The Safety Evaluation System Research About The Existing Metro Lines In Karst Area Abstract

As an emerging traffic patterns, city rail transit are being recognized and admitted by more and more city. It has become one of the most effective methods to solve the city traffic congestion and ease traffic pressure. The consequent problem need to be solved urgently such as the metro technical excavation updates, the improvement of metro operation speed and accuracy, subway tunnel construction strategy in the poor geological conditions, the safety monitoring and evaluation after completion. Bad geological situation such as the soft soil foundation, water gushing conditions and caves has become the subway construction and operation safety hidden troubles. Especially in the karst geological conditions, the subway construction and operation are inevitably affected by the cave, which may cause ground subsidence, endanger surrounding buildings and underground pipeline safety, economic damage and casualties. China is a multi karst country, which is particularly common in Yunnan, Guizhou, Guangxi and Guangzhou. Therefore the study of karst tunnel stability factors and reasonable assessment of tunnel safety index has become an important issue to be settled urgently in city subway construction.This thesis is aimed at more scientifically evaluating its safety on karst geological condition, new subway excavation on adjacent existing subway security implications as the engineering background. Combining with the engineering characteristics, further investigation to the construction site conduct the scientific identification of risk factors. Through the finite element numerical simulation, explore influence of each factor on the safety of the existing metro line, and establish the relationship between the risk factors and the safety index, and then through the fuzzy mathematical principles to achieve quantitative safety evaluation on the existing metro line in karst area. This thesis mainly completes the following works:1) Through the ways such as data collection, computer numerical simulation to establish the risk factors set, safety evaluation index set and sample set of the stability of tunnel in karst geological;2) By application of engineering fuzzy mathematics related principles to establish fuzzy regression model, calculate function equation between the safety index and risk factors;3) Establish the safety assessment system software of existing subway in karst area, we can achieve the safety assessment just through simple man-machine dialogue; 4) Conducingt the safety evaluation on key conditions of the Guangzhou metro line nine, validating the accuracy of the evaluation system combined with the actual case to provide related theoretical support for the project.