Numerical Modeling for Yield Pillar Design: A Case Study

Li, Wenfeng; Bai, Jianbiao; Peng, Syd S.; Wang, Xiangyu; Xu, Ying

doi:10.1007/s00603-013-0539-8

Cited by 134 publications

(67 citation statements)

References 3 publications

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“…Therefore, the application of those failure criteria for ground control operations is very complicated and often met with prediction failure (Peng, 2007;Peng, 2008;Li et al, 2015). This is believed to be one of the main reasons that cause the discrepancy between the model predicted and in-mine observation or instrumentation results in most of the case studies handling the issues of coal mine ground control by using numerical modeling (Morsy & Peng, 2002;Suchowerska et al, 2013;Li et al, 2014). To address the dilemma, many researchers have developed plenty of failure criteria that can be implemented in the numerical modeling packages to simulate the transversely isotropic behavior of rocks (Hoek & Brown, 1980;Kulatilake et al, 1995;Tien & Kuo, 2001).…”

Section: Introductionmentioning

confidence: 99%

Experimental Study On The Effect Of Micro-Cracks On Brazilian Tensile Strength

Wang¹

2015

Archives of Mining Sciences

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For coal mine ground control issues, it is necessary to propose a failure criteria accounting for the transversely isotropic behaviors of rocks. Hence, it is very helpful to provide experimental data for the validation of the failure criteria. In this paper, the method for preparing transversely isotropic specimens and the scheme of the Brazilian tensile strength test are presented. Results obtained from Brazilian split tests under dry and water-saturated conditions reflect the effect of the development direction β of the structural plane, such as the bedding fissure, on the tensile strength, ultimate displacement, failure mode, and the whole splitting process. The results show that the tensile strength decreases linearly with increasing β. The softening coefficient of the tensile strength shows a sinusoidal function. The values of the slope and inflection point for the curve vary at the different stages of the Brazilian test. The failure mode of the rock specimen presented in this paper generally coincides with the standard Brazilian splitting failure mode. Based on the test results, the major influencing factors for the Brazilian splitting strength are analyzed and a mathematical model for solving the Brazilian splitting strength is proposed. The findings in this paper would greatly benefit the coal mine ground control studies when the surrounding rocks of interest show severe transversely isotropic behaviors.Keywords: Brazilian split test; Dry and water saturation; Bedding fissure; Strength coefficient; Coal mine ground control W związku z zagadnieniami ochrony powierzchni w kopalniach węgla, konieczne jest opracowanie odpowiednich kryteriów klasyfikacji uszkodzeń skał uwzględniających ich poprzeczną izotropowość. Pomocnym jest także dostarczenie danych eksperymentalnych niezbędnych do walidacji kryteriów uszkodzeń. W pracy tej zaproponowano metodę przygotowywania próbek wykazujących izotropowość poprzeczną, omówiono także sposób przeprowadzania testu na rozciąganie metodą brazylijską. Wyniki testu uzyskane na sucho oraz w warunkach nasycenia próbki wodą wskazują wpływ kierunku rozwoju β płaszczyzny strukturalnej (np. płaszczyzn spękań) na wytrzymałość próbki na rozciąganie, maksymalne przemieszczenia, rodzaj uszkodzenia oraz przebieg procesu pękania. Wyniki testu wskazują, że wytrzymałość na rozciąganie maleje liniowo wraz ze wzrostem wartości β. Współczynnik mięknienia próbki w trakcie próby wytrzymałościowej na rozciąganie ma przebieg krzywej sinusoidalnej. Wartości kąta nachylenia oraz punkt przegięcia krzywej różnią się dla poszczególnych etapów próby wytrzymałościowej. Tryb uszkodzeń próbek skalnych przedstawiony w artykule zasadniczo pozostaje w zgodzie z typowymi odkształceniami rejestrowanymi w trakcie testu metodą brazylijską. W oparciu o wyniki eksperymentu, przeanalizowano główne czynniki wpływające na wytrzymałość próbek na rozciąganie i zaproponowano odpowiedni model matematyczny do obliczania wytrzymałości. Wyniki przedstawione w artykule stanowią poważny przyczynek do badań stabilności gruntu...

