季节冻土区隧道洞口衬砌开裂机理及防治

Lining Cracking Mechanism and Treatment Measures at Tunnel Portal in Seasonally-frozen Soil Regions

研究目的:近年来,在我国西北、东北等高纬度季节冻土区,短隧道或长隧道洞口段冬季衬砌开裂、春融期渗漏水等病害时有出现,严重影响隧道结构和列车运营安全。本文以东北地区某铁路线ZEST隧道为例,采用现场试验、数值模拟等手段研究案例隧道冬季洞口段衬砌开裂、春融期渗漏水的发生机理,比较不同整治措施后,提出适合该类隧道病害的整治措施。研究结论:(1)隧址区每年冰冻期约5个月,极端温度年较差60℃以上,年平均气温2℃,属典型季节冻土区;(2)衬砌开裂段主要穿过粉质黏土层,含水率大,衬砌开裂主要由围岩冻胀力荷载作用所致;(3)建议采用喷涂12~13 cm厚保温层+防火砂浆,水沟中铺设电伴热电缆,并对既有损伤衬砌结构进行锚杆补强和对衬砌裂缝进行环氧树脂嵌补处理的整治措施;(4)从隧道病害整治效果来看,本文提出的整治措施效果显著,衬砌开裂、春融期渗漏水等问题得以解决。

Research purposes： In recent years, lining cracking in winter and water leaking during spring thawing period have occasionally occurred at portal sections of either short tunnel or long tunnel, especially in high -latitude seasonally - frozen regions of China＇s northwest and northeast, it seriously affected the tunnel structure and operation safety. Taking the ZEST tunnel of a railway line in northeast region as an example in this paper, the mechanism of lining cracking in winter and water leaking during spring thawing period at tunnel portal section are studied by means of field tests and numerical simulation, and based on comparing the different treatment measures, the treatment measures suitable for such type of tunnel is put forward. Research conclusions：（ 1 ） The annual frozen period in tunnel area is about 5 months, the extreme annual range of temperature is above 60 ℃ and the annual average temperature is 2 ℃ , which is a typical seasonally - frozen region. （2） Because the lining cracking section mainly passes through the silty clay stratum and the water content in surrounding rocks is larger, the main cause of lining cracking is the loading effects of frost - heaving force in surrounding rocks. （3） It is recommended to use the treatment measures of ＂spraying the insulating layer of 12 - 13 cm thickness and the fireproof mortar, and laying electric heat tracing cables in both side drains＂ , meanwhile, the anchor bolt reinforcement is adopted for the existing damages of lining structure and the epoxy resin embedded processing is used on lining cracks （4） After evaluating the effects of different treatment measures for these tunnel diseases, the treatment measures proposed in this paper are quite effective and the problems such as cracking and water leaking of tunnel lining are completely solved