A Three-zone Structure Loading Model Of Overlying Strata And Its Application On Rockburst Evaluation

Rock burst is one of the main disasters in coal mines.The forecasting and controlling of rock burst are still to be solved.The core concept of rock burst controlling of this paper is "controlling under classification".The method of classification and evaluation of the rock burst based on the relationship between stress and surrounding rock was put forward according to this concept.In order to meet the needs of rock burst controlling,a three-zone structure loading model was established.The mechanism and main influencing factors of rockburst were studied by means of theoretical analysis,case study,mechanical calculation,field application,numerical simulation and engineering analogy.The main innovations are as follows:1)The model of three-zone structure loading model was established.Considering the relationship between the strata boundary condition and the overlying structure,the overlying strata of the stope were divided into "instant loading zone","delayed loading zone" and "static loading zone" according to the different rock loading method.The model realized the continuous expression of the structural features of the heading face,the single working face and the multiple working faces.2)The estimation model of the stress influence range under typical mining boundary condition was established.According to the movement law of the three-zone rock strata during the mining process,the value and distribution of the strike and dip abutment pressure whick applied to the coal during the mining process were calculated.3)The method of calculating the local stability of surrounding rock was put foward.The deformation and failure modes of deep roadway were analyzed.Ten types of space relations of the "roadway-coal seam-rock formation" and its relationship between the impact positions was studied.The rib stability coefficient,roof stability coefficient and floor stability coefficient(i.e.IB,ID,IF)were established to estimate the local stability of surrounding rock.4)The method of evaluation of the rock burst based on the relationship between "three-zone" stress and surrounding rock was put forward.Eight kinds of typical external force along with ten kinds of typical roadway spatial positions were combined to realize the classification of rock burst.The structural stability and local stability of the roadway were estimated by stress superposition and three-zone structure loading model.Combining with the impact tendency,the rock burst hazard could be assessed.The control measures of rock burst under the concept of "controlling under classification" were put forward.Results of this research have been applied widely in Shandong Energy Group and achieved remarkable outcomes.