Abstract:The disasters of water leakage of the Kunlun Mountain Tunnel in Qinghai—Tibet Railway are introduced by the time step based on the measured in-situ data. From the viewpoint of the chain-styled rule,the chain-styled mechanisms of the water leakage disaster in Kunlun Mountain Tunnel are proposed. According to the principle of the chain breakage and the chain-styled mechanisms of the water leakage disaster,a new-typed method of the chain breakage is presented based on the principle of protecting the frozen soil layer from thawing using the ripped-stone method. The design of the ripped-stone is considered;and the key techniques during designing and constructing the ripped-stone are put forward. According to the basic theories of heat transfer and seepage,considering the coupled effects of seepage field and temperature field,a three-dimensional computational model of the coupled issues is given. The finite element formulae of this problem are obtained by Galerkin¢s method;and the computer programme of the finite element is written. Using this model and the computer program,the three-dimensional nonlinear analysis for the coupled issues of seepage field and temperature field of the flat segment DK977+578—DK977+682 in Kunlun Mountain Tunnel on Qinghai—Tibet Railway is made under the two conditions of using and not using the ripped-stone method. The results show that it is feasible that the ripped-stone method is used for breaking the chain of the water leakage hazard in the permafrost tunnels. So,the theoretic foundation of the ripped-stone method is provided for its application and design in cold region tunnels. And the new analysis method,the new prevention and reinforcement measures are proposed for the water leakage disaster in cold region tunnels.