Strip Insulating Layer in Tunnel in Cold Region and its Temperature Field Analysis

Strict waterproof is the key to prevent frost damage to tunnel in the cold region. Improving drainage system has benefits to obtain good waterproof effect. Aim at the drain pipe freeze in cooling and warming period, we design a strip partial insulating layer to the drainage system :(1) The girth drainage pipe connects to the central drainage pipe directly, and the lengthways drainage pipe connects to the girth drainage pipe by tee. (2) Interval decorating insulation layer to the tunnel girth drainage pipe, using the strip insulation layer behind the lining and setting annular insulation around drainage pipe under the tunnel road. (3) The strip insulation layer is sandwiched by two layers of flashing; one of them forms a whole system with the tunnel flashing and the other posts on its surface. The temperature field finite element analysis of surrounding rock and lining concrete show that: As the girth drainage pipe if there is insulation layer is placed with a certain interval between each other. Two kinds of drain pipe's freeze-thaw state has a time gap. It is beneficial to solve the problem of the poor drainage after the lining in the cooling and warming period.