Dynamic Characteristics of Green Sandstone Subjected to Repetitive Impact Loading: Phenomena and Mechanisms

Li, S. H.; Zhu, Wancheng; Niu, Leilei; Yu, Miao; Chen, C. F.

doi:10.1007/s00603-018-1449-6

Cited by 90 publications

(30 citation statements)

References 56 publications

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“…In these experiments, samples were loaded by a single compressive pulse, remounted, and then subsequently loaded again by repeating tests (up to 40 times), resulting in long resting periods between loading cycles due to the time required for resetting the SHPB. Reductions in dynamic compressive strengths have also been documented for granite (Zhou et al, 2018) and sandstone (Li et al, 2018;Tong et al, 2019) using similar experiments. Reductions in dynamic compressive strengths have also been documented for granite (Zhou et al, 2018) and sandstone (Li et al, 2018;Tong et al, 2019) using similar experiments.…”

Section: Introductionmentioning

confidence: 52%

The Effect of Dynamic Stress Cycling on the Compressive Strength of Rocks

Braunagel

Griffith

2019

Geophysical Research Letters

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Quasi‐static rock strength is a nonconservative property, as fatigue during cyclic loading reduces the macroscopic strength. When strain rate under compressive loading increases above a lithology‐specific threshold, the primary failure mechanism transitions from localized failure along discrete fractures to distributed fracturing. However, the role of load path under high strain rate conditions has not been explored in any detail. We examine the effect of rapid stress cycles on the dynamic compressive strength of Westerly Granite using a modified split Hopkinson pressure bar approach and explore the implications of our results for the formation of pulverized fault zone rocks. Under cyclic loading conditions, the compressive strength can be reduced by a factor of 2, demonstrating that, like the quasi‐static strength, the dynamic rock strength is also a nonconservative property. Therefore, traditional high strain rate experimental approaches utilizing simple load paths may overestimate strength when rocks are subjected to complex load paths.

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Section: Introductionmentioning

confidence: 52%

The Effect of Dynamic Stress Cycling on the Compressive Strength of Rocks

Braunagel

Griffith

2019

Geophysical Research Letters

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“…Currently, some scholars have built structural mechanical models [53][54][55][56] for roof cutting, such as the transfer rock beam mechanical model [53], mechanical model of fracturing roofs to maintain entry approach [54], dynamic pressure area mechanical model [55], and main roof breaking upon retracement channel mechanical model [56]. These mechanical models revealed the role of various supporting structures, such as roadside backfill and coal support, and the basic characteristics of the main roof movement in GER.…”

Section: Discussionmentioning

confidence: 99%

“…In addition, the roof cutting parameters play a significant role in the process of roof cutting. Currently, roof cutting parameters are mostly based on field engineering experience or empirical formulas [54][55][56], which limit its application scope. Moreover, the FLAC3D software is used to determine the parameters of roof cutting [57,58].…”

Section: Discussionmentioning

confidence: 99%

“…We define the cutting height as the maximum vertical height of the roof cutting borehole. According to the theoretical analysis [55][56][57][58], the cutting height has great impact on the cutting effect. In the numerical simulation, various cutting heights of 3, 4, 6, 7, 8, and 9 m are adopted.…”

Section: Cutting Heightmentioning

confidence: 99%

“…This will not only cause accidents such as supporting failure and rib spalling in deep mining conditions, but also increase the supporting cost and workload, affect the mining progress and continuity. Therefore, the technique of no-pillar mining with automatically formed GER was proposed [53][54][55][56][57][58]. The roof was presplit along the gob side by borehole blasting, the gob-side roof was cut down, and the goaf was filled owing to the working face advanced, which based on "roof-cutting short cantilever beam" theory.…”

