寒区运营隧道洞口段冻害分析及对策

王晓宇¹，杨明宇^2*

1.辽宁省公路勘测设计公司，辽宁 沈阳  110006；

2.天津大学建筑工程学院，天津 300072

摘要：为解决寒区公路运营隧道的冻害问题，分析冻害形成机理，依据冻融周期内隧道现场拱顶、边墙和路面3个测孔位置不同孔深处的监测温度数据，分析隧道洞口段冻害类型。结果表明：在冻融期，隧道洞口段边墙从隧道二次衬砌表面沿径向延伸至围岩深部的温度逐渐升高，拱顶位置从衬砌表面向深部延伸处温度先升高后降低，路面从隧道路面边缘表面沿径向延伸至围岩深部温度逐渐升高；洞口段在冰冻季节温度均低于冰点，冻害风险较高，极易造成洞口段环向排水系统冻结，隧道洞顶边仰坡冻融作用造成的滑塌、二次衬砌开裂、衬砌渗漏水挂冰、路面积冰等病害。对比分析不同测孔同一深度的温度可知，隧道洞口段拱顶温度、边墙温度、路面温度依次升高。对隧道洞口段采取防冻措施时，先后做好浅埋段洞顶、边墙、排水系统及路面的防冻措施，针对不同病害类型分别采取衬砌结构抗冻等级增强、增设保温板、围岩注浆隔水、提高隧道内温度、增加地下水的热量、电伴热保温隔热、深埋中心排水沟等方法。改造后的监测结果表明，隧道洞口段内各结构保温性能良好，可为设计类似工程洞口段冻害的防治方案提供依据。

关键词：寒区隧道；冻害；温度监测；防冻措施

Analysis and countermeasures of freezing damage at the tunnel portal section operation in cold region

WANG Xiaoyu¹，YANG Mingyu^2*

1.Liaoning Provincial Highway Survey & Design Company，Shenyang 110006,China;

2.School of Architectural Engineering, Tianjin University, Tianjin 300072, China

Abstract:To solve the freezing damage problem of highway tunnels in cold region, the freezing damage mechanism and the types of freezing damage at the tunnel entrance are analyzed according to the temperature monitoring data of different hole depths at the three hole positions of the tunnel vault, side wall and pavement during the freezingthawing period. The results show that the temperature of the side wall extending from the secondary lining surface to the deep part of the surrounding rock gradually increases, and the temperature of the vault extending from the lining surface to the deep part increases firstly and then decreases, and the temperature of the pavement extending from the edge surface of the tunnel to the deep part of the surrounding rock gradually increases. In bithe freezing season, the temperature of the entrance section is lower than the freezing point, and the risk of freezing damage is high, which can easily cause the freezing of the circumferential drainage system in the entrance section, the collapse of the upward slope at the top of the tunnel due to freezing and thawing, the cracking of the secondary lining, the leakage of the lining and the ice on the road surface, etc. By comparing and analyzing the temperatures of different measuring holes at the same depth, the vault temperature of tunnel entrance section is less than that of side wall and pavement. When taking antifreezing measures for the tunnel entrance section, the antifreezing measures for the roof, side wall, drainage system and pavement of the shallow buried section should be done successively. According to different types of diseases, the following methods are adopted: strengthening the frost resistance grade of lining structure, adding insulation board, grouting surrounding rock to prevent water, increasing the temperature in tunnel, increasing the heat of groundwater, keeping heat and insulating with electric tracing, and burying the central drainage ditch deeply. The monitoring results show that the thermal insulation properties of each structure in the tunnel entrance section is good, which can provide scientific basis for designing the prevention and control program of freezing damage in the tunnel entrance section of similar project.

Keywords:tunnel in cold region; freezing damage; temperature monitoring; antifreezing measure