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Section: Introductionmentioning

confidence: 99%

Experimental Study On The Effect Of Micro-Cracks On Brazilian Tensile Strength

Wang¹

2015

Archives of Mining Sciences

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“…According to the literature [26], the frictional angle between the filling body and floor strata in the roadway was 40°, and the vertical height hc in the y-direction, equivalent width d, and bulk density of the filling body were 2 m, 2.5 m, and 15.25 kN/m 3 , respectively. Based on the obtained field data and laboratory experimental results, the shear stress τ on the roadside filling body was calculated to be 15.89 MPa using Equation (7).…”

Section: Shear Strength Of Roadside Filling Bodymentioning

confidence: 99%

An Innovative Support Structure for Gob-Side Entry Retention in Steep Coal Seam Mining

Ning

Wang

et al. 2017

Minerals

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This study considered longwall working face No. 41101-located in a steeply inclined coal seam at the Awuzisu coal mine in Xinjiang, China-as an example in which macroscopic shear cracks had occurred in the cement-based filling body of the gob-side entry retention structure. A mechanical model of the support structure for the gob-side entry retention was first established. Then, field observations and laboratory tests were used to obtain the force exerted by the coal wall on the main roof, the relationship between the axial bearing capacity and compression ratio of the rubble inside the gob, the supporting force exerted by the rubble and filling body, and the thrust of the rubble on the filling body. The shear stress experienced by the roadside filling body of the gob-side entry retention in working face No. 41101 was calculated to be 15.89 MPa. To meet the needs of roadside support, an innovative roadside backfill-truss support structure was adopted, with a 60 • angle of inclination used for the anchor bolts of the gob-side entry retention structure. In this way, the ultimate shear strength was improved by 107.54% in comparison with the cement-based filling body.

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“…The width of the rib pillar needs to be carefully determined, otherwise it may be too narrow to maintain stability [25] or too wide to induce stress concentration and cause a potential coal burst accident [36].…”

Section: Previous Studies On Gob-side Entriesmentioning

confidence: 99%

“…This issue is more serious in longwall top coal caving panels because the Chinese government regulates that the recovery rate for panels using this mining method must be higher than 75% [15]. Also, an unsuccessful yield pillar design in GER panels may lead to coal burst accidents [36]. Previous studies on gob-side entries are focused on identifying the influencing factors on entry stability.…”

Section: Research Gapsmentioning

confidence: 99%

A New Gob-Side Entry Layout Method for Two-Entry Longwall Systems

et al. 2018

Energies

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Abstract:The gob-side entry layout is popular at two-entry longwall mine sites in China for the benefit of improving the coal recovery rate. Currently, two methods have been widely used to develop gob-side entries, including gob-side entry retaining and gob-side entry driving. Gob-side entry retaining maximizes the recovery rate by pillarless mining but increases the difficulty in gob-side entry support. Also, this method has limited applications in hard roof conditions. The gob-side entry driving mine site uses the rib pillar to separate the gob entry and the gob area of the previous panel, which leads to additional coal losses. The waste is more intolerable in large-cutting-height panels and longwall top coal caving panels as the Chinese government limits the minimum recovery rate of longwall panels using these mining methods. In this paper, a new gob-side entry layout method, termed gob-side pre-backfill driving, is established to overcome the shortcomings of the existing methods. The new method eliminates rib pillar losses and enhances gob-side entry stability. The feasibility of gob-side pre-backfill driving is studied by numerical modelling and a field trial at Changcun Mine in China. The results indicate that gob-side pre-backfill driving is an alternative for gob-side entry development. This method is practical and also has the potential to bring significant economic benefits to the mining industry.

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Numerical Modeling for Yield Pillar Design: A Case Study

Cited by 134 publications

References 3 publications

Experimental Study On The Effect Of Micro-Cracks On Brazilian Tensile Strength

Experimental Study On The Effect Of Micro-Cracks On Brazilian Tensile Strength

An Innovative Support Structure for Gob-Side Entry Retention in Steep Coal Seam Mining

A New Gob-Side Entry Layout Method for Two-Entry Longwall Systems

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