The Study Of Structure Damage And Reliability Of Cold Region Tunnel

The frost heave of surrounding rock permafrost is the most key issues when build a tunnel in a cold regions. Surrounding rock permafrost in winter can produce freezing expansion force, and the deformation due to frost heaving can get only part of recovery in warm season, that is the residual deformation on the lining structure still exists. Because each year permafrost will freezing and thawing, the frost heave on the lining will increase at the same time, equal to cumulative effect. So there’s a hidden trouble during the lining operation time. This paper gives a detailed introduction on the damage of a lining caused by frost heave, and also a discussion on tunnel lining’s safety and reliability problems when the damage is known. This article carried on the tunnel lining reliability analysis through the actual tunnel project-----the Kunlun mountain tunnel as a background. Here is a briefly describe of the study this paper have to do:(1) Give a introduction of the lining structure’s damage caused by frost heave, and also introduces the damage’s specific forms and mechanism, this have practical significance to prevent a further development of the lining damage.(2) All the structure’s damage forms are closely related with the properties of materials. The damage process of a lining structure is actually a development process that the residual deformation’s accumulation effect after the lining has a frost heave and the macro expansion crack interwoven process. This article combinates with the cold runnel’s actual situation, get a discussion that the lining structure will suffer a repeated freezing expansion force, and this force is a long from cycle fatigue load. Therefore this paper respectively analysis the damage mechanism from angles a structure under pressure and a structure under a fatigue load. This has practical guidance function to a lining structure how to choose material by material properties during the construction process.(3) This paper do a research based on the actual Kunlun mountain tunnel project. Firstly analysis the uncertainty of the results of the lining’s frost heave question, get a conclusion of the lining’s stress response (mainly refers to the maximum stress, minimum and maximum stress deformation) under the coupled action of freezing expansion force and gravity stress. According to the three kinds of mechanical response (specific analysis for the designated variables), and then by using ANSYS PDS module, this passage evaluates the tunnel lining structure of the Kunlun mountain’s reliability. Through the analysis of the sensitivity of all kinds of input variables (mainly refers to the surrounding rock mass physical parameters, the anchorage zone physical parameters, a line physical parameters and two lining physical parameters) will get the results:the reliability of the Kunlun mountain’s tunnel lining structure has a very big relation with the thickness of the lining and the surrounding rock’s poisson’s ratio. Through the cumulative distribution function diagram of the outcome variables get the concrete reliability of the Kunlun mountain tunnel lining. The result shows that assess a reliability of the lining structure by these three mechanical responses can guarantee the reliability of the lining structure more than93%.