Bedding Dip Angle Research Articles

Numerical Analysis on the Excavation Damage Evolutions of Layered Tunnels: Investigations on the Influences of Confining Pressure and Layer Angles.

The bedding structure of layered tunnels has a significant impact on the evolution of excavation damage, yet research on the relevant evolution mechanisms is scarce. In view of this, this paper develops a mesh-free numerical method to simulate the progressive damage process of tunnel excavation and proposes a method for applying stress boundaries within the SPH framework. Through this method, simulations of tunnel excavation damage under different bedding dip angles and stress ratios are conducted. The results show that the following: in the simulation of excavation damage of a tunnel without bedding structures, specific areas around the tunnel exhibit characteristics of tensile-shear composite failure and shear failure, verifying the rationality of the algorithm; under different bedding dip angles, a damage zone is first generated around the tunnel, and shear cracks appear at the tangent of the bedding plane and the tunnel, with the damage degree being the largest when α = 30° and the smallest when α = 45°; and under different stress ratios, the damage starts around the tunnel, continuously evolves, and finally forms a failure zone inside the bedding plane joints tangent to the tunnel, and the damage degree increases with the increase in the stress ratio. This study discusses the damage mechanisms under different calculation schemes and provides a reference for understanding the excavation damage mechanisms of layered tunnels.

Experimental study on mechanical properties of 3D Printed layered rock like materials

Layered rocks are prevalent in the Earth’s crust and are frequently encountered in underground engineering construction. Due to their pronounced anisotropy, the deformation and failure mechanism of layered rock are complex. Laboratory tests are an effective way to study these mechanisms. However, natural layered rocks present challenges, such as difficult sampling and large discreteness. Additionally, current methods for creating layered rock models are often costly or lack precision, limiting research into their mechanical properties. In this study, a 3D printing process using wet material extrusion was adopted, with a wide range of material options and low production costs. Five layered model samples with bedding dip angles of 0°, 30°, 45°, 60° and 90° were printed using this method. Uniaxial compression tests were conducted, supplemented by digital image correlation (DIC) to capture detailed stress–strain data and failure patterns. The results demonstrate that the mechanical properties of the 3D-printed samples closely resemble those of natural layered rocks and exhibit significant anisotropy. This approach presents a new cost-effective method for studying the mechanical behavior of layered rock.

Experimental and Numerical Investigations on the Slate Shearing Mechanical Behavior

Multi-scale assessment of shear behavior in the tunnel carbonaceous slate is critical for evaluating the stability of the surrounding rock. In this study, direct shear tests were conducted on carbonaceous slates from the Muzhailing Tunnel, considering five bedding dip angles (β) and four normal stresses (σn). The micro-mechanism was also examined by combining acoustic emission (AE) and energy rate with PFC2D Version 5.0 (particle flow code 2D Version 5.0 software) numerical simulations. The results showed a linear relationship between peak shear stress and normal stress, with the rate of increase inversely related to β. Cohesion increased linearly with β, while internal friction angle and AE activity decreased; the energy release rate is 3.92 × 108 aJ/s at 0° and 1.93 × 108 aJ/s at 90°. Shearing along the preset fracture plane was the main failure mode. Increased normal stress led to lateral cracks perpendicular to or intersecting the shear plane. Cracks along the bedding plane formed a broad shear band with concentrated compressive force, and inclined bedding was accompanied by a dense tension chain along the bedding plane.

Optimal mine pitwall profiles in jointed anisotropic rock masses

ABSTRACT A new methodology based on the limit analysis upper bound method for the topological optimisation of slopes is presented, to determine geotechnically optimal slope profiles in anisotropic jointed rock masses. The methodology accounts for the effects of discontinuities such as joints, bedding planes, and tension cracks. We applied this methodology to the context of open pit mines, with the goal of achieving geotechnically optimal pitwall profiles. The optimal profiles maximise the Overall Slope Angle (OSA) while maintaining a prescribed Factor of Safety (FoS) and satisfying the geometric constraints imposed by benches and ramps. The method, implemented in the software OptimalSlope, utilises direction-dependent cohesion and internal friction angle parameters to replicate the effect of joints on slope stability. Key inputs include joint orientation, non-persistence, and probability of occurrence. We tested the methodology on a Mexican open pit mine to be excavated into Cretaceous siltstone featuring eight different joint sets and a primary bedding plane. Optimal pitwall profiles were determined for various combinations of bedding dip angles (0°, 15°, 30°, 45°, 60°, 75°, 90°) and mine pitwall orientations (hanging wall, footwall, side walls), considering the three-dimensional kinematics of the joints through anisotropic functions of cohesion and friction angle. Results indicate that the optimal pitwall profiles generally exhibit higher OSA compared to planar profiles with the same FoS, except in one bedding dip direction. Additionally, stability analyses performed using Rocscience Slide2 independently verified the FoS values of the optimal profiles.

