（重庆市建筑科学研究院， 重庆 400015）

［摘要］分析了岩石单轴抗压强度折减法确定地基承载力特征值时存在的问题，通过对大量的原位平板岩基载荷试验与同条件岩石单轴抗压强度试验工程案例进行对比分析，讨论了围压约束效应对岩基承载力的影响。结果表明，考虑围压约束效应影响时，地基承载力可提高1-5～2-8倍；砂岩的围压约束效应较泥岩高；具有95%保证率时，砂岩的围压效应系数为1-7，泥岩为1-5。根据统计分析结果，提出了重庆地区的基于围压约束效应影响的岩石单轴抗压强度折减法确定的地基承载力特征值计算公式，该公式计算的地基承载力特征值较《建筑地基基础设计规范》(GB 50007—2011)计算式的结果有大幅提高且有足够的安全储备，经济效益明显。

［关键词］围压约束效应； 单轴抗压强度； 原位载荷试验； 软岩地基； 承载力特征值

中图分类号：TU318， TU391文献标识码：A文章编号：1002-848X(2017)09-0090-04

Experiment study on bearing capacity of soft rock foundation in Chongqing area

Li Chengfang, Chen Kui, Xiong Qidong, Zhong Wei

(Chongqing Institute of Building Research, Chongqing 400015, China)

Abstract:The problem for determining the characteristic value of  bearing capacity of the rock foundation using the rock uniaxial compressive strength reduction method was analyzed. Influence of confining pressure effect on the bearing capacity of the rock foundation was discussed through a large number comparative analyses on engineering cases of in-situ slab rock foundation loading tests and uniaxial compressive strength tests on rock with the same conditions. The results show that foundation bearing capacity can be increased by 1-5 to 2-8 times considering the influence of confining pressure effect. Confining pressure effect of sandstone is higher than that of mudstone. Confining pressure effect of sandstone is 1-7 and confining pressure effect of mudstone is 1-5 with a 95% guarantee rate. According to the results of statistical analysis, the calculation formula of foundation bearing capacity determined by the uniaxial compressive strength reduction method of the rock based on confining pressure effect in Chongqing area was presented. The calculated characteristic value of bearing capacity of foundation by the formula is significantly higher than that of the Code for design of building foundation (GB 50007—2011) and this formula has sufficient safety reserves with obvious economic benefits.

Keywords:confining pressure effect; uniaxial compressive strength; in-situ loading test; soft rock foundation; characteristic value of bearing capacity

*重庆市自然科学基金项目（CSTC,2010BB7334）。

作者简介：李成芳，博士，教授级高级工程师，一级注册结构工程师，Email: LCF9133@163.com。