The existing bypotheses of coal and gas outburst mechanism are all based on the elasticity mechanies. Since they have not taken time factor into eonsideration, these hypotheses can not give a satisfactory explanation ...The existing bypotheses of coal and gas outburst mechanism are all based on the elasticity mechanies. Since they have not taken time factor into eonsideration, these hypotheses can not give a satisfactory explanation of the oceurrence and development of the outburst. A creep mathematital model of gas-contaming coal,which can better expdri the phenomenon of coal and methane outbursts,has been set up through creep tests and analyses under the condition of triaxiai compression.The tests have proved that there isn’ t essential difference between the rheological properties of outburst prone coal and non-outburst prone coal. Outburst can happen in any kind of coal if the rheologicai conditions exist. The creep mathematital model provides a soild foundation for establlshing a comprebcnsive criterion of coal and gas outburst.展开更多
Further evidences show that most mining dynamic disasters are mainly oc- curred nearby NNE and near SN geological structures.In-situ stress measurement in Fuxin basin shows that the orientation of major compressed str...Further evidences show that most mining dynamic disasters are mainly oc- curred nearby NNE and near SN geological structures.In-situ stress measurement in Fuxin basin shows that the orientation of major compressed stress is near EW.At this stress field,geological structures with deferent strike have deferent stress state and dis- place mode.NNE and near SN geological structures are compressed to thrust and come into being high stress zone.NWW and NEE geological structures are tensile to separate and not prone to being low stress zone.NW structure is intervenient of them.So NEE and near SN structures are easy to occurre mining dynamic disasters and NWW and NEE structures is 'safety' comparatively.The mining dynamic disaster is controlled by stress state of geologic structure,which is determined by its strike.展开更多
In line with the sensitivity of coal drillings temperature and coalbed temperature to the dangerous zone of coal and gas outburst, two temperature sensitive indexes (△Tm, △tm) for forecasting dangerousness of coal f...In line with the sensitivity of coal drillings temperature and coalbed temperature to the dangerous zone of coal and gas outburst, two temperature sensitive indexes (△Tm, △tm) for forecasting dangerousness of coal face and heading face outburst are defined, and deal with the foundation on drillings and coalbed temperatures used as sensitive indexes and the principle and method of determining drillings and coalbed temperatures. On the basis of this, we put forward the method for forecasting dangerousness of coal face and heading face outburst by two temperature sensitive indexes and determine the critical values of two temperature sensitive indexes (△Tm= 5.5℃, △tm = 4.5℃) by in-situ observation and requirement for determining sensitive index.展开更多
Based on the study of regional displaying rules of coal and gas outburst controlled by geological structure in Pingdingshan mining area, the geological structure features in outburst sites were investigated emphatical...Based on the study of regional displaying rules of coal and gas outburst controlled by geological structure in Pingdingshan mining area, the geological structure features in outburst sites were investigated emphatically. The combination type, orientation and least seam thickness in outburst sites were put forward. This research provides a geological mark for forecasting gas outbursts in deep mining.展开更多
Based on the damage analysis of elliptical aperture,the mechanism of coal damagein the developing process of coal and gas outburst was researched.The results show thatthe damage to coal by gas is mainly caused by the ...Based on the damage analysis of elliptical aperture,the mechanism of coal damagein the developing process of coal and gas outburst was researched.The results show thatthe damage to coal by gas is mainly caused by the concentrated tensile stress appearing nearthe endpoint of the pores.Fractures in coal,gas pressure,ground stress and the tensilestrength of the coal matrix are the major controlling factors of this kind of damage.When theground stress releases abruptly and the gas pressure is high,tensile failure will occur aroundthe endpoint of the small pores due to gas pressure,and the coal may be broken up like powder;this is called pulverization.Otherwise,when the gas pressure is low,the tensile stress canonly occur around the endpoint of the large pores and fractures due to gas pressure,the fracturesin coal extend and link together,the fracture extension direction is statistically perpendicularto the direction of the minor principal stress.This kind of damage is shown as the stratifiedspall around the outburst hole.展开更多
In order to explain the mechanism for gas outburst, the process of evolving fractures in coal seams is described using system dynamics with variable boundaries. We discuss the failure modes of coal containing gas and ...In order to explain the mechanism for gas outburst, the process of evolving fractures in coal seams is described using system dynamics with variable boundaries. We discuss the failure modes of coal containing gas and then established the flow rules after failure. The condition under which states of deformation convert is presented and the manner in which these convert is proposed. In the end, the process of gas outbursts is explained in detail. It shows that a gas outburst is a process in which the boundaries of coal seams are variable because of coal failure. If the fractures are not connected or even closed owing to coal/rock stress, fractured zones will retain a certain level of carrying capacity because of the self-sealing gas pressure. When the accumulation of gas energy reaches its limit, coal seams will become unstable and gas outbursts take place.展开更多
Based on the statistical data of 26 outburst prone coal seams in China, this paper presents the relationship among the threshold gas pressure in coal and gas outburst and the volatile content and hardness of coal by m...Based on the statistical data of 26 outburst prone coal seams in China, this paper presents the relationship among the threshold gas pressure in coal and gas outburst and the volatile content and hardness of coal by mathematical statistics. The threshold value of gas pressure for outburst pmin in MPa may be calculated by formula Pmin =5(0. 1+0. 07Kf), where / is the hardness and V the volatile content (%) of a soft bed. In China, the value of Pmin of some outburst prone coal seams ranges from 0. 57 to 0. 1 MPa.展开更多
文摘The existing bypotheses of coal and gas outburst mechanism are all based on the elasticity mechanies. Since they have not taken time factor into eonsideration, these hypotheses can not give a satisfactory explanation of the oceurrence and development of the outburst. A creep mathematital model of gas-contaming coal,which can better expdri the phenomenon of coal and methane outbursts,has been set up through creep tests and analyses under the condition of triaxiai compression.The tests have proved that there isn’ t essential difference between the rheological properties of outburst prone coal and non-outburst prone coal. Outburst can happen in any kind of coal if the rheologicai conditions exist. The creep mathematital model provides a soild foundation for establlshing a comprebcnsive criterion of coal and gas outburst.
