scholarly journals Experimental and Numerical Study of Strength and Failure Behavior of Precracked Marble under True Triaxial Compression

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Yong Han ◽  
Yuemao Zhao ◽  
Jinglong Li
Keyword(s):  
Shear Failure ◽  
Numerical Study ◽  
Triaxial Compression ◽  
Numerical Results ◽  
Peak Strength ◽  
Failure Behavior ◽  
Compression Tests ◽  
True Triaxial ◽  
Fracturing Process ◽  
True Triaxial Compression

Cracks play an important role in evaluating the strength and failure behavior of engineering rock mass. In order to increase the understanding of strength and failure mechanism of precracked rock, crack propagation and coalescence from preexisting cracks under true triaxial compression are investigated using true triaxial compression tests and Cellular Automata Software for engineering Rockmass fracturing process (CASRock). Three types of specimens were studied experimentally and numerically. Experimental and numerical results show that both the preferential angle and areal intensity of preexisting cracks can affect the compressive strength and failure behavior of the specimens. The peak strength firstly decreases and then increases with increase of the preferential angle. Also, the peak strength nonlinearly decreases with the increase of cracks’ areal intensity. The numerical results show that the crack initiation and coalescence are observed and characterized from the inner and outer tips of preexisting cracks in specimens containing single crack and multiple parallel cracks. The main shear failure in the specimen containing multiple unparallel preexisting cracks initiate and propagate from one of the macroscopic preexisting cracks, and other preexisting cracks do not initiate, propagate, and coalesce until reaching the peak strength.

Behavior of EPS geofoam in true triaxial compression tests

2008 ◽  
Vol 26 (2) ◽  
pp. 175-180 ◽  
Author(s):  
Chin Jian Leo ◽  
M Kumruzzaman ◽  
Henry Wong ◽  
Jin H Yin
Keyword(s):  
Triaxial Compression ◽  
Compression Tests ◽  
Eps Geofoam ◽  
True Triaxial ◽  
True Triaxial Compression ◽  
Triaxial Compression Tests

A Novel Application of Strain Energy for Fracturing Process Analysis of Hard Rock Under True Triaxial Compression

2019 ◽  
Vol 52 (11) ◽  
pp. 4257-4272
Author(s):  
Yan Zhang ◽  
Xia-Ting Feng ◽  
Xiwei Zhang ◽  
Zhaofeng Wang ◽  
Mostafa Sharifzadeh ◽  
...  
Keyword(s):  
Strain Energy ◽  
Hard Rock ◽  
Process Analysis ◽  
Triaxial Compression ◽  
True Triaxial ◽  
Fracturing Process ◽  
True Triaxial Compression

scholarly journals Experimental Study of Size Effects on the Deformation Strength and Failure Characteristics of Hard Rocks under True Triaxial Compression

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Qiang Han ◽  
Yaohui Gao ◽  
Yan Zhang
Keyword(s):  
Size Effect ◽  
Sample Size ◽  
Triaxial Compression ◽  
Peak Strength ◽  
Failure Characteristics ◽  
True Triaxial ◽  
Rock Samples ◽  
True Triaxial Compression ◽  
The Relationship ◽  
Rock Size

Size effect has always been the focus of rock mechanics as a bridge between laboratory test and engineering site. Previously, the research conditions and objects of the rock size effect have mostly focused on cylindrical rock samples with different height-to-diameter ratios (H/Ds) under uniaxial or conventional triaxial compression, while there has been little research on the rock size effect under true triaxial compression (TTC), especially rectangular rock samples with different sizes and the same length-to-width-to-height ratio. Based on this, the deformation, strength, and failure characteristics of Beishan (BS) granite and Baihetan (BHT) basalt with different sample sizes under TTC were studied by a comparative analysis method. The size effect of deformation and failure characteristics under TTC are not obvious, including stress-strain curves, Young’s modulus, peak strains, failure angles, and macrofailure mode. However, the damage stress (σcd) and peak strength (σp) have obvious size effect; that is, the smaller the sample size is, the higher the strength is. Additionally, the relationship among the peak strength, sample size, and intermediate principal stress (σ2) is power function. In addition, by comparing the peak strength increment caused by the sample size of the two types of rocks, the σp of the fine-grained BHT basalt is more sensitive to sample size than that of the coarse-grained BS granite. Finally, by analyzing the relationship between the size of the mineral grains or clusters in the two types of hard rocks and the complexity of crack propagation in the fracture surface under TTC, it is suggested that the minimum side length of rock samples should not be less than 10 times the maximum mineral clusters (such as feldspar phenocrysts in BHT basalt). In addition, the method of estimating elastic strain is established by analyzing the relationship between the size of the rock sample σ2 and the elastic strain under TTC.

scholarly journals Experimental Investigation on the Deformation, Strength, and Acoustic Emission Characteristics of Sandstone under True Triaxial Compression

