Study on parameters of probability integral method for predicting surface subsidence in deep mining of weakly cemented overburden

In recent years, the exploitation of coal resources in Inner Mongolia’s Ordos Basin has progressively expanded from its shallow to deep rock strata. The deep overburden at these great depths consist of thick Jurassic-Cretaceous sandstones with weak cementation. The characteristics and patterns of surface subsidence resulting from deep mining differ markedly from those observed in the shallow of the Ordos Basin and eastern Carboniferous-Permian strata in China. The construction of oil and gas pipelines, high-voltage transmission lines, and highways in this region pose challenges to the safe coal mining. Therefore, establishing a mining damage assessment method and parameters suitable for this region has become one of the keys to the safe and efficient extraction of weakly cemented deep mining. It constructs a numerical model based on an analysis of factors influencing surface subsidence and its primary controlling elements in the region. This model is informed by limited data obtained from regional surface movement observation stations, and it is used to calculate surface movement and deformation under varying degrees of mining. Inverse calculations are also conducted to derive the corresponding prediction parameters of probability integral method. Our findings indicate that: ①most coal seams in the region are nearly horizontal, different degrees of mining being the primary factor affecting the predicted parameters of surface subsidence; ②in the prediction parameters of probability integral method, subsidence factor, tangent of major influence angle, and deviation of inflection point are positively correlated with the width-to-depth ratio of the working face, while the horizontal movement coefficient exhibits a negative correlation. On these basis, it performs a function fitting on the prediction parameters and derived an empirical formula that links the subsidence prediction parameters of the probability integral method to different degrees of mining. This formula is subsequently validated using an engine. The research results provide effective technical support for the assessment of mining damage in deep weakly cemented overburden.