临坡条形基础极限承载力上限计算
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摘要
利用极限分析中的机动法,构建临近边坡条形基础承受极限承载力的二维机动许可破坏模式.根据外力功率与内部耗能相等获得极限承载力的目标表达式,并把其转化成了一个求含有非线性约束的极限承载力上限解最小值问题计算模型.通过编制和调用计算程序,对建立的计算模型采用序列二次规划法(SQP)进行了优化求解.研究结果表明:边坡倾斜程度δ和岩土体内摩擦角φ对临坡条形基础地基承载力影响较大;边坡坡角δ的增加将使地基破坏区域发生显著变化,使各分项系数Nγ,Nc,Nq迅速减小;而内摩擦角φ增加对Nγ、Nc、Nq的影响则相反.
The bearing capacity of a near strip footing under action of ultimate bearing capacity problem was studied by means of the kinematical approach of limit analysis theory.And the planar knematically admissible failure mechanism was constructed elaborately for the calculation schemes.The objective functions of bearing capacity were obtained by equating the work rate of external force to internal dissipation along the velocity discontinuities,and then the objective functions were transformed as a upper-bound mathematic optimization model for bearing capacity as low as possible.The result of upper bound method for planar failure mechanism was obtained by use of the sequential quadratic programming(SQP).From the numerical results,it can be seen that the dip angle of slope(δ) and internal friction angle(φ) of foundation have significant effects on the bearing capacity factor(Nγ,Nc,Nq) of near strip footing.
The bearing capacity of a near strip footing under action of ultimate bearing capacity problem was studied by means of the kinematical approach of limit analysis theory.And the planar knematically admissible failure mechanism was constructed elaborately for the calculation schemes.The objective functions of bearing capacity were obtained by equating the work rate of external force to internal dissipation along the velocity discontinuities,and then the objective functions were transformed as a upper-bound mathematic optimization model for bearing capacity as low as possible.The result of upper bound method for planar failure mechanism was obtained by use of the sequential quadratic programming(SQP).From the numerical results,it can be seen that the dip angle of slope(δ) and internal friction angle(φ) of foundation have significant effects on the bearing capacity factor(Nγ,Nc,Nq) of near strip footing.
引文
[1]Saran S,Sud V K,Handa S C.Bearing capacity offootings adjacent to slopes[J].Journal of Geotechni-cal Engineering,1989,115(4):553-573.
[2]酆庆增.临近边坡的基础的极限承载力[J].力学季刊,1999,20(1):24-27.
[3]王红雨,杨敏.临近基坑条形基础地基承载力简化上限解[J].同济大学学报:自然科学版,2006,34(3):319-324.
[4]Yang X L,Wang Z B,Zou J F,et al.Bearing capac-ity of foundation on slope determined by energy dissi-pation method and model experi ments[J].Journal ofCentral South University of Technology,2007,14(1):125-128.
[5]赵杰,邵龙潭.土体结构极限承载力的有限元分析[J].岩石力学与工程学报,2007,26(增刊1):3183-3189.
[6]李耘宇,胡晓敏,张嵘峰.地震液化对桥梁桩基础极限承载力的影响[J].武汉理工大学学报:交通科学与工程版,2006,30(6):1044-1047.
[7]赵炼恒,李亮,杨峰,等.基于SQP和上限法的非饱和土条形基础极限承载力计算[J].岩石力学与工程学报,2009,28(增刊1):3021-3028.
[2]酆庆增.临近边坡的基础的极限承载力[J].力学季刊,1999,20(1):24-27.
[3]王红雨,杨敏.临近基坑条形基础地基承载力简化上限解[J].同济大学学报:自然科学版,2006,34(3):319-324.
[4]Yang X L,Wang Z B,Zou J F,et al.Bearing capac-ity of foundation on slope determined by energy dissi-pation method and model experi ments[J].Journal ofCentral South University of Technology,2007,14(1):125-128.
[5]赵杰,邵龙潭.土体结构极限承载力的有限元分析[J].岩石力学与工程学报,2007,26(增刊1):3183-3189.
[6]李耘宇,胡晓敏,张嵘峰.地震液化对桥梁桩基础极限承载力的影响[J].武汉理工大学学报:交通科学与工程版,2006,30(6):1044-1047.
[7]赵炼恒,李亮,杨峰,等.基于SQP和上限法的非饱和土条形基础极限承载力计算[J].岩石力学与工程学报,2009,28(增刊1):3021-3028.
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