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Yield pillar behavior at Jim Walter No. 7 mine: stress and strata measurements of yield and abutment pillars
396A
REINFORCEMENT:GROUTING
provide hydraulic power, automatic control and monitoring systems which will improve operations, reduce manpower requirements and improve management information. Clear design requirements were determined in order to allow selection on a commercial basis. A method of tendering is described with the subsequent analysis and selection process. (from Author)
can predict the performance of such a pillar system in UK mines. (from Authors)
Grouting
958284 Innovative concept in tailgate entry support: elimination of crib blocks through utifization of new high capacity roof truss systems J. C. Stank'us, Song Guo, J. J. McCaffrey & S. S. Peng, in:
958287 Aspects on a theory of grouting R. Widmann, in: Eurock '93. Safety and environmental issues
Proc. 13th international conference, ground control in mining, Morgantown, WV, 1994, ed S.S. Peng, 0VVUflJSBM), 1994,
ed L. Ribeiro E Sousa & N.F. Grossmann, (Balkema), 1995, pp 1165-1172.
pp 166-174.
Grouting has been performed for nearly 2 centuries all over the world, but a theory of grouting could not be developed until now. The reasons are not only the heterogeneity of the underground, but mainly the fact that the different flow properties of water and grout are not considered in the evaluation of the permeability tests. The lack of knowledge of the relevant characteristic properties of the grout fluid and of the pressure acting in the joints add to the problem. (Author)
This new concept utilizes a new high capacity roof truss system in lieu of conventional wooden crib block. The first field test was conducted at Bailey Mine (USA) and was very successful. The test data has shown that the dynamic roof truss system effectively controls and the various abutment pressures caused by longwall mining thus maintaining a stable tailgate entry. (from Authors) 958285 The massive collapse of coal pillars - case histories from the United States F. E. Chase, R. K. Zipf Jr & C. Mark, in: Proc. 13th
international conference, ground control in mining, Morgantown, WV, 1994, ed S.S. Peng, (WVU/USBM), 1994, pp 6980. A massive pillar collapse occurs when undersized pillars fail and rapidly shed their load to adjacent pillars which in turn fail. This chain reaction-like failure may involve hundreds, even thousands, of pillars and the consequences have been catastrophic. One effect of a massive pillar collapse can be a powerful, destructive, and a potentially hazardous airblast. On eleven recent occasions, massive pillar collapses have occurred in six southern West Virginia coal mines. Research was conducted at four mines where massive pillar collapses occurred. Geotechnical evaluations of roof rock, coalbed, and floor conditions were made. Evidence indicates that in each case a massive and competent roof rock unit was able to bridge a relativelywide span, creating a pressure arch. Eventually, the pressure arch apparently broke down, and the structural characteristics of the pillar system were such that sudden, massive pillar failures occurred. Data collected at the failure sites also indicates that all the massive collapses occurred where the pillars width-to-height ratio was 3.0 or less. Numerical modeling, supports the conclusions that the extent of the mined-out-area, the bridging capability of the main roof, and the width-to-height ratio of the piUars are probably all significant factors in the occurrence of massive pillar failures. (from Authors) 958286 Yield pillar behavior at Jim Walter No. 7 Mine: stress and strata measurements of yield and abutment pillars J. Brasfield & G. Hendon, in: Proc. 13th international
conference, ground control in mining, Morgantown, WV, 1994, ed S.S. Peng, (WVU/USBM), 1994, pp 91-99. Describes the steps taken to determine stresses on the strata surrounding the pre-driven development entries. It also describes the installation and monitoring of stress cells and extensometers used to quantify the stress build-up and strata movement associated with the headgate pass of a longwall panel. The findings of this study will he used to design and predict the performance of a 2 entry yield pillar system in the Parkgate Seam at Welbeck Colliery in the UK. Stress measurements and stata movement data from No. 7 Mine and Welbeck will be used to develop a computer model that
in rock engineering. Proc. symposium, Lisboa, 1993, Vol. 2,
958288 Fluid-rock interaction and grouting C. Kutzner, in: Eurock '93. Safety and environmental issues
in rock engineering. Proc. symposium, Lisboa, 1993. Vol. 2, ed L. Ribeiro E Sousa & N.F. Grossmann, (Balkema), 1995, pp 1173-1174. Designers of grout curtains are very often faced with the fact that the take of grout and subsequent effect can hardly be derived from the water pressure tests which are seen as to represent the permeability and the groutability of the given rock mass. There are many reasons for this. The consequence is that in parallel to water pressure tests grout tests should be made in individual boreholes during the investigation phase of a project. Such grouting tests will help the engineers involved to find a better feeling of rock groutability and of the grouting requirements in the given case. (from Author) 958289 Study on the high-pressure grouting of the overburden for subsidence control W. J. Guo, L. M. Liu, C. J. Lian & G. H. Shen, in: Proc.
