| On the basis of related literature of freezing damage in tunnel, this paper investigates to the tunnel and consults the regional geological data in Ji-Mingyi tunnel of DaTong-ZhunGeer railway. According to engineering geological conditions of tunnel zone, the meteorological and hydrologic conditions were mainly summarized and analyzed, and relevant experiments were performed. The tunnel generalized and analyzed type of freezing damage, had a statistics about Ji-Mingyi tunnel, found out and analyzed serious zone of freezing damage. Finally, corresponding treatment measures were put forward, which combined with practical situation of Ji-Mingyi tunnel. The main contents and results are as follows:(1)Tunnel freezing damage situation was related to the precipitation between autumn and winter, and the bigger precipitation, the greater the freezing depth. In winter, as freezing depth reached stability, freezing depth was related to illumination time. And freezing depth becomes smaller when the illumination time change to be long. The longitudinal temperature variation in tunnel effected by the predominant wind. Due to the wind in tunnel zone is between southwest and northwest, and the tunnel orientation is between northwest and west. In winter,the wind will be blown into tunnel, then it will reduce the temperature further and make freezing damage become more serious.(2)Groundwater of tunnel zone supplies mainly by atmospheric precipitation and is unrelated to the replenishment of mountain of northeast. Groundwater is separated by a ditch which developed near a station in the north of tunnel zone. And groundwater in tunnel cannot be supplied by the water which comes from the mountain of northeast. And one part of atmospheric precipitation is discharged though the ground, the other infiltrates to the tunnel plane by rock mass fracture and gathering behind tunnel lining.When it is frozen,the lining will be damaged.(3)The degree of rock weathering is high in tunnel of K170+200～K170+350 and K170+462～K170+732,and the rock mass is broken.The groundwater infiltrates through fractures. Due to the weathering line exists depressions,one part infiltrates to the section of K170+462～K170+732, the other is runoff though the section of K170+200-K170+350, and the depressions will gather some groundwater, then it provides material conditions for tunnel freezing damage.(4)Aimed at the freezing damage situation of Ji-Mingyi tunnel,this paper puts froward to treatment measures especially for the section of K170+200～K170+350 and K170+ 462～K170+732. The measures mainly include interception, antifreeze, lining crack prevention, grouting of surrounding rock and insulation layer to lining and drainage ditch. And then the freezing damage of tunnel would be completely and totally controlled. |
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