考虑桩体刺入变形的透水混凝土桩复合地基固结理论研究

Theoretical study of consolidation of composite ground with permeable concrete piles considering pile penetration deformation

现有的多元复合地基利用两种或者两种以上的桩型对地基土进行加固,以期提高地基承载力、加速地基固结。提出了一种兼具散体材料桩和刚性不排水桩自身优点的透水混凝土桩复合地基固结模型。工程中刚性桩与土体的压缩量并不相等,这与等应变条件存在着不一致的地方。为此,抛弃传统等应变假设,考虑桩体向垫层和下卧层的刺入变形,对传统等应变假定进行修正,同时考虑了扰动区土体水平渗透系数的抛物线变化和水在桩体内的径向、竖向渗流,给出了此类固结问题的控制方程和解答以及复合地基固结度的表达式,并对复合地基固结度的解进行了讨论。最后与其他复合地基解做了比较并对固结性状进行了分析,并针对透水混凝土桩孔隙引起的桩阻作用对地基固结速度的影响进行了验证。

The existing multivariate composite foundation uses two or more kinds of piles to strengthen the foundation soil in order to improve the bearing capacity and accelerate the consolidation of the foundation.In this paper,a consolidation model of permeable concrete pile composite foundation,which has the advantages of both bulk material pile and rigid undrained pile,is proposed.In the practical project,the compression amount of rigid pile and soil is not equal,which is inconsistent with the equal strain condition.For this reason,this work abandons the traditional equal strain hypothesis,considers the amount of penetration of the pile to the cushion and underlying layer,and modifies the traditional equal strain hypothesis.At the same time,the parabolic change of horizontal permeability coefficient of soil in disturbed area and the blocking effect of fine particles on water seepage in permeable concrete pile are considered.Besides,the governing equation and solution of this kind of consolidation problem and the expression of consolidation degree of composite foundation are given.The solution of consolidation degree of composite foundation is also discussed.Finally,the solution of this work is compared with other composite foundation solutions,the consolidation behavior is analyzed,and the influence of pile resistance caused by pores of permeable concrete pile on the consolidation velocity of foundation is verified.