HKCV Rheological Constitutive Model of Mudstone under Dry and Saturated Conditions

Advances in Materials Science and Engineering

Lian

et al. 2018

Self Cite

The effect of temperature and pressure, which play important roles in the mechanical properties of rocks during deep energy exploitation, has not been sufficiently studied in the previous rock creep models. In order to investigate thermal effect in creep models, a modified Nishihara rheological model, taking into account the coupled effect of thermal damage and stress, was proposed by combining the theoretical formula for thermal damage of rocks with the modified Nishihara model. The improved model introduces a nonlinear viscous dashpot, which can accurately describe the accelerated rheological phase of rocks. To verify the proposed model, a triaxial rheological experiment was conducted on sandstone subjected to thermal damage (600°C). In addition, the stress-strain curves within whole creep process of the rheological experiment were analyzed. Furthermore, the theoretical curves of the modified Nishihara rheological model were compared with the experimental results. Results showed that the theoretical curves relatively agree well with the experimental data, suggesting that the proposed new model is more preferred to describing the rheological curve of sandstone subjected to thermal damage at different rheological stages, in particular, it is capable of depicting the accelerated rheological stage of the sandstone, providing a good ability to describe the creep behavior of rocks under thermal-mechanical coupling.

Section: Introductionmentioning

confidence: 99%

Modified Nishihara Rheological Model considering the Effect of Thermal‐Mechanical Coupling and Its Experimental Verification

Wang

Advances in Materials Science and Engineering

Lian

et al. 2018

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“…Discontinuities include bedding planes, faults, fissures, fractures, joints, etc. e orientation of discontinuities is known to greatly affect the kinematical and mechanical behavior of rock [2][3][4][5]. ese orientations can be observed on rock exposures such as outcrops, tunnel faces, pit faces, and drillhole faces.…”

Section: Introductionmentioning

confidence: 99%

Correction of Line‐Sampling Bias of Rock Discontinuity Orientations Using a Modified Terzaghi Method

Tang

Zhang

Advances in Civil Engineering

et al. 2018

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The Terzaghi method is widely used to correct the line-sampling bias of rock discontinuity orientations. The method includes four procedures, one of which is meshing the stereographic projection diagram into cells. The method is based on the bias-compensatory factor, 1/sin θ, where θ is the angle between the scanline and the discontinuity defined at each cell center. This paper presents a modified Terzaghi method that eliminates meshing, thereby reducing the method to three steps that (1) count the frequencies, (2) weigh the frequencies by the bias-compensatory factor, and (3) round the weighed frequencies to the nearest integer. Due to the elimination of the mesh, the counting object has changed to the frequency at each pole, and θ in the bias-compensatory factor is redefined as the angle between the scanline and the discontinuity at each pole. The applicability of the redefined bias-compensatory factor is verified through a mathematical logical deduction. The accuracy of the conventional and the modified Terzaghi methods are compared using a case study in Wenchuan, China, revealing improved accuracy for the latter.

“…However, the potential impact of various factors (e.g., clay mineral composition, water content, grain gradation, and confining pressure) has not yet been reported. Despite numerous previous works investigating the impact factors of the dynamic strength of common fine-grain soils [2][3][4][5][6][7][8][9][10][11], little is known as to whether the same impacts occur in mudded intercalations, which are a special soil type whose main mineral composition is clay with breccia and rock fragments.…”

Section: Introductionmentioning

confidence: 99%

Identifying the Impact Factors of the Dynamic Strength of Mudded Intercalations during Cyclic Loading

Yan

Xiaoli

Advances in Civil Engineering

2018

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Despite reports on previous research associated with the dynamic strength of mudded intercalations during cyclic loading, a systematic investigation of the impact factors of this strength is still valuable. This work aimed at experimentally revealing the impact factors of the strength along with their impacts. The potential impact factors considered in this work include (i) water content, (ii) clay mineral composition, (iii) clay content, (iv) confining pressure, and (v) cyclic failure time. Specimens of mudded intercalations were collected from China and were remolded and prepared for a dynamic triaxial test under cyclic loads. The test results showed that the dynamic strength is impacted by water content (strongly), clay mineral composition (moderately), confining pressure (moderately), and cyclic failure time (weakly); no significant impact of clay content was detected. Moreover, the dynamic cohesion is correlated with clay mineral composition (strongly), water content (moderately), and cyclic failure time (weakly); no significant correlation with clay content or confining pressure was detected. Finally, the dynamic friction angle is correlated with water content (strongly), clay content (moderately), and cyclic failure time (weakly); no significant correlation with clay mineral composition or confining pressure was detected.