The database of 254 rockburst events was examined for rockburst damage classification using stochastic gradient boosting （SGB） methods. Five potentially relevant indicators including the stress condition factor, the...The database of 254 rockburst events was examined for rockburst damage classification using stochastic gradient boosting （SGB） methods. Five potentially relevant indicators including the stress condition factor, the ground support system capacity, the excavation span, the geological structure and the peak particle velocity of rockburst sites were analyzed. The performance of the model was evaluated using a 10 folds cross-validation （CV） procedure with 80%of original data during modeling, and an external testing set （20%） was employed to validate the prediction performance of the SGB model. Two accuracy measures for multi-class problems were employed： classification accuracy rate and Cohen’s Kappa. The accuracy analysis together with Kappa for the rockburst damage dataset reveals that the SGB model for the prediction of rockburst damage is acceptable.展开更多
The ejection velocity of rock fragments during rock burst, one of the important indexes representing the rock burst strength, is used most conveniently in the supporting design of tunnel with rock burst tendency and i...The ejection velocity of rock fragments during rock burst, one of the important indexes representing the rock burst strength, is used most conveniently in the supporting design of tunnel with rock burst tendency and is often determined by means of observation devices. In order to calculate the average ejection velocity of rock fragments theoretically, the energy of rock burst was divided into damage consuming energy and kinetic energy gained by unit volume of rock firstly, and then the rock burst kinetic proportional coefficient η was brought up which could be determined according to the rock-burst damage energy index W_D , at last the expression of the average ejection velocity of rock fragments during rock burst was obtained and one deep level underground tunnel was researched using the mentioned method. The results show that the calculation method is valid with or without considering the tectonic stress of tunnels, and that the method can be a reference for supporting design of deep mining.展开更多
Innovations of mining technologies were proposed by beneficial utilizations of unfavorable factors such as high geostress,high geotemperature and high mining depth to achieve green mining as mining depth increases ine...Innovations of mining technologies were proposed by beneficial utilizations of unfavorable factors such as high geostress,high geotemperature and high mining depth to achieve green mining as mining depth increases inevitably.Cuttability of deep hard rock was investigated by experimental and regressed analyses to find the reasonable stress adjustment method to improve non-explosive mechanized fragmentation for hard ore-rock.A non-explosive mechanized and intellectualized mining method was proposed to continuously and precisely exploit phosphate underground,which promoted the high-recovery,low-waste and high-efficiency exploitation of phosphate with recovery rate over 90%,dilution rate near 5%and cutting efficiency about 107.7 t/h.A circular economy model and the backfill system were proposed to conduct resource utilizations of solid waste,by which the utilization amount of waste increased year after year.In 2018,the utilization amounts of phosphogypsum,yellow phosphorus slag and waste rock increased to 1853.6×10^3 t/a,291.1×10^3 t/a and 1493.8×10^3 t/a,respectively.展开更多
The rockburst of the poal pillar under a thick hard roof stratum is modelled as the instability failure problem of coal pillars under strata subject to elastic support. The instability mechanism of rockburst is studie...The rockburst of the poal pillar under a thick hard roof stratum is modelled as the instability failure problem of coal pillars under strata subject to elastic support. The instability mechanism of rockburst is studied by applying cusp catastrophic theory. The effects of the stiffness ratio of the system and loads imposed on the system on the rockburst are explicated.The factors affecting rockbursts are discussed. Based on them, the evolution process, the forewarning regularity arid forewarning sings of rockbursts are studied. It is indicated that the subsidence velocity of roof stratum, which increases quickly and tends to infinity, is the forewarning measurable signs of the rockbursts of coal pillar.展开更多
