Olivine phenocryst compositions and whole-rock chemical compositions are used to identify primitive picrite basalts from the early part of flood basalt successions in the western part of the Emeishan large igneous pro...Olivine phenocryst compositions and whole-rock chemical compositions are used to identify primitive picrite basalts from the early part of flood basalt successions in the western part of the Emeishan large igneous province （ELIP）, southwestern China. The Fo contents of olivine phenocrysts of komatiites with MgO-21.79 wt% range from 85.2% to 91.4%. The composition of unerupted parental melts is calculated from the compositions of the most Fo-rich olivine phenocrysts. These melts had -22 wt% MgO, and originated in mantle with a potential temperature of -1600℃ and at about 4.2 GPa pressure, supporting the conclusion that the generation of ELIP can be attributed to melting of a plume head beginning at -138 km depth.展开更多
This paper reviews underground mining methods for total thickness of a thick coal seam in single lift （TI＇rCSSL）. Review shows the required engineering for extraction of thick seams needs to be fitted with thicknes...This paper reviews underground mining methods for total thickness of a thick coal seam in single lift （TI＇rCSSL）. Review shows the required engineering for extraction of thick seams needs to be fitted with thickness of the seam, behavior of rock-mass and surrounding stress conditions for efficient mining. Variants of TI＇rCSSL are able to extract a maximum 10-12 m thickness only. An improvement in bending moment of the overlying coal band in longwall top coal caving （LTCC） provides better under-winning opportunity for the roof coal band. An acceptable limit of 25 MPa compressive strength of coal for the success of LTCC may be increased under favorable geo-technical conditions. Bord and pillar in India adopted induced caving of roof coal band for single lift depillaring of total thickness （SLDTr） of a compe- tent thick coal seam developed along floor. Case studies are given to arrest the adverse effects of extrac- tion height on pillars.展开更多
The methods combined by test, field monitoring and theoretical analysis were adopted to do the systemic research on the rock mass from micro-structure to macro-deformation, and rheological model of Jinchuan rock mass ...The methods combined by test, field monitoring and theoretical analysis were adopted to do the systemic research on the rock mass from micro-structure to macro-deformation, and rheological model of Jinchuan rock mass was established to discuss the reasonable supporting time. Resuhs show that supporting after suitable stress and displacement release can benefit for the long-term stability of surrounding rock.展开更多
To establish the movement relationship for the roof breaking under shallow mining conditions, the mechanical model of the roof rock beam was built, then the structure instability process of the roof rock beam was anal...To establish the movement relationship for the roof breaking under shallow mining conditions, the mechanical model of the roof rock beam was built, then the structure instability process of the roof rock beam was analyzed. The changing criterion of the vertical displacement was established and the relationship between the deflection and the rotary motion of roof block was determined. Regarding a mining face in Shangwan Mine, the responsing laws of the deflection and horizontal thrust of the roof rock beam were obtained through FLAC3D numerical analysis. The results show that the structure instability of the cracked roof rock beam depends on the interaction between the vertical load and the horizontal thrust.For the roof rock beam, when the vertical load keeps constant, the horizontal thrust fluctuating rises with increasing deflection. The horizontal thrust increases constantly with the deeper buried depth and the smaller span.展开更多
Development of failure in brittle materials is associated with microcracks,which release energy in the form of elastic waves called acoustic emissions. This paper presents results from acoustic emission measurements o...Development of failure in brittle materials is associated with microcracks,which release energy in the form of elastic waves called acoustic emissions. This paper presents results from acoustic emission measurements obtained during three point bending tests on Nestos marble under laboratory conditions.Acoustic emission activity was monitored using piezoelectric acoustic emission sensors,and the potential for accurate prediction of rock damage based on acoustic emission data was investigated. Damage localization was determined based on acoustic emissions generated from the critically stressed region as scattered events at stresses below and close to the strength of the material.展开更多
