砼芯水泥土桩复合地基工作性状研究

Research on working behavior of concrete-cored DCM pile composite foundation

考虑地基土体分层以及砼芯和深层水泥土搅拌桩(DCM桩)长度不同的情况,提出刚性基础下砼芯水泥土桩复合地基工作性状的迭代分析方法,并将该法所得沉降计算结果与实测结果进行比较,验证该方法的可靠性;随后采用所提方法分析含芯率、芯长比、面积置换率以及荷载水平等因素对复合地基桩土应力比和沉降的影响。研究结果表明:含芯率、芯长比、面积置换率以及荷载水平均会对复合地基的工作性状产生较大影响,且含芯率、芯长比与桩土应力比呈正相关,面积置换率、荷载水平与桩土应力比呈负相关;在复合地基各部分的沉降中,纯水泥土桩段压缩所造成的沉降量占比较高,且受芯长比、面积置换率以及荷载水平的影响较大。

A settlement calculation method was proposed for concrete-cored deep cement mixing(DCM)pile composite foundation based on rigid foundation,and the relative length of core concrete pile and cemented soil column,the layered soils around the concrete-cored DCM pile were considered in the algorithm.Then,the reliability of the proposed calculation method was demonstrated by comparing the calculated load-displacement of concrete-cored DCM pile composite foundation with the measured results of a field test.The proposed method was then used to analyze the influencing factors such as the area ratio of core concrete pile and cemented soil column,the length ratio of core concrete pile and cemented soil column,area replacement ratio and load level from rigid foundation on the pile-soil stress ratio and settlement of composite foundation.The results show that all influencing factors mentioned above have significant influences on the load transfer mechanism of composite foundation.The pile-soil stress ratio increases with the increase of the area ratio of core concrete pile and cemented soil column,while decreases with the increase of area replacement ratio and the load from rigid foundation.The elastic shortening of the pure cemented soil pile section accounts for the majority in the entire elastic shortening of concrete-cored DCM pile,and it is significantly affected by the length ratio of core concrete pile and cemented soil column,area replacement ratio and the load from rigid foundation.