按地基允许变形确定既有建筑地基承载力的试验方法

An Experimental Test Method of Determining the Foundation Bearing Capacity of Existing Buildings through Allowable Subsoil Deformation

通过持载的荷载试验确定既有建筑的地基承载力,地基允许变形是其控制标准。实际工程中通过荷载试验确定的地基承载力特征值所对应的沉降值与实际基础沉降值会因荷载板尺寸效应和空间效应出现差异。本文通过大比尺室内模型试验,结合实例分析荷载试验沉降值与实际基础沉降值之间的比例关系。在实际工程确定既有建筑地基承载力时,是在建筑物旁相同性质的土体上做持载7d的荷载试验,将持载7d的试验沉降值与实例计算的基础最终沉降值对比分析,结合既有建筑增层改造前对建筑物允许变形的鉴定评价以及规范规定的地基允许变形值,通过一定的比例关系将实际基础沉降允许值转换为试验沉降允许值,根据试验沉降允许值的范围,选择合适的允许变形指标确定既有建筑的地基承载力。

The foundation bearing capacity of existing buildings should be determined through load test,the allowable subsoil deformation is the control standard.The settlement of load test is different from that of practical foundation because of size effect and space effect of loading plate.The proportional relation between load test settlement and practical foundation settlement combined with instance is analyzed through large scale indoor model test.The seven days sustained load test is done on the soil of same nature near the buildings when determining the foundation soil bearing capacity of existing buildings in practical engineering,the settlement of seven days sustained load test and the settlement of instance analysis are compared and analyzed.The practical foundation settlement can be changed into load test settlement through certain proportion relationship combined with evaluation of buildings' allowable deformation before story-adding reconstruction on the existing buildings and allowable subsoil deformation ruled by the code,then the appropriate allow deformation index can be chosen to determine the foundation soil bearing capacity of existing buildings through the range of load test allowable deformation.