Research On The Distance Comprehensive Prediction Of Roof Weighting In Fully-mechanized Top Caving In Steeply Seam

Coal has become the economical pillar in western China, as the Chinese Governmentswitches its focus from eastern areas to the west. There is a lot of steeply dipping seam morethan35°in western China,lots of which are thick coal seam by fully-mechanized top cavingmining. So it is meaningful to do a lot of researches on the exploitation of steeply seam.The step distance of roof weighting, is directly related to the rupture pattern and pressurestrength of roof, but also directly related to the support form of work face, density and themanagement method of disposing gob roof, which is one of the most importantparameters.Therefore, the prediction of the step distance and intensity of roof weighting, hasthe important guiding significance for the production management.According to the geological conditions of the seam, which is mined by fully-mechanizedmining with top coal caving,with soft roof,soft floor and soft coal of No.11201working faceof Yao Jie in Gansu coking coal group,application of the engineering analogy method,combined with the physical similarity material simulation, numerical simulation (FLAC3D)and the prediction theory of grey mathematics,we have been research on the distancecomprehensive prediction of roof weighting in fully-mechanized top caving in steeply seam,the results are shown as follow:The working face of steeply seam by fully mechanized top-coal caving in the direction ofabutment,is similar with the horizontal seam about pressure characteristics, migration ofoverlying strata and stress characteristics; the characteristics of abutment pressure in the dipdirection,have the following performance, the peak pressure of coal wall,which is in thefront of working face, is smaller than the part of middle and lower high,and the location isfarther than the others. And the caving form and stress distribution of overburden rock,haveobvious characteristics of the distribution of asymmetry.The advancing speed of working face for the distance of initial pressure is the mostimportant influencing factors, followed by the caving height, the dips of seam, depth,coaldrawing, the roof tensile strength,the tendency length, the mining height, and finally the roof thickness; the dips of seam for the distance of periodic pressure is the most importantinfluencing factors, followed by depth, coal drawing, the tendency length, the advancingspeed of working face, the roof thickness, the caving height, the roof tensile strength,, andfinally the mining height; the dips of seam for the distance of roof weighting is the mostimportant influencing factors, followed by depth, coal drawing, the advancing speed ofworking face, the caving height,,the tendency length, the roof tensile strength, the roofthickness,and finally the mining height.Fully-mechanized caving face for the11201working face of Chang shanzi, applicationsthe model which is built by gray prediction, combined with the experimental results, the roofof the long mountains of coal the initial weighting step prediction interval range (38.88m,49.15m), oldthe top cycle weighting step prediction interval range (11.80m,16.20m).The distance comprehensive prediction of roof weighting in fully-mechanized top cavingin steeply seam,have given the strata features and roof pressure step prediction interval of11201working face in Chang shanzi coalmine, which provides an important parameter forthe control of roof and rock management, and provides a theoretical basis for the selection offace support and support equipment.