针对土钉放坡+地连墙+内支撑联合支护在施工过程中的安全系数及失稳变化情况,依托济南地铁六号线项目文化中心站~中央公园站工程,采用极限平衡、强度折减等方法,对联合支护在工程中的安全系数进行了研究,同时采用ABAQUS有限元软件进行数值模拟计算分析。采用能量法推导出主、被动土压力对内支撑支护结构最下道支撑点的力矩,进而得到了基于能量法和直线+对数螺旋线滑移面的基坑嵌固深度稳定性安全系数,与传统的计算方式相对比增加考虑了基坑宽度对稳定性的影响。在ABAQUS中根据强度折减法计算,得到在基坑开挖完成后基坑稳定性系数,对比预留核心土前后系数变化。随着开挖深度的增加,预留核心土在组合支护体系中所起贡献逐渐增大,基坑位移变形及塑性变形的发展受到抑制,表现为基坑的稳定性系数逐渐增大。
Based on the safety factor and instability change of soil napping slope+ground wall+internal support combined support in the construction process, the safety factor of combined support in the project of Jinan Metro Line 6 is studied by using the methods of limit balance and strength reduction. Meanwhile, ABAQUS finite element software is used for numerical simulation. The energy method is used to deduce the torque of the main and passive earth pressure at the lowest support point of the inner supporting structure, and then the stability safety factor of the foundation pit anchoring depth based on the energy method and the linear+logarithmic spiral sliding surface is obtained, and the results are compared with the traditional calculation method. Based on the strength reduction method, the stability coefficient of foundation pit after excavation is obtained in ABAQUS, and the coefficient changes before and after reserving core soil are compared. With the increase of excavation depth, the contribution of reserved core soil in the combined support system gradually increases, and the development of displacement deformation and plastic deformation of foundation pit is inhibited, which shows that the stability coefficient of foundation pit is gradually increased.
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