Influence of goaf on the stability and leakage of reservoir dam foundation

Combined with the engineering geological condition of Yan'an reservoir and a proposed goaf occurrence condition, on the basis of the analysis of the forms and the mechanism of destruction and deformation of goaf of room and pillar mining, the paper analyzes the influence of room and pillar goaf on the stability and leakage of the dam foundation of reservoir. The results of stability analysis show that the goaf is in an unstable state, under action of dam load, the goaf will be "activated" and seriously impact the stability of dam foundation, sluicing culvert and other auxiliary structures. The results of leakage analysis results show that the goaf is a serious impact on the leakage of reservoir. When there is no destruction induced by arch caving and roof collapse at large area in the goaf, the leakage caused by the goaf is 1 671.9 m³/d, about 17.9% of the average annual runoff of reservoir watershed. When arch caving and roof collapse occur at large area in the goaf, the destruction induced by arch caving and roof collapse in the goaf will cause turbulent flow in dam foundation and at the two sides of the dam abutment, a step will occur at the contact zone of the collapse area and non-disturbed zone, at the direction perpendicular to the dam foundation axis, upstream and downstream through cracks or void will be formed, forming piping-induced destruction and causing the instability of the dam body. In view of this, efficient control should be conducted for the dam foundation at the goaf so as to ensure the safety of the construction project.