13th international conference, ground control in mining, Morgantown, WV, 1994, ed S.S. Peng, (WVU/USBM), 1994, pp 320-324. Combining the field survey results and laboratory simulation research, the author has investigated bed separation and its mechanisms and effect of backfilling the bed separation and its mechanisms. Finally backfilling application in three mines are introduced, including grout flow chart, grouting pressure, and radius. (from Authors) 958290 Jet grouting in construction J. Morey & R. R. W. Harris, in: Engineering geology of construction, ed M. Eddleston & others, (Geological Society of London; Engineering Geology Special Publication, 10), 1995, pp 105-114. This paper outlines the basic jet grouting methods, and provides examples of their versatile application in applied geotechnical engineering. However, the technique requires the application of concentrated force and could be immensely destructive if incorrectly applied. A cautionary section of this paper is therefore devoted to the control of this force in order to achieve the require results. (Authors)
REINFORCEMENT:GROUTING
provide hydraulic power, automatic control and monitoring systems which will improve operations, reduce manpower requirements and improve management information. Clear design requirements were determined in order to allow selection on a commercial basis. A method of tendering is described with the subsequent analysis and selection process. (from Author)
can predict the performance of such a pillar system in UK mines. (from Authors)
Grouting
958284 Innovative concept in tailgate entry support: elimination of crib blocks through utifization of new high capacity roof truss systems J. C. Stank'us, Song Guo, J. J. McCaffrey & S. S. Peng, in:
958287 Aspects on a theory of grouting R. Widmann, in: Eurock '93. Safety and environmental issues
Proc. 13th international conference, ground control in mining, Morgantown, WV, 1994, ed S.S. Peng, 0VVUflJSBM), 1994,
ed L. Ribeiro E Sousa & N.F. Grossmann, (Balkema), 1995, pp 1165-1172.
pp 166-174.
Grouting has been performed for nearly 2 centuries all over the world, but a theory of grouting could not be developed until now. The reasons are not only the heterogeneity of the underground, but mainly the fact that the different flow properties of water and grout are not considered in the evaluation of the permeability tests. The lack of knowledge of the relevant characteristic properties of the grout fluid and of the pressure acting in the joints add to the problem. (Author)
This new concept utilizes a new high capacity roof truss system in lieu of conventional wooden crib block. The first field test was conducted at Bailey Mine (USA) and was very successful. The test data has shown that the dynamic roof truss system effectively controls and the various abutment pressures caused by longwall mining thus maintaining a stable tailgate entry. (from Authors) 958285 The massive collapse of coal pillars - case histories from the United States F. E. Chase, R. K. Zipf Jr & C. Mark, in: Proc. 13th
international conference, ground control in mining, Morgantown, WV, 1994, ed S.S. Peng, (WVU/USBM), 1994, pp 6980. A massive pillar collapse occurs when undersized pillars fail and rapidly shed their load to adjacent pillars which in turn fail. This chain reaction-like failure may involve hundreds, even thousands, of pillars and the consequences have been catastrophic. One effect of a massive pillar collapse can be a powerful, destructive, and a potentially hazardous airblast. On eleven recent occasions, massive pillar collapses have occurred in six southern West Virginia coal mines. Research was conducted at four mines where massive pillar collapses occurred. Geotechnical evaluations of roof rock, coalbed, and floor conditions were made. Evidence indicates that in each case a massive and competent roof rock unit was able to bridge a relativelywide span, creating a pressure arch. Eventually, the pressure arch apparently broke down, and the structural characteristics of the pillar system were such that sudden, massive pillar failures occurred. Data collected at the failure sites also indicates that all the massive collapses occurred where the pillars width-to-height ratio was 3.0 or less. Numerical modeling, supports the conclusions that the extent of the mined-out-area, the bridging capability of the main roof, and the width-to-height ratio of the piUars are probably all significant factors in the occurrence of massive pillar failures. (from Authors) 958286 Yield pillar behavior at Jim Walter No. 7 Mine: stress and strata measurements of yield and abutment pillars J. Brasfield & G. Hendon, in: Proc. 13th international
conference, ground control in mining, Morgantown, WV, 1994, ed S.S. Peng, (WVU/USBM), 1994, pp 91-99. Describes the steps taken to determine stresses on the strata surrounding the pre-driven development entries. It also describes the installation and monitoring of stress cells and extensometers used to quantify the stress build-up and strata movement associated with the headgate pass of a longwall panel. The findings of this study will he used to design and predict the performance of a 2 entry yield pillar system in the Parkgate Seam at Welbeck Colliery in the UK. Stress measurements and stata movement data from No. 7 Mine and Welbeck will be used to develop a computer model that
in rock engineering. Proc. symposium, Lisboa, 1993, Vol. 2,
958288 Fluid-rock interaction and grouting C. Kutzner, in: Eurock '93. Safety and environmental issues
in rock engineering. Proc. symposium, Lisboa, 1993. Vol. 2, ed L. Ribeiro E Sousa & N.F. Grossmann, (Balkema), 1995, pp 1173-1174. Designers of grout curtains are very often faced with the fact that the take of grout and subsequent effect can hardly be derived from the water pressure tests which are seen as to represent the permeability and the groutability of the given rock mass. There are many reasons for this. The consequence is that in parallel to water pressure tests grout tests should be made in individual boreholes during the investigation phase of a project. Such grouting tests will help the engineers involved to find a better feeling of rock groutability and of the grouting requirements in the given case. (from Author) 958289 Study on the high-pressure grouting of the overburden for subsidence control W. J. Guo, L. M. Liu, C. J. Lian & G. H. Shen, in: Proc.
13th international conference, ground control in mining, Morgantown, WV, 1994, ed S.S. Peng, (WVU/USBM), 1994, pp 320-324. Combining the field survey results and laboratory simulation research, the author has investigated bed separation and its mechanisms and effect of backfilling the bed separation and its mechanisms. Finally backfilling application in three mines are introduced, including grout flow chart, grouting pressure, and radius. (from Authors) 958290 Jet grouting in construction J. Morey & R. R. W. Harris, in: Engineering geology of construction, ed M. Eddleston & others, (Geological Society of London; Engineering Geology Special Publication, 10), 1995, pp 105-114. This paper outlines the basic jet grouting methods, and provides examples of their versatile application in applied geotechnical engineering. However, the technique requires the application of concentrated force and could be immensely destructive if incorrectly applied. A cautionary section of this paper is therefore devoted to the control of this force in order to achieve the require results. (Authors)