scholarly journals Experimental investigation on creep behavior of clastic rock

2020 ◽  
Vol 165 ◽  
pp. 03051
Author(s):  
Zhang Yu ◽  
Zhang Yan ◽  
Mei Song-hua
Keyword(s):  
Axial Strain ◽  
Triaxial Compression ◽  
Testing Machine ◽  
Creep Model ◽  
Test Results ◽  
Creep Failure ◽  
Creep Properties ◽  
Clastic Rock ◽  
Confining Pressures ◽  
The Relationship

Many deflected fault zones exist under the dam foundation Xiang-jiaba Hydropower Station in southwestern China. Clastic rock is the main medium with poor physical and mechanical properties. In or-der to study the creep properties of the clastic rock, triaxial compression creep experiments were carried out on a rock servo-controlling rheology testing machine. From the test results, it can be concluded that the clastic rock has obvious creep characteristics, and the time-dependent deformation is large. Based on the test results, the relationship between axial strain and time under different confining pressures is studied. The relationship between axial strain rates and deviatoric stress under different stress levels is also discussed in de-tail. Furthermore, the creep failure mechanism under different confining pressures is analyzed as well. Therefore, the creep law of the clastic rock specimen is gained. The relationship between the Burgers creep model and its parameters is obtained by fitting the creep curve with Burgers creep model. The result shows that Burgers model can accurately describe the creep properties of the clastic rock in Xiang-jiaba Hydro-power Project.

scholarly journals Experimental Research into the Evolution of Permeability of Sandstone under Triaxial Compression

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 5065
Author(s):  
Liming Zhang ◽  
Shengqun Jiang ◽  
Jin Yu
Keyword(s):  
Axial Strain ◽  
Triaxial Compression ◽  
Testing Machine ◽  
Volumetric Strain ◽  
Confining Pressure ◽  
Rate Of Change ◽  
Peak Strength ◽  
Sudden Increase ◽  
Seepage Pressure ◽  
Confining Pressures

Failure tests on sandstone specimens were conducted under different confining pressures and seepage pressures by using an MTS triaxial rock testing machine to elucidate the corresponding correlations of permeability and characteristic stress with confining pressure and pore pressure during deformation. The results indicate that permeability first decreases and presents two trends, i.e., a V-shaped increase and an S-shaped trend during the non-linear deformation stage. The greater the seepage pressure, the greater the initial permeability and the more obvious the V-shaped trend in the permeability. As the confining pressure was increased, the trend in the permeability gradually changed from V- to S-shaped. Compared with the case at a high confining pressure, the decrease of permeability occurred more quickly, the rate of change becomes greater, and the sudden increase observed in the permeability happened earlier under lower confining pressures. Within the range tested, confining pressure exerted a greater effect on the permeability than the seepage pressure. In comparison with the axial strain, volumetric strain better reflected changes in permeability during compaction and dilation of sandstone. The ratio of crack initiation stress to peak strength ranged from 0.37 to 0.50, while the ratio of dilation stress to peak strength changed from 0.58 to 0.72. Permeabilities calculated based on Darcy and non-Darcy flow changed within the same interval, while the change in permeability was different.

scholarly journals An Experimental Investigation of the Progressive Failure of Sandstone and Its Energy Evolution Characteristics

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Yan Chen ◽  
Baohua Guo
Keyword(s):  
Crack Propagation ◽  
Crack Closure ◽  
Progressive Failure ◽  
Axial Strain ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Energy Evolution ◽  
Evolution Characteristics ◽  
Confining Pressures ◽  
The Relationship

