降水对CFG桩复合地基沉降影响的研究  

Study on CFG Pile Composite Foundation Settlement Induced by Dewatering

作　　者：魏焕卫[1] 陈念琛 邱玉[1] 

机构地区：[1]山东建筑大学土木工程学院,济南250101

出　　处：《地下空间与工程学报》2013年第S1期1758-1761,1782,共5页Chinese Journal of Underground Space and Engineering

基　　金：山东省自然科学基金(ZR2012EEM016);山东建筑大学博士基金(XNBS1206)

摘　　要：针对基坑降水引起的周边建筑物的沉降计算中的难点问题,通过分析降水前后的应力变化,并结合实测资料,给出了降水对CFG桩复合地基影响的计算方法。基坑降水引起的土体中自重应力增量在水位降幅范围内呈三角形分布,在降水后的水位以下呈矩形分布。土体中自重应力的增量首先使得CFG桩复合地基的桩间土发生沉降,由于CFG桩的刚度要远远大于桩间土的刚度,进而造成上部结构的荷载边全部或者部分转移至CFG桩上面.CFG复合地基的沉降为桩端土层自重应力的增加引起的沉降S1和桩顶荷载的增加引起的沉降S2之和。根据计算范围内的应力增量按照规范中的分层总和法计算CFG桩桩端沉降S1,通过等效基底附加压力增量的方式计算由于CFG桩桩顶荷载引起的沉降S2。通过工程实测与理论的对比分析,表明该计算半经验半理论计算方法具有一定的合理性。It is a difficult problem to accurately calculate the settlement of surrounding buildings induced by pit dewatering. Combined with the measured data,the stress variation analysis before and after pit dewatering is carried out,then the calculation method of CFG pile composite foundation settlement caused by pit dewatering is given. The distributions of soil self-gravity stress increment induced by pit dewatering were a triangular under the water level drop,while those were a rectangular under the water level drop. The self-gravity stress increment firstly caused the settlement of soil between CFG piles. Because the CFG pile stiffness is much larger than that of the soil,the upper structure load were transferred to the CFG piles. The settlement of CFG pile composite foundation can be divided into two parts,including the pile tip settlement S1 induced by soil self-gravity stress increment at the pile tip,and the pile top settlement S2 caused by the increment of the pile top load. The pile tip settlement S1 can be obtained with the layer-summation method in the code,and the pile top settlement S2 can be given by equivalent additional stress at the foundation bottom. The comparison between theoretical result and measured data shows that the semi-empirical calculation method is reasonable.

关 键 词：基坑降水 自重应力 CFG桩 复合地基 沉降 

分 类 号：TU473.1[建筑科学—结构工程]