| With the formulation and implementation of the “13th Five-year”plan and “along the way” strategy,there will be a new round of climax in highway construction.Our country is a mountainous one where the mountainous area accounts more than 2 / 3.In order to meet the needs of the development of traffic construction,more road and railway tunnels will be built.Accidents in tunnel happen rather often with the development of the longer,the greater depth of burial and more complex geological conditions tunnel construction,among which the most common accidents is collapse.Once collapse take place,not only delay the construction period,greatly improve the cost of the project,but also will cause personal injury to the construction workers and even life threatening.Therefore,the research on the pre-warning of tunnel collapse is of great significance in the construction safety,saving investment and so on.This paper analysed the deformation law of surrounding rock and determined base value of pre-warning indexes through the data analysis and mathematical statistics of measured data of tunnel engineering,which are based on the investigate and survey of classification,influencing factors,precursor of tunnel collapse.On this basis,pre-warning methods toward barrel and tunnel face collapse were studyed with the application of quantitative monitoring combined with qualitative phenomena method and multi-objective decision-making method.Based on the research of pre-warning methods along with experience and needs of engineering technical personnel,the pre-warning system was designed and developed.It takes tunnels of Yakang highway as examples of engineering application.The main findings and the major works are as follows:(1)On the basis of statistical analysis of tunnel collapse cases,the classification,influencing factors and precursors of collapse are analyzed.In view of the statistical results of collapse site and research based on the demand,this paper classified collapse into barrel and tunnel face.Barrel section has the monitoring condition,so the pre-warning method with quantitative monitoring combined with qualitative phenomena is the most direct and effective.While tunnel face without monitoring conditions,pre-warning work should be closely combined with the collapse-causing factors for collapse hazard assessment.(2)Study on deformation law of tunnel surrounding rock.Stage characteristics of deformation and variation characteristics of monitoring physical quantity were obtained with the analysis of typical deformation monitoring curve in Yakang highway tunnel.Based on the characteristics of typical collapse deformation monitoring curves,the pre-warning indexes of different types of collapse deformation process were put forward.Finally,regularities of distribution of monitoring data in 15 tunnels of Yakang highway were obtained.Confidence interval of steady deformation were suggested.(3)Study on pre-warning method of tunnel collapse.Comprehensive pre-warning model of barrel section collapse with quantitative indexes like accumulated deformation,rate of deformation,accelerated velocity and precursory qualitative phenomena were established based on the above research.By using efficacy coefficient method and studying on the collapse-causing factors,risk assessment model of tunnel face collapse was established in order to pre-warn collapse in fault fracture zone,jointed rock mass,terrene surrounding rock.(4)R&D of pre-warning system for tunnel collapse.The pre-warning system was designed and developed based on the research of pre-warning methods along with experience and needs of engineering technical personnel.(5)The application in tunnels of Yakang highway show that the pre-warning model for collapse has certain accuracy and practical significance.The pre-warning system has rapid response to collapse danger with convenient operation and friendly interface. |
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