CONSTRUCTION LICENSE MECHANISM AND ITS APPLICATION BASED ON KARST WATER INRUSH RISK EVALUATION

Water inrush and mud gushing are the typical common geologic hazards for the karst tunnel construction.Based on risk evaluation model of water inrush,management system of construction permission mechanism can be established to reduce the economic loss and water inrush risk.The major factors are summed up and selected as the impact factor of fuzzy analytic hierarchy process(FAHP) by collecting and collating information of water inrush examples of karst tunnels in recent 50 years,the membership function is proposed between the factors and the probability of occurrence of water inrush and its volume,and a FAHP model of risk evaluation for water inrush is established by a comprehensive assigning method which is adopted to determine the weight of evaluation indices;and water inrush risk can be evaluated for the three different stages of tunnel construction.Firstly,based on the preliminary evaluation for environment of dangerous source at the prospecting stage,the risk factors effect and construction of risk reduction can be determinated.Secondly,pre-evaluation of water inrush for environment of dangerous and risk factors can be done in order to prove the effectiveness of construction organization at the design stage.At last,based on distribution of the pre-evaluation results,risk grade can be modified by tracing the hydrogeology,mechanical and geophysical information of exposed rock during the excavation process;and risk control criterion and countermeasures for different excavated sections can be determined by identifying the environment of dangerous source and risk factors for next excavated section;and management system of construction risk can be established in order to get the accurate,effective and real-time risk control of water inrush.The risk management system of water inrush has been proved that the evaluation result is accurate and reliable by its application to three typical karst tunnel of Sanxia highway,which can be further used for other underground projects.