A non-blasting mechanized mining experiment was carried out with a high-frequency impact hammer,and the daily mining performance was recorded to explore the applicability of the high-frequency impact hammer in deep ha...A non-blasting mechanized mining experiment was carried out with a high-frequency impact hammer,and the daily mining performance was recorded to explore the applicability of the high-frequency impact hammer in deep hard rock mines.Before the field application,the scope of the excavation damage zone was monitored,and rock samples were obtained from the ore body to be mined to carry out a series of laboratory experiments.Field application results show that the overall excavation efficiency reaches 50.6 t/h,and the efficiency of pillar excavation after excavating stress relief slot reaches 158.2 t/h.The results indicate that the non-blasting mechanized mining using high-frequency impact hammer has a good application in deep hard rock mines,and the stress relief slot is conducive to mechanical excavation.In addition,the high-frequency impact hammer also exhibits the advantages of high utilization rate of labor hours,small lumpiness of spalling ore,little dust,and little excavation damage.Finally,according to the field application and laboratory experiment results,a non-blasting mechanized mining method for hard rock mines based on high-frequency impact hammer is proposed.展开更多
The stress hardening characteristics of the reinforced rock mass in uniaxial compression tests were revealed by means of the experimental study on mechanical characteristics of cracked rock mass reinforced by bolting ...The stress hardening characteristics of the reinforced rock mass in uniaxial compression tests were revealed by means of the experimental study on mechanical characteristics of cracked rock mass reinforced by bolting and grouting. And the load-beating mechanism of the reinforced rock mass was perfectly reflected by the experiment. The results can offer some useful advice for support design and stability analysis of deep drifts in unstable strata.展开更多
Based on the geological condition of Zhangxiaolou deep mine in Xuzhou mining area, under 986 m in depth, 20.6-31.6 MPa in maximum horizontal principal stress, and friable and fractured surrounding rock, test researche...Based on the geological condition of Zhangxiaolou deep mine in Xuzhou mining area, under 986 m in depth, 20.6-31.6 MPa in maximum horizontal principal stress, and friable and fractured surrounding rock, test researches on partial relieving pressure were completed for the entry with U-steel arched yielding support. The relieving pressure parameters, technology process and results of springing blasting by boreholes and excavating pockets in the two sides of entry were introduced. It is demonstrated that springing will not be shaped under the condition of single borehole arrangement after exploded, the arrangement by a group, it will make borehole bottom form springing in 0.6-0.8 m in diameter, that convergence of two sides and roof to floor have some increments by using springing blasting for reliving pressure. This kind of method for reliving pressure is not suitable to use in the deep mine, and that the convergence of two sides obviously declined by excavating pocket in two sides, it can be still used in the entry with metal support, while maintenance of entry in deep mines is difficult, and can not be supported by bolt or bolt with wire mesh.展开更多
基金Project(2015CX005)supported by the Innovation Driven Plan of Central South University of ChinaProject supported by the Sheng Hua Lie Ying Program of Central South University,China
文摘The database of 254 rockburst events was examined for rockburst damage classification using stochastic gradient boosting （SGB） methods. Five potentially relevant indicators including the stress condition factor, the ground support system capacity, the excavation span, the geological structure and the peak particle velocity of rockburst sites were analyzed. The performance of the model was evaluated using a 10 folds cross-validation （CV） procedure with 80%of original data during modeling, and an external testing set （20%） was employed to validate the prediction performance of the SGB model. Two accuracy measures for multi-class problems were employed： classification accuracy rate and Cohen’s Kappa. The accuracy analysis together with Kappa for the rockburst damage dataset reveals that the SGB model for the prediction of rockburst damage is acceptable.
文摘The ejection velocity of rock fragments during rock burst, one of the important indexes representing the rock burst strength, is used most conveniently in the supporting design of tunnel with rock burst tendency and is often determined by means of observation devices. In order to calculate the average ejection velocity of rock fragments theoretically, the energy of rock burst was divided into damage consuming energy and kinetic energy gained by unit volume of rock firstly, and then the rock burst kinetic proportional coefficient η was brought up which could be determined according to the rock-burst damage energy index W_D , at last the expression of the average ejection velocity of rock fragments during rock burst was obtained and one deep level underground tunnel was researched using the mentioned method. The results show that the calculation method is valid with or without considering the tectonic stress of tunnels, and that the method can be a reference for supporting design of deep mining.
