Study On Calculation And Evaluation Method Of Underground Reservoir Capacity In Abandoned Mine

With the development of the times and the continuous mining of coal resources,more and more coal mines in China are facing closure or abandonment due to various reasons,such as low production capacity,resource depletion,etc.Experts and scholars have put forward the strategic concept of transformation and upgrading for these huge coal mine underground space resources,and the underground reservoir is one of the important transformation ways,The establishment of underground reservoirs can provide water resources protection for mining areas with insufficient water resources.Therefore,it is of great significance to carry out research on problems related to abandoned mine underground reservoirs.In this paper,considering the key parameter of underground reservoir storage capacity calculation in abandoned mines — water storage coefficient,a number of influencing factors are comprehensively considered,a numerical simulation scheme is designed based on the orthogonal test method,and a numerical model of movement and fracture evolution of overlying strata under different levels of factors is established.The water storage coefficient of the numerical model is processed and calculated by MATLAB software,and the relationship between the water storage coefficient and the influencing factors is analyzed by the orthogonal test analysis method,and the primary and secondary order,significance level and distribution characteristics of water storage coefficient in stope space of each factor are obtained.The main conclusions are as follows:1.The influence degree of each factor on water storage coefficient is as follows:working face length > coal seam buried depth > hard strata thickness > coal seam thickness > coal seam dip angle > immediate top thickness;The factor level combination of the optimal water storage coefficient is: coal seam thickness 8m,coal seam dip angle 65,working face length 20 m,hard strata thickness 32 m,immediate top thickness 7m and coal seam buried depth 200 m.Coal seam dip angle and hard rock thickness are positively correlated with water storage coefficient,and the water storage coefficient increases with the increase of both.There is a negative correlation between the face size and the water storage coefficient.With the increase of the face length,the water storage coefficient gradually decreases.When the face length exceeds 80 m,the decreasing trend of the water storage coefficient gradually slows down;2.Coal thickness,working face size,hard strata thickness and buried depth have highly significant influence on water storage coefficient.Coal dip angle has a general significant influence on water storage coefficient;The influence of immediate top thickness on water storage coefficient is not significant;3.For coal seams with dip angle ≤ 25,the water storage coefficient in caving zone and water-conducting fracture zone generally decreases gradually from bottom to top;Moreover,if the ratio of hard strata thickness to immediate roof thickness is ≤0.2,that is,when the hard strata is thin and the immediate roof is thick,the development height of cracks in overlying strata is relatively low,and the overall water storage coefficient of stope is relatively small;4.Applying AHP-fuzzy comprehensive evaluation method,the suitability evaluation system of underground reservoir construction in abandoned mines is studied and constructed.In the process of research,the weights of evaluation indexes are obtained,and the subordinate relationship between evaluation indexes and evaluation terms is established.Taking Xiegou Coal Mine as an engineering example,the evaluation system was applied to evaluate it,and the evaluation results were obtained.The first-class indexes of suitability evaluation of abandoned underground reservoir construction are ranked as follows: coal seam geological factors >hydrological factors = safety factors > mining factors;According to the weight,the top five indexes are: coal pillar dam width > geological structure complexity > coal seam hardness > goaf treatment method > dam permeability coefficient.Figure Nineteen Table twenty-four Reference One hundred and eleven...