富水砂层地铁联络通道施工安全风险管控与应用研究

郑智鹏

摘 要

随着我国经济的持续快速发展，城市化进程越来越高，地铁项目的建设规模不断扩大，在地铁建设过程中，为满足乘客安全疏散、隧道排水及防火、防灾等功能要求，一般地铁两条隧道之间应设联络通道。联络通道施工存在安全隐患，首先，其施工存在涌水涌砂、通道坍塌、对既有隧道影响、施工范围管线破坏等工程风险，其次，施工中还存在触电、设备故障、物体打击等非工程风险。在实际的联络通道工程建设中，安全事故时有发生，特别在富水砂层等软弱土层中，由于土层自身的稳定性差，突发性涌水、涌砂造成地面塌陷等重大风险事故的情况较多。因此，对富水砂性土层条件下的联络通道施工安全风险管控开展研究是十分必要的。

首先，本文从地铁联络通道施工方法入手，通过查阅国内外研究现状，对明挖、暗挖、先明挖后暗挖3类联络通道开挖方法以及地面加固、隧道内注浆加固以及冻结法加固3类辅助施工方法进行了分析对比，然后，依据富水砂性土层的地质特性确定“冻结+暗挖”施工方法较为适合富水砂性地层联络通道施工。

其次，对富水砂性土层环境下联络通道采用“冻结+暗挖”施工的全过程进行了风险识别、评估，确定了其施工过程中的主要风险与一般风险，并制定了相应风险控制措施，并应用ABAQUS有限元数值模拟软件对积极冷冻的合理时间控制及冷冻产生的位移变形进行仿真分析，用以指导确定合理的积极冷冻时间和隧道加固措施的确定。

最后，本文以某市地铁5号线某富水砂层联络通道为依托进行了实证分析。结合工程实际情况，依据制定的富水砂层地铁联络通道冻结暗挖施工主要安全风险控制措施，提出了针对性的工程风险控制措施；应用ABAQUS有限元软件模拟了积极冻结期的冻结帷幕发展情况和土体冻胀位移情况，提出本工程积极冷冻期不少于45天，隧道内采用常规加固措施的具体指导建议。通过该实际工程施工效果验证了富水砂层地铁联络通道采用“冻结+暗挖”施工及主要安全风险控制措施的可行性，可为类似工程施工安全风险控制措施研究提供借鉴与参考。

关键词：联络通道 富水砂层  数值模拟  冻结法  风险控制

Abstract

With the sustained and rapid economic development and the increased urbanization, the construction scale of subway projects is constantly expanding. In the process of subway construction, in order to meet the functional needs, such as passenger evacuation, tunnel drainage, fire prevention, and disaster prevention, the cross passage should be established between the two subway tunnels. There are hidden safety hazards in the construction of the connected aisle . Firstly, it involves engineering risks such as water gushing, sand collapse, impact on existing tunnels, and damage to pipelines in the construction area . Secondly , there are non-engineering risks such as electric shock, equipment failure and object strike . In the actual construction of the connected aisle project, safety accidents occur from time to time . Especially in soft soil layers such as water-rich sand layers. There are many major risk accidents such as the ground to collapse caused by sudden water gushing and sand gushing due to the poor stability of the soil layer itself. Therefore, it is necessary to carry out research on the safety risk management of the connected aisle construction under the conditions of water-rich sandy soil layer.

First of all, by consulting the research status at home and abroad, this article starts with the construction method of the subway connected aisle . Analyzed and compared the three types of excavation methods of open-cut method, hidden digging, first open digging and then deep digging, as well as three types of auxiliary construction methods of ground reinforcement, grouting reinforcement in the tunnel and freezing method. Then, come by with the characteristics of the water-rich sandy soil layer, the frozen excavation is more suitable for the construction of the connection channel of the water-rich sandy layer.

Secondly, by conducting risk identification and evaluation of the whole process of the frozen excavation of the cross passage in the water-rich sandy soil environment, the main risks and general risks in the construction process are determined, and the corresponding risk control measures are formulated.  At the same time, the ABAQUS finite element numerical simulation software is used to simulate and analyze the reasonable time of active freezing and the displacement caused by freezing. Based on this, reasonable active freezing time and tunnel reinforcement measures are determined.

Finally , an empirical analysis has been studied, which based on the subway connection channel of a water-rich sand layer of Metro Line 5 in a city. According to the main safety risk control measures for the construction of the frozen excavation of the water-rich sand layer subway connected aisle , targeted engineering risks control measures are proposed combined with the actual situation . After using the ABAQUS finite element software to simulate the development of the freezing curtain and the frost heave displacement of the soil during the active freezing period, it is proposed that the active freezing period of this project should be in 45 to 55 days, and specific guidance suggestions for the use of conventional reinforcement measures in the tunnel. The feasibility of using freezing method and main safety risk control measures for the water-rich sand layer subway connection channel has been confirmed through the actual construction effect. And the result could provide a reference for the research on safety risk control measures of similar projects.

Key words: Connected Aisle, Water-rich Sand Layer, Numerical Simulation, Freezing Method, Risk Control