基模型(等效渗透系数)两种模型坝体和坝基的渗流场。结果表明,采用复合地基等效渗透系数计算的坝体和坝基渗流场基本符合精细模拟振冲碎石桩时计算的渗流场,可见该方法合理、有效,可用于类似工程渗流场的计算分析。

Calculation Method of Equivalent Permeability Coefficient for Vibroflotation Gravel Pile Composite Foundation

Vibroflotation gravel pile has been widely used to reinforce the dam foundation, resulting in the complicated seepage condition involved multiple materials and interaction between the piles and foundation. However, engineering design needs a simple and efficiency method to calculate the seepage characteristics of composite foundation. Considering the effect of vibration and compaction, this paper proposed an equivalent calculation method of permeability coefficient based on the distribution and area ratio of vibroflotation gravel pile and foundation. This method was used to simulate the seepage field of a hydropower station using three-dimensional finite element method. The seepage flow volume and field results indicated the correctness and effectiveness of the method, and it basically coincided with the fine model. This equivalent calculation method can be apply in seepage analysis of the similar project.