基底宽度对承载力系数N_γ的影响分析  

Effect of base width on bearing capacity factor N_γ

作　　者：杜佐龙[1,2] 黄茂松[1,2] 秦会来[1,2] 

机构地区：[1]同济大学岩土及地下工程教育部重点实验室,上海200092 [2]同济大学地下建筑与工程系,上海200092

出　　处：《岩土工程学报》2010年第3期408-414,共7页Chinese Journal of Geotechnical Engineering

基　　金：国家杰出青年科学基金项目(50825803)

摘　　要：在地基极限承载力计算中,基底宽度对极限承载力产生重要影响。在通用的条形基础承载力计算公式中,Nc和Nq已有真解,此两项与基底宽度无关;而Nγ目前还没有准确的统一解,因此基底宽度对极限承载力的影响就转化为其对Nγ的影响。基于Mohr-Coulomb准则,对不同基底粗糙程度和不同剪胀角情况下的基底宽度对γ–c–φ土地基Nγ的影响进行了弹塑性有限元分析,计算结果与经典的极限平衡法和极限分析法以及多块体上限解的对比证明了本文方法的合理性和有效性。分析结果表明:相比于粗糙基础,基底宽度对光滑基础的Nγ影响更大;相比于关联流动法则,考虑非关联流动法则时基底宽度对Nγ影响更大,剪胀角越小,影响越大。In the analysis of the ultimate bearing capacity of foundation,the base width plays a very important role.In a general formula of a centrally and vertically loaded strip base,Nc and Nq have accurate values which are not affected by the base width;while Nγ does not have a true uniform solution.Therefore,the effect of base width on bearing capacity is converted to that on Nγ.Based on the Mohr-Coulomb theory,the effect of B on Nγ of γ-c-φ soil with different surface roughnesses and different dilation angles is analyzed by the elasto-plastic finite element method.Excellent agreement is obtained by the comparison among the finite element method and the classical limit equilibrium methods,limit analyses,multi-block upper bound method.The results show that the base width has more remarkable effect on Nγ under smooth base than that under rough base.The effect is much more remarkable when the non-associated flow rule is considered,particularly with the little dilation angle.

关 键 词：刚性条形基础 地基极限承载力系数 基底宽度 基底粗糙程度 剪胀角 

分 类 号：TU432[建筑科学—岩土工程]