非对称荷载下内撑式基坑支护结构参数分析及设计优化探讨

Parameter analysis and discussion on design optimization of support structure of internal bracing foundation excavation under asymmetric loads

非对称荷载作用下,内撑式基坑会向荷载小侧整体偏移,这将不利于基坑的稳定,因此有必要对支护结构进行设计优化。本研究以某偏压综合管廊基坑为例,通过有限元软件PLAXIS 2D对该基坑进行了仿真模拟,模拟结果与实测数据吻合良好,验证了模型的有效性。进一步对该基坑进行参数分析,研究了支护结构长度、等效厚度和弹性模量对支护结构变形和基坑安全性的影响。研究结果表明,在两侧支护结构均按偏压侧进行设计的基础上,增大某侧支护结构长度,会使该侧支护结构水平位移最大值增大,分别增大两侧支护结构等效厚度、弹性模量,均可以减小该侧支护结构水平位移最大值和非偏压侧支护结构顶部逆向位移。基于参数分析,提出一种针对非对称荷载基坑的简单有效、经济可行的优化思路,并通过数值模拟对优化效果进行了分析,证明了该优化思路的可行性。

Under the action of asymmetrical load,the internal bracing foundation excavation will skew to the small side of the load,which will be deleterious to the stability of the foundation pit,so it is necessary to optimize its design.A unsymmetrical loaded pipe gallery foundation pit is used as an example in this paper,and the finite element software plaxis 2D was used to simulate this foundation pit.The simulation results are in good agreement with the measured data,which verifies the validity of the model.Then the supporting structure parameters of the foundation pit are analyzed,and the influence of the length,equivalent thickness and elastic modulus of the supporting structure on the deformation of the supporting structure and the safety of the foundation pit is studied.The research results show that when the supporting structures on both sides are designed according to the biased side,the maximum horizontal displacement of a side supporting structure increases with the equivalent thickness of the side supporting structure.And with the increase of the equivalent thickness and elastic modulus of the supporting structure on both sides,the maximum horizontal displacement of the side supporting structure and the reverse displacement of the top of the non-biased side supporting structure will decrease.Finally,a simple and economical optimization idea for asymmetric load foundation pits is proposed by parameter analysis,and the optimization effect is analyzed through numerical simulation,which proves the effectiveness of the optimization idea.The conclusions and optimization idea can provide references for similar projects.