临近基坑条形浅基础地基承载力减损的下限估算
Lower-bound solution for bearing capacity of strip footings near excavations
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摘要: 利用极限分析有限元方法和下限定理,分析计算了考虑土体自重的临近基坑(边坡)条形浅基础c-?土地基极限承载力下限解。作为一种简化手段,分别按土的粘聚力、基础埋深(超载)和土的自重这3项承载力影响系数表达临近基坑地基极限承载力,获得了基础位置、基坑开挖的边坡角度以及土的内摩擦角取不同值时,相应的地基承载力系数下限解答,并对计算结果进行了讨论。最后将计算结果与已有文献资料以及利用多滑块Prandtl破坏模式得到的极限分析上限解答进行了分析对比,从上、下限给出了临近基坑既有建筑物地基承载力系数取值范围及其承载力上、下限平均值时的减损因数,分析了影响计算结果的因素。Abstract: The lower-bound solution for bearing capacities of existing strip footings locat on the top of excavated slope was obtained by using finite elements and linear programming.As accepted in other proposals,the estimate of the limit load near an excavation was obtained herein respectively from the cohesion,the footing depth(overburden) and the soil weight.The results with various footing locations,slope angles and internal friction angles were given in terms of the bearing capacity coefficients,and their characteristics were discussed.Furthermore,the results were compared to those from the reference and the upper-bound solutions by using multi-blocks of Prandtl’s collapse mechanism.Finally,the reduction factors were calculated according to the average values between lower and upper bound.The possible influences on the solution of the present method were also discussed.