Investigations of mechanical and failure properties of 3D printed columnar jointed rock mass under true triaxial compression with one free face

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Yingjie Xia ◽  
Bingchen Liu ◽  
Chuanqing Zhang ◽  
Ning Liu ◽  
Hui Zhou ◽  
...  
Keyword(s):  
Rock Mass ◽  
Triaxial Compression ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
True Triaxial ◽  
Free Face ◽  
Failure Properties ◽  
Columnar Jointed Rock Mass ◽  
3D Printed ◽  
True Triaxial Compression

scholarly journals Seepage Flow Properties of a Columnar Jointed Rock Mass in a True Triaxial Experiment

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Yanxin He ◽  
Zhende Zhu ◽  
Wenbin Lu ◽  
Yunjin Hu ◽  
Xinghua Xie ◽  
...  
Keyword(s):  
Rock Mass ◽  
Principal Stress ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Intermediate Principal Stress ◽  
True Triaxial ◽  
Minimum Principal Stress ◽  
Baihetan Hydropower Station ◽  
Columnar Jointed Rock Mass ◽  
Seepage Characteristics

A columnar jointed rock mass is a type of rock mass with strong geometric anisotropy and high interface permeability. Its seepage characteristics pose new challenges to the construction and maintenance of the Baihetan Hydropower Station on the Jinsha River. The research object in this study is the columnar jointed rock mass (basalt) in the dam area of Baihetan Hydropower Station. Similar-material model samples of the columnar jointed rock mass with different column dip angles ( α = 0 ° ~90°) were prepared following a similar principle. A true triaxial seepage–stress coupling test was conducted to evaluate the seepage characteristics of similar-material samples with different dip angles under intermediate principal stress and minimum principal stress. The experimental results showed that the columnar jointed rock mass exhibited apparent seepage anisotropy. The relationship curve between the volume flow rate Q and the pressure gradient − d P / d L of the samples with different dip angles showed evident nonlinear seepage under intermediate principal stress, which could be well expressed using the Forchheimer equation. It shows the characteristics of a typical linear Darcy flow under minimum principal stress. The law of variations in the permeability of the samples with different dip angles under intermediate principal stress can be well expressed using the one-dimensional quadratic function equation k = a + b σ 2 + c σ 2 2 , and the law of variations in the permeability of the samples with different dip angles under minimum principal stress can be well expressed using the logarithmic function k = a + b ln σ 3 . The permeabilities of the columnar jointed rock mass with dip angles of 0°, 15°, 30°, and 60° were most sensitive to changes in stress, and the seepage characteristics increased in complexity after changes in stress.

Numerical simulation of the anisotropic properties of a columnar jointed rock mass under triaxial compression

2018 ◽  
Vol 35 (4) ◽  
pp. 1788-1804 ◽  
Author(s):  
Long Yan ◽  
Weiya Xu ◽  
Rubin Wang ◽  
Qingxiang Meng
Keyword(s):  
Failure Modes ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Jointed Rock ◽  
Deformation Characteristics ◽  
Rock Masses ◽  
Content Type ◽  
True Triaxial ◽  
Columnar Jointed Rock Mass ◽  
True Triaxial Compression

Purpose The purpose of this paper is to investigate the anisotropic characteristics of the special structure of a columnar jointed rock masses and provide reference to forecast the behavioral characteristics of real samples. Design/methodology/approach This study used FLAC3D numerical software to simulate the mechanical behavior of columnar jointed rock masses with different columns angles (ß) under different stress conditions. The peak strength, elastic modulus and Poisson’s ratio were obtained to investigate the strength, deformation characteristics and failure modes of the rock masses under conventional and true triaxial compression. Findings The results showed that the compressive strength of the specimens presents a U-shape under different joint inclinations. The strength of the specimens reaches a maximum value when ß = 90°, and the value for ß = 0° is slightly lower and reaches a minimum value when ß = 50°. The elastic modulus and Poisson’s ratio of the samples are obviously anisotropic, the anisotropic coefficient decreases with increasing confining pressure. When σ2 ≠ σ3, the peak strengths of the samples are related to the direction of the minor principal stress, and the failure modes of the samples are related to the confining pressure and joint inclination. Originality/value The present paper uses a numerical simulation method to examine the strength and deformation characteristics of a columnar jointed rock mass under conventional and true triaxial compression. The aim is to provide a reference to forecast the mechanical characteristics of test samples in the laboratory.

