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基于宁波软土地区典型土层分布和经工程反演的计算参数,通过MIDAS/GTS有限元分析软件对不同开挖面积和开挖深度的18个三维基坑有限元模型进行数值计算。根据数值模拟结果,提出了确定宁波地区地铁隧道控制保护区范围的修正方法。通过对工程实例的实测结果进行分析,证明了该修正方法的可行性和必要性。进一步对比分析了基坑的开挖面积与深度对邻近隧道位移的影响;通过建立两类不同分坑措施的基坑模型,比较了不同分坑措施在控制基坑和隧道位移方面上的效果。结果表明,隧道最大位移随邻近基坑开挖面积的增加呈非线性递增;采用分隔墙与隧道垂直的分坑措施对隧道位移控制更为有利。研究成果可为宁波软土地区地铁隧道控制保护区内的基坑设计提供参考。
Based on the calculation of typical soil distribution and engineering inversion in soft soil area of Ningbo, 18 3D finite element models of excavation with different excavation area and excavation depth were calculated by using MIDAS / GTS finite element analysis software. According to the numerical simulation results, a correction method to determine the scope of the metro tunnel control and protection zone in Ningbo is proposed. Through the analysis of the measured results of engineering examples, the feasibility and necessity of the correction method are proved. The influence of excavation area and depth on the displacement of adjacent tunnels is further contrasted and analyzed. The effect of different sub-pit measures on the control of foundation pit and tunnel displacement is compared by establishing two types of foundation pit models. The results show that the maximum displacement of the tunnel increases nonlinearly with the increase of the excavation area of the adjacent foundation pit. The vertical sub-pit measures of the partition wall and the tunnel are more favorable to the tunnel displacement control. The research results can provide references for the design of foundation pit in metro tunnel control and protection zone in soft soil area of Ningbo.