Effect of rock strength on failure mode and mechanical behavior of composite samples

Liu, Jie; Wang, Enyuan; Song, Dazhao; Wang, Siheng; Niu, Yue

doi:10.1007/s12517-014-1574-9

Cited by 106 publications

(44 citation statements)

References 15 publications

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“…Previous studies found that as a result of the deviatoric stress, tension cracks and compressional shear cracks appeared inside rocks. [40][41][42][43] When the principal fracture propagated forward at its front ends, several groups of microcracks first occurred, either isolated from one another or forming fork-shapes, then connected to one another, forming macroscopic fractures and closing some microcracks around it.…”

Section: Effect Of Fluids On Strength and Micro-mechanical Mechanismsmentioning

confidence: 99%

Effects of different fluids on microcrack propagation in sandstone under true triaxial loading conditions

Bai

2017

Greenhouse Gases

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The mechanical behavior of rock under conditions of multiphase fluids is currently a key scientific issue in the field of geotechnical engineering. In this work, we conducted triaxial compression experiments of initially water‐saturated samples, which were flooded with CO2 using the semipermeable separator method; comparatively investigated the mechanical behaviors of sandstone under the conditions of mono‐phase fluids CO2/N2/H2O and biphase fluid CO2‐H2O; and analyzed the stress‐strain characteristics, internal crack expansion, and macrocrack failure patterns of sandstones. Compared with H2O, CO2 and N2 could lead sandstone cracks to show a pattern of multiple fractures, displaying a double shear failure mode and multiple branch cracks along principal fractures. Moreover, the cracking effect of supercritical CO2 was more evident. Under the conditions of pore pressure of 10 MPa and temperature of 323 K, the ratio of work done by CO2, N2 and H2O during crack expansion was 23.5:24.1:1, with transient pressure drops to 7.82 MPa, 9.25 MPa, and 0.1 MPa, respectively. Overall, the study analyzed the mechanisms of physicochemical interactions of fluid types and the number of phases in sandstone minerals at the microscale and revealed the mechanical mechanism between fluids and rock minerals, as well as the impacts of these fluids on the strength, internal crack expansion and deformation of sandstone. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd.

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Section: Effect Of Fluids On Strength and Micro-mechanical Mechanismsmentioning

confidence: 99%

Effects of different fluids on microcrack propagation in sandstone under true triaxial loading conditions

Bai

2017

Greenhouse Gases

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“…The failure and instability mechanisms of compound coal‐rock structures with discontinuities have been widely investigated, and frictional slip along discontinuities, especially faults, can directly result in dynamic phenomena, such as rock bursts at the microscale and earthquakes at the macro‐scale . Frictional slip along a discontinuity is controlled by fault strength, normal stress to the discontinuity and shear stress along the discontinuity, as well as the stress distribution and frictional property of the discontinuity, which may relate to the Mohr‐Coulomb theory .…”

Section: Introductionmentioning

confidence: 99%

Slip and instability mechanisms of coal‐rock parting‐coal structure (CRCS) under coupled dynamic and static loading

Liu

et al. 2019

Energy Science & Engineering

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The slip and instability mechanisms of coal‐rock parting‐coal structure (CRCS) under coupled dynamic and static loading were investigated using theoretical analysis and numerical simulations, and the fracture and instability processes were described by monitoring the displacement, strain, and acoustic emissions (AEs) of coal and rock parting blocks. Based on the parameters of dynamic load, three different effects on slip and instability characteristics of CRCS were presented, and the effect mechanisms of static stress, as well as amplitude and frequency of dynamic stress wave, were analyzed in detail. Finally, the direct effect on the slip and instability strength of CRCS and the frequency range of dynamic load for generating synchronous slip along two discontinuities sandwiched between coal and rock parting blocks were discussed. This work is relevant for early warning coal‐rock dynamic disasters that are triggered by the slip and fracture instability of CRCS under coupled dynamic and static loading in coal mines.

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“…Coal burst in an underground coal mine is mainly expressed in the form of sudden coal pillar yield, instantaneous vibration, and causes massive destruction of macroscopic characteristics [1][2][3][4]. It has been a long-term objective of the mining community to pursue safety, while maintaining high productivity and efficiency.…”

Section: Introductionmentioning

confidence: 99%

Numerical Assessment of the Influences of Gas Pressure on Coal Burst Liability

Zhao

Kaunda

2018

Energies

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When coal mines exploit deep seams with high-gas content, risks are encountered due to the additional high likelihood of rock bursting potential problems. The bursts of coal pillars usually lead to severe fatalities, injuries, and destruction of property, including impeding access to active mine workings underground. The danger exists given that conditions in the already highly brittle coal material can be exacerbated by high stress and high gas pressure conditions. It is thus critical to develop methods that improve current understanding about bursting liability, and techniques to forecast or prevent coal bursting in underground coal mines. This study uses field data from a deep coal mine, and numerical modeling to investigate the effects of gas pressure and mechanical compressive stresses on coal bursting liability in high gas content coal seams. The bursting energy index is adopted to determine the coal bursting liability under high gas pressure conditions. The adopted methodology uses a two-staged approach comprising investigating the influence of gas pressure on the bursting liability of coal pillar, and the influence of the gas pressure on the resulting pillar failure mode. Based on numerical simulations of coal pillars, correlations are observed between the magnitudes of gas pressures and the bursting energy index. Irrespective of pillar size, failure time is shortest when the gas pressure achieves a threshold value between 50 kPa to 70 kPa. At 50 kPa, the value of the BEI increases by 50% going from the 4 m pillar to the 6 m pillar. The value of the BEI increases by 43% going from the 6 m high pillar to the 8 m high pillar at 50 kPa. When pillars fail there is a degree of stress relief leading to a reduction in bursting liability. The results suggest that before 50 kPa, pillar failure is largely due to mechanical loading. After 50 kPa, pillar failure is largely due to excessive gas pressures.

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Effect of rock strength on failure mode and mechanical behavior of composite samples

Cited by 106 publications

References 15 publications

Effects of different fluids on microcrack propagation in sandstone under true triaxial loading conditions

Effects of different fluids on microcrack propagation in sandstone under true triaxial loading conditions

Slip and instability mechanisms of coal‐rock parting‐coal structure (CRCS) under coupled dynamic and static loading

Numerical Assessment of the Influences of Gas Pressure on Coal Burst Liability

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