Structural characteristics of key strata and strata behaviour of a fully mechanized longwall face with 7.0m height chocks

Ju, Jinfeng; Xu, Jialin

doi:10.1016/j.ijrmms.2012.09.006

Cited by 189 publications

(108 citation statements)

References 7 publications

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“…3d) [37]. In some cases, collapse of the roof behind the face support does not take place immediately [38,39]. That leads to the opening of contacts in a goaf bedrock and hence, create conditions for GDP occurrence (Fig.…”

Section: Results Of Mathematical Modelingmentioning

confidence: 99%

About the mechanism of localization of gas dynamic phenomena focuses in the bedrock of sylvinite formations

Baryakh¹,

Andreyko²,

Fedoseev³

2017

Вестник ПНИПУ. Геология. Нефтегазовое и горное дело

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Section: Results Of Mathematical Modelingmentioning

confidence: 99%

About the mechanism of localization of gas dynamic phenomena focuses in the bedrock of sylvinite formations

Baryakh¹,

Andreyko²,

Fedoseev³

2017

Вестник ПНИПУ. Геология. Нефтегазовое и горное дело

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“…These thick-and-hard strata, called KS could be seen as a control mechanism for rock mass movement; while the soft strata could be seen as the body of the load on the bottom of the thick-and-hard strata (KS). The controlling effect of the KS means that when KS break, the soft strata controlled by the KS break simultaneously, which is the basis of the KS theory proposed by Chinese academic, Qian [24]. The controlling effect of KS can be seen in Figure 9.…”

Section: Determination Of Reasonable Support Capacitymentioning

confidence: 89%

“…The controlling effect of KS can be seen in Figure 9. Based on this, the determination method of the location of the KS in overlying strata is given by Qian, which can be seen in reference [24]. Therefore, factors such as weakening top-coal, eliminating the overhanging of top-coal and upgrading its crushing degree should be taken into consideration.…”

Section: Determination Of Reasonable Support Capacitymentioning

confidence: 99%

“…The controlling effect of KS can be seen in Figure 9. Based on this, the determination method of the location of the KS in overlying strata is given by Qian, which can be seen in reference [24]. Prior to the determination of support capacity, the structural characteristics of key strata [25], which control the overlying strata movement, should be identified.…”

Section: Determination Of Reasonable Support Capacitymentioning

confidence: 99%

“…Prior to the determination of support capacity, the structural characteristics of key strata [25], which control the overlying strata movement, should be identified. Generally, if the key strata are close to the coal seam or the thickness of coal seam is large, the key strata will be located in the caving zone and form a cantilever beam structure (CBS), while if the key strata siting is far away from the coal seam or located in the fractured zone, it will be hinged together (i.e., the broken blocks of key strata can be hinged with each other) to form a voussoir beam structure (VBS) [24], as shown in Figure 10a. According to the observed results of the height of the caving zone in the longwall top-coal caving face of the extra-thick coal seam in the Datong coalfield [2] and the determination method of the structure of the key strata [24], it can be concluded that the sub-key stratum (SKS) 1 of LTCC-west8101 forms the CBS, whereas the SKS 2 (main roof) forms the VBS, as shown in Figure 10b.…”

Section: Determination Of Reasonable Support Capacitymentioning

confidence: 99%

See 2 more Smart Citations

Mechanism and Prevention of a Chock Support Failure in the Longwall Top-Coal Caving Faces: A Case Study in Datong Coalfield, China

Zhu

et al. 2018

Energies

Self Cite

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Longwall chock support failures seriously restrain the safety and high-efficiency of mining of extra thick coal seams, as well as causing a great waste of coal resources. During longwall top-coal caving (LTCC), the influential effect of the properties and the movement regulation of top-coal on strata behavior cannot be ignored, since the top-coal is the medium through which the load of the overlying strata is transferred to the chock supports. Taking Datong coalfield as an example, the mechanism of a chock support failure in the LTCC face was investigated. Research findings indicated that the hard top-coal and insufficient chock support capacity were primary reasons for chock support failure accidents. On account of the field-measured results, a new method to determine support capacity was proposed, which fully took the impact of the top-coal strength into consideration. The calculation revealed that the required support capacity had exceeded the existing production maximum, at about 22,000 KN. Since it was unrealistic to simply increase chock support capacity, other approaches, according to the theoretical analysis, were proposed, such as lowering the integrity and strength of the top-coal, and upgrading its crushing effect to weaken the support load effectively during the weighting period, which reduces the likelihood of chock support accidents occurring. Based on this, hydraulic fracturing for hard top-coal and optimization of the caving process (chock supports raised up and down repeatedly by manual operation before moving forward) were presented. The proposed solutions were successfully applied in LTCC-west8101 for subsequent mining and achieved substantial benefits. The above research provides valuable references and ideas for the control of strata behavior to ensure safe and highly efficient mining in extremely thick and hard coal seams with the LTCC method.

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Analytical examination for the stability of a competent stratum and implications for longwall coal mining

2019

Energy Science & Engineering

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Rational estimation of the mechanical state of a competent rock layer is of prime importance for structural and support design in longwall coal mining. This paper analytically examines the stability of a voussoir‐structured stiff rock by considering it acting as a symmetric flat arch with discontinuities at the abutments and midspan. Three typical failure modes including snap through, midspan crush and sliding failure are inspected. The solution assumes that the shape of the compressive arch obeys a parabolic variation as the voussoir beam deflects downwards with large‐deformation. The crush failure due to stress concentration in the beam hinge is predicted by relating the squeezing area with the beam rotation, which is absent in previous studies. The proposed approach can examine the voussoir beam stability without cumbersome iteration. Primarily, this work facilitates the evaluation of the support requirements to reinforce roof beds in longwall panels. After accounting for the total loads of the overlying rock layers, the stability assessment developed in this paper can further be utilized to predict the span limit of the main roof above a longwall panel and to estimate the critical width which governs the magnitude of mining subsidence.

show abstract

Structural characteristics of key strata and strata behaviour of a fully mechanized longwall face with 7.0m height chocks

Cited by 189 publications

References 7 publications

About the mechanism of localization of gas dynamic phenomena focuses in the bedrock of sylvinite formations

About the mechanism of localization of gas dynamic phenomena focuses in the bedrock of sylvinite formations

Mechanism and Prevention of a Chock Support Failure in the Longwall Top-Coal Caving Faces: A Case Study in Datong Coalfield, China

Analytical examination for the stability of a competent stratum and implications for longwall coal mining

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