Cracking Processes and Coalescence Modes in Rock-Like Specimens with Two Parallel Pre-existing Cracks

Zhao, Cheng; Zhou, Yingqi; Chao, Zhao; Bao, Chong Gao

doi:10.1007/s00603-018-1525-y

Cited by 102 publications

(34 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Acoustic emission (AE) was used to monitor the increasing damage and estimate the failure process. Based on the cracking process under shear stress, this study focused on the preshear stress of 0, 0.2 τ p (where τ p = 24.2 MPa is the peak shear strength with no injection pressure), 0.6 τ p , and 0.8 τ p , respectively, corresponding to the microcrack closing, microcrack initiation, and microcrack coalescence stages …”

Section: Resultsmentioning

confidence: 99%

“…Based on the cracking process under shear stress, this study focused on the preshear stress of 0, 0.2τ p (where τ p = 24.2 MPa is the peak shear strength with no injection pressure), 0.6τ p , and 0.8τ p , respectively, corresponding to the microcrack closing, microcrack initiation, 48 and microcrack coalescence stages. [51][52][53] The experiment was divided into two stages ( Figure 6): (a) preshear stress stage and (b) hydraulic fracturing stage. When preshear stress was not applied, AE activities corresponded to hydraulic pressure ( Figure 6A).…”

Section: Shear Behavior and Ae Events Inducedmentioning

confidence: 99%

See 1 more Smart Citation

Short‐term failure mechanism triggered by hydraulic fracturing

Wang

Liu

2019

Energy Science & Engineering

View full text Add to dashboard Cite

Hydraulic fracturing may induce or trigger an earthquake while injecting fluid into strata to initiate a new fracture so as to promote oil and gas production. Previous studies have confirmed that the injection of fluids into the formation, especially hydraulic fracturing, is closely related to seismic activity. However, the mechanism through which fluid injection changes the stress field of rock mass and interacts with the in situ stress state is still poorly understood. This study focused on the short‐term mechanism coupling shear stress and hydraulic fracturing in an experimental simulation. Preexisting tension fractures were initiated and propagated by loading shear force. The fracture propagation path of hydraulic fracturing was closely related to the preexisting fractures formed by the preshear stress. Short‐term hydraulic fracturing promoted fracture propagation and acoustic emission events (or microearthquake signals), but it was less likely to cause rock mass instability or a large earthquake. The long‐term fluid injection could saturate preexisting fractures and infiltrate rock mass to increase the pore pressure and change the in situ stress field in a large area to induce an earthquake.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Shear Behavior and Ae Events Inducedmentioning

confidence: 99%

Short‐term failure mechanism triggered by hydraulic fracturing

Wang

Liu

2019

Energy Science & Engineering

View full text Add to dashboard Cite

show abstract

“…In this way, the decomposition of minerals will produce a range of cracks with a broad distribution of dimensions (length and width), orientations, and shapes, which will result in a higher porosity and fractal dimension. Besides, according to the study of Yu et al [55] and Liu et al [56], crystal recrystallization facilitates crack propagation in the grain-boundary regions by enabling intergranular fracture and decohesion between mineral grains; secondly, rock is a heterogeneous body composed of different minerals, and the thermal expansion coefficients of each mineral are different at high temperature [57][58][59][60]. e inconsistency of expansion and deformation of mineral grains under relatively high temperature will cause high thermal stress in the mineral structure.…”

Section: Weakening Mechanism Of Sandstone At Real-time Highmentioning

confidence: 99%

Mode I Fracture Toughness Test and Fractal Character of Fracture Trajectory of Red Sandstone under Real-Time High Temperature

Zhang

2019

Advances in Materials Science and Engineering

View full text Add to dashboard Cite

To evaluate the stability and compactness of high-temperature underground construction, it is necessary to test the fracture toughness of surrounding rock (red sandstone) under real-time high temperature. In this paper, SCB specimens recommended by the International Society for Rock Mechanics are used to measure the mode I fracture toughness of red sandstone at real-time high temperatures. Also, to reveal its fracture characteristics and fracture mechanism, the fracture morphology observation (SEM experiment), XRD experiment, mercury intrusion porosimetry testing, and fractal measurement of fracture trajectory are carried out on the red sandstone specimens at various temperatures. The results show that (1) temperature may have a significant impact on the fracture toughness and fracture characteristics of red sandstone. On the whole, the fracture toughness values decrease with the increase in temperature, while the fractal dimensions of fractal trajectories increase with the increase in temperature. (2) Temperature has a significant influence on the fracture mode of red sandstone. At relatively low temperatures (20°C–400°C), the main fracture mode is transgranular failure. At relatively high temperatures (400°C–700°C), the fracture mode is mainly intergranular failure. (3) The weakening mechanism of red sandstone is mainly due to the effect of thermal dehydration when the temperature is between 100°C and 400°C. When the temperature is between 400°C and 700°C, the weakening mechanism is mainly due to thermal cracking and the α-β phase transition of quartz.

show abstract

“…The stress concentration caused by slope excavation leads to the continuous expansion and penetration of joints to the position of rock bridge. The penetration failure of rock bridge is usually the main cause of rock slope instability [5,6]. The cracks propagation, coalescence, and penetrating through in the rock bridge will eventually lead to the failure of rock mass, which can be termed as "rock bridge failure".…”

Section: Introductionmentioning

confidence: 99%

Investigating the Effect of Rock Bridge on the Stability of Locked Section Slopes by the Direct Shear Test and Acoustic Emission Technique

Guo

Pan

Cai

et al. 2020

Sensors

View full text Add to dashboard Cite

As a portion of intact rock separating joint surfaces, rock bridge plays a significant role in the stability of rock slopes. This paper aims to investigate the effect of different rock bridges on the mechanical properties and failure mode of rock slope by means of the direct shear test and acoustic emission technique. Field conditions were simulated in direct shear tests which were carried out on specimens with rock bridges at different continuity rates, normal stress, arrangements, and joint angles. Experimental results indicate that the strength of specimens is controlled by the rock bridge and the structural plane. The rock bridge contributes to the strength of the specimen, while the through plane weakens the strength of the specimen. The increase of normal stress can weaken the stress concentration near the tip of the rock bridge and improve the shear resistance of the specimen. The different arrangement of rock bridge has little effect on the normal displacement of the specimen, and has a great influence on the shear strength. The shear capacity of the specimen is related to the angle of the crack, and the angle of the crack is approximately proportional to the peak shear strength. For the specimens with different joint occurrence, the mode of crack propagation at the initial stage is basically the same, and the specimen is finally damaged due to the generation of through cracks in the core area of rock bridge. The instantaneous release of the huge energy generated during the experiment along the shear direction is the root cause of the sudden failure of the rock bridge. The formation, aggregation, and transfixion process of rock bridge is of concern and has been experimentally investigated in this paper for the prevention and control of the locked section rock slope with sudden disasters.

show abstract

Cracking Processes and Coalescence Modes in Rock-Like Specimens with Two Parallel Pre-existing Cracks

Cited by 102 publications

References 43 publications

Short‐term failure mechanism triggered by hydraulic fracturing

Short‐term failure mechanism triggered by hydraulic fracturing

Mode I Fracture Toughness Test and Fractal Character of Fracture Trajectory of Red Sandstone under Real-Time High Temperature

Investigating the Effect of Rock Bridge on the Stability of Locked Section Slopes by the Direct Shear Test and Acoustic Emission Technique

Contact Info

Product

Resources

About