Although conventional coal mine designs are conservative regarding pillar strength,local failures such as roof-falls and pillar bursts still affect mine safety and operations.Previous studies have identified that disc...Although conventional coal mine designs are conservative regarding pillar strength,local failures such as roof-falls and pillar bursts still affect mine safety and operations.Previous studies have identified that discontinuous,layered roof materials have some self-supporting capacity.This research is a preliminary step towards understanding these mechanics in coal-measure rocks.Although others have considered broad conceptual models and simplified analogs for mine roof behavior,this study presents a unique numerical model that more completely represents in-situ roof conditions.The discrete element method(DEM)is utilized to conduct a parametric analysis considering a range of in-situ stress ratios,material properties,and joint networks to determine the parameters controlling the stability of single-entries modeled in two-dimensions.Model results are compared to empirical observations of roof-support effectiveness(ARBS)in the context of the coal mine roof rating(CMRR)system.Results such as immediate roof displacement,overall stability,and statistical relationships between model parameters and outcomes are presented herein.Potential practical applications of this line of research include:(1)roof-support optimization for a range of coal-measure rocks,(2)establishment of a relationship between roof stability and pillar stress,and(3)determination of which parameters are most critical to roof stability and therefore require concentrated evaluation.展开更多
Mass movements are very common problems in the eastern Black Sea region of Turkey due to its climate conditions, geological, and geomorphological characteristics. High slope angle, weathering, dense rainfalls, and ant...Mass movements are very common problems in the eastern Black Sea region of Turkey due to its climate conditions, geological, and geomorphological characteristics. High slope angle, weathering, dense rainfalls, and anthropogenic impacts are generally reported as the most important triggering factors in the region. Following the portal slope excavations in the entrance section of Cankurtaran tunnel, located in the region, where the highly weathered andesitic tuff crops out, a circular toe failure occurred. The main target of the present study is to investigate the causes and occurrence mechanism of this failure and to determine the feasible remedial measures against it using finite element method(FEM) in four stages. These stages are slope stability analyses for pre-and postexcavation cases, and remediation design assessments for slope and tunnel. The results of the FEM-SSR analyses indicated that the insufficient initial support design and weathering of the andesitic tuffs are the main factors that caused the portal failure. After installing a rock retaining wall with jet grout columns and reinforced slope benching applications, the factor of safety increased from 0.83 to 2.80. In addition toslope stability evaluation, the Rock Mass Rating(RMR), Rock Mass Quality(Q) and New Austrian Tunneling Method(NATM) systems were also utilized as empirical methods to characterize the tunnel ground and to determine the tunnel support design. The performance of the suggested empirical support design, induced stress distributions and deformations were analyzed by means of numerical modelling. Finally, it was concluded that the recommended stabilization technique was essential for the dynamic long-term stability and prevents the effects of failure. Additionally, the FEM method gives useful and reasonably reliable results in evaluating the stability of cut slopes and tunnels excavated both in continuous and discontinuous rock masses.展开更多
Objective To evaluate the clinical effectiveness of professor WU Lian-zhong＇s ＂resuscitation and regulating muscle＂ acupuncture method for spasmodic torticollis（ST） based on syndrome differentiation,and to compar...Objective To evaluate the clinical effectiveness of professor WU Lian-zhong＇s ＂resuscitation and regulating muscle＂ acupuncture method for spasmodic torticollis（ST） based on syndrome differentiation,and to compare the efficacy of acupuncture treatment between the patients with spasmodic torticollis who were not given botulinum toxin A by injection and the patients given botulinum toxin A by injection.Methods Forty patients were divided into treatment group（not given botulinum toxin A by injection） and control group（given botulinum toxin A by injection）,with 20 patients in each group.＂Resuscitation and regulating muscle＂ acupuncture method was adopted in both two groups,and the treatment lasted for 6 months.The clinical efficacy in both two groups was compared after treatment.Tsui＇s Scale was applied to evaluate the overall effect,the abnormal posture of cervical spine and dystonic tremor.Toronto Western Spasmodic Torticollis Rating Scale（TWSTRS） was used for scoring the severity of torticollis,quality of life and pain.Results After treatment,the markedly effective rate and the total effective rate in treatment group were 35.0% and 90.0%,respectively,which were superior to those in control group,namely 20.0% and 75.0%,and the efficacy difference was statistically significant for the total effective rate（P0.05）.It was shown according to the Tsui＇s Scale and TWSTRS that the differences were statistically significant when compared the two groups before and after treatment（all P0.01）;the difference of intergroup comparison after treatment was statistically significant（P0.05）.No adverse effect was found in both two groups during acupuncture treatment.Conclusion ＂Resuscitation and regulating muscle＂ acupuncture method can effectively improve the clinical symptoms of ST patients,and better efficacy is found in the patients not given botulinum toxin A by injection.The course of treatment of acupuncture treatment for torticollis patients is longer,and the patients should insist展开更多
基金sponsored by the Alpha Foundation for the Improvement of Mine Safety and Health, Inc. (Alpha Foundation)the funding provided for this project by the Alpha Foundationpartially funded by the National Institute of Occupational Health and Science (NIOSH) under Grant Number 200-2016-90154.
