Research On The Control Of Overlying Strata’s Subsidence In Backfilling Mining For The Protection Coal Pillar Of Caitun Mine’s Industrial Square

China’s quantity of the coal under buildings, railroads and water bodies （CUBRW） is13.79billion tons by1996and now the quantity is a lot of more because of the developing of thevillages and the founding of the new mines. The mining of the CUBRW is a lot of importancesince China’s urgent energy situation. The backfilling mining is a significant pathway which canmine the CUBRW and make the coal mining to be a kind of green industry. The high-waterexpanding material which was manufactured in1980s attracts more and more attention based onits properties of early strength, adjustable setting time and expanding volume. The method ofnumerical simulation, theoretical simulation and numerical analysis are used to research thevariations of overlying strata and ground in backfilling mining. The main research processes andconclusions are as follows:（1）The backfilling mining is researched through the numerical simulation on thebackground of backfilling mining with the high-water expanding material for the protection coalpillar of Caitun Mine’s industrial square in the paper. It is confirmed that the stope’s stress andstrain resulted from mining are decreased in the backfilling mining. And the displacement andstrain of rock strata and ground are decreased when the backfilling body’s strength is enhanced,but the stress of the backfilling body is increased. The function relationship between backfillingbody compression ratio and stope stress variation coefficient and the function relationshipbetween equivalent mining thickness ratio and ground subsidence coefficient are ascertainedbased on the control variate method. And their parameters’ reference values are given. The bestbackfilling body strength’s evaluated criterion is given based on the relational indexes.（2）The extreme values and contour lines of ground displacement and deformation inCaitun Mine’s backfilling mining are got through the ground subsidence prediction softwarewhich is called as the mining subsidence predicting and mapping system version2.0in the paper.According to the relevant standards the extreme values of ground displacement and deformationare much smaller than the critical value of buildings in level Ⅰdamage.（3）The program which can be used to draw the curves of ground displacement anddeformation on the goaf main section is developed with the Matlab software on the theoreticalbase of probability integral method in the paper. It is the man-machine interactive interface thatmakes the program can be operated easily. And it is the straightforward programming language that makes the program can be improved easily. The relevant curves of this backfilling miningare obtained with this program, which makes sure that this program is practical.（4）Finally, the growing process of displacement and deformation of ground and overlyingstrata is expounded according to the space conservation law in terms of energy.