带支撑基坑围檩受力性状分析及数值模拟

Force Character Analysis and Numerical Simulation for Circuit Purlin of Foundation Pit with Support

通过对带支撑基坑围檩受力性状的分析,提出支撑与围檩正交、斜交分别对应的几种基坑围檩轴力分布形式,并以武汉市凯德广场古田项目为例,从实测数据出发,分析了基坑围檩轴力的变化规律,在对基坑内支撑平面有限元计算中设置在围檩上的边界条件的特性进行深入研究的基础上,使用数值模拟手段对基坑围檩轴力进行了计算与数值模拟验证。结果表明:与开挖工况一致,围檩轴力呈现"两阶段"增长过程,地下室主体结构施工完成后,围檩轴力趋于稳定;桩(墙)平行于围檩走向的切向约束客观存在,本例中围檩轴力呈现梯形交替递增分布形式;桩(墙)对围檩的约束方向包括切向和法向,其约束形式表现为线约束和弹性约束。

With the force character analysis on circuit purlin of fourdation pit,this paper presents several kinds of purlin axial force distribution respectively corresponding to the orthogonal and oblique between support and circuit purlin.Based on the measured data of Gutian Kaide Square project,the paper analyzes the laws for axial force of circuit purlin development.The paper discusses the characteristics of the boundary conditions on the purlin setting in the finite element calculation of supporting plane in foundation pit,compiles software to calculate the axial force, and verifies the results by numerical simulation.The results show that axial force of circuit purlin presents ‘TwoStage Growth Process’,which is consistent with the excavation condition.After the completion of the construction of the main structure of the basement,the axial force of circuit purlin tend to be stable;the tangential constraint of retaining piles（retaining walls）exists objectively which parallels to circuit purlin,the axial force of circuit purlin obey the distribution regularity of trapezoidal cyclic growth;the direction of the constraint which is provided by the pile （wall） to the purlin includes tangential and normal,and the constraint forms are line constraint and elastic constraint.