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Ensuring the stability of rock masses accommodating large underground cavities
410A
UNDERGROUND EXCAVATIONS:FAILURE MECHANISMS
influence the gateroad stability and presents some measures to alleviate the problem. (Authors)
Stresses around underground openings 958392 Influence of irregular boundary weakening on the block caving process S. Zhang & G. Tong, International Journal of Rock Mechanics & Mining Sciences, 32(2), 1995, pp 135-142. A study is presented of the influence of the irregular boundary weakening on the caving process using the threedimensional elastic finite element method and is also based on the mechanical properties and the load-carrying conditions of the rock masses of Tongkuangyu Mine in China. (Authors)
958393 Ensuring the stability of rock masses accommodating large underground cavities J. M. Kazikaev, A. M. Grigoriev, B. A. Fomin & S. N. Zhurin, in: Eurock "93. Safety and environmental issues in rock engineering. Prec. sympoMum, Lisboa, 1993. Vol. 2, ed L. Ribeiro E Sonsa & N.F. Grossmann, (Balkema), 1995, pp 1047-1051. Based on the results of integrated geomechanical investigations, parameters of underground hollows (chambers) and pillars have been established. These will ensure the stability of rock masses accomodating large underground caverns, preservation of terrain and safe operation of engineering installations. Stability of stressed and deformed mining system structural elements over time and the possibility of using chambers for the purposes different from mineral resourses mining are noted. (from Authors)
958394 Stability and stress evaluation in mines using in-seam seismic methods E. M. Williams & E. C. Westman, in: Prec. 13th international conference, ground control in mining, Morgantown, WV, 1994, ed S.S. Peng, (WVU]USBM), 1994, pp 290-297. Seismic surveys performed through a longwall panel and pillars near the face can provide valuable information on geologic anomalies, high stress regions, tailgate support performance and other conditions that could endanger miners or interrupt production. This paper describes the details of the equipment and data analysis techniques used, and the significant results obtained and their implications for ground control. (from Authors)
958395 Design of roadway support using a strain softening model J. Hematian, I. Porter & N. I. Aziz, in: Prec. 13th international conference, ground control in mining, Morgantown, WV, 1994, ed S.S. Peng, (WVU/USBM), 1994, pp 5057. This paper addresses the significance of the post-failure behaviour of rocks on the stability of underground structures which are under the influence of a high horizontal stress field. A number of 2-D FE model of roadways were constructed based on the data obtained from laboratory testing and field investigations. The models were then analysed using three different solution techniques; simple linear-elastic, non-finear elastic-plastic and elastic-plastic with consideration of postfailure behaviour (softening model). Results indicated that the post-failure behaviour of rocks significantly influence the stress and displacement patterns around the roadway. The stress and displacement patterns as well as the extent of the
yield zone around the roadway predicted by the softening model were in good agreement with that from the field study. Based on the results of the study, an appropriate support system has been suggested to govern the stability of roadways. (from Authors)
958396 Recent investigation of extent of fractured zone and displacement of rocks around the roadways On Chinese) Fu Guobin, Journal - China Coal Society, 200), 1995, pp 304-310. Analytical formulae for calculating the radius of a fractured zone, radius of plastic zone and peripheral displacement are deducted by taking into consideration strength attenuation (strain softening) and volumetric expansion of rocks after fragmentation. Research has shown that the degree of strain softening has direct bearing on extent of fractured zone, which affects roadway convergence. Expansion of rock has little effect on extent of fractured zone, but has obvious effect on roadway convergence. When the rocks are fractured, roadway convergence is mainly due to expansion deformation of the surrounding rock within the fractured zone in a residual-strength state. (English summary)
958397 Maintenance of roadways in soft rocks by destress blasting of roadway-rib (in Chinese) Duan Kexin, Journal - China Coal Society, 20(3), 1995, pp 311-316. The principles, destress results and technical parameters for destress blasting in the side wall of roadway are studied in a field test, numerical simulation and simulation test with equivalent materials. After blasting, the surrounding rocks will experience two stages of deformation, ie vigorous deformation in a short period and gentle deformation in a long period. The relation between the softening factor of the destressed zone and borehole spacing and row spacing is a hyperbolic curve. Destressing blasting has a broad prospect in roadway maintenance in soft rock. (English summary)
Underground excavation failure mechanisms
958398 Automation of a progressive failure procedure for analysis of underground mine pillar designs N. P. Kripakov, M. C. Sun & D. A. Donato, in: Proc. 13th international conference, ground control in mining, Morgantown, WV, 1994, ed S.S. Peng, 0VVU/USBM), 1994, pp 5868. USBM is conducting research to develop a practical computer-based tool that will allow coal mine planners to anticipate rock mass behavior surrounding mine entries prior to actual mining. More specifically, this tool estimates to what degree and extent the immediate roof and floor strata and the coal pillar ribs surrounding an opening will weaken or fail for a given set of mining parameters. Outputs from plan-view, linear-elastic, boundary-element models executed at different mining stages are used as input to a detailed, section-view, finite-element model to estimate the degree and extent of failure expected to occur around the periphery of an entry system. Examples of computer-generated output from generic sample models representing typical mining situations are presented and results discussed. (from Authors)