After water is impounded in a reservoir, rock mass in the hydro-fluctuation belt of the reservoir bank slope is subject to water saturation- dehydration circulation （WSDC）. To quantify the rate of change of rock mec...After water is impounded in a reservoir, rock mass in the hydro-fluctuation belt of the reservoir bank slope is subject to water saturation- dehydration circulation （WSDC）. To quantify the rate of change of rock mechanical properties, samples from the Longtan dam area were measured with uniaxial compression tests after different numbers （1, 5, 10, 15, and 20） of simulated WSDC cycles. Based on the curves derived from these tests, a modified Hock- Brown failure criterion was proposed, in which a new parameter was introduced to model the cumulative damage to rocks after WSDC. A case of an engineering application was analyzed, and the results showed that the modified Hock-Brown failure criterion is useful. Under similar WSDC-influenced engineering and geological conditions, rock mass strength parameters required for analysis and evaluation of rock slope stability can be estimated according to this modified Hoek-Brown failure criterion.展开更多
Cooling energy needs, for mines in Northern Ontario, are mainly driven by the mining depth and its operation. Part I of this research focusses on the thermal energy loads in deep mines as a result of the virgin rock t...Cooling energy needs, for mines in Northern Ontario, are mainly driven by the mining depth and its operation. Part I of this research focusses on the thermal energy loads in deep mines as a result of the virgin rock temperature, mining operations and climatic conditions. A breakdown of the various heat sources is outlined, for an underground mine producing 3500 tonnes per day of broken rock, taking into consideration the latent and sensible portions of that heat to properly assess the wet bulb global temperature. The resulting thermal loads indicate that cooling efforts would be needed both at surface and underground to maintain the temperature underground within the legal threshold. In winter the air might also have to be heated at surface and cooled underground, to ensure that icing does not occur in the inlet ventilation shaft-the main reason why coolin~ cannot be focussed solely at surface.展开更多
Rock fall related accidents continue to occur in coal mines,although artificial support mechanisms have been used extensively. Roof stability is primarily determined in many underground mines by a limited number of me...Rock fall related accidents continue to occur in coal mines,although artificial support mechanisms have been used extensively. Roof stability is primarily determined in many underground mines by a limited number of methods that often resort to subjective criteria. It is argued in this paper that stability conditions of mine roof strata,as a key factor in sustainability in coal mines,must be determined by a survey which proactively investigates fundamental aspects of said mine. Failure of rock around the opening happens as a result of both high rock stress conditions and the presence of structural discontinuities. The properties of such discontinuities affect the engineering behavior of rock masses causing wedges or blocks to fall from the roof or sliding out of the walls. A practical rule-based approach to assess the risk of a roof fall is proposed in the paper. The method is based on the analysis of structural data and the geometry and stability of wedges in underground coal mines. In this regard,an accident causing a huge collapse in a coal mine leading to 4 fatalities is illustrated by way of a case study. Horizontal and vertical profiles are prepared by geophysical methods to define the falling zone and its boundaries. The collapse is then modeled by the use of sophisticated computer programs in order to identify the causes of the accident.展开更多
The non-coupled charge explosion and geo-mechanical dynamics problem in real air condition is studied in this paper. It analyzes and calculates the problem by using the real air state equations. Through researching on...The non-coupled charge explosion and geo-mechanical dynamics problem in real air condition is studied in this paper. It analyzes and calculates the problem by using the real air state equations. Through researching on the non-coupled charge rock bench blasting with big clearance of air, its result indicates that the borehole wall reflection overpressure is far higher than strength of rock, but much lower than detonation front pressure of the charge. So non-coupled charge explosion blasting engineering is very successful. Furthermore, it introduces the method of shaft forming by blasting once and the new tube room technology. And the non-coupled charge explosion is used successfully in the method of shaft forming by blasting once. As it drills and blasts in the top and removes the broken rock from the bottom tunnel, it increases the construction efficiency significantly. This paper has important reference on the improvement of the large-span underground engineering construction.展开更多
文摘Olivine phenocryst compositions and whole-rock chemical compositions are used to identify primitive picrite basalts from the early part of flood basalt successions in the western part of the Emeishan large igneous province （ELIP）, southwestern China. The Fo contents of olivine phenocrysts of komatiites with MgO-21.79 wt% range from 85.2% to 91.4%. The composition of unerupted parental melts is calculated from the compositions of the most Fo-rich olivine phenocrysts. These melts had -22 wt% MgO, and originated in mantle with a potential temperature of -1600℃ and at about 4.2 GPa pressure, supporting the conclusion that the generation of ELIP can be attributed to melting of a plume head beginning at -138 km depth.
