Study on Creep Characteristics and Nonlinear Fractional-Order Damage Constitutive Model of Weakly Cemented Soft Rock

Weakly cemented soft rock (WCSR) strata are widespread in Western China, and their creep characteristics with geo-stress change significantly affect coal mine safety production. To study the long-term mechanical properties of WCSR, creep tests were performed under an initial confining pressure of 0–...

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Bibliographic Details
Published in:Rock mechanics and rock engineering 2023-11, Vol.56 (11), p.8061-8082
Main Authors: Ru, Wenkai, Hu, Shanchao, Zhou, Aohui, Luo, Pingkuang, Gong, Hao, Zhang, Chenxi, Zhou, Xuedong
Format: Article
Language:English
Subjects:
Axial stress
Cement constituents
Civil Engineering
Coal mines
Confining
Constitutive equations
Constitutive models
Constitutive relationships
Creep rate
Creep strength
Creep tests
Damage
Deformation
Earth and Environmental Science
Earth Sciences
Failure mechanisms
Failure modes
Geophysics/Geodesy
Mathematical models
Mechanical properties
Mining accidents & safety
Occupational safety
Original Paper
Pressure
Residual strength
Roads
Rock
Rocks
Solifluction
Stability
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Summary:Weakly cemented soft rock (WCSR) strata are widespread in Western China, and their creep characteristics with geo-stress change significantly affect coal mine safety production. To study the long-term mechanical properties of WCSR, creep tests were performed under an initial confining pressure of 0–6 MPa. The results indicated that with a greater initial confining pressure, the WCSR enters the stable creep stage faster. Using the experimental data, a nonlinear damage constitutive model was constructed to describe the creep failure process while considering the residual strength characteristics of the WCSR sample. Each parameter in the constitutive equation was analyzed for its influence on the creep characteristics of the WCSR. It was found that the axial stress, axial deformation, and stable creep rate of WCSR samples entering the stable creep stage under different initial confining pressures are 18.67 MPa, 1.49% and 0.011%/h, respectively. Based on this study, criteria for determining the creep deformation stability of the WCSR roadways and support suggestions are proposed. These findings will aid in further understanding of the creep failure mechanism and control ideas regarding WCSR roadways. Highlights The effect of the initial confining pressure on the creep characteristics of weakly cemented soft rock was investigated. The effect of the initial confining pressure on the macroscopic and mesoscopic creep failure modes of weakly cemented soft rock was investigated. A nonlinear fractional-order damage constitutive model was proposed to describe the creep failure process of weakly cemented soft rock based on its residual strength characteristics. Based on the deformation and stress characteristics of weakly cemented soft rock under different initial confining pressures, a criterion for determining weakly cemented soft rock roadway deformation stability is proposed.
ISSN:0723-2632
1434-453X
DOI:10.1007/s00603-023-03493-y