Experimental and numerical study on the mechanical behavior of layered rock anchored by CRLD anchor cable

The study of the mechanical behavior of layered anchored rock is essential for addressing the stability control challenges of surrounding rock of the roadway in layered rock masses. This paper focuses on a novel constant resistance large deformation (CRLD) anchor cable and conducts a comparative study on the uniaxial compressive mechanical behavior of unanchored rock, conventional high-strength (HS) anchor cable, and CRLD anchor cable anchored rock under different bedding dip angles α (30°, 45°, 60°, 75°, and 90°). The strength characteristics, failure characteristics, and acoustic emission characteristics of various specimen types were analyzed with emphasis. The results indicate that with the increase of bedding dip angle, the elastic modulus, peak strength, and residual strength of all specimen types exhibit a trend of decreasing first and then increasing. Compared to unanchored and HS anchored rock, the values of various mechanical parameters for CRLD anchored rock show varying degrees of improvement. The failure modes of various specimen types under different bedding dip angles can be classified into five categories based on the characteristics of the crack distribution. Through comparison, it was found that the CRLD anchor cable can effectively restrict the occurrence of bedding shear failure within the anchored zone in layered rocks with smaller dip angles (30°, 45°). It also transforms the failure mode of layered rocks with larger dip angles (60°, 75°) from a single mode of bedding shear failure to a mixed mode of bedding-bedrock failure. However, under a bedding dip angle of 90°, the two types of anchored rocks exhibit similar failure forms. Comparing the acoustic emission characteristics of the two types of anchored rocks, it is observed that under different bedding dip angles, CRLD anchored rocks exhibit a more uniform distribution of acoustic emission counts, a smoother energy release process, and significantly lower peak count and cumulative energy values. Finally, a numerical model for layered CRLD anchored rocks was constructed based on the discrete element method. The reliability of the experimental results from the physical model in this study was verified by statistically analyzing the quantity evolution process and orientation distribution of microcracks in the numerical model.

Modeling the Hydraulic Fracturing Processes in Shale Formations Using a Meshless Method

Complex bedding properties and in situ stress conditions of shale formation lead to complex hydraulic fracturing morphologies. However, due to the limitations of traditional numerical methods, the simulation of hydraulic fracturing in shale formation still needs further development. Based on this, the liquid–solid interaction modes and the SPH governing equations considering liquid–solid interaction force have been introduced. The smoothing kernel function in the traditional SPH method is improved by introducing the fracture mark ξ, which can realize the simulation of rock hydraulic fracturing processes. The stress boundary of the SPH method is applied by stress mapping of “stress particles”, and the feasibility and correctness of the method are verified by two numerical examples. Then, the simulation of hydraulic fracturing processes of bedding shale formations are carried out. With the increase of horizontal stress ratio, the total number of damaged particles decreases, but the initiation and extension pressure increase gradually. The initiation stress of small bedding dip angles (θ < 45°) is larger than that of big bedding dip angles (θ > 45°). The hydraulic fracture propagation range at low horizontal stress ratio is wider and the fracture is along the direction of maximum principal stress, while the hydraulic fracture propagation range at high horizontal stress ratio is limited to the perforation. The hydraulic fracture will propagate through the bedding with small dip angles. However, when the bedding dip angle is larger, the hydraulic fracture will propagate along the bedding direction.