基金funded by the Singareni Collieries Company Limited (SCCL)the support of Department of Mining Engineering, ISM for making use of different facilities
文摘This paper reviews underground mining methods for total thickness of a thick coal seam in single lift （TI＇rCSSL）. Review shows the required engineering for extraction of thick seams needs to be fitted with thickness of the seam, behavior of rock-mass and surrounding stress conditions for efficient mining. Variants of TI＇rCSSL are able to extract a maximum 10-12 m thickness only. An improvement in bending moment of the overlying coal band in longwall top coal caving （LTCC） provides better under-winning opportunity for the roof coal band. An acceptable limit of 25 MPa compressive strength of coal for the success of LTCC may be increased under favorable geo-technical conditions. Bord and pillar in India adopted induced caving of roof coal band for single lift depillaring of total thickness （SLDTr） of a compe- tent thick coal seam developed along floor. Case studies are given to arrest the adverse effects of extrac- tion height on pillars.
文摘The methods combined by test, field monitoring and theoretical analysis were adopted to do the systemic research on the rock mass from micro-structure to macro-deformation, and rheological model of Jinchuan rock mass was established to discuss the reasonable supporting time. Resuhs show that supporting after suitable stress and displacement release can benefit for the long-term stability of surrounding rock.
基金supported by the National Natural Science Foundation of China (Nos. 51474188, 51074140, and 51774112)the Natural Science Foundation of Hebei Province of China (No. E2014203012)+4 种基金the International Cooperation Project of Henan Science and Technology Department (No. 182102410060)International Cooperative Talent Project of Henan Province (No. 2016GH22)the Doctoral Fund of Henan Polytechnic University of China (No. B2015-67)the Research Fund of State and Local Joint Engineering Laboratory for Gas Drainage & Ground Control of Deep Mines (Henan Polytechnic niversity)of China (No. G201614)Taihang Scholars Program
文摘To establish the movement relationship for the roof breaking under shallow mining conditions, the mechanical model of the roof rock beam was built, then the structure instability process of the roof rock beam was analyzed. The changing criterion of the vertical displacement was established and the relationship between the deflection and the rotary motion of roof block was determined. Regarding a mining face in Shangwan Mine, the responsing laws of the deflection and horizontal thrust of the roof rock beam were obtained through FLAC3D numerical analysis. The results show that the structure instability of the cracked roof rock beam depends on the interaction between the vertical load and the horizontal thrust.For the roof rock beam, when the vertical load keeps constant, the horizontal thrust fluctuating rises with increasing deflection. The horizontal thrust increases constantly with the deeper buried depth and the smaller span.
基金supported by the THALES Program of the Ministry of Education of Greecethe European Union in the framework of the project ‘‘Integrated understanding of Seismicity,using innovative methodologies of Fracture Mechanics along with Earthquake and Non-Extensive Statistical Physics-Application to the geodynamic system of the Hellenic Arc-SEISMO FEAR HELLARC"
文摘Development of failure in brittle materials is associated with microcracks,which release energy in the form of elastic waves called acoustic emissions. This paper presents results from acoustic emission measurements obtained during three point bending tests on Nestos marble under laboratory conditions.Acoustic emission activity was monitored using piezoelectric acoustic emission sensors,and the potential for accurate prediction of rock damage based on acoustic emission data was investigated. Damage localization was determined based on acoustic emissions generated from the critically stressed region as scattered events at stresses below and close to the strength of the material.
