The stability of a backfill wall is critical to implement gob-side entry driving technology in which a small coal pillar is substituted by a waste backfill wall. Based on features of surrounding rock structures in the...The stability of a backfill wall is critical to implement gob-side entry driving technology in which a small coal pillar is substituted by a waste backfill wall. Based on features of surrounding rock structures in the backfill wall, we propose a mechanical model on the structural effect of a soft-hard backfill wall using theory analysis, physical experiments and a numerical simulation. The results show thatChe deformation of the structure of the soft-hard backfill wall is coordinated with the roof and floor. The soft structure on the top of the backfill wall can absorb the energy in the roof by its large deformation and adapt to the given deformation caused by the rotation and subsidence of a key rock block. The hard structure at the bottom of the backfill wall can absorb the strong supporting resistance from the top surrounding rock. The soft structure on the top protecting the hard bottom structure by its large deformation contributes to the stability of the entire backfill wall. An application indicated that the stress in the backfill wall effec- tively decreased and its deformation was significantly reduced after the top coal remained. This ensured the stability of the backfill wall.展开更多
Oil is extremely crucial to the development of the modern economy. It is important to forecast the oil supply capacity due to its scarcity and non-renewability. This paper attempts to forecast and analyze thirty-five ...Oil is extremely crucial to the development of the modern economy. It is important to forecast the oil supply capacity due to its scarcity and non-renewability. This paper attempts to forecast and analyze thirty-five current and potential net oil-exporting countries. Integrating both qualitative and quantitative methods, the oil production and consumption are predicted based on historical data, so that the world net oil-exporting capacity can be obtained. The results show that the ＂roof effect＂ of the world net oil-exporting capacity may appear before 2030. Unconventional oil will play an important role in the future world oil market. The competition and cooperation relationships between OPEC and non-OPEC will last for a long time.展开更多
基金Financial supports for this work, provided by the New Century Excellent Talents in University (No.NCET-05-0480)the Research Fund of the State Key Laboratory of Coal Resources and Mine Safety of CUMT (No.09KF06)the Scientific Research Fund of CUMT (No.OA090239)
文摘The stability of a backfill wall is critical to implement gob-side entry driving technology in which a small coal pillar is substituted by a waste backfill wall. Based on features of surrounding rock structures in the backfill wall, we propose a mechanical model on the structural effect of a soft-hard backfill wall using theory analysis, physical experiments and a numerical simulation. The results show thatChe deformation of the structure of the soft-hard backfill wall is coordinated with the roof and floor. The soft structure on the top of the backfill wall can absorb the energy in the roof by its large deformation and adapt to the given deformation caused by the rotation and subsidence of a key rock block. The hard structure at the bottom of the backfill wall can absorb the strong supporting resistance from the top surrounding rock. The soft structure on the top protecting the hard bottom structure by its large deformation contributes to the stability of the entire backfill wall. An application indicated that the stress in the backfill wall effec- tively decreased and its deformation was significantly reduced after the top coal remained. This ensured the stability of the backfill wall.
基金support from Key Projects of Philosophy and Social Sciences Research of Ministry of Education(09JZD0038)
文摘Oil is extremely crucial to the development of the modern economy. It is important to forecast the oil supply capacity due to its scarcity and non-renewability. This paper attempts to forecast and analyze thirty-five current and potential net oil-exporting countries. Integrating both qualitative and quantitative methods, the oil production and consumption are predicted based on historical data, so that the world net oil-exporting capacity can be obtained. The results show that the ＂roof effect＂ of the world net oil-exporting capacity may appear before 2030. Unconventional oil will play an important role in the future world oil market. The competition and cooperation relationships between OPEC and non-OPEC will last for a long time.