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Zhaolin Li ◽  
Lianguo Wang ◽  
Yinlong Lu ◽  
Wenshuai Li ◽  
Kai Wang
Keyword(s):  
Acoustic Emission ◽  
Axial Strain ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Lateral Strain ◽  
Compression Tests ◽  
True Triaxial ◽  
Shear Slip ◽  
True Triaxial Compression ◽  
Triaxial Compression Tests

The study of deformation, strength, and other mechanical characteristics of sandstone under true triaxial compression is significant for understanding failure mechanisms in rock and evaluating the stability of underground structures. Conventional and true triaxial compression tests for sandstone are conducted for different stress states in this study using the self-developed true triaxial electrohydraulic servo test system combined with acoustic emission (AE) testing. This study presents an in-depth and systematic investigation of deformation, strength, and AE characteristics. The results show significant differences in deformation, strength, and acoustic emission characteristics for the rock under conventional triaxial and true triaxial compression tests, respectively. The peak strength, axial strain, lateral strain, and incremental strain (in unstable crack growth stage) increase with increasing confining pressure under conventional triaxial compression, and the AE count gradually decreases while shear crack proportion gradually increases, indicating that increasing confining pressure gradually inhibits the shear slip effect along fractures, delays perforation of the rock shear fracture surface, and enhances the ability of the rock to withstand deformation and load. Under true triaxial compression, the peak strength increases and then decreases with increasing intermediate principal stress σ2 and the axial strain ε1 and lateral strain ε2 gradually decrease; besides, the lateral strain (expansion) of the rock is mainly in the minimum principal stress σ3 direction, and lateral expansion tends to decrease before increasing. AE events first weaken and then enhance with increasing σ2, and the proportion of shear cracks increases first and then decreases, indicating that the confining pressure gradually changes from the shear slip effect that controls crack offset to the damage effect that promotes crack tension with increasing σ2. In addition, the protective effect of confining pressure improves when σ3 increases.

scholarly journals Breakage Mechanism of Layered Sandstone Penetrated by TBM Disc Cutter

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Yingji Bao ◽  
Jianlong Cheng ◽  
Binsong Jiang
Keyword(s):  
Failure Mode ◽  
Surface Deformation ◽  
Triaxial Compression ◽  
Disc Cutter ◽  
Compression Tests ◽  
Confining Stress ◽  
Tunnel Face ◽  
True Triaxial ◽  
True Triaxial Compression ◽  
Breakage Mechanism

In this paper, the breakage mechanism of layered sandstone subjected to the TBM disc cutter was investigated. A series of typical layered sandstone specimens were prepared for true triaxial compression tests in the laboratory to simulate the disc cutter action at the tunnel face, and an acoustic emission (AE) system was used to monitor the breaking process during the penetration tests. Furthermore, a DV recorder was employed to capture the surface deformation. Then, the failure specimens were scanned by high resolution X-ray micro-CT. The results show that the failure mode of layered sandstone in terms of cracking transforms into local crushing with increasing confining stress. The propagation pattern of the cracks varies with the bedding inclination, which is distinctly different from intact rock. The results also indicate that the peak force presents linear variation with the confining stress and an increasing trend with the bedding inclination at the first penetration, and the failure mode of the second penetration is mainly related to the broken status from the first penetration.

Damage Evolution and Failure Behavior of Sandstone under True Triaxial Compression

2018 ◽  
Vol 42 (3) ◽  
pp. 20170295 ◽  
Author(s):  
Yinlong Lu ◽  
Wenshuai Li ◽  
Lianguo Wang ◽  
Zhaolin Li ◽  
Xingyu Meng ◽  
...  
Keyword(s):  
Damage Evolution ◽  
Triaxial Compression ◽  
Failure Behavior ◽  
True Triaxial ◽  
True Triaxial Compression

scholarly journals The Fracture Characteristic of Three Collinear Cracks under True Triaxial Compression

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Jianjun Liu ◽  
Zheming Zhu ◽  
Bo Wang
Keyword(s):  
Numerical Study ◽  
Triaxial Compression ◽  
Collinear Cracks ◽  
Confining Stress ◽  
True Triaxial ◽  
Concrete Plate ◽  
Critical Stresses ◽  
Inclination Angles ◽  
Abaqus Code ◽  
True Triaxial Compression

The mechanical behavior of multicracks under compression has become a very important project in the field of fracture mechanics and rock mechanics. In this paper, experimental and numerical studies on the fracture property of three collinear cracks under compression were implemented. The specimens were a square concrete plate, and the cracks were made by a very thin film. The tests were conducted by using true triaxial loading device. In the numerical study, the Abaqus code was employed. The effect of crack orientation and the confining stress on cracked specimen compressive strength were investigated. The results show that the critical stresses of cracked specimens change with crack inclination angles, and, as the angle is 45°, the critical stress is the lowest; the critical stresses increase with the confining stresses.

Sign in / Sign up

Export Citation Format

Share Document