考虑非线性接触地铁基坑施工过程变形研究

Study on Deformation during Construction Process of Subway Foundation Pit Considering Nonlinear Contact

探究土体与地下结构之间的接触行为,本文首先对砂土和粉质黏土与围护结构的接触面进行了试验,获得了两类土体与围护结构的接触面力学特性。其次采用基于Clough与Duncan应力-位移双曲线模型的无厚度Goodman接触单元,验证了接触面非线性的切向行为合理性。考虑实际工程中土体与围护结构的接触非线性问题,基于无厚度Goodman接触单元对地铁基坑施工变形过程进行预测,并结合模拟接触切向行为的罚函数法线性模型,对比罚函数法线性接触模型与Goodman非线性接触模型对基坑开挖变形的影响,研究包括围护桩墙后土体垂直沉降、围护桩墙侧向水平位移以及围护桩墙顶端水平位移。最后将研究因素与实际监测数据对比,结果表明:在考虑非线性土与结构相互作用的基坑开挖过程中,计算结果与实际监测结果的相对误差均保持在10%以内,计算结果更合理,为类似土与结构相互作用的岩土工程接触分析提供参考和理论基础。

In order to explore the contact behavior between soil and underground structures,firstly,the contact surfaces between sand or silty clay and retaining structure were tested. The mechanical properties of the contact surfaces between two types of soil and enclosure structure were obtained. The Goodman element of zero thickness based on the stress displacement hyperbola model of Clough and Duncan was adopted,and the rationality of the tangent behavior with the nonlinear contact surface was verified. Considering the nonlinear contact between soil and retaining structure in practical engineering,based on the Goodman element of zero thickness,the deformation process of subway foundation pit construction was predicted,and combined with the penalty function method for simulating contact tangential behavior,the influence of the penalty function method and the Goodman nonlinear contact model on the simulated deformation process of the foundation pit was compared. The analysis included the vertical settlement of the soil behind retaining structure,the lateral displacement of retaining wall and the horizontal displacement of retaining wall tap. Finally,the research factors were compared with the actual monitoring data. The results show that simulation results are more reasonable in the excavation process considering the interaction of nonlinear contact between soil and structure,and the relative error between the calculated results and the actual monitoring results is within 10%. It provides a reference and theoretical basis for the contact analysis of geotechnical engineering similar to the interaction between soil and structure.