文摘Although conventional coal mine designs are conservative regarding pillar strength,local failures such as roof-falls and pillar bursts still affect mine safety and operations.Previous studies have identified that discontinuous,layered roof materials have some self-supporting capacity.This research is a preliminary step towards understanding these mechanics in coal-measure rocks.Although others have considered broad conceptual models and simplified analogs for mine roof behavior,this study presents a unique numerical model that more completely represents in-situ roof conditions.The discrete element method(DEM)is utilized to conduct a parametric analysis considering a range of in-situ stress ratios,material properties,and joint networks to determine the parameters controlling the stability of single-entries modeled in two-dimensions.Model results are compared to empirical observations of roof-support effectiveness(ARBS)in the context of the coal mine roof rating(CMRR)system.Results such as immediate roof displacement,overall stability,and statistical relationships between model parameters and outcomes are presented herein.Potential practical applications of this line of research include:(1)roof-support optimization for a range of coal-measure rocks,(2)establishment of a relationship between roof stability and pillar stress,and(3)determination of which parameters are most critical to roof stability and therefore require concentrated evaluation.
文摘Mass movements are very common problems in the eastern Black Sea region of Turkey due to its climate conditions, geological, and geomorphological characteristics. High slope angle, weathering, dense rainfalls, and anthropogenic impacts are generally reported as the most important triggering factors in the region. Following the portal slope excavations in the entrance section of Cankurtaran tunnel, located in the region, where the highly weathered andesitic tuff crops out, a circular toe failure occurred. The main target of the present study is to investigate the causes and occurrence mechanism of this failure and to determine the feasible remedial measures against it using finite element method(FEM) in four stages. These stages are slope stability analyses for pre-and postexcavation cases, and remediation design assessments for slope and tunnel. The results of the FEM-SSR analyses indicated that the insufficient initial support design and weathering of the andesitic tuffs are the main factors that caused the portal failure. After installing a rock retaining wall with jet grout columns and reinforced slope benching applications, the factor of safety increased from 0.83 to 2.80. In addition toslope stability evaluation, the Rock Mass Rating(RMR), Rock Mass Quality(Q) and New Austrian Tunneling Method(NATM) systems were also utilized as empirical methods to characterize the tunnel ground and to determine the tunnel support design. The performance of the suggested empirical support design, induced stress distributions and deformations were analyzed by means of numerical modelling. Finally, it was concluded that the recommended stabilization technique was essential for the dynamic long-term stability and prevents the effects of failure. Additionally, the FEM method gives useful and reasonably reliable results in evaluating the stability of cut slopes and tunnels excavated both in continuous and discontinuous rock masses.
基金Supported by WU Lian-zhong Inheritance Studio of National Famous and Veteran TCM Experts
文摘Objective To evaluate the clinical effectiveness of professor WU Lian-zhong＇s ＂resuscitation and regulating muscle＂ acupuncture method for spasmodic torticollis（ST） based on syndrome differentiation,and to compare the efficacy of acupuncture treatment between the patients with spasmodic torticollis who were not given botulinum toxin A by injection and the patients given botulinum toxin A by injection.Methods Forty patients were divided into treatment group（not given botulinum toxin A by injection） and control group（given botulinum toxin A by injection）,with 20 patients in each group.＂Resuscitation and regulating muscle＂ acupuncture method was adopted in both two groups,and the treatment lasted for 6 months.The clinical efficacy in both two groups was compared after treatment.Tsui＇s Scale was applied to evaluate the overall effect,the abnormal posture of cervical spine and dystonic tremor.Toronto Western Spasmodic Torticollis Rating Scale（TWSTRS） was used for scoring the severity of torticollis,quality of life and pain.Results After treatment,the markedly effective rate and the total effective rate in treatment group were 35.0% and 90.0%,respectively,which were superior to those in control group,namely 20.0% and 75.0%,and the efficacy difference was statistically significant for the total effective rate（P0.05）.It was shown according to the Tsui＇s Scale and TWSTRS that the differences were statistically significant when compared the two groups before and after treatment（all P0.01）;the difference of intergroup comparison after treatment was statistically significant（P0.05）.No adverse effect was found in both two groups during acupuncture treatment.Conclusion ＂Resuscitation and regulating muscle＂ acupuncture method can effectively improve the clinical symptoms of ST patients,and better efficacy is found in the patients not given botulinum toxin A by injection.The course of treatment of acupuncture treatment for torticollis patients is longer,and the patients should insist