Study of wellbore instability in shale formation considering the effect of hydration on strength weakening

Shale formations often contain a high proportion of clay minerals, which, upon contact with drilling fluid, undergo hydration expansion. This leads to wellbore instability, a problem that poses significant challenges globally. This study aims to investigate the variation of mechanical properties of shale with respect to hydration time. We employ an empirical model that relates shale strength parameters to the time of drilling through geological formations. Additionally, we consider both shear failure along the wellbore boundary and shear sliding along bedding planes in the analysis. We establish a predictive model for wellbore instability in shale formations. The model quantitatively analyzes the variation of wellbore collapse pressure with drilling time. The research findings indicate that, when the influence of bedding is considered, both the wellbore collapse pressure and the optimal well trajectory undergo significant changes, in addition, for some wellbore trajectories, the collapse pressure can increase by more than 30%. Therefore, it is essential to account for the influence of bedding in wellbore stability analysis in shale formations. As the bedding dip angle changes, both the numerical values and distribution range of wellbore collapse pressure and the optimal well trajectory change noticeably. Changes in bedding dip direction, however, do not affect the numerical values of collapse pressure but do influence the distribution region of the optimal well trajectory. Thus, in wellbore trajectory design within shale formations, it is crucial to determine the orientation of bedding and adjust the well trajectory accordingly to enhance wellbore stability. Furthermore, shale hydration does not impact the optimal well trajectory for a block, but with prolonged hydration, the minimum drilling fluid density required to maintain wellbore stability gradually increases. This suggests that hydration intensifies the weakening effect on bedding plane strength. The research results are helpful to understand the effect of hydration on shale wellbore stability and ensure shale wellbore stability during drilling cycle.

Study on the mechanical and damage properties of laminated limestone under acid mine drainage dissolution

To explore the chemical and mechanical effects of acid mine drainage on water and rock, acid mine drainage (AMD) dissolution tests, triaxial compression tests, and acoustic emission tests were performed on limestone rock samples with different bedding dip angles. Combined with scanning electron microscopy and nuclear magnetic resonance analyses, the changes in the internal pores and surface morphologies of the rock samples before and after dissolution were analyzed. The results were as follows. (1) AMD dissolution mainly occurred in the shallow surfaces and bedding planes of the limestone samples. During dissolution, the shape of the matrix crystal disappeared to form small pores, and residual substances appeared during the dissolution of the bedding plane. These small pores were prone to the creation of large honeycomb-like dissolved pores. (2) With increasing bedding plane angle, the compressive strengths and elastic moduli of the limestone samples exhibited V-shaped distributions. Additional branch cracks were derived from the limestone samples after dissolution, and dissolution reduced the mechanical strength of the limestone by decreasing the crack initiation stress and damage stress. (3) With increasing bedding dip angle, the uniaxial failure modes of the rock samples changed from matrix tensile failure and shear failure along the bedding plane to plane tensile failure. After dissolution, the limestone matrix was prone to cracking and spalling along the surface of the sample. (4) There were differences in the triaxial compression failure modes between the dissolved limestone and the undissolved limestone. When α = 0° or 90°, the limestone samples formed additional branch fissures after dissolution. When α = 45°, the formation of penetrating cracks along the bedding plane was obviously controlled by the bedding plane. (5) A chemical–mechanical damage model was established and modified by the compression coefficient K, which could effectively reflect the deformation of the dissolved rock sample during loading.

Crack-tip plastic zone and initiation mechanism of rock based on Eshelby stress

The crack initiation and propagation mechanism of rock is significantly related to characteristics of the crack-tip plastic zone due to energy dissipation. In this paper, conservation integral and configurational stress/force is derived by the Noether’s method. The crack-tip configurational stress field is then deduced and analyzed. Additionally, the Drucker–Prager yield criterion of configurational stress is derived and it is used to predict the crack-tip plastic zone of rock. The fracture criteria of rock are also developed based on the critical area and minimum polar radius of the crack-tip plastic zone. Subsequently, the effects of bedding dip angles and porosity on rock mixed mode fracture are investigated, and the fracture resistance of rock is assessed using the resistivity and wave velocity. It is shown that the configurational force as the crack driving force is induced by the invariant transformation of an action integral with respect to translation of a defect. It is also found that the crack-tip plastic zone assessed by Drucker–Prager yield criterion of Cauchy stress is discontinuous at the crack surface while that predicted by yield criterion of configurational stress is continuous. The present fracture criteria take into account the internal friction angle, and the predicted initiation angles and fracture loads are in good agreement with those determined by the maximum tensile stress (MTS) fracture criterion and experiments. The fracture loading envelope decreases with the porosity, bedding dip angles and resistivities of rock, but increases with wave velocity.

