Evolution laws of strength parameters of soft rock at the post-peak considering stiffness degradation

Zhao, Zenghui; Wang, Weiming; Gao, Xin

doi:10.1631/jzus.a1300314

Cited by 17 publications

(12 citation statements)

References 13 publications

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“…In the post-peak deformation stage, the development of strain softening is induced by the change of the rock strength parameters [12][13][14].…”

Section: Analysis Of the Rock Parameters Of Thementioning

confidence: 99%

“…Fang and Harrison [12] utilized the concept of a degradation index to describe the variation in degradation that rock exhibits when it is subjected to various confining pressures. Zhao et al [13] established evolution laws of the strength parameters of soft mudstone at the post-peak stage by considering stiffness degradation. By introducing the concept of generalized friction angle and generalized cohesion, Lu et al [14] constructed the post-peak computing model combined with FLAC code.…”

Section: Introductionmentioning

confidence: 99%

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Study of Post‐Peak Strain Softening Mechanical Behaviour of Rock Material Based on Hoek–Brown Criterion

Lin

Cao

Wang

2018

Advances in Civil Engineering

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In order to build the post-peak strain softening model of rock, the evolution laws of rock parameters (m, s) were obtained by using the evolutionary mode of piecewise linear function regarding the maximum principle stress. Based on the nonlinear Hoek-Brown criterion, the analytical relationship of the rock strength parameters (m, s), cohesion (c), and friction angle (φ) has been developed by theoretical derivation. According to the analysis on the four different types of rock, it is found that, within the range from 0 to σ 3min , the peak hardness of the rock becomes smaller as the confining pressure increases and the degree of rock fragmentation decreases as well. e post-peak stress-strain curves obtained from the developed softening model are in good agreement with the laboratory test results under different confining pressures. In conclusion, the analytical method is reasonable, and it can predict the post-peak mechanical behaviour of rock well, which provides a new thought for the rocksoftening simulation.

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“…In the post-peak deformation stage, the development of strain softening is induced by the change of the rock strength parameters [12][13][14].…”

Section: Analysis Of the Rock Parameters Of Thementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Study of Post‐Peak Strain Softening Mechanical Behaviour of Rock Material Based on Hoek–Brown Criterion

Lin

Cao

Wang

2018

Advances in Civil Engineering

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“…We now define the stress concentration factor k=2, overlying rock formation gravity =18 kN/m 3 , coal seam Poisson's ratio ] m =0.32, and buried depth H=100-500 m. According to the geological exploration data of weakly cemented soft rock, the limit equilibrium zone width is analyzed using three groups of parameters, as seen in Table 1 [3,4,32]. Table 1 is displayed in Figure 7.…”

Section: An Analysis Of Factors Influencing the Limit Equilibriummentioning

confidence: 99%

“…The weakly cemented soft rocks, e.g., Cretaceous and Jurassic mudstone, argillaceous siltstone, sandstone, and silt, are widely distributed in Xinjiang, Gansu, Ningxia, western Inner Mongolia, and other areas in western China. The unique physical and mechanical properties of weakly cemented soft rocks are formed in western China due to its special geographical and climate conditions, sedimentary process, and geological conditions, and the rocks are characterized by a low strength, poor cementation, possible weathering, possible argillization and disintegration when encountering water, unstable mechanical properties, and large areas of disturbance, and quick deformation in the surrounding rock after the coal seam has been excavated, resulting in frequent engineering accidents or disasters, such as a large caving in the roof and high walls, and serious floor heave, all of which can cause considerable economic losses and threats to the security of energy engineering construction in western China [1][2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Prediction Model of Failure Zone in Roadway Sidewall considering the Lithologic Effect of Rock Formation

