Rock Tunnel Frost Heaving Force Calculation And Frost Damage Classification

Along with our country speed up the pace of reform and opening up, China's infrastructure construction was in full swing, and highway, railway tunnel ware builded in the northeast, north, northwest, southwest region in a rapid speed. Which on the one hand, marks a more comprehensive national transportation system effectively, on the other hand, with the people to the contemplation of the frost damage problem of the tunnel.Based on the review of related literature at home and abroad, four of research status of induction aspects are summarized, which included frost heaving force calculation of the tunnel, tunnel freezing injury mechanism, the tunnel freezing injury classification and tunnel frost heave prevention measures. On this basis the frost heaving force calculation model of rock tunnel and frost damage method of classification ware analyzed, and the main work content is as follows:(1) Through the study of water frost heave theory, revised existing water frost heave model deficiencies:Models ware created to ignore itself freeze expansion effect of surrounding rock; Not considering the influence of water freezes elastomer deformation in the calculation process; Not mentioned parameter selection which caused the difficulty in engineering application. Based on the theory of elastic mechanics, the new local water frost heave model was established, and the frost heaving force calculation expression was deduced. Then the parameter selection method was given:Frost heave of surrounding rock of tunnel radial depth, local water along the tunnel radial depth, elastic resistance coefficient of surrounding rock, lining and equivalent elastic coefficients of surrounding rock and ice frost heave rate. Introducing the engineering example, the frost heaving force when lining behind existed no water was calculated to contrast with freeze-thaw lithosphere whole frost heave theory of frost heaving force elastic expression results, then verifying the rationality of the new local water frost heave model.(2) Using finite element numerical analysis method to analysis the rationality of the new local water frost heave model, and discuss the relationship between frost heaving force and related parameters.By the ANSYS finite element software to simulate tunnel engineering examples, it proved its rationality that to compare water behind the lining of the cold expansion force and local water frost heaving force model analysis results. Through the way of parameter adjustment, the relationship of frost heaving force and frost heave rate of surrounding rock, lining stiffness and longitudinal water depth ware analyzed.(3) A new tunnel freezing injury grading standard and index evaluation method was put forward. On the base of three major indexes of quantitative groundwater, temperature and surrounding rock properties, the new tunnel frost damage classification standard was put forward by using the weighted average hierarchy comprehensive evaluation method; Summarizes the tunnel freezing injury prevention construction precautions:low temperature heating heat preservation measures, waterproof and drainage measures, concrete construction, the new tunnel frost damage classification standard was corrected by effectiveness of construction measures.(4) Based on the new local water frost heave model, the existing tunnel frost damage classification standard was established and the index evaluation method was put forward. Tunnel was distinguished between new and existing tunnel by the indicator for concrete intensity of long-term growth. Taking the minimum and maximum reinforcement ratio of concrete lining as the weak or strong standards of frost heaving force classification, and frost heaving force threshold value ware calculated. And then, the incidence in ice hole affect normal use and the lining structure degradation ware quantized. Finally the existing tunnel frost damage classification standard was established by the comprehensive qualitative evaluation principle:the quantitative indicators, single index evaluation, the maximum priority and qualitative evaluation.(5) According to the Da Weigou tunnel engineering, the new local water frost heave model was applied to calculate the lining of cold expansion force in this tunnel; The Da Weigou tunnel type was judged by the new and existing tunnel discriminant standard, and adopting corresponding type tunnel freezing damage grade evaluation standard to evaluate.