基金Projects(41630642,51904335,51904333)supported by the National Natural Science Foundation of China
文摘Innovations of mining technologies were proposed by beneficial utilizations of unfavorable factors such as high geostress,high geotemperature and high mining depth to achieve green mining as mining depth increases inevitably.Cuttability of deep hard rock was investigated by experimental and regressed analyses to find the reasonable stress adjustment method to improve non-explosive mechanized fragmentation for hard ore-rock.A non-explosive mechanized and intellectualized mining method was proposed to continuously and precisely exploit phosphate underground,which promoted the high-recovery,low-waste and high-efficiency exploitation of phosphate with recovery rate over 90%,dilution rate near 5%and cutting efficiency about 107.7 t/h.A circular economy model and the backfill system were proposed to conduct resource utilizations of solid waste,by which the utilization amount of waste increased year after year.In 2018,the utilization amounts of phosphogypsum,yellow phosphorus slag and waste rock increased to 1853.6×10^3 t/a,291.1×10^3 t/a and 1493.8×10^3 t/a,respectively.
文摘The rockburst of the poal pillar under a thick hard roof stratum is modelled as the instability failure problem of coal pillars under strata subject to elastic support. The instability mechanism of rockburst is studied by applying cusp catastrophic theory. The effects of the stiffness ratio of the system and loads imposed on the system on the rockburst are explicated.The factors affecting rockbursts are discussed. Based on them, the evolution process, the forewarning regularity arid forewarning sings of rockbursts are studied. It is indicated that the subsidence velocity of roof stratum, which increases quickly and tends to infinity, is the forewarning measurable signs of the rockbursts of coal pillar.
基金supported by the National Natural Science Foundation of China (Nos. 52174099, 51904333)the Natural Science Foundation of Hunan Province, China (No. 2021JJ30842)
文摘A non-blasting mechanized mining experiment was carried out with a high-frequency impact hammer,and the daily mining performance was recorded to explore the applicability of the high-frequency impact hammer in deep hard rock mines.Before the field application,the scope of the excavation damage zone was monitored,and rock samples were obtained from the ore body to be mined to carry out a series of laboratory experiments.Field application results show that the overall excavation efficiency reaches 50.6 t/h,and the efficiency of pillar excavation after excavating stress relief slot reaches 158.2 t/h.The results indicate that the non-blasting mechanized mining using high-frequency impact hammer has a good application in deep hard rock mines,and the stress relief slot is conducive to mechanical excavation.In addition,the high-frequency impact hammer also exhibits the advantages of high utilization rate of labor hours,small lumpiness of spalling ore,little dust,and little excavation damage.Finally,according to the field application and laboratory experiment results,a non-blasting mechanized mining method for hard rock mines based on high-frequency impact hammer is proposed.
基金Projects50490273 and 50474063 supported by National Natural Science Foundation of China
文摘The stress hardening characteristics of the reinforced rock mass in uniaxial compression tests were revealed by means of the experimental study on mechanical characteristics of cracked rock mass reinforced by bolting and grouting. And the load-beating mechanism of the reinforced rock mass was perfectly reflected by the experiment. The results can offer some useful advice for support design and stability analysis of deep drifts in unstable strata.
基金Supported by the Key Project of the National Natural Science Foundation （50490273）
文摘Based on the geological condition of Zhangxiaolou deep mine in Xuzhou mining area, under 986 m in depth, 20.6-31.6 MPa in maximum horizontal principal stress, and friable and fractured surrounding rock, test researches on partial relieving pressure were completed for the entry with U-steel arched yielding support. The relieving pressure parameters, technology process and results of springing blasting by boreholes and excavating pockets in the two sides of entry were introduced. It is demonstrated that springing will not be shaped under the condition of single borehole arrangement after exploded, the arrangement by a group, it will make borehole bottom form springing in 0.6-0.8 m in diameter, that convergence of two sides and roof to floor have some increments by using springing blasting for reliving pressure. This kind of method for reliving pressure is not suitable to use in the deep mine, and that the convergence of two sides obviously declined by excavating pocket in two sides, it can be still used in the entry with metal support, while maintenance of entry in deep mines is difficult, and can not be supported by bolt or bolt with wire mesh.