基金the Major State Basic Research Development Program of China"973"Program(2005CB221501)the General Project of the National Natural Science Foundation of PR China(50574047)
文摘Further evidences show that most mining dynamic disasters are mainly oc- curred nearby NNE and near SN geological structures.In-situ stress measurement in Fuxin basin shows that the orientation of major compressed stress is near EW.At this stress field,geological structures with deferent strike have deferent stress state and dis- place mode.NNE and near SN geological structures are compressed to thrust and come into being high stress zone.NWW and NEE geological structures are tensile to separate and not prone to being low stress zone.NW structure is intervenient of them.So NEE and near SN structures are easy to occurre mining dynamic disasters and NWW and NEE structures is 'safety' comparatively.The mining dynamic disaster is controlled by stress state of geologic structure,which is determined by its strike.
文摘In line with the sensitivity of coal drillings temperature and coalbed temperature to the dangerous zone of coal and gas outburst, two temperature sensitive indexes (△Tm, △tm) for forecasting dangerousness of coal face and heading face outburst are defined, and deal with the foundation on drillings and coalbed temperatures used as sensitive indexes and the principle and method of determining drillings and coalbed temperatures. On the basis of this, we put forward the method for forecasting dangerousness of coal face and heading face outburst by two temperature sensitive indexes and determine the critical values of two temperature sensitive indexes (△Tm= 5.5℃, △tm = 4.5℃) by in-situ observation and requirement for determining sensitive index.
基金National Natural Science Foundation of China(4 0 0 0 2 0 10 ) and Research Fund for Doctoral Program of Higher Edu-cation (92 2 90 0 8)
文摘Based on the study of regional displaying rules of coal and gas outburst controlled by geological structure in Pingdingshan mining area, the geological structure features in outburst sites were investigated emphatically. The combination type, orientation and least seam thickness in outburst sites were put forward. This research provides a geological mark for forecasting gas outbursts in deep mining.
基金Supported by the National Basic Research Program(973)of China(2005CB221503)the Key Project of Natural Science Foundation of China(50534080)
文摘Based on the damage analysis of elliptical aperture,the mechanism of coal damagein the developing process of coal and gas outburst was researched.The results show thatthe damage to coal by gas is mainly caused by the concentrated tensile stress appearing nearthe endpoint of the pores.Fractures in coal,gas pressure,ground stress and the tensilestrength of the coal matrix are the major controlling factors of this kind of damage.When theground stress releases abruptly and the gas pressure is high,tensile failure will occur aroundthe endpoint of the small pores due to gas pressure,and the coal may be broken up like powder;this is called pulverization.Otherwise,when the gas pressure is low,the tensile stress canonly occur around the endpoint of the large pores and fractures due to gas pressure,the fracturesin coal extend and link together,the fracture extension direction is statistically perpendicularto the direction of the minor principal stress.This kind of damage is shown as the stratifiedspall around the outburst hole.
基金financial support from the National Basic Research Program of China (No.2005CB221500)the National Natural Science Foundation of China (Nos.50534049,50674087 and 50974107)the Natural Science Foundation of Jiangsu Province (No.BK2007029)
文摘In order to explain the mechanism for gas outburst, the process of evolving fractures in coal seams is described using system dynamics with variable boundaries. We discuss the failure modes of coal containing gas and then established the flow rules after failure. The condition under which states of deformation convert is presented and the manner in which these convert is proposed. In the end, the process of gas outbursts is explained in detail. It shows that a gas outburst is a process in which the boundaries of coal seams are variable because of coal failure. If the fractures are not connected or even closed owing to coal/rock stress, fractured zones will retain a certain level of carrying capacity because of the self-sealing gas pressure. When the accumulation of gas energy reaches its limit, coal seams will become unstable and gas outbursts take place.
文摘Based on the statistical data of 26 outburst prone coal seams in China, this paper presents the relationship among the threshold gas pressure in coal and gas outburst and the volatile content and hardness of coal by mathematical statistics. The threshold value of gas pressure for outburst pmin in MPa may be calculated by formula Pmin =5(0. 1+0. 07Kf), where / is the hardness and V the volatile content (%) of a soft bed. In China, the value of Pmin of some outburst prone coal seams ranges from 0. 57 to 0. 1 MPa.
