兰州地铁砂岩地层联络通道冻结法加固技术分析

为研究冻结法加固技术在强风化砂岩(红砂岩)地层中的适用性,依托兰州地铁1号线联络通道工程,首先介绍地层加固方案,通过经典解析法核算冻结壁平均设计温度。基于包含土体、隧道和联络通道的三维数值模型,讨论施工各阶段的冻结壁安全系数。最后,根据监测结果分析隧道收敛、地表沉降等关键施工控制参数。结果表明:冻结壁平均设计温度符合要求,可保证各阶段冻结壁安全系数满足规定,各项监测指标均未超过控制标准。冻结法在强风化砂岩(红砂岩)地层中具有很好的适用性,能够有效解决其他加固技术难以克服的难题。

Analysis on Freezing Reinforcement Technology of Connecting Passage in Sandstone Stratum of Lanzhou Metro

In order to study the applicability of the freezing reinforcement technology in strongly weathered sandstone(red sandstone) stratum, analysis is carried out based on Lanzhou Metro Line 1 connecting passage project, combined with theoretical analysis, numerical calculation and field monitoring. Firstly, the stratum reinforcement scheme is introduced, and the average design temperature of the freezing wall is calculated by classical analytical method. A three-dimensional numerical model including soil, tunnel and connecting passage is established, and the safety factors of the frozen wall in each construction stage are discussed. Finally, the key construction control parameters, such as tunnel convergence and surface settlement, are analyzed according to the monitoring results. The results show that the average design temperature of the freezing wall meets the requirements, the safety factors of the freezing wall in each stage are guaranteed, and all monitoring indexes do not exceed the control limits. It is concluded that the freezing method has good applicability in strong weathered sandstone(red sandstone) stratum, and can effectively solve the difficult problems that other reinforcement technologies can hardly overcome.