Ground Failures In Coal Mines With Weak Roof

  • Ground control in undergound mines - SlideShare

    Apr 04, 2011· Ground control in undergound mines 1. U Siva Sankar Email: [email protected] Mining Ground ControlGround Control : A collective term given to the techniques that are usedto regulate and prevent the collapse and failure of mine openings.Ground control is the science that studies the behaviour of rockmass intransition from one state of equilibrium to another.It provides the …

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  • A study of the ground control effects of mining longwall ...

    The data indicate that the roof fall type of failure is less likely when intensive roof reinforcement (bolts, cables and trusses) is employed together with higher-capacity shields. The overburden weighting failures, in contrast, occurred when the roof was weak …

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  • CDC - Mining - Shale Failure Mechanics and Intervention ...

    Authors: MM Murphy Ground control research in underground coal mines has been ongoing for over 50 years. One of the most problematic issues in underground coal mines is roof failures associated with weak …

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  • A Study of the Ground Control Effects of Mining Longwall ...

    Weighting failures were not greatly affected by the density of roof reinforcement. In one of the overburden weighting cases, in a Pittsburgh coal bed mine, stress cell, convergence, bolt load and extensometer data have been used to analyze the failure in detail. Key words: coal mining, ground control, longwall, recovery room.

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  • Christopher MARK | Principal Roof Control Specialist | PhD ...

    Ground Failures in Coal Mines with Weak Roof. Article. Jan 2010; Greg Molinda. Christopher Mark. Coal miners who work and travel under supported roof expect to be protected from rock falls ...

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  • CDC - Mining - Ground Failures in Coal Mines with Weak ...

    Experience at coal mines with large numbers of falls indicates that many have weak roof. Control of this roof may require additional ground control measures. An understanding of the geologic and stress conditions which lead to roof falls is necessary to assess the risk of failure and to design roof reinforcement to improve stability.

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  • Shale Failure Mechanics and Intervention Measures in ...

    Oct 12, 2015· Ground control research in underground coal mines has been ongoing for over 50 years. One of the most problematic issues in underground coal mines is roof failures associated with weak shale. This paper will present a historical narrative on the research the National Institute for Occupational Safety and Health has conducted in relation to rock mechanics and shale.

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  • Ground Failures in Coal Mines with Weak Roof

    Unplanned roof failures in coal mines can be caused by a number of different factors. These include geologic defects in the roof rock, moisture degradation of shales, extreme loading conditions under high cover, multiple seam mining, and inadequate support to name just a few.

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  • FUNDAMENTALS OF COAL MINE ROOF SUPPORT

    Utah. Ground conditions and roof bolt densities from three ma-jor coal mining countries are compared in figure 4 [Mark 1999b]. Roof bolt design guidelines are presented elsewhere in these Proceedings [Mark 2000]. ROOF SPAN In underground coal mining, the excavation geometry does not vary much, but the span can be very important. The basic

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  • Proceedings: New Technology for Ground Control in …

    mines are operating above and/or beneath previously mined seams. The effects of multiple-seam interactions can include roof falls, rib spalling, and floor heave, which can seriously disrupt mining operations and threaten the safety of miners. In early 2006, a West ia coal miner was killed by rib roll that occurred in a high-stress zone

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  • Analysis on the Breaking Law of Soft and Thick Roof of ...

    Jun 17, 2020· The study of roof breaking law is very important for the behavior of the underground pressure in fully mechanized top-coal caving face under the condition of weak roof. In this paper, the research is to study the soft and thick roof breaking law in the fully mechanized top-coal caving face 2–100 in coal seam 2#. The theoretical analysis, numerical simulation …

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  • Understanding roof deformation mechanics and parametric ...

    Jan 01, 2020· Ground failures in coal mines with weak roof. Electron J Geotech Eng, 15 (F) (2010), pp. 547-588. View Record in Scopus Google Scholar. S. Sinha, G. Walton. A progressive S-shaped yield criterion and its application to rock pillar behavior. Int J Rock Mech Min Sci, 105 (2018), pp. 98-109.

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  • An updated empirical model for ground control in U.S ...

    Dec 31, 2020· Ground instability is the most common effect of a multiple seam interaction. A severe interaction can result in roof deformation, severe rib sloughing, and/or floor heave ().A survey of 36 U.S. multiple seam coal mines conducted in the mid-2000′s identified 77 individual cases of instability that were attributed to interactions .In 29 of these cases, development had …

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  • Coal Mine Roadway Stability in Soft Rock: A Case Study ...

    The mine was using a longwall method to extract coal at a depth of approximately 350 m. Both the coal seam and surrounding rock strata were extremely weak and vulnerable to weathering. Large roadway deformation and severe roadway instabilities had been experienced in the past, and hence an investigation of the roadway failure mechanism and new ...

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  • CDC - Mining - Preventing Falls of Ground in Coal Mines ...

    Mines with exceptionally low-strength roof (UCS <3,500 psi and CMRR <40) are much more likely to struggle with roof falls than other mines. Weak roof is a particular problem for many room and pillar mines in the Midwestern and Northern Appalachian coal basins.

