磁器口车站中洞法施工的非线性二维数值模拟

研究目的：为了预测北京地铁五号线磁器口车站中洞法施工引起的地表沉降，评价各部开挖过程的土体稳定性，在开工前需对施工过程进行数值模拟。 研究方法：运用大型通用有限元软件（ANSYS）模拟计算磁器口车站中洞开挖过程，采用合理的计算参数和“生死”单元法对其进行非线性数值模拟分析，给出中洞开挖引起的地表沉降计算结果；对分析显示的土体薄弱部分进行及时加固，确保开挖过程中土体处于稳定状态。 研究结果：通过对监测结果与数值分析结果的比较，证明了计算模型和参数选取的合理性以及计算结果的正确合理性。 研究结论：理论计算地表沉降曲线与施工实测曲线趋势和数值基本一致；数值模拟结果用于定性分析土体稳定性非常有用，要做到定量分析难度很大；数值模拟时必须对关键参数（如变形模量等）及其敏感性加以讨论和分析。

The Nonlinear Two-dimensional Finite Element Analysis for the Construction of Ciqikou Tunneling Subway Station with Center Drifts Excavation Method

Research purposes:In order to forecast the ground subsidence of Ciqikou Tunneling subway stations in Beijing Metro 5# Line and to evaluate the stability of the soil in the construction,the numerical simulation was carried out.Research methods:This paper simulatedly calculated with ANSYS software the excavating process of center drifts excavation method,and analyzed the nonlinear numerical model with reasonable parameter and "dead and live" element method.The weak area was reinforced in time to ensure the surrounding soil in stable condition.Research results:Through comparing and analyzing the monitoring information with numerical result,this paper approved that the numerical model and parameter selection were rational and the calculation results were right and reasonable.Research conclusions:The theoretical computation subsidence curve was fundamentally unanimous with the practical monitoring curve.It proved that the numerical simulation was in agreement with practice.The numerical simulation result was valuable in qualitative analysis the stability of the soil,but quantitative analysis was quite difficult.It was necessary that the key parameter(such as deformation modulus etc.) and its sensitivity were discussed and analyzed when the numerical simulation was carried out.