Research on anisotropic characteristics and energy damage evolution mechanism of bedding coal under uniaxial compression

Bedding structures are commonly present in the underground coal mine pillar rock mass, posing a certain threat to its stability. In order to gain a deeper understanding of the damage, destruction, and energy conversion of bedding coal, uniaxial compression experiments were conducted on bedding coal samples. The research results reveal that the compressive strength of coal is highest when the bedding dip angle is 0° (28.74 MPa), followed by 30° and 90° (15.03 and 14.02 MPa), and lowest at 60° (10.03 MPa). The damage evolution curve of coal at a bedding dip angle of 60° exhibits an early sharp increase, indicating that macroscopic damage is easily induced along the bedding planes under this condition. As the bedding dip angle increases from 0° to 90°, the degree of damage to coal under energy drive exhibits a pattern of difficulty-ease-difficulty. When the bedding dip angle is 0°, the coal sample fractures steadily as cracks expand. At 30°, the failure process involves a gradual and steady expansion of cracks followed by an unstable extension. At 60° and 90°, the fractures result in sudden and unstable damage. Furthermore, this study explores the inherent mechanisms of anisotropy and the evolution models of damage in bedding coal.

Experimental study on failure mode and fracture evolution characteristics of red shale in Kaiyang Phosphorus mining area

In order to study the failure mode and fracture evolution characteristics of red shale in Kaiyang Phosphorus mining area, conventional triaxial compression mechanical tests of red shale with different bedding dip angles were carried out by using DSTD-1000 electro-hydraulic servo rock mechanics experiment system. Based on the laboratory test results, the conventional triaxial particle flow simulation of red shale samples with different bedding dip angles was carried out using discrete element PFC2D. The results show that: (1) the failure mode of red shale is controlled by bedrock when the bedding dip angle is 0° and 60° ~ 90°. When the bedding dip angle is 15° ~ 45°, the rock failure mode is controlled by bedding. The compressive strength of rock is the minimum when the bedding dip angle is 30°and the maximum at 0°, which is about 2 times of the minimum. (2) In the failure process of red shale, the cracks with different bedding dip angles show slow growth stage, accelerated growth stage and stable stage with axial strain. The whole failure process is dominated by tensile cracks, accompanied by a few shear cracks. (3) The type of displacement field varies with the bedding dip angle: tensile failure and shear failure are the main displacement field types at 15° ~ 45°, and mixed failure is often the main mode at 60° ~ 90°and 0°. The research results provide the basis and reference for the safety control of red shale roadway.

Study on the extension mechanism of hydraulic fractures in bedding coal

This study is aimed at investigating the formation process and extension mechanism of hydraulic fractures (HFs) in bedding coal. To achieve this aim, a numerical model of hydraulic fracturing of bedding coal was established based on the cohesive element. Furthermore, the influences of stress field, bedding dip angle and fracturing fluid displacement on the extension law of HFs in bedding coal were studied, and the formation process and extension mechanism of HFs in bedding coal were analyzed. The following beneficial results were obtained. HFs prefer penetrating the bedding plane when extending towards it at a large angle, while they tend to extend along the bedding plane when the angle is small. Under certain stress field conditions, during hydraulic fracturing, changing the extension direction of original HFs enables HFs to develop into a complex fracture network under the combined effect of bedding structure and stress field. Meanwhile, altering injection displacement can enlarge the extension range of HFs on the bedding plane. The principle can be explained as follows: under the action of continuous unstable pressure waves caused by fluctuant injection displacement, coal is likely to undergo fatigue damage, which further promotes the generation of micro cracks within coal and facilitates the opening and extension of HFs. The pore pressure near HFs increases linearly with the rise of fluid pressure in HFs, decreases linearly with the growth of distance from HFs, and is inversely proportional to the square root of the fracturing fluid’s filtration time. After HFs penetrate the bedding plane, coal is prone to shear failure and further generates secondary fractures under the filtration effect of fracturing fluid. Under the joint effect of fracturing parameters such as bedding, ground stress and displacement, main HFs and secondary HFs can intersect to form a complex fracture network when penetrating the bedding plane.

A damage constitutive model of layered slate under the action of triaxial compression and water environment erosion

