Study On Construction Risk Assessment And Advance Geological Forecast Of Lao Anshan Tunnel

Mountain railway tunnel through the geological conditions of complex,the construction of large risk,in the tunnel construction process prone to collapse,flood water,rock burst and other risk accidents.Based on the characteristics of the disaster of mountain railway tunnel construction,this paper uses the fuzzy analytic hierarchy process to establish the accident probability evaluation model.The risk consequence equivalence estimation method is used to establish the accident consequence evaluation model,and the construction risk classification is divided according to the Interim Provisions on Railway Tunnel Risk Assessment and Management.Lao Anshan tunnel length of 15161 m,the overall depth of the larger geological complex,as a typical mountain railway tunnel.By analyzing the engineering geology,hydrogeology and poor geological conditions of Laoyan tunnel,the tunnel is divided into 24 sections,and the risk assessment model of the tunnel is established.The risk assessment model of the tunnel is established,and the risk assessment of the tunnel The development of comprehensive forecasting program for over-period geological forecast,the main research results are:(1)Aiming at the characteristics of the construction of the railway tunnel,the typical risk events of landslide,flood burst and rockburst are selected as the three primary indexes of construction risk assessment and the corresponding 16 secondary indexes.(2)The risk analysis model of the construction of Longgangling railway tunnel is established by fuzzy analytic hierarchy process.The weight of each risk factor is determined by using analytic hierarchy process.The membership degree of quantitative factors is determined by trapezoidal distribution function.using fuzzy membership function proposed by Karwowski et al.determine the membership of qualitative factors.(3)Based on the concept of "equivalent",the contingency estimation method is used to establish the accident consequence evaluation model for the non-uniformity of the measurement methods such as the loss of construction period,environmental loss and social loss in the assessment of the risk consequences of the construction of the Longgangling railway tunnel.(4)By analyzing the engineering geology,hydrogeology and poor geological conditions of Laoyan tunnel,the tunnel is divided into 24 sections,and the construction risk risk model of each section is evaluated by using the established construction risk assessment model of Changtoushanling railway tunnel.The evaluation result is : 3 high risk zones,13 moderate risk zones and 8 low risk zones.According to the length statistics,the total length of the old Anshan tunnel is 15161 m,of which the height risk zone is 601 m,accounting for 4%;the middle risk zone is 9265 m,61%;the low risk zone is 5295 m,accounting for 35%.(5)This paper summarizes the advantages and disadvantages and the applicable conditions of each period of geological forecasting method.According to the construction risk level of each section of the old Anshan tunnel,the comprehensive forecasting scheme of different risk grades is worked out and the construction risk level of the old Anshan tunnel is moderate and Height of the two paragraphs of the application,and achieved good forecast results,verify the feasibility of comprehensive advanced geological prediction.