Fuzzy Comprehensive Evaluation for Stability of Strata over Gob Influenced by Construction Loads

Due to the development of cities and towns, the shortage of constructible land becomes a serious problem for public. Thus, lots of industrial and residential buildings have to be built within mining subsidence areas. Such these construction works may break the relative balance of overburden strata over gobs and active the strata with secondary deformations and movements, and surface constructions would be induced to subside, partial crack and tilt even fall down. Hence, the foundations of these constructions are more complicated than any others due to their special geological conditions. Generally, a number of influence factors could control the mining subsidence process, and they are also difficult to describe with a quantitative point. The limits for different corresponding stability levels are also too vague to identify (stability level itself is not restricted.). Therefore, classical mathematical method or mechanics model could not be used here to treat this problem. In this paper, based on fuzzy mathematics, some key question such as establishing the assessment index system, calculating the weighting factors and building the membership functions are discussed. Finally, a fuzzy comprehensive evaluation model for stability of strata over gob affected by surface construction loads is established. It is a beneficial attempt to apply the fuzzy method in this research field. It evolves the mining subsidence area stability evaluation from the traditional qualitative description or the semiquantitative analysis, into the combination of qualitative and quantitative methods, and makes the entire evaluation process to become a quantitative calculation and analysis,which can provide a more scientific results for using the surface land in mining subsidence areas