Based on the macroscopic structure control theory, The slate with a significant bedding plane is a composite rock mass composed of rock blocks containing microscopic defects, joint surface closure elements, and shear deformation elements. Considering the coupling damage effect of water erosion and triaxial compressive load on bedding structure plane, the transversely isotropic damage constitutive model of slate under triaxial compressive load is derived with the dip angle of bedding and confining pressure as the variable. Firstly, based on the statistical theory of continuous damage mechanics and the maximum tensile strain criterion, the transversely isotropic deformation constitutive model of rock block with micro-defects is given; Secondly, based on the phenomenological theory of closed deformation and shear-slip deformation mechanism of layered structural plane under the coupling action of water erosion and triaxial compression load, the calculation formula of axial deformation of layered structural plane under the coupling action is given; Finally, to verify the accuracy of the established constitutive model, triaxial compression tests are carried out to study the influence of dip angle and confining pressure on the macroscopic mechanical properties and mechanism of slate. The results show that: the established triaxial compression damage constitutive model of bedding slate can accurately describe the stress–strain relationship of bedding slate after water environment erosion. With the increase of bedding dip angle, the strength and deformation capacity of the bedding slate first decreases and then increases, showing a U-shaped distribution as a whole. There are three main types of failure: tension shear composite failure, shear slip failure, and splitting tension failure.

Brazilian splitting experiment and finite element simulation analysis of the influence of bedding loading angle on shale fracture mode

During the diagenetic processes of compaction and cementation, shale forms multiple beddings, significantly effecting the rock anisotropy. Therefore, it is important to study the effect of bedding on the mechanical properties of shale to guide fracturing engineering. To study the failure mode and fracture morphology of shale with bedding planes under different bedding dip angles, Brazilian disc splitting tests and finite element numerical simulations are performed for shale samples and the results are compared. (1) The bedding angle has a significant effect on the failure mode and tensile strength of shale, and the tensile strength tends to increase with increasing bedding angle. (2) The failure modes of shale under different bedding dip angles can be divided into three types: tensile failure along the bedding plane; comprehensive shear and tensile failure of the matrix and the bedding plane; and matrix tensile failure. (3) The direction of secondary cracks is mostly perpendicular to the bedding plane, and a smaller angle between the load application direction and the bedding direction results in a larger number of generated cracks with more complex shapes. (4) When the loading angle of the bedding is 30°, the tensile strength is low and the matrix and the bedding plane are comprehensively destroyed by shear and tension, resulting in a more complex joint mesh; conversely, when the bedding angle is greater than 60°, the tensile strength increases and the complexity of the seam mesh decreases. These findings can provide guidance for the selection of the bedding angle and the design of fracturing schemes in fracturing engineering.

Research on damage failure mechanism and dynamic mechanical behavior of layered shale with different angles under confining pressure

AbstractThe hydrostatic or confining pressure of deep rocks has a significant impact on the mechanical behavior of brittle materials. Especially when confining pressure is applied, the mechanical properties of rock materials will undergo significant changes. Considering that the process of shale sample subjected to impact load is in a closed container in the dynamic triaxial SHPB test, the failure process of the sample cannot be observed. Meanwhile, the activation volume of the shale sample would be large and local failure would occur in the test under the high strain rate loading. Therefore, the finite element model of shale considering the bedding effect under confining pressure was established in this study. Taking shale materials with different bedding dip angles as simulation objects, the dynamic failure characteristics of shale were studied using the dynamic analysis software ANSYS/LS‐DYNA from three aspects: stress‐strain curve, failure growth process, and failure morphology. The research results obtained can serve as the key technical parameters for deep resource extraction.

Evaluation of bedding effect on the bursting liability of coal and coal-rock combination under different bedding dip angles

Heat injection well reaches temperatures above 400 ◦C during the process of heat injection, Heat injection is essential for oil shale in-situ conversion technology. The downhole of the and part of the high-temperature gas dissipates through the wellbore annulus. Consequently, in addition to causing energy loss, the dissipation causes thermal damage to the casing and wellhead. To avoid dissipation, components that are suitable for high-temperature environments should be sealed and used during heat injection while mining. Therefore, this study presents the design of a packer composed of elastic graphite rubber and a high-temperature-resistant material. The influence of numerous factors, such as downhole temperature, working load, and height of rubber, on the reliability of the packer was analyzed. Subsequently, the numerical simulation analysis of the packer reliability in in-situ conversion mining under high temperature and pressure environments was performed. The results indicate that when the operating temperature is stable, the operating load has the most obvious influence on the sealing reliability of the packer, whereas the change in the height of the rubber has the least significant effect on the maximum contact stress between the casing and rubber. The change in the operating temperature has the least significant effect on the overall sealing performance of the packer. Moreover, the rise of the temperature will increase the sealing reliability of the packer, and on the contrary, the drop in the temperature will decrease it. Cited as: Guo, W., Shui, H., Liu, Z., Wang, Y., Tu, J. Reliability analysis of elastic graphite packer in heat injection well during oil shale in-situ conversion. Advances in Geo-Energy Research, 2023, 7(1): 28-38. https://doi.org/10.46690/ager.2023.01.04