In this research study, the progressive failure and energy evolution characteristics of sandstone samples with different sizes were explored under uniaxial and triaxial compression conditions. The characteristic stresses and strains were captured using the crack axial strain levels and dissipative energy. The results showed that, with the increase in the ratios of the height to diameter (H/D), the crack closure stresses increased, while the crack damage stresses decreased. However, the levels of both the crack closure stresses and crack damages were observed to increase with the H/D. With increase in the confining pressure, it was found that the crack closure and crack damage stresses increased, while their levels decreased. The strains of the crack closures, peak crack axial, and crack propagation were observed to decrease with the H/D, while the crack closure strain levels increased. Also, the crack propagation strains were observed to increase with the confining pressures, while the crack closure, peak crack axial, and crack closure strain levels decreased. The progress failure of the sandstone samples was also obtained based on the evolution characteristics of the dissipative energy. The relationship between the energy densities during each phase and the H/D was also analyzed. It was determined that, with the increasing of the H/D, the input, elastic, and dissipative energy densities displayed different evolution characteristics. Furthermore, with the increases in the characteristic stresses, the input and elastic energy densities were found to increase. The dissipative energy density displayed a slight increase with the increases in the peak strength, which resulted in variations with regard to the crack closures and crack damage stresses.

scholarly journals Energy Evolution Law of Marble Failure Process Under Different Confining Pressures Based on Particle Discrete Element Method

2021 ◽  
Vol 8 ◽  
Author(s):  
Yan-Shuang Yang ◽  
Wei Cheng ◽  
Zhan-Rong Zhang ◽  
Hao-Yuan Tian ◽  
Kai-Yue Li ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Energy Dissipation ◽  
Axial Strain ◽  
Triaxial Compression ◽  
Failure Process ◽  
Rock Failure ◽  
Biaxial Compression ◽  
Energy Evolution ◽  
Confining Pressures ◽  
Energy Dissipated

The energy dissipation usually occurs during rock failure, which can demonstrate the meso failure process of rock in a relatively accurate way. Based on the results of conventional triaxial compression experiments on the Jinping marble, a numerical biaxial compression model was established by PFC2D to observe the development of the micro-cracks and energy evolution during the test, and then the laws of crack propagation, energy dissipation and damage evolution were analyzed. The numerical simulation results indicate that both the crack number and the total energy dissipated during the loading process increase with confining pressures, which is basically consistent with the experiment results. Two damage variables were presented in terms of the density from other researchers’ results and energy dissipation from numerical simulation, respectively. The energy-based damage variable varies with axial strain in the shape of “S,” and approaches one more closely than that based on density at the final failure period. The research in the rock failure from the perspective of energy may further understand the mechanical behavior of rocks.

Creep Characteristics Analysis of Oil Shale and its Application

2010 ◽  
Vol 29-32 ◽  
pp. 2614-2619 ◽  
Author(s):  
Jun Guang Wang ◽  
Bing Liang
Keyword(s):  
Oil Shale ◽  
Stability Control ◽  
Creep Model ◽  
Test Results ◽  
Creep Properties ◽  
Creep Stage ◽  
Creep Characteristics ◽  
Roadway Stability ◽  
Theoretical Significance ◽  
Characteristics Analysis

to study oil shale creep properties, we use rock SJ-1B three-axis creep instrument on oil shale to carry three axis creep test. Through test results, the creep of oil shale is nonlinear, and in accelerating creep stage oil shale injury increased dramatically. Using Burgers creep model introduced damage variable to analyse the oil shale surrounding stress and displacement field and Systematically analyse the creep properties under various support intensity. So it has important theoretical significance and value for the oil shale resource development and roadway stability control.

scholarly journals Comparison of Mechanical Properties of Fiber-Reinforced Sand under Triaxial Compression and Direct Shear

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Reza Noorzad ◽  
Seyed Taher Ghoreyshi Zarinkolaei
Keyword(s):  
Shear Strength ◽  
Axial Strain ◽  
Triaxial Compression ◽  
Polypropylene Fiber ◽  
Triaxial Tests ◽  
Direct Shear ◽  
Test Results ◽  
Peak Reduction ◽  
Shear Tests ◽  
Direct Shear Tests