UNDERGROUND EXCAVATIONS:FAILURE MECHANISMS
influence the gateroad stability and presents some measures to alleviate the problem. (Authors)
Stresses around underground openings 958392 Influence of irregular boundary weakening on the block caving process S. Zhang & G. Tong, International Journal of Rock Mechanics & Mining Sciences, 32(2), 1995, pp 135-142. A study is presented of the influence of the irregular boundary weakening on the caving process using the threedimensional elastic finite element method and is also based on the mechanical properties and the load-carrying conditions of the rock masses of Tongkuangyu Mine in China. (Authors)
958393 Ensuring the stability of rock masses accommodating large underground cavities J. M. Kazikaev, A. M. Grigoriev, B. A. Fomin & S. N. Zhurin, in: Eurock "93. Safety and environmental issues in rock engineering. Prec. sympoMum, Lisboa, 1993. Vol. 2, ed L. Ribeiro E Sonsa & N.F. Grossmann, (Balkema), 1995, pp 1047-1051. Based on the results of integrated geomechanical investigations, parameters of underground hollows (chambers) and pillars have been established. These will ensure the stability of rock masses accomodating large underground caverns, preservation of terrain and safe operation of engineering installations. Stability of stressed and deformed mining system structural elements over time and the possibility of using chambers for the purposes different from mineral resourses mining are noted. (from Authors)
958394 Stability and stress evaluation in mines using in-seam seismic methods E. M. Williams & E. C. Westman, in: Prec. 13th international conference, ground control in mining, Morgantown, WV, 1994, ed S.S. Peng, (WVU]USBM), 1994, pp 290-297. Seismic surveys performed through a longwall panel and pillars near the face can provide valuable information on geologic anomalies, high stress regions, tailgate support performance and other conditions that could endanger miners or interrupt production. This paper describes the details of the equipment and data analysis techniques used, and the significant results obtained and their implications for ground control. (from Authors)
958395 Design of roadway support using a strain softening model J. Hematian, I. Porter & N. I. Aziz, in: Prec. 13th international conference, ground control in mining, Morgantown, WV, 1994, ed S.S. Peng, (WVU/USBM), 1994, pp 5057. This paper addresses the significance of the post-failure behaviour of rocks on the stability of underground structures which are under the influence of a high horizontal stress field. A number of 2-D FE model of roadways were constructed based on the data obtained from laboratory testing and field investigations. The models were then analysed using three different solution techniques; simple linear-elastic, non-finear elastic-plastic and elastic-plastic with consideration of postfailure behaviour (softening model). Results indicated that the post-failure behaviour of rocks significantly influence the stress and displacement patterns around the roadway. The stress and displacement patterns as well as the extent of the
yield zone around the roadway predicted by the softening model were in good agreement with that from the field study. Based on the results of the study, an appropriate support system has been suggested to govern the stability of roadways. (from Authors)
958396 Recent investigation of extent of fractured zone and displacement of rocks around the roadways On Chinese) Fu Guobin, Journal - China Coal Society, 200), 1995, pp 304-310. Analytical formulae for calculating the radius of a fractured zone, radius of plastic zone and peripheral displacement are deducted by taking into consideration strength attenuation (strain softening) and volumetric expansion of rocks after fragmentation. Research has shown that the degree of strain softening has direct bearing on extent of fractured zone, which affects roadway convergence. Expansion of rock has little effect on extent of fractured zone, but has obvious effect on roadway convergence. When the rocks are fractured, roadway convergence is mainly due to expansion deformation of the surrounding rock within the fractured zone in a residual-strength state. (English summary)
958397 Maintenance of roadways in soft rocks by destress blasting of roadway-rib (in Chinese) Duan Kexin, Journal - China Coal Society, 20(3), 1995, pp 311-316. The principles, destress results and technical parameters for destress blasting in the side wall of roadway are studied in a field test, numerical simulation and simulation test with equivalent materials. After blasting, the surrounding rocks will experience two stages of deformation, ie vigorous deformation in a short period and gentle deformation in a long period. The relation between the softening factor of the destressed zone and borehole spacing and row spacing is a hyperbolic curve. Destressing blasting has a broad prospect in roadway maintenance in soft rock. (English summary)
Underground excavation failure mechanisms
958398 Automation of a progressive failure procedure for analysis of underground mine pillar designs N. P. Kripakov, M. C. Sun & D. A. Donato, in: Proc. 13th international conference, ground control in mining, Morgantown, WV, 1994, ed S.S. Peng, 0VVU/USBM), 1994, pp 5868. USBM is conducting research to develop a practical computer-based tool that will allow coal mine planners to anticipate rock mass behavior surrounding mine entries prior to actual mining. More specifically, this tool estimates to what degree and extent the immediate roof and floor strata and the coal pillar ribs surrounding an opening will weaken or fail for a given set of mining parameters. Outputs from plan-view, linear-elastic, boundary-element models executed at different mining stages are used as input to a detailed, section-view, finite-element model to estimate the degree and extent of failure expected to occur around the periphery of an entry system. Examples of computer-generated output from generic sample models representing typical mining situations are presented and results discussed. (from Authors)