scholarly journals Study on the mechanical behaviour of Columnar Jointed Rock Mass under uniaxial compression state

2021 ◽  
Vol 861 (7) ◽  
pp. 072106
Author(s):  
Z P Xiang ◽  
S L Huang ◽  
H L Wang ◽  
W Y Xu ◽  
X L Ding ◽  
...  
Keyword(s):  
Rock Mass ◽  
Uniaxial Compression ◽  
Mechanical Behaviour ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Columnar Jointed Rock Mass

scholarly journals The Method of Determining Excavation Damaged Zone by Acoustic Test and the Application in Engineering Cases

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Qian-Cheng Sun ◽  
Hao-Sen Guo ◽  
Zhi-Hua Xu ◽  
Yue Liu ◽  
Xiao Xu
Keyword(s):  
Rock Mass ◽  
Damage Evolution ◽  
Hard Rock ◽  
Damage Zone ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Surrounding Rock ◽  
Excavation Damaged Zone ◽  
Damaged Zone ◽  
Columnar Jointed Rock Mass

It is very important to accurately determine the depth of excavation damaged zone for underground engineering excavation and surrounding rock stability evaluation, and it can be measured by acoustic test, but there is no quantitative method for analysis of the results, and it relies heavily on the experience of engineers, which leads to the low reliability of the results and also limits the application of the acoustic method. According to substantial field test data and the feedback of surrounding rock support parameters, the boundary method is proposed to determine the depth of excavation damaged zone in surrounding rock based on the relation between the ultrasonic velocity of measured point and the background wave velocity of rock mass. When the method is applied to the columnar jointed rock mass of Baihetan and the deep-buried hard rock of Jinping, the excavation damaged zone was well judged. The results in the Baihetan project show that the proposed method of determining excavation damage zone by the acoustic test can well demonstrate the anisotropy characteristics of the columnar jointed rock mass, and the damage evolution characteristics of jointed rock mass at the same position can also be obtained accurately. Moreover, the method also can accurately reveal the damage evolution process of the deep-buried hard rock under the condition of high ground stress, which proved the applicability of this method in jointed or nonjointed rock masses.

scholarly journals Experimental Study on Seepage Anisotropy of a Hexagonal Columnar Jointed Rock Mass

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Yanxin He ◽  
Zhende Zhu ◽  
Wenbin Lu ◽  
Yuan Tian ◽  
Xinghua Xie ◽  
...  
Keyword(s):  
Rock Mass ◽  
Principal Stress ◽  
Material Model ◽  
Jointed Rock ◽  
Maximum Principal Stress ◽  
Jointed Rock Mass ◽  
Good Correspondence ◽  
Columnar Jointed Rock Mass ◽  
Seepage Characteristics ◽  
The Relationship

Many columnar jointed rock masses (basalt) are present at the Baihetan hydropower dam site, and their seepage characteristics have a significant impact on the project’s safety and stability. In this study, model samples consisting of material similar to the columnar jointed rock mass with different inclination angles (0°–90°) were prepared and laboratory triaxial seepage tests were performed to study the seepage characteristics of the columnar jointed rock mass under maximum axial principal stress. The experimental results showed that the similar material model samples of columnar jointed rock mass showed obvious seepage anisotropy. The nonlinear seepage characteristics were well described by the Forchheimer and Izbash equations, and the fitting coefficients of the two equations were in good correspondence. The curves describing the relationship between the inherent permeability and the stress of the samples with different dip angles were U-shaped and L-shaped, and a one-variable cubic equation well described the relationship. The 45° angle specimen had the highest sensitivity to the maximum principal stress, and its final permeability increased by 144.25% compared with the initial permeability. The research results can provide theoretical support for the stability evaluation of the Baihetan hydropower station.

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