Research On The Mechanism Of Water Inrush Disaster Caused By Water Pressure Filling Type Karst Cave Roadway

Frequent coal mine water inrush accidents in karst areas have long plagued the safety of mine production.As one of the common karst phenomena,water pressure filling karst cave is the key factor to induce sudden water inrush accident.To reveal the disaster-causing mechanism of water inrush in waterfilled karst caves can provide an important reference for water inrush monitoring and prevention technology.In order to study the mechanism of water inrush in the roadway with water pressure filling type karst cave,this paper takes the water inrush accident in the working face of a coal mine 11609 as the background,analyzes the cause of water inrush accident and expounds the disaster mode of water pressure filling type karst cave on the basis of finding out the hydrogeological conditions of the mine field.The mechanical properties of rock mass with different water content coefficients were studied through physical experiments,and the influence of water on rock mass deterioration was analyzed.Numerical simulation method is used to study the process of water inrush caused by water pressure filling karst cave tunnel,and suggestions for prevention and control measures are put forward.The following conclusions were drawn:(1)Combined with the characteristics of karst cave development and water inrush process,it is concluded that the water pressure filling karst cave above the working face is an important reason for the water inrush accident of 11609 working face.The three disaster-causing stages of hydraulic filling karst cave are further expounded: the disaster-causing source is activated,the water-retaining layer is destroyed,and the filling material gushes out.(2)According to the rock infiltration test and uniaxial compression failure test under different water bearing conditions,it is found that the water absorption rate of limestone in different periods is different,and the limestone specimen spalling phenomenon will occur during the soaking process,which directly reflects the damage caused by water to limestone.The strength and elastic modulus of rock decrease with the increase of soaking time.(3)Based on the analysis of fracture expansion and evolution in the process of water inrush,the evolution process of water inrush channel formed by the fracture penetration of water resisting rock mass is reproduced,and the formation track of water inrush channel is analyzed.In the process of water inrush disaster,the water pressure stored in the karst cave is the fundamental factor leading to the instability and failure of watertight rock mass,while the mining disturbance is the direct factor leading to the release of water pressure.(4)Based on the research results,the mechanism of water inrush disaster of water pressure filled karst roadway is summarized: mining disturbance induces water pressure activation of karst cave,causes stress redistribution,causes water resisting rock mass to germinate cracks,forms fractured rock mass,accelerates crack expansion under fluid solid coupling,and finally forms water inrush channel.The formation of water inrush channel means the occurrence of water inrush disaster.For similar projects,according to the numerical simulation study,the suggestion of adopting drainage and depressurization prevention technology is put forward.