Construction Risk Assessment And Advance Geological Forecast Of Railway Tunnel

The construction period of the mountain railway tunnel is long,the construction risk is high,and there are many hidden dangers.During the construction process,the geological conditions passing through the stratum are relatively complicated,and the construction risks such as landslide,inrush water and rockburst are easily generated.Funded by the China Railway 21st Bureau Science and Technology Research and Development Program(19C-4),based on the characteristics of the construction accident of the mountain railway tunnel,the fuzzy hierarchical comprehensive evaluation method is used to establish the sample data of the BP network algorithm based on the relevant geological information of the mountain railway tunnel.Then the data analysis software is used to establish the railway tunnel construction risk probability assessment model based on BP network algorithm.The evaluation model is built to clarify the probability level of risk occurring during construction.The risk consequence equivalent method is used to construct the construction risk consequence assessment model to determine the level of consequences of the construction risk,and the construction risk level is classified according to the relevant regulations of the railway tunnel in China.The Dengjiawan Tunnel of the Chengdu-Kunming Railway Line is a typical mountain railway tunnel.The geological and hydrological conditions of the D2K372+305-D2K373+200 section of the Dengjiawan Tunnel are analyzed.The import section is divided into 30 sections and the construction has been constructed.The stage risk estimation model carries out the construction stage risk assessment for the 30 segments,and the corresponding advanced geological prediction plan is made according to the different construction risk levels of the Dengjiawan Tunnel.The main research contents are as follows:(1)According to the characteristics of the excavation construction accident of the mountain railway tunnel,this paper selects the typical risk accidents in the three tunnel constructions of collapse,inrush water and rock burst as the three first-level indicators for the assessm ent of the risk of the mou nta in railway tunnel,combined with the ten Six secondary indicators are constructed to form a system framework for con struction risk assessment.(2)The sample data of neural netw ork is established by fuzzy hierar chical comprehensive evaluation method.The weight value of each risk fa ctor is determin ed by AHP.The qua ntita tive analy sis of the three primary indicators is determined by the trapezoidal membership distribution fun ction and the Karwowski fuzzy membership function.The membership value of factors and qualitative factors.(3)Based on the sample data establish ed by the fuzzy hierarchy evaluation method,the construction risk probability evaluation model of the mountain railway tunnel based on BP neural network algorithm is constru cted,and the probability level of risk occurrence in the construction phase is clarified.The construction risk c onsequence assessment model is used to clarify the risk consequence level of the construction phas.e and use the comp rehensive assessment of construction risk.(4)According to the surrounding rock grade of the excavation construction risk assessment of each section of the Dengjiawan tunnel entra nce se ction,a comprehensive geological forecasting scheme for different construction risk levels was made.The comprehensive advanced geological forecasting scheme was carried out in the construction of the mileage section with high construction risk level in the entrance section of the Dengjiawan tunnel,and the ideal forecasting effect was obtained.