AbstractThis research investigates the behavior of sand reinforced with polypropylene fiber. To do this, 40 direct shear tests and 40 triaxial tests were performed on the coastal beaches of Babolsar, a city in the North of Iran. The effect of parameters such as fiber content, length of fiber and normal or confining pressure on the behavior of Babolsar sand have been studied. In this study, four various fiber contents (0, 0.25, 0.5 and 1 percent), three different lengths of fiber (6, 12 and 18 mm) and four normal or confining pressures (50, 100, 200 and 400 kPa) have been employed. The test results show that fiber inclusion has a significant effect on the behavior of sand. In both direct shear and triaxial tests, the addition of fibers improved shear strength parameters (C, '), increased peak shear strength and axial strain at failure, and also limited the amount of post-peak reduction in shear resistance. The comparison of the test results revealed that due to better fiber orientation toward the direction of principal tensile strain in triaxial test as compared to direct shear tests, the fiber efficiency and its effect on soil behavior is much more significant in triaxial specimens.

scholarly journals The Effect of Confining Pressure on the Mechanical Properties of Sand–Ice Materials

1973 ◽  
Vol 12 (66) ◽  
pp. 469-481 ◽  
Author(s):  
Bernard D. Alkire ◽  
Orlando B. Andersland
Keyword(s):  
Axial Strain ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Silica Sand ◽  
Creep Tests ◽  
Ice Volume ◽  
Coulomb Failure ◽  
Confining Pressures ◽  
Sand Material ◽  
Cylindrical Samples

Cylindrical samples containing 0.59 mm to 0.84 mm diameter silica sand at about 97% and 55% ice saturation (the ratio of ice volume to sand pore volume) were tested at a temperature of −12° C in triaxial compression. Both constant axial strain-rate tests and step-stress creep tests provide information on the influence of confining pressure on the shear strength and creep behavior of the sand–ice material. Changes in the degree of ice saturation help show the influence of the ice matrix versus the sand material on the mechanical behavior. Data are discussed in terms of the Mohr–Coulomb failure law and creep theories. It is shown that the cohesive component of strength depends on response of the ice matrix, whereas the frictional component of strength responds in a manner very similar to unfrozen sand tested at high confining pressures. Experimental data show that creep rates decrease exponentially and creep strength increases with an increase in confining pressure.

scholarly journals Test Study on the Creep Behaviors of Tianjin Clays

2019 ◽  
Vol 136 ◽  
pp. 07029
Author(s):  
Gang Li ◽  
Zhen Yan ◽  
Jinli Zhang ◽  
Jia Liu ◽  
Yu Xi
Keyword(s):  
Strain Rate ◽  
Axial Strain ◽  
Deviatoric Stress ◽  
Test Results ◽  
Creep Tests ◽  
Creep Properties ◽  
Test Study ◽  
Undisturbed Samples ◽  
Calculation Results ◽  
Triaxial Creep

The drained triaxial creep tests were carriedout to investigate the relationshipsbetween axial strain and time, axial strain and deviatoricstress, and axial strain rate and time for the undisturbed samples of muddy clay and clay in Tianjin.Based on the creep test results, the Singh-Mitchell modelwas used for creep calculation. The results showed that the muddyclay and clay exhibited typical non-linear creep properties. The axial strain increasedwith time and then gradually tendedto be stable.The strain rate increasedasthe deviatoric stress increased, and the muddy clay and clay showedthe characteristics of attenuation creep under deviatoricstresses. The axial strain of muddy clay wassignificantly larger than that of clay, and reachedthestable state within 3000 minutes.Under low deviatoricstress, the slope of the isochronal curve was smaller; while under high deviatoric stress, the slope of the isochronal curve waslarger.The test results were in good agreement with the calculation results, which indicated that the Singh-Mitchell model wassuitable for describing the creep behaviorsof the undisturbed claysin Tianjin.

scholarly journals Effect of Prior Cyclic Loading on Triaxial Compression Strength of Sliding Zone Soil of the Huangtupo Landslide

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Qiong Chen ◽  
Deshan Cui ◽  
Yu Chen ◽  
Xianyu Tao ◽  
Wei Xiang
Keyword(s):  
Cyclic Loading ◽  
Loading Condition ◽  
Stress Ratio ◽  
Axial Strain ◽  
Triaxial Compression ◽  
Cycle Period ◽  
Confining Pressures ◽  
Number Of Cycles ◽  
Logarithmic Relation ◽  
Sliding Zone

