Observations and classification of roof strata behaviour over longwall coal mining panels in India

Das, Sudhanshu Sekhar

doi:10.1016/s1365-1609(99)00123-9

Cited by 70 publications

(31 citation statements)

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“…For this purpose, 324 numerical models of longwall panel are developed consist of various parameters as show in Table 1. The variations are based on the analysis of the detailed borehole data results from various coalfields across India as well as from published literatures based on Indian coal measures (Das 2002).…”

Section: Finite Element Modeling Of Longwall Panelmentioning

confidence: 99%

Longwall Face Stability Index for Estimation of Chock-Shield Pressure and Face Convergence

Verma

Deb

2010

Geotech Geol Eng

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The paper discusses the concept and methodologies for the development of longwall face stability index (LFSI). LFSI is used for estimation of chock-shield pressure and face convergence. The index comprises of engineering properties of main roof, depth of mining, different support capacities and mechanical properties of coal seam being mined and provides a numerical value in the range of -6.17 to 8.13. In this study, 324 finite element models of longwall panel are developed based on various combinations of geomining conditions of Indian coal measure strata. The LFSI is an outcome of the results from finite element models. This paper illustrates a real life example for the estimation of chock shield pressure and face convergence based on LFSI. Validation of the LFSI based calculation is carried out with the field monitored data and found that the LFSI based approach is sufficient to forecast face stability parameters at longwall face.

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Section: Finite Element Modeling Of Longwall Panelmentioning

confidence: 99%

Longwall Face Stability Index for Estimation of Chock-Shield Pressure and Face Convergence

Verma

Deb

2010

Geotech Geol Eng

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“…1; a caved zone, a fractured zone and a continuous deformation zone, in ascending order from the roofline [1]. The extent of each zone depends on the geological and geotechnical conditions of the overburden strata including the mechanical properties of the rock, in situ stress, the thickness of the coal seam and immediate strata, and the type and nature of the strata [2]. Understanding the failure mechanism associated with the progressive caving of strata is very important for predicting ground subsidence, roadway, face support and mine layout design.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of coal longwall caving characteristics using an innovative UDEC Trigon approach

Gao

Stead

Coggan³

2014

Computers and Geotechnics

154

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The paper presents an innovative numerical approach to simulate progressive caving of strata above a longwall coal mining panel. A proposed Trigon logic is incorporated within UDEC to successfully capture the progressive caving of strata which is characterized by fracture generation and subsequent propagation. A new damage index, D, is proposed that can quantify regions of both compressive shear and tensile failure within the modelled longwall. Many features of progressive caving are reproduced in the model and found to fit reasonably well with field observations taken from a case study in the Ruhr coalfield. The modelling study reveals that compressive shear failure, rather than tensile failure, is the dominant failure mechanism in the caved strata above the mined-out area. The immediate roof beds act like beams and can collapse in beam bending when vertical stress is dominant or in beam shear fracture when horizontal stress is dominant. The proposed numerical approach can be used to guide the design of longwall panel layout and rock support mechanisms.

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“…When considering the caving angle, there are many different publications indicating its various values (Das 2000;Hosseini et al 2013). A wide range of research performed in Indian underground coal mines shows that the value of this angle depends on the type of rock and its strength.…”

Section: Numerical Modeling For Determination Of Grcs In Longwallsmentioning

confidence: 99%

“…There has been a range of studies and underground observations by many researchers (Winstanley 1951;Dubois 1960;Herwig 1981;Jacobi 1981;Peng 1987;Frith 2005Frith , 2013Keim and Miller 1999;Das 2000;Payne 2008;Sastry and Nair 2009;Trueman et al 2010;Prusek 2014) on the basis of which the impact of various geological or mining factors on the roof stability in longwalls can be determined. Based on these research findings, many theories and methods for calculating load on shield support in longwalls, shield support capacity, or methods enable the assessment of the conditions for maintaining the roof in longwalls (Płonka et al 2003;Hussain et al 2013;Wilson 1975;Smart and Redfern 1986;Biliński 1976;Jacobi 1981;Peng 2006;Barczak and Oyler 1991;Langosch et al 2003;Özel and Ünal 1998).…”

Section: Introductionmentioning

confidence: 99%

Applying the ground reaction curve concept to the assessment of shield support performance in longwall faces

2016

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The longwall method is used in many countries around the world in the underground extraction of coal seams. This method enables significantly improved production results to be achieved when compared to the bord and pillar mining system. However, this mining method requires higher capital investment compared to bord and pillar mining. One of the essential elements required to achieve the anticipated level of production from longwall panels is good shield-strata interaction. This means that the shields used in the longwall faces should have an adequate capacity to ensure the maintenance of roof stability in the longwall working. The issue of determining shield capacity has been the goal of research in many countries resulting in a number of different methods for calculating the required capacity of shields. In recent years, numerical modeling and ground reaction curves (GRCs) have been used to determine adequate shield capacity. An important factor to be considered in analyses using the concept of GRC for shield support selection for ground and mining conditions is roof convergence. This paper presents an analysis of shieldroof strata interaction in two longwall panels with natural roof caving in the gob using the concept of GRC. The GRCs for the specific mining conditions in the two longwall faces were determined by means of numerical modeling using Phase 2 software. Performance characteristics of two-leg shields were obtained from underground measurements conducted continuously during the retreat of the longwall panels. In a specially prepared measuring shield, the changes in the leg pressures were measured. In addition, the changes in shield geometry were assessed by means of inclinometers. For the two longwall panels studied, the selected variations of leg pressures and changes of shield height in time are presented for a single shield's cycle during the longwall operations for shield advance, setting, loading, and lowering. An analysis of the interaction between the shield and the roof strata rock mass was performed based on a comparison of the GRC and the operating characteristics of the shield. The values of the roof convergence, which occurred in the longwall faces during the single shield's cycle, are presented. It is strongly recommended that a system enabling the characterization and mining conditions appropriate for shield capacity determination and selection be developed.

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Observations and classification of roof strata behaviour over longwall coal mining panels in India

Cited by 70 publications

References 1 publication

Longwall Face Stability Index for Estimation of Chock-Shield Pressure and Face Convergence

Longwall Face Stability Index for Estimation of Chock-Shield Pressure and Face Convergence

Evaluation of coal longwall caving characteristics using an innovative UDEC Trigon approach

Applying the ground reaction curve concept to the assessment of shield support performance in longwall faces

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