Underpinning-based simultaneous extraction of contiguous sections of a thick coal seam under weak and laminated parting

Mandal, Prabhat Kumar; Singh, Rajendra; Maiti, J.; Singh, Amit Kumar; Kumar, Rakesh; Sinha, A.

doi:10.1016/j.ijrmms.2007.03.005

Cited by 50 publications

(20 citation statements)

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“…It can be defined as the direct caving movement type of a cantilever structure (direct caving). Besides, the condition to be satisfied for direct caving of SKS 1 should not only satisfy inequality (3), but also satisfy inequality (5), restated as (7), below:…”

Section: Movement Type Of Cantilever Structure Of Sksmentioning

confidence: 99%

“…[5][6][7] Moreover, field observations show that the coal recovery rate achieved using FMMTLMH is 10%-15% higher than with fully mechanized top coal caving mining. Although fully mechanized top coal caving mining has the advantages of high output and high efficiency, it has some disadvantages, such as increased risk of coal spontaneous combustion in the goaf, high dust concentration in the face, and a low coal recovery rate, compared with FMMTLMH.…”

mentioning

confidence: 99%

“…Although fully mechanized top coal caving mining has the advantages of high output and high efficiency, it has some disadvantages, such as increased risk of coal spontaneous combustion in the goaf, high dust concentration in the face, and a low coal recovery rate, compared with FMMTLMH. [5][6][7] Moreover, field observations show that the coal recovery rate achieved using FMMTLMH is 10%-15% higher than with fully mechanized top coal caving mining. 8,9 Therefore, in China FMMTLMH has become the common method for extracting thick coal seams whose thickness is less than 7.0 m as this method has lower roadway driving rate, and a high coal recovery rate among other advantages.…”

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Determination of working resistance based on movement type of the first subordinate key stratum in a fully mechanized face with large mining height

Zou

2019

Energy Science & Engineering

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The increase in extraction height will increase the mining‐induced overlying strata failure height. In this scenario, the strata pressure behavior is strong in a fully mechanized face with large mining height (FMFLMH), which frequently causes coal wall falls, roof falls, and hydraulic support failure accidents (e.g., support closure and hydraulic column damage). The key to solving these issues is to determine support's working resistance of the FMFLMH. In this paper, comprehensive theoretical analysis, numerical simulation, and field observation were applied to determine the support's working resistance in the FMFLMH based on movement type of the first subordinate key stratum (SKS 1). First, six kinds of movement types of SKS 1 in the FMFLMH are found and defined by theoretical analysis and numerical simulation, which are the direct caving movement type of cantilever structure (direct caving), the double‐sided rotation movement type of cantilever structure (double‐side rotation), the quadratic rotation movement type of cantilever structure (quadratic rotation), the alternative movement type of cantilever structure hinged structure (alternate hinged), the voussoir beam structure movement type (voussoir), and the short voussoir beam structure movement type (short voussoir), respectively. Besides, based on this, the support load calculation model of each movement type was established, and a formula for the support working resistance of each movement type was obtained. Finally, the correctness of the formulae for the support working resistance under six types of movement of SKS 1 were verified using measurement data from four FMFLMHs in China. These research results have important guiding significance for reasonable selection of support and ensuring safe mining of the FMFLMH.

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Section: Movement Type Of Cantilever Structure Of Sksmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Determination of working resistance based on movement type of the first subordinate key stratum in a fully mechanized face with large mining height

Zou

2019

Energy Science & Engineering

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“…Scholars from China and other countries have done much work on the structure characteristics of the overlying strata at thick seam fully-mechanized faces [4][5][6][7][8][9]. There is a common belief that the equilibrium mechanical structure in the strata will move up as mining height increases.…”

