Analysis of the current rib support practices and techniques in U.S. coal mines

来源 :International Journal of Mining Science and Technology | 被引量 : 0次 | 上传用户:eworld5008
下载到本地 , 更方便阅读
声明 : 本文档内容版权归属内容提供方 , 如果您对本文有版权争议 , 可与客服联系进行内容授权或下架
论文部分内容阅读
Design of rib support systems in U.S. coal mines is based primarily on local practices and experience. A better understanding of current rib support practices in U.S. coal mines is crucial for developing a sound engineering rib support design tool. The objective of this paper is to analyze the current practices of rib control in U.S. coal mines. Twenty underground coal mines were studied representing various coal basins,coal seams,geology,loading conditions,and rib control strategies. The key findings are:(1) any rib design guideline or tool should take into account external rib support as well as internal bolting;(2) rib bolts on their own cannot contain rib spall,especially in soft ribs subjected to significant load—external rib control devices such as mesh are required in such cases to contain rib sloughing;(3) the majority of the studied mines follow the overburden depth and entry height thresholds recommended by the Program Information Bulletin 11-29 issued by the Mine Safety and Health Administration;(4) potential rib instability occurred when certain geological features prevailed—these include draw slate and/or bone coal near the rib/roof line,claystone partings,and soft coal bench overlain by rock strata;(5) 47% of the studied rib spall was classified as blocky—this could indicate a high potential of rib hazards; and(6) rib injury rates of the studied mines for the last three years emphasize the need for more rib control management for mines operating at overburden depths between 152.4 m and 304.8 m. Design of rib support systems in US coal mines is based primarily on local practices and experience. A better understanding of current rib support practices in US coal mines is crucial for developing a sound engineering rib support design tool. The objective of this paper is to analyze the current practices of rib control in US coal mines. Twenty underground coal mines were studied representing various coal basins, coal seams, geology, loading conditions, and rib control strategies. The key findings are: (1) any rib design guideline or tool should take into account external rib support as well as internal bolting; (2) rib bolts on their own can not contain rib spall, especially in soft ribs subject to significant load-external rib control devices such as mesh are required in such cases to contain rib sloughing ; (3) the majority of the studied mines follow the overburden depth and entry height thresholds recommended by the Program Information Bulletin 11-29 issued by the Mine Safety an d Health Administration; (4) potential rib instability occurred when certain geological features prevailed-these include draw slate and / or bone coal near the rib / roof line, claystone partings, and soft coal bench overlain by rock strata; (5) 47% of the studied rib spall was classified as blocky-this could indicate a high potential of rib hazards; and (6) rib injury rates of the studied mines for the last three years emphasize the need for more rib control management for mines operating at overburden depths between 152.4 m and 304.8 m.
其他文献
现如今,为实现淡水短缺问题的优化解决,海水淡化可谓是一种十分有效的方式,占据关键应用地位,重要性不容忽视.海水淡化集成涉及多方面因素,其耗能相对较高,会使工艺应用与推
目的:观察血栓通治疗脑出血亚急性期的临床疗效。方法60例脑出血亚急性患者随机分成治疗组和对照组各30例,对照组给予常规治疗,治疗组在脑出血7~21 d时,在常规治疗的基础上,加用血栓通,300 mg/d,静脉滴注。观察比较两组在治疗前后NIHSS评分及血肿变化情况。结果治疗21 d后,治疗组血肿体积(3.3±2.6)ml明显小于对照组的(7.2±3.7)ml(t =4.102,P<0.05),治疗
目的:探讨对习惯性流产应用综合干预的临床疗效,评价其价值。方法:选取2013年4月~2015年4月我院产科收治的68例习惯性流产患者,按治疗方法不同分为对照组(34例,常规疗法),观察组(34例,综
急性颅脑损伤患者伤后血糖水平增高的机制,主要是身体对损伤应激反应的结果.我们对247例急性颅脑损伤患者进行血糖监测,旨在观察研究血糖升高幅度与损伤程度及预后的相关性.
期刊
目的:评价采用肱骨近端锁定接骨板(LPHP)、肱骨近端解剖钛板、钢针3种手术固定方法治疗老年肱骨近端粉碎骨折的疗效。方法:采用肱骨近端锁定接骨板(LPHP)内固定的58例为A 组,采
目的:探讨饮食控制对妊娠期糖尿病产妇新生儿体质量、胎盘功能及羊水的影响。方法93例妊娠期糖尿病产妇在知情同意下按入院单双号随机分成观察组50例和对照组43例,两组均按常规治疗,包括运动、健康教育和药物治疗,观察组在上述基础上加用饮食控制,观察比较两组产妇胎盘成熟程度、羊水情况和胎儿体质量情况。结果观察组正常体质量儿38例(76.0%)、低体质量儿9例(18.0%)、巨大儿3例(6.0%),对照组分
水力压裂技术是页岩气开发的核心技术之一,现已广泛应用在页岩气井的增产作业中.文中对目前常用的水力压裂技术(多级压裂、清水压裂、同步压裂、水力喷射压裂和重复压裂)进行
目的:观察经纤维支气管镜治疗机械通气并发肺部感染的临床效果。方法 回顾性分析42例机械通气并发重症肺部感患者的临床资料,均经纤维支气管镜行气道检查、分泌物清除、取痰培养、支气管肺泡灌洗治疗,统计分析治疗前后动脉血气变化情况。结果42例患者共进行了81例次纤维支气管镜检查治疗,治疗后氧分压( PaO2)上升、二氧化碳分压(PaCO2)降低、SaO2升高,与治疗前差异均有统计学意义(t=-188.53
我院自1995年6月~1997年10月,对24例脑胶质瘤病人,采取超选择颈内动脉灌注替尼泊甙(VM_(26))和口服环已亚硝脲(CCNU)联合化疗取得较满意效果,现报告如下。 In our hospital