Abstract:

 Thermal insulation design concept and thermal insulation structure of "waterproofing sheet + thermal insulation layer + waterproofing protection layer" are proposed for tunnels in permafrost soil on QinghaiTibet Railway on basis of analysis on the causes for the frostinduced diseases of tunnels in frost soil and the variation rules of the frostthaw rings. The variation of the temperatures of the surrounding rock mass are measured and analyzed, which confirms that the surrounding rock mass is in gradual refreezing state and in turn verifies that the thermal insulation design is reasonable. This design method and design concept can be served as reference for similar projects in the future.

Key words: railway, frost soil tunnel, thermal insulation, frost thaw ring, frost induced heaving, refreezing