Earthquakes or cyclic loadings cause significant changes in the strength characteristics of soil. These changes, especially for sliding zone soil, can lead to catastrophic landslides. Taking into account this characteristic, this paper investigates the effects of prior cyclic loading on the consolidated undrained triaxial compression strength of sliding zone soil with the KTL triaxial automated system. Our experimental results indicate that the prior cyclic loading has a significant effect on the strength behaviour of saturated sliding zone soil. Under different confining pressures, cycle periods, and number of cycles, the samples exhibit the characteristics of strain-hardening. Deviatoric stress under cyclic loading condition is smaller than that with monotonic loading condition under different confining pressures, cycle periods, and number of cycles. As the confining pressure and cycle period increase, the failure stress ratio decreases. The axial strain exhibits a steep rise first and then stays stable under a cycle period of 90 s, while the axial strain shows a linear increase with an increase in the number of cycles under a cycle period of 10 s under confining pressures of 100 kPa and 400 kPa, respectively. The logarithmic relation correlates well with the failure stress ratio in the cyclic loading tests, which preliminary validates the applicability of logarithmic relation for sliding zone soil influenced by prior cyclic loading, providing a theoretical basis and guidance for the further understanding of strength characteristics of sliding zone soil.

scholarly journals Experimental Study on Viscoplastic Property of Unsaturated Reticulate Red Clay Used as an Engineered Barrier

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Chuang Zhang ◽  
Jian-Zhong Li ◽  
Yong He
Keyword(s):  
Axial Strain ◽  
Confining Pressure ◽  
Matric Suction ◽  
Triaxial Tests ◽  
Red Clay ◽  
Reticulate Red Clay ◽  
Confining Pressures ◽  
Loading Tests ◽  
Engineered Barrier ◽  
The Relationship

In this study, to explore the feasibility of a compacted red clay as an engineered barrier in landfills, the viscoplastic property of remodeled unsaturated reticulate red clay was studied through a series of triaxial tests. According to the deviatoric stress–axial strain curves obtained through loading tests with varying strain rates and under different conditions, the viscoplastic parameter β of remodeled reticulate red clay was obtained. The effects of different matric suctions and net confining pressures on the viscoplasticity of unsaturated reticulate clay were analyzed. The test results showed that remodeled reticulate red clays with different degrees of saturation have similar viscoplastic properties, and their stress–strain curves are all isotach. The stiffness of unsaturated reticulate red clay increased with increasing confining pressure and matric suction. The relationship between β and the net confining pressure can be described using a linear equation. The β value of the specimens increased with increasing matric suction under a constant net confining pressure. A similar linear relationship was observed between β and the matric suction. These relationships are explained considering the loading rate effect mechanism.

Triaxial Compression Experimental Study on Post-Peak Deformation Characteristics of Rock Masses with Persistent Joints

2014 ◽  
Vol 1030-1032 ◽  
pp. 1074-1077
Author(s):  
Yang Ping ◽  
Shu Chen Li
Keyword(s):  
Triaxial Compression ◽  
Jointed Rock ◽  
Peak Strain ◽  
Deformation Characteristics ◽  
Test Results ◽  
Rock Masses ◽  
Underground Excavations ◽  
Jointed Rock Masses ◽  
Confining Pressures ◽  
The Stability

Controlling the stability of surrounding rocks in underground excavations during in-depth resource development must be confronted with post-peak deformation and failure problems of jointed rock masses. This paper describes routine triaxial compression testing on standard cylinder specimen with persistent joints in different inclinations and under different confining pressures, and analyzes deformation characteristics of rock masses with persistent joints in different inclinations and under different confining pressures. Test results show that the peak strength, residual strength, and peak strain of the jointed specimen basically increase with increasing confining pressures but decrease with increasing joint inclinations. Test results well reflect that it is incorrect to evaluate deformation characteristics of jointed rock masses with continuum mechanics and research results provide a reference for the research on the stability of surrounding rocks in underground excavations.

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