大型地铁隧道局部垂直冻结加固技术研究

Study on Regional Vertical Freezing Preservation for Large Tunnel of Civil Subsurface Station

大型地下工程如何进行精准、可靠的冻结加固一直是困扰施工者的主要难题之一。以广州地铁3号线机场段隧道冻结加固工程为例,从冻结壁设计和冻结孔设计两个方面入手,介绍了大体量冻结工程的设计方法,并根据现场实测数据,对该工程冻结过程温度场演化以及关键技术指标的形成情况进行分析。研究结果表明冻结壁设计平均温度-10℃、厚度3 m(底部平底4 m)时,冻土帷幕的总体承载能力足够满足项目需求。在不具备明挖和水平加固条件下,垂直冻结技术的应用能够节约能量,有效降低了项目成本,也为后续类似工程的开展提供了参考依据。

Accurate and reliable freezing reinforcement of large underground engineering projects is one of the primary challenges for con‐struction practitioners.Takes the freezing reinforcement project of Guangzhou metro line 3 airport section tunnel as an example,introduces the design methods of large-volume freezing projects from two perspectives:freezing wall design and freezing bore design,and analyzes the evolution of layer temperature field during the freezing process and the formation of key technical indicators based on field experimental data.The research results show that when the average temperature of the freezing wall is-10℃and the thickness is 3 meters(4 meters at the bottom),the overall bearing capacity of the frozen soil curtain is sufficient to meet the project requirements.Without the availability of exca‐vation and horizontal reinforcement,the application of vertical freezing technology can save energy,effectively reduce project costs,and also provide reference basis for the development of similar projects in the future.