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confidence: 99%

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Roof Cutting Parameters Design for Gob-Side Entry in Deep Coal Mine: A Case Study

et al. 2019

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Roof cutting is an effective technique for controlling the deformation and failure of the surrounding rock in deep gob-side entry. The determination of the roof cutting parameters has become a popular research subject. Initially, two mechanical models are established for the non-roof-cutting and roof-cutting of gob-side entry in deep mining conditions. On this basis, the necessity and significance of roof cutting is revealed by analysing the stress and displacement of roadside prop. The Universal Distinct Element Code numerical simulation model is established to determine the key roof-cutting parameters (cutting angle and cutting height) according to the on-site situation of No. 2415 headentry of the Suncun coal mine, China. The numerical simulation results show that with the cutting angle and height increase, the vertical stress and horizontal displacement of the coal wall first increase and then decrease, as in the case of the vertical stress and displacement of roadside prop. Therefore, the optimum roof cutting parameters are determined as a cutting angle of 70 • and cutting height of 8 m. Finally, a field application was performed at the No. 2415 headentry of the Suncun coal mine. In situ investigations show that after 10 m lagged the working face, the stress and displacement of roadside prop are obviously reduced with the hanging roof smoothly cut down, and they are stable at 19 MPa and 145 mm at 32 m behind the working face, respectively. This indicates that the stability of the surrounding rock was effectively controlled. This research demonstrates that the key parameters determined through a numerical simulation satisfactorily meet the production requirements and provide a reference for ensuring safe production in deep mining conditions. about 100-500 m, the microstructures, basic mechanical characteristics, and engineering responses of coal and rock have changed significantly in response to the "three highs and one disturbance" environment [10][11][12][13]. The main features are that the surrounding rock has a large deformation, high deformation speed, long deformation duration, and rheological characteristics. Hence, maintenance of the gob-side entry becomes extremely difficult, and large deformation and failure accidents occur occasionally [14][15][16][17][18].Many theoretical studies and field practices on GER technology under deep mining conditions have been completed, and three major advancements should be considered. First, the surrounding rock deformation characteristics and failure evolution law of deep GER are revealed under various geological conditions [19][20][21][22][23]. The roof of the gob-side entry is simplified into a rectangular "superposed stratified plate" structure [24,25], and the concept of the strip segmentation method for the roof load is proposed according to the theory of elastoplastic mechanics. On this basis, used a numerical analysis method to identify the influence mechanism of the roof fracture location, roof rotation, and long-term creep of the surrounding rock in deep ...

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Assessment of pillar stability and its control in a double roadway layout

Huang,

Zhao,

Zhang

et al. 2024

Energy Science & Engineering

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To solve the problem of controlling the stability of small coal pillars under the mining disturbance of the adjacent working face, the fourth panel 403 and 404 working faces of the Gaojiabao coal mine with two mining roadways is taken as the object of this research. The comprehensive research method of combining mechanical theory analysis, coal dynamic disturbance experiments and field engineering practice was adopted. First, the analysis determined the magnitude and frequency of fracture‐related disturbance loading on the overburden roof of the working face; next, the strain and stress threshold indicators of the coal body, sensitive to the external disturbance load of 103 J magnitude (continuous disturbance deformation), were tested and obtained through a self‐developed rock creep disturbance experimental system, and the stress threshold indicators of coal body specimens sensitive to creep disturbance were defined as the long‐term strength. Then, a coal pillar‐roof mechanics structure model was established in the premining and postmining areas of the working face, and the overlying support pressure on the coal pillar body was analysed. Finally, a small coal pillar composite reinforcement support technology with ‘two‐way buttressing anchor cable for pressure reinforcement + steel pipe concrete pier column + overhead roof break’ was designed to ensuring that the coal pillar body would not be destabilised by cumulative disturbance and large deformation under disturbance. According postmining area support capacity calculations, the support loading acting on the coal pillar is approximately 17593 kN, with the stress being 2.93 MPa; and the factor of safety is approximately 1.23. After engineering practice application of this approach, the vertical deformation of the small coal pillar body and side heave disturbance deformation were effectively controlled during the working face mining disturbance, the vertical deformation of the reinforced coal pillar was only 187 mm, and the side heave deformation was finally stabilised at approximately 124 mm, which maintained good stability.

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Dynamic Characteristics of Green Sandstone Subjected to Repetitive Impact Loading: Phenomena and Mechanisms

Cited by 90 publications

References 56 publications

The Effect of Dynamic Stress Cycling on the Compressive Strength of Rocks

The Effect of Dynamic Stress Cycling on the Compressive Strength of Rocks

Roof Cutting Parameters Design for Gob-Side Entry in Deep Coal Mine: A Case Study

Assessment of pillar stability and its control in a double roadway layout

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