Energy response characteristics and dynamic instability mechanism of coal pillar in fully-mechanized top-coal caving face induced by the dynamic and static loads
Aiming at the coal pillar's dynamic instability induced by the high static load and strong dy-namic load in the process of fully-mechanized top-coal caving face,taking Jiangjiahe Coal Mine in Shaanxi Province as the engineering background,adopts theoretical analysis,numerical simulation,lab experiment and field measurement method to study the coal pillar's instability energy criterion,the ultimate energy analytic solution,static load induced coal pillar's stress,limit energy evolution rule and dynamic response characteristics,from the point of energy to clarify the dynamic instability mechanism,and accurate forecasts the dynamic instability danger area.The results show that the coal pillar's dynamic instability should meet the requirement of energy release per unit time＞energy dissipation,while the static instability should meet the requirement of energy release per unit time≤energy dissipation.There is a quadratic positive correlation between the limit energy of coal pillar and the minimum principal stress,and the deepening of coal damage will reduce the limit energy of coal pillar.Under the combination influ-ence of dynamic and static loads,both the stress and elastic energy of coal pillar increase.The mining-in-duced influence range is about 80 m in front of the working face,and the elastic energy of coal pillar in the plastic zone is greater than the limit energy,which verifies the correctness of the theoretical analysis.The negative difference between elastic energy and limit energy is represented as the coal pillar's dynamic instability risk.The greater the negative difference leads the higher the dynamic instability risk.Under dy-namic load,the vertical stress peak value of coal pillar increases from 41.87 MPa to 43.02 MPa,the elas-tic energy peak value increases from 0.22 MJ/m3 to 0.24 MJ/m3,and the plastic zone gradually extends and even cut-through.The maximum negative energy difference is about 0.02 MJ/m3,which is mainly lo-cated at the top and two sides of coal pillar.The peak value of negative energy difference locates about 3.0 m away from the gob side of coal pillar in advance section,which is a high risk area for dynamic instabili-ty of coal pillar.The rationality of the study on dynamic instability mechanism of coal pillar is verified by comparing the monthly microseismic energy events of working face.
dynamic and static loadcoal pillarsenergy responsedynamic instabilitysafe and effi-cient mining
万方数据
维普