Evaluation of bedding effect on the bursting liability of coal and coal-rock combination under different bedding dip angles

Evaluation of bedding effect on the bursting liability of coal and coal-rock combination under different bedding dip angles

Influence of Layer Thickness Ratio on the Mechanical and Failure Properties of Soft-Hard Interbedded Rock-like Material

To figure out the influence of soft-hard layer thickness ratio on specimens' mechanical properties evolution and microcracking mechanism, combined with digital image correlation technology and acoustic emission facility, uniaxial compression tests were conducted on soft-hard interbedded rock-like materials considering seven bedding dip angles and two soft-hard layer thickness ratios. The results are as follows: 1) The failure mode and failure pattern of layered rock masses are mainly determined by the bedding dip angle α and are less related to the soft-hard thickness ratio. With the increase of dip angle, the failure strength curve of the specimen is approximately U-shaped, and the soft-hard layer thickness ratio affects the U-shaped. The decrease in soft-hard layer thickness ratio will reduce the uniaxial compressive strength of specimens with low dip angles (α≦30°), cause differences in the evolution path of local strain fields of layered rock masses and reduce the horizontal displacement of the main crack. 2) The increase of the proportion of soft layer in the soft-hard layer thickness ratio will reduce the proportion of tensile cracks in the tensile failure specimens and shear cracks in the shear failure specimens, complicating the process of cracks of the layer rock mass. 3) Increasing the proportion of soft layers in the soft-hard layers thickness ratio promotes the generation of secondary cracks in layered rock masses and further reduces the integrity of specimens. Finally, through the findings in this paper, it can provide a reference for analyzing the crack propagation behavior of layered rock.

Propagation of multiple hydraulic fractures in a transversely isotropic shale formation

Shale anisotropy can lead to deviated patterns of hydraulic fractures in multi-stage hydraulic fracturing (MSHF) operations, significantly hindering hydrocarbon production. Such deviation usually occurs in formations where the induced fractures interfere with natural bedding planes or where the stress shadow is created. In this work, the elastic behavior of a transversely isotropic shale rock during MSHF is investigated using the extended finite element method (XFEM) in conjunction with the cohesive zone model (CZM) in ABAQUS. In comparison to the linear elastic fracture mechanics approach, the CZM considers the plasticity and softening effects at the fracture tip, and therefore, leads to a more accurate prediction of fracture geometry. The XFEM model is capable of simulating fractures with an arbitrary path without requiring re-meshing. The 2D numerical model is first verified against the Kristianovich-Geertsma-de Klerk (KGD) analytical solutions. Five injection clusters in a single fracturing stage are simulated to analyze the effects of the material isotropy, the dip angle of shale bedding, and the fracture spacing on the geometry of multiple hydraulic fractures. The transversely isotropic poroelasticity model predicts narrower and longer hydraulic fractures than the isotropic poroelasticity model. The bedding dip angle plays a crucial role in the deviation and the shape of multiple hydraulic fractures. Increasing the dip angle from zero to 90° results in an increase in the average fracture width and an increase-peak-decrease trend in the fracture length. A strong correlation is observed between the fracture spacing and the fracture geometry, and a spacing of 75 m is considered optimal because it results in no discernible stress shadow at all dip angle cases.

Experimental and constitutive modeling of the anisotropic mechanical properties of shale subjected to thermal treatment

The physical and mechanical properties of shale exhibit significant anisotropy, impacting the design and construction of high geothermal tunnels and deep resource mining. Laboratory studies on the physical and anisotropic mechanical properties of shale after various thermal treatments showed that rising temperatures caused an exponential decline in shale’s bulk and density, and the uneven expansion of the mineral particles within the rock caused a decrease in its uniaxial compression strength (UCS) and elastic modulus while increasing their anisotropy. The UCS is U-shaped with a change in bedding dip angle, whereas the elastic modulus is U-shaped or shoulder-shaped. Under the assumption that the rock microelement obeyed the Weibull distribution, the microstructure tensor improved Hoek–Brown strength criterion was introduced as the damage basis. Then a thermal–mechanical coupling damage constitutive model considering bedding dip angle and temperature was established. The model was found to be valid via the test results, especially in capturing the compaction and yield softening stages of shale. These findings have reference value for both underground structural engineering and deep resource mining.