A modified Hoek-Brown failure criterion for unsaturated intact shale considering the effects of anisotropy and hydration

Zhang, Qiangui; Yao, Bowei; Fan, Xiangyu; Li, Yong; Li, Minghui; Zeng, Feitao; Zhao, Pengfei

doi:10.1016/j.engfracmech.2020.107369

Cited by 21 publications

(7 citation statements)

References 56 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Hoek and Brown introduced the Hoek-Brown strength criterion in 1980 [24,25], but this criterion shows limited applicability to anisotropic rock masses. Various scholars have enhanced and refined it by incorporating the anisotropic parameter [26,27], which accounts for the effects of stress and fabric tensors' relative orientations. This enhancement better represents the failure strength of foliated rock masses when combined with the Hoek-Brown criterion.…”

Section: Compressive Strength Anisotropymentioning

confidence: 99%

Experimental Study on Mechanical Properties of Anisotropic Slate under Different Water Contents

Yang,

Li,

Zhang

et al. 2024

Applied Sciences

View full text Add to dashboard Cite

Slate typically possesses a pronounced layered structure and tends to soften when exposed to water, leading to numerous detrimental effects on the construction of related underground projects. In this study, X-ray diffraction (XRD) analysis was first performed to investigate the mineral composition of the typical slate from Changsha, China. Then, uniaxial and triaxial compression tests under varying bedding angles (i.e., 0°, 30°, 45°, 60°, and 90°) and moisture levels (i.e., dry state, natural state, and saturated state) were conducted to explore the anisotropy characteristics and susceptibility to water-induced softening of the slate. The results reveal that: (1) The exposure of slate to water exacerbates the deterioration of its layered structure, making it more prone to shear failure along the bedding planes. Furthermore, the energy released during shear-slip damage is reduced, which is macroscopically manifested by the decrease in slate brittleness and the increase in plasticity. (2) The slate’s compressive strength, elastic modulus, and cohesion vary in a U-shaped pattern with the increase in bedding angles. However, Poisson’s ratio and internal friction angle are slightly affected by the bedding angle and water content, which do not exhibit a clear variation pattern. (3) In addition, the formulations for strength and stiffness predictions of slate were also discussed in this study. The results show that the modified Hoek–Brown criterion characterizes the uniaxial and triaxial compressive strengths of slate more accurately, and the generalized Hooke’s Law more effectively predicts the elastic modulus.

show abstract

Section: Compressive Strength Anisotropymentioning

confidence: 99%

Experimental Study on Mechanical Properties of Anisotropic Slate under Different Water Contents

Yang,

Li,

Zhang

et al. 2024

Applied Sciences

View full text Add to dashboard Cite

show abstract

“…Studies have investigated the borehole stability in shale 15 – 22 , hydration models and the influence of salinity on hydration 23 , 24 , factors affecting the mechanical properties of shale 25 – 32 , and failure criteria of shale 33 , 34 . Additionally, other studies have explored the impact of shale and other rock characteristics on underground openings 21 , 35 – 38 in various regions.…”

Section: Introductionmentioning

confidence: 99%

Potential of carboxymethyl cellulose solution to increase the shale stability

Alam,

Fujii,

Dipu

et al. 2023

Sci Rep

View full text Add to dashboard Cite

Slope failures in Bangladesh's Chittagong division are a growing concern, with fatalities increasing from 19 in 2000 to 162 in 2017 and projected to rise further. This study aims to identify the most vulnerable rock formation and assess Carboxymethyl Cellulose (CMC) as a solution for enhancing shale strength and mitigating slope failures. The research began by evaluating weathering susceptibility and stability of different rock layers, revealing the high instability of shale in the Bhuban Formation. Slake durability tests measured cation concentration to understand shale instability mechanisms. Laboratory experiments, including immersion tests and grained-and-molded shale specimens, examined CMC's potential to improve shale stability. Results indicated that the shale of the Bhuban Formation had the highest hammer value variations, indicating increased weathering susceptibility. Shale instability was attributed to illite layer dissolution, releasing K+. Intact shale specimens treated with CMC showed enhanced penetration resistance, shear strength, and deformation behavior, suggesting CMC's potential in increasing shale stability. Grained-and-molded shale specimens treated with CMC demonstrated increased shear strength, critical shear displacement, and contraction deformational behavior. Optical microscopy and scanning electron microscopy revealed the formation of cross-links between shale grains, contributing to improved shale stability. Further research is needed to explore the application of CMC for enhancing in situ rock slope stability. This study emphasizes the importance of addressing slope failures in the Chittagong division and provides insights into mitigating the risks through CMC-based interventions.

show abstract

“…There are obvious bedding planes in shale, and the weak bedding planes lead to the shale forming significant transverse isotropic characteristic [8][9][10]. This characteristic causes the direction of stress loading on the shale bedding to have a significant impact on the failure of shale.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties of Lamellar Shale Considering the Effect of Rock Structure and Hydration from Macroscopic and Microscopic Points of View

et al. 2022

Self Cite

View full text Add to dashboard Cite

It is well known that the effect of shale hydration causes wellbore instability due to water phase invasion of drilling fluid to lamellar shale rich formations. This is because of that the mechanical properties (compressive strength, elastic modulus, etc.) of lamellar shale surrounding the borehole, which is rich in clay minerals, will decrease significantly after hydration. In this study, using the lamellar shale in the continental stratum of the southern Ordos Basin, the mechanical properties of lamellar shale were studied by compression tests considering the effect of lamellar structure and hydration from a macroscopic point of view. In addition, the mechanical mechanism was discussed combined with the CT scanning tests results from a microscopic point of view. The results demonstrate the following points. Lamellar shale has stronger anisotropy than bedding shale, the compressive strength (deviatoric stress) and elastic modulus of lamellar shale are both lower than those of bedding shale, and it is more prone to tension fracture. With the increase in the angle (β) between the lamina and the axial direction from 0° to 90°, the compressive strength of lamellar shale decreases when β < 30° and then increases, the elastic modulus of lamellar shale decreases greatly when β < 30° and then tends to flatten. With the increase in hydration time, the compressive strength and elastic modulus of lamellar shale both gradually decrease, and the rates of their decrements reduce. The mechanical properties of lamellar shale are more affected by hydration than those of bedding shale. The hydration of lamellar shale leads to the formation of new fractures and the expansion of existing fractures in the junction area between the laminae and rock matrix, resulting in easy tension fracture along the laminae of shale.

show abstract

A modified Hoek-Brown failure criterion for unsaturated intact shale considering the effects of anisotropy and hydration

Cited by 21 publications

References 56 publications

Experimental Study on Mechanical Properties of Anisotropic Slate under Different Water Contents

Experimental Study on Mechanical Properties of Anisotropic Slate under Different Water Contents

Potential of carboxymethyl cellulose solution to increase the shale stability

Mechanical Properties of Lamellar Shale Considering the Effect of Rock Structure and Hydration from Macroscopic and Microscopic Points of View

Contact Info

Product

Resources

About