Evaluation on influence of repeated coal mining on the stability and leakage of irrigation canal

In order to evaluate the security of irrigation canal under the influence of repeated coal mining, around the two main lines which are "canal safety" and "coal mining safety", on the basis of the investigation, by means of theoretical analysis, numerical simulation and probability integral method, the deformation characteristics of canal under the influence of repeated mining were analyzed and evaluated. First, from the aspects of the engineering geological structure, hydrogeological structure, strata structure, mining structure and mechanics structure, the structural characteristics of rock and earth mass were analyzed, the variation law of the height of water-flowing fractured zone induced by mining of different seams were analyzed and simulated by using FLAC^3D, at the same time, according to the prediction results of surface movement and deformation, the influence of surface subsidence, tilted deformation and horizontal deformation caused by repeated mining on the dam body of canal was analyzed. The results show that water-flowing fractured zone will not affect the surface water of canal nor the coal mining safety after mining of multiple seams; Repeated mining disturbance will result in canal subsidence to varying degrees, the elevation of dam was reduced from 69.34 m to 65.50 m, the top surface of dam was 1.94 m lower than the designed water surface, the water-flowing cross section was reduced from 580 m² to 196 m², the designed flow will loss by 66%, which affects the safe operation of the canal.