Zhao

Chen

et al. 2018

Mathematical Problems in Engineering

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Coal seam damage area and its stress distribution law in roadway with medium thickness or extrathick coal seam are important issues for understanding the instability mechanism of roadway surrounding rock in weakly cemented soft rock strata in western China. Firstly, a variable parameter microelement analysis model is established based on the assumption of a plane stress integrating with the coal seam-rock’s interface and the rock formation on both sides; moreover, a formula is established by the strain compatibility relationship to express the state of stress in rock bodies on both sides of the interface. Then, a method for calculating the stress limit equilibrium zone width of the coal side and regional stress distribution is presented, which considers the coupling effect of the coal side-rock formation and is based on the loose medium limit equilibrium theory. Finally, the validity of the model is verified through a comparison with previous research and by being applied to an engineering example. The results show the following: (1) the interface adhesion effect results in an abrupt change of the stress state of both the rock formation and coal seam and is related to their deformation parameters; i.e., there is a coupling effect; (2) the limit equilibrium zone width is not only related to the buried depth of the roadway, excavated coal seam thickness, coal seam strength parameters, stress concentration factor, lateral pressure coefficient, and supporting strength of the side of the roadway, but it also has an effect on the aforementioned coupling effect; (3) due to the roof-coal seam-floor comprehensive structural effect, the model presented in this paper is applicable to both the coal seam failure and the failure along the coal seam-rock’s interface.

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“…As a permanent deformation zone, the weak intercalation formed by weathering has poor support capability (Zhao et al, 2014;Le et al, 2018). Therefore, the weak interlayer is a poor rock mass system with variable thickness and weak mechanical properties, which plays a controlling role in the stability of the dam foundation against sliding and seepage.…”

Section: Introductionmentioning

confidence: 99%

An Experimental and Numerical Study of Diorite-Porphyrites With Different Weathered Degree in the Direct Shear Test

Fan

Sun

et al. 2020

Front. Earth Sci.

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There are many well-developed weathered diorite-porphyrites, except main rocks, in the Jurong pumped storage power station of Jiangsu Province, China. Due to different geological environments, diorite-porphyrites emerged by invading faults and can alter from weakly weathered to strongly weathered in less than half a year, which directly affected the safety and stability of hydraulic structures. Therefore, it is important to study the mechanical properties of diorite-porphyrites with different degrees of weathering. The main purpose of this paper is to investigate the effects of the different degrees of weathering on the shear behavior and the mechanical properties of diorite-porphyrites. Experimental and numerical direct shear tests were performed under normal stresses of 0.54, 0.77, 1.53, and 2.30 MPa on strongly weathered, moderately weathered, and weakly weathered samples, respectively. The test results show that with the increase of the degree of weathering, the chemical composition changed; the cohesion and the internal friction angle both decreased. Crack initiation, propagation, and coalescence were all observed with the numerical simulations using two-dimensional particle flow code (PFC 2D). The numerical results are in good agreement with the experimental results, and this numerical approach can reproduce the shear behavior of the weathered diorite-porphyrites under different shear conditions. Based on the gradient of the prepeak stage, the peak stress, and the residual stress, the shear stress-displacement curves can be categorized into three types: type A (mostly for the strongly weathered diorite-porphyrite), type B (mostly for the moderately weathered diorite-porphyrite), and type C (mostly for the weakly weathered diorite-porphyrite). A set of microparameters that can properly simulate the weathered diorite-porphyrites in PFC 2D was proposed, which can be applied in the engineering simulation for further analysis.

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Evolution laws of strength parameters of soft rock at the post-peak considering stiffness degradation

Cited by 17 publications

References 13 publications

Study of Post‐Peak Strain Softening Mechanical Behaviour of Rock Material Based on Hoek–Brown Criterion

Study of Post‐Peak Strain Softening Mechanical Behaviour of Rock Material Based on Hoek–Brown Criterion

Prediction Model of Failure Zone in Roadway Sidewall considering the Lithologic Effect of Rock Formation

An Experimental and Numerical Study of Diorite-Porphyrites With Different Weathered Degree in the Direct Shear Test

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