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  • UNDERSTANDING AND IMPROVING THE PERFORMANCE …

    Mar 01, 2013· in underground mines. This is worse in coal mines because the immediate roof strata are typically weak and prone to frequent skin failures and even massive failures in some cases. Industry reports claim that over 1,500 roof falls occur every year in US coal mines. To minimize or prevent falls of roof, approximately 68 million rock bolts are ...

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  • Geologic data collection and assessment techniques in coal ...

    Jan 01, 2020· The roof and floor lithology should be examined because the roof and floor are critical coal mine structural members and this can help detect weak roof in future reserves. Of all the commonly used geotechnical investigation methods, drilled core provides the best quality data when mapping for geological trends.

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  • (PDF) Coal Mine Roadway Stability in Soft Rock: A Case Study

    The mine was using a longwall method to extract coal at a depth of approximately 350 m. Both the coal seam and surrounding rock strata were extremely weak and vulnerable to weathering.

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  • Fundamentals of modern ground control management in ...

    Sep 01, 2020· Ground failures pose a high-level risk to both individuals and production in underground coal mines. Therefore, Australian mines have developed over time what is considered the best practice pro-active ground control management strategy globally, to provide work areas both safe for employees and to minimise unplanned delays to production.

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  • Simulation of roof shear failure in coal mine roadways ...

    Sep 01, 2014· Shear failure is a common failure mechanism in underground coal mine roadways and is usually caused by high horizontal stress acting on relatively weak roof rock. Fig. 1 shows an example of roof shear failure in a Chinese coal mine roadway.

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  • Influences of Water Vapor on Roof Fall Accidents in ...

    The Directorate General of Mines Safety (DGMS) reported in 2011 that 32% of the total fatal accidents occurred due to roof falls in Indian coal mines. In spite of all the precautions taken in this regard, it was revealed that the trend of fatal accidents caused by the failure of roof and sides would remain a huge problem to contain.

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  • Coal Mine Roadway Stability in Soft Rock: A Case Study

    ground mines and ahead of the longwall face where the abutment load is high. This paper reports a case study on roadway stability at an underground coal mine in Shanxi Province, China, where maintaining roadway stability had been a challeng-ing task due to the combined failure of roof sag (Type 3) and rib spalling (Type 6). The study includes ...

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  • (PDF) Performance of roof support under high stress in a U ...

    Site A: The experimental site was located in the Pittsburgh coal bed under a relatively weak shale roof with coal stringers at 180 m depth of cover (Oyler et al., 2004). The UCS of the shale in ...

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  • Numerical Modeling Procedures For Practical Coal Mine Design

    ground failure are almost always severe. Ground failures helped trigger recent mine disasters in Alabama (2001) and Utah (2000) by disrupting ventilation that led to gas explosions. Together, these incidents claimed the lives of 15 coal miners. So far in 2006, six coal miners have lost their lives in four roof falls, a rib fall and a coal mine ...

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  • Geologic Hazards and Roof Stability in Coal Mines

    Figure 1.–Injuries caused by the fall of roof and rib in U.S. coal mines, 1983-99. Figure 2.–Fatalities caused by the fall of roof and rib in U.S. coal mines, 1983-99. safety and productivity. These structures weaken the roof beam and can cause damage that is not prevented by conventional roof support. In addition, the occurrence of the

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  • Factors Influencing Intersection Stability in U.S. Coal Mines

    Detailed field investigations have resulted in a database of U.S. coal mines containing 12 mines and 639 roof falls so far. By using the roof fall rate as the outcome variable, correlations between roof geology (CMRR), intersection span, and roof support have been established.

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  • Geologic factors affecting coal mine roof stability in the ...

    @article{osti_6429427, title = {Geologic factors affecting coal mine roof stability in the eastern United States}, author = {Kane, W F and Milici, R C and Gathright, II, T M}, abstractNote = {Roof falls in underground coal mines are a continuing source of trouble for mine operators. Fatalities and injuries are a prominent concern, but lost time due to cleanup and disruption of mining ...

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  • Floor Heave Analysis In A Deep Coal Mine | U.S. Rock ...

    A case study was performed on a western coal mine approximately 915 m (3,000 ft) deep to determine the conditions contributing to floor heave in the mine. Keywords: Reservoir Characterization , floor heave , floor member , MPa , floor heave analysis , reservoir geomechanics , Ground Control , horizontal stress , Parting thickness , strength

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  • Roof bolt placement critical in underground mining

    “Falls of ground are still the biggest cause of fatalities in South African coal mines and, upon investigation, it was found that the main cause of these incidents is excessive roof bolt spacing.

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  • Overview of Coal Mine Ground Control Issues in the ...

    Some of the most difficult coal mine roof in the U.S. can be found in the Illinois Basin. Factors contributing to the high roof fall rate include: weak moisture-sensitive roof rock, high horizontal stress, and limited longwall mining. The depth of cover ranges from 90-1,000 ft and roof damage from horizontal stress can be severe. Moisture

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