基金supported by the National Natural Science Foundation of China under No. 41630639the National Basic Research Program of China (2014CB744703)+1 种基金Natural Science Basic Research Plan in Shaanxi Province of China (No. 2016JQ4014)China Postdoctoral Science Foundation (2016M602743)
文摘After water is impounded in a reservoir, rock mass in the hydro-fluctuation belt of the reservoir bank slope is subject to water saturation- dehydration circulation （WSDC）. To quantify the rate of change of rock mechanical properties, samples from the Longtan dam area were measured with uniaxial compression tests after different numbers （1, 5, 10, 15, and 20） of simulated WSDC cycles. Based on the curves derived from these tests, a modified Hock- Brown failure criterion was proposed, in which a new parameter was introduced to model the cumulative damage to rocks after WSDC. A case of an engineering application was analyzed, and the results showed that the modified Hock-Brown failure criterion is useful. Under similar WSDC-influenced engineering and geological conditions, rock mass strength parameters required for analysis and evaluation of rock slope stability can be estimated according to this modified Hoek-Brown failure criterion.
基金CEMI (Centre for Excellence in Mining Innovation) for their funding to support this research
文摘Cooling energy needs, for mines in Northern Ontario, are mainly driven by the mining depth and its operation. Part I of this research focusses on the thermal energy loads in deep mines as a result of the virgin rock temperature, mining operations and climatic conditions. A breakdown of the various heat sources is outlined, for an underground mine producing 3500 tonnes per day of broken rock, taking into consideration the latent and sensible portions of that heat to properly assess the wet bulb global temperature. The resulting thermal loads indicate that cooling efforts would be needed both at surface and underground to maintain the temperature underground within the legal threshold. In winter the air might also have to be heated at surface and cooled underground, to ensure that icing does not occur in the inlet ventilation shaft-the main reason why coolin~ cannot be focussed solely at surface.
文摘Rock fall related accidents continue to occur in coal mines,although artificial support mechanisms have been used extensively. Roof stability is primarily determined in many underground mines by a limited number of methods that often resort to subjective criteria. It is argued in this paper that stability conditions of mine roof strata,as a key factor in sustainability in coal mines,must be determined by a survey which proactively investigates fundamental aspects of said mine. Failure of rock around the opening happens as a result of both high rock stress conditions and the presence of structural discontinuities. The properties of such discontinuities affect the engineering behavior of rock masses causing wedges or blocks to fall from the roof or sliding out of the walls. A practical rule-based approach to assess the risk of a roof fall is proposed in the paper. The method is based on the analysis of structural data and the geometry and stability of wedges in underground coal mines. In this regard,an accident causing a huge collapse in a coal mine leading to 4 fatalities is illustrated by way of a case study. Horizontal and vertical profiles are prepared by geophysical methods to define the falling zone and its boundaries. The collapse is then modeled by the use of sophisticated computer programs in order to identify the causes of the accident.
文摘The non-coupled charge explosion and geo-mechanical dynamics problem in real air condition is studied in this paper. It analyzes and calculates the problem by using the real air state equations. Through researching on the non-coupled charge rock bench blasting with big clearance of air, its result indicates that the borehole wall reflection overpressure is far higher than strength of rock, but much lower than detonation front pressure of the charge. So non-coupled charge explosion blasting engineering is very successful. Furthermore, it introduces the method of shaft forming by blasting once and the new tube room technology. And the non-coupled charge explosion is used successfully in the method of shaft forming by blasting once. As it drills and blasts in the top and removes the broken rock from the bottom tunnel, it increases the construction efficiency significantly. This paper has important reference on the improvement of the large-span underground engineering construction.
