复杂工况下超长联络通道冻结法设计与施工

Design and Construction of Freezing Method for Ultra-long Cross Passage under Complex Working Conditions

不同于常规联络通道冻结工程,超长联络通道的设计与施工存在巨大差异。以福州市轨道交通2号线紫阳站—五里亭站区间超长联络通道及泵站工程为例(两隧道中心距65.8 m),系统介绍了复杂工况条件下超长联络设计与施工中的关键技术,包括:区间隧道与联络通道结构优化与调整、长距离水平钻孔试验与质量控制、冻结加固设计理念与主要技术参数、开挖前冻结效果评价、开挖构筑分段与过程管控、冻胀压力释放与后期融沉控制等方面。该工程已安全、顺利完成,开创了国内超长联络通道冻结工程的全新记录。其成功经验表明:超长联络通道采用双泵站结构、双向冻结加固的方案是可行的,整体风险可控;采取分区冻结、错时冻结,对控制冻土体量、减小冻胀量具有重要作用;长距离水平钻孔过程中,应加强过程控制,以最大终孔间距作为控制指标,及时修正下一冻结孔钻孔参数;双向开挖和分段浇筑二次结构,兼顾了效率与风险管控,值得肯定。另外,施工中也存在一些需进一步深入研究问题,如:长距离水平钻孔偏斜控制、长距离泄压、融沉控制等。

Different from the conventional cross passage freezing engineering,the design and construction of ultra-log cross passage are quite different.This paper systematically introduces the key technologies in the design and construction of ultra-long contact under complex working conditions,which takes the ultra-long communication cross passage and pumping station between the Ziyang Station and Wuliting Station of Fuzhou Rail Transit Line 2 as an example(the distance between the two tunnels is 65.8m).The key technologies includes structural optimization and adjustment of interval tunnels and cross passages,long-distance horizontal drilling test and quality control,design concept and main technical parameters of freezing reinforcement,evaluation of freezing effect before excavation,segmentation and process control of excavation structure,frost heave release and later thawing settlement control,etc.The project has been completed safely and smoothly,and it has created a new record for the freezing of the long cross passage in China.It's successful experience shows that:it is feasible to adopt double pumping station structure and two-way freezing reinforcement for ultra-long cross passage,and the overall risk is controllable.It is important to control the volume of frozen soil and reduce the amount of frost heave.In the process of long-distance horizontal drilling,the process control should be strengthened,and the maximum final hole spacing should be taken as the control index to timely correct the drilling parameters of the next freezing hole.The two-way excavation and sectional construction of secondary structure take into account the efficiency and risk control,which is worthy of recognition.In addition,there are some problems that need to be further studied in the construction,such as:deflection control of long-distance horizontal drilling,long-distance pressure relief,and control of thawing settlement,etc.