Research On Mining Subsidence Laws In Shaanxi Loess Gully Region

In the loess gully coal mining area of Shaanxi, as the topography is complex and the thickness of loess layer is great, the ground deformation has special properties by underground mining. Thorough researches on mining subsidence laws have significant value for the safe coal mining in western mining areas.Based on the surface subsidence observed data of Weibei mining area, the mining subsidence laws and particularity is revealed through similar material model experiment and Flac numerical simulation. This paper mainly studies the mining subsidence laws in the soil layers and the features about the surface mining slip in loess gully region.The main achievements of this paper are shown as follows:(1) Surface movement and deformation in loess mining area has the main characteristics of fast development, fast stability and short active period. The thickness of loess layer is the most important factor in the laws of surface dynamic movement, and has certain relevance with surface movement parameters. The lateral slipping of slope by mining in loess gully region is the important feature of the surface movement and deformation in Weibei mining area.(2) In the mining areas of thick loess layer and thin bedrock layer, the subsidence deformation of loess layer will keep synchronous movement with the bedrock subsidence. Compared with the bedrock layers, mining impacting rate in loess layer is obviously fast than the rate in bedrock layer, subsidence factor is larger than the factor in bedrock layer, subsidence attenuation and vertical separation have the growth degree to be low, and surface movement appears asymmetric above the coal pillars and the mined-out area.(3) Generally, the loess has an affection of equivalent load effect to the bedrock mining, which is smaller than gravity load of loess and changes with width depth ratio of mining (mining degree) and gravity of loess layer (thickness of loess layer). Meanwhile, this paper composes a quantitative relationship between the equivalent load with the thickness of loess layer and the width depth ratio of mining.(4) In the areas of Loess Mountains, the effect of the mining intensity and time is different at the slope's different parts, which has different affects on mining subsidence and slope plastic sliding. Under the direction of positive slope conditions that the direction of surface tendency is consistent with the slope direction of the mining subsidence, sliding deformation will increase the slope's mining subsidence deformation, but under the reverse slope's direction conditions that the direction of surface tendency is opposite to the slope direction of the mining subsidence, sliding deformation will decrease the slope's mining subsidence deformation.