Section: Introductionmentioning

confidence: 99%

A Case Study of Effective Support Working Resistance and Roof Support Technology in Thick Seam Fully-Mechanized Face Mining with Hard Roof Conditions

et al. 2017

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This paper presents the engineering geological properties and roof control tecnology for a thick coal seam fully-mechanized face mining with hard roof conditions (THC) at the Jinhuagong Coal Mine (JCM), northwest China. The effective support working resistance and appropriate roof control technology are two critical factors for safe and productive mining in the THC. The load-estimate-method (LOEM) is the effective method to determine the support working resistance for normal working conditions (the mining height less than 3.5 m). In order to prevent support crushing accidents from happening and to ensure the safety and high-efficiency in the THC, the LOEM was modified based on the structure of the overlying strata in the THC. The strata which can form the voussoir beam structure in normal working conditions and will break in the form of cantilever beam in the THC is defined as the key strata in the immediate roof. Therefore, the hanging length of the key strata in the immediate roof was considered in the LOEM. Furthermore, a method for calculating the hanging length of the key strata in the immediate roof and its influencing factors were proposed using cantilever beam theory analysis of the structure of the overlying strata. Moreover, in order to fully fill the goaf area with caving roof to reduce the energy accumulation of main roof movement, it was decided to apply destress blasting technique (DEBT) at the JCM to control the large hanging length of the hard roof, so as to reduce the impact of the hard main roof movement on the working face. The key technique parameters of the roof caving borehole were also proposed. The obtained results demonstrated that the theoretical analysis is reasonable, and the chosen support type and the DEBT could meet the roof control requirements. The THC has achieved safety and high-efficiency mining.

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“…[9]. Mandal et al(2008) conducted instrumentation study in the contiguous seams, where weak and laminated roof parting existed in the coal seam, at a depth of cover varying from 25 to 170 m. Convergence was detected in the stations from the goaf edge at a distance of 120m in top section as compared to 135m in bottom section and the stress measured to 1.8MPa in top seam and 0.35 MPa in the bottom seam was observed [10]. In one of the strata instrumentation study (Singh et al,3) for evaluation of parting stability and caving behaviour, cumulative convergence at the face was observed to be 3mm per day, where full parting caved down completely at a cover depth of about 80m with a parting thickness of 2-3m.…”

Section: Introductionmentioning

confidence: 99%

Strata control monitoring in a contiguous seam depillaring working

K¹,

Galav²,

Behera³

et al. 2016

Proceedings of the Conference on Recent Advances in Rock Engineering (RARE 2016)

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-Most of the underground coal mines in the Indian Geo-mining conditions are developed and depillared by Bord and Pillar method. Caving behaviour and strata control are the major concerns to be considered while extraction of coal seams in such workings. This paper describes the results of a scientific strata control monitoring study during depillaring in a contiguous seam working. It includes instrumentation for determining the induced stresses in the pillars and roof-floor convergence in the galleries and junctions with distance from the goaf edges in the working. The mining induced stresses on the pillars were observed to be more in the top seam than that in the bottom seam working. Convergence monitoring was done with Telescopic Convergence Indicators (TCI) and Remote convergence recorders. In general, higher convergence was observed in the junctions as compared to the galleries. The junctions located at distant location suffered more convergence than the galleries is nearer to the goaf edge. Based on the field observation, convergence classification has also been done in terms of average distance of the goaf edge from the point of observation to assess the state of 'No-convergence', 'Initial convergence' and 'Maximum convergence'. The convergence observed in the bottom seam is more than that of the top seam.

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Underpinning-based simultaneous extraction of contiguous sections of a thick coal seam under weak and laminated parting

Cited by 50 publications

References 8 publications

Determination of working resistance based on movement type of the first subordinate key stratum in a fully mechanized face with large mining height

Determination of working resistance based on movement type of the first subordinate key stratum in a fully mechanized face with large mining height

A Case Study of Effective Support Working Resistance and Roof Support Technology in Thick Seam Fully-Mechanized Face Mining with Hard Roof Conditions

Strata control monitoring in a contiguous seam depillaring working

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