Study on the law of dynamic surface movement and prediction of mining under thick alluvium

In order to study the dynamic subsidence law of ground under thick alluvium, based on the measured data, the evolution law of the surface dynamic movement parameters with the working face advancing was analyzed. The results show that the influence distance of the advance movement of surface, the maximum subsidence velocity of surface and its lag distance increase with the increase of mining distance of the working face. When the working face advances to about 350 m, the increase of the three parameter values decreases and finally stabilizes at 225 m, 34.5 mm/d and 124 m, respectively, thereafter, the curve of surface subsidence velocity moves forward with fixed shape and lag distance from the working face; based on multiple statistical analysis of mining cases in some domestic thick loose layer mining areas, the empirical relations between the maximum surface subsidence velocity and the tangent of its lag angle with geological mining parameters were constructed; finally, combined with the evolution law of the surface dynamic movement parameters, the prediction formula of the subsidence velocity of different points on the main cross section of the ground strike with the working face advancing to any time was constructed. The comparison with the measured value shows that the predicted accuracy can meet the needs of engineering practice.