Mechanical properties and damage constitutive model for uniaxial compression of salt rock at different loading rates

2021 ◽  
pp. 105678952098386
Author(s):  
Junbao Wang ◽  
Qiang Zhang ◽  
Zhanping Song ◽  
Yuwei Zhang ◽  
Xinrong Liu
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Uniaxial Compression ◽  
Loading Rate ◽  
Peak Stress ◽  
Test Results ◽  
Salt Rock ◽  
Loading Rates ◽  
Damage Constitutive Model ◽  
Rock Specimens

To study the effect of loading rate on the mechanical properties of salt rock, uniaxial compression tests and acoustic emission tests at different loading rates were carried out on salt rock specimens. The test results show that with increases in loading rate, the peak stress of salt rock increases first and then essentially remains unchanged, and the elastic modulus increases gradually, while the strain at peak stress decreases gradually. Moreover, the Poisson’s ratio is independent of loading rate. The macroscopic failure modes of the salt rock specimens at different loading rates are all ‘X’-type conjugate shear failure. However, the loading rate is closely related to the degree of fracture, such that the smaller the loading rate is, the higher is the degree of fracture of salt rock. In order to describe the stress–strain behaviour in the process of salt rock failure, a damage variable expression represented by the deformation modulus was proposed, and a rock damage constitutive model was established according to the theory of continuum damage mechanics. The rationality of the damage constitutive model was verified by using the present uniaxial compression test results of salt rock and existing test data from the literature. The results show that the model can accurately describe the stress–strain response of rock in the failure process.

scholarly journals Physical and Mechanical Properties Evolution of Coal Subjected to Salty Solution and a Damage Constitutive Model under Uniaxial Compression

Mathematics ◽  
2021 ◽  
Vol 9 (24) ◽  
pp. 3264
Author(s):  
Min Wang ◽  
Qifeng Guo ◽  
Yakun Tian ◽  
Bing Dai
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Uniaxial Compression ◽  
Immersion Time ◽  
Physical And Mechanical Properties ◽  
Relative Mass ◽  
Stress Strain ◽  
Damage Constitutive Model ◽  
Underground Reservoirs

Many underground reservoirs for storing water have been constructed in China’s western coal mines to protect water resources. Coal pillars which work as dams are subjected to a long-term soaking environment of concentrated salty water. Deterioration of the coal dam under the attack of the salty solution poses challenges for the long-term stability and serviceability of underground reservoirs. The evolution of the physical and mechanical properties of coal subjected to salty solutions are investigated in this paper. Coal from a western China mine is made to standard cylinder samples. The salty solution is prepared according to chemical tests of water in the mine. The coal samples soaked in the salty solution for different periods are tested by scanning electron microscope, nuclear magnetic resonance, and ultrasonic detector techniques. Further, uniaxial compression tests are carried out on the coal specimens. The evolutions of porosity, mass, microstructures of coal, solution pH values, and stress–strain curves are obtained for different soaking times. Moreover, a damage constitutive model for the coal samples is developed by introducing a chemical-stress coupling damage variable. The result shows that the corrosion effect of salty solution on coal samples becomes stronger with increasing immersion time. The degree of deterioration of the longitudinal wave velocity (vp) is positively correlated with the immersion time. With the increase in soaking times, the porosity of coal gradually increases. The relative mass firstly displays an increasing trend and then decreases with time. The peak strength and elastic modulus of coal decreases exponentially with soaking times. The developed damage constitutive model can well describe the stress–strain behavior of coal subjected to salty solution under the uniaxial compression.

scholarly journals Uniaxial Compression Behavior of Cement Mortar and Its Damage-Constitutive Model Based on Energy Theory

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1309 ◽  
Author(s):  
Yunliang Tan ◽  
Qingheng Gu ◽  
Jianguo Ning ◽  
Xuesheng Liu ◽  
Zhichuang Jia ◽  
...  
Keyword(s):  
Constitutive Model ◽  
Uniaxial Compression ◽  
Loading Rate ◽  
Cement Mortar ◽  
Axial Stress ◽  
Great Influence ◽  
Strain Curve ◽  
Compression Tests ◽  
Whole Process ◽  
Damage Constitutive Model

The mechanical properties of mortar materials in construction are influenced both by their own proportions and external loads. The trend of the stress–strain curve in cracks compaction stage has great influence on the relationship between the strength and deformation of cement mortar. Uniaxial compression tests of mortar specimens with different cement–sand ratios and loading rates were carried out, and the stored and dissipated energies were calculated. Results indicated that the elastic modulus and strength of mortar specimens increase with the cement–sand ratio and loading rate. The energy dissipation shows good consistency with the damage evolution. When the loading rate is less than 1.0 mm/min, most of the constitutive energy at the peak point is stored in the specimen and it increase with cement–sand ratio. A simple representation method of axial stress in cracks compaction stage was proposed and an energy-based damage constitutive model—which can describe well the whole process of cement mortar under uniaxial compression—was developed and verified.

Uniaxial Compression Fractal Damage Constitutive Model of Rock Subjected to Freezing and Thawing

2020 ◽  
Author(s):  
Shengtao Zhou ◽  
Nan Jiang ◽  
Xuedong Luo ◽  
Wen Fang ◽  
Xu He
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Uniaxial Compression ◽  
Residual Strength ◽  
Structural Damage ◽  
Compression Fracture ◽  
Peak Strain ◽  
Freeze Thaw ◽  
Deformation Stage ◽  
Damage Constitutive Model

Mechanical properties of the rock in the cold regions are often affected by freeze-thaw cycles and loads. It is of great theoretical significance and engineering value to establish a uniaxial compression damage constitutive model of the rock under freeze-thaw cycles that can reflect the relationship between macroscopic and mesoscopic structural damage. In this paper, macroscopic and mesoscopic methods are combined with statistical methods to quantitatively analyze the damage degree of rock under freeze-thaw cycles and loads. Combined with the fractal features of the macroscopic image of the section, a fractal damage constitutive model considering the residual strength of rock is established. In addition, the model is subsequently verified by the experiment. The experiment shows that the mechanical properties of rocks subjected to freeze-thaw cycles and loads are determined by freeze-thaw damage variables, load damage variables, and their coupling effects. As the number of freeze-thaw cycles increases, the uniaxial compressive strength and elastic modulus of rocks decrease, and peak strain increases. By using the fractal dimension of the compression fracture surface as a bridge considering the residual strength of the rock, the constitutive model can better reflect the compaction stage, elastic deformation stage and plastic deformation stage of the uniaxial compression process of the freeze-thaw rocks.

Uniaxial compression mechanical properties and damage constitutive model of limestone under osmotic pressure

2021 ◽  
pp. 105678952110454
Author(s):  
Zhanping Song ◽  
Tong Wang ◽  
Junbao Wang ◽  
Kehui Xiao ◽  
TengTian Yang
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Osmotic Pressure ◽  
Uniaxial Compression ◽  
Influencing Factor ◽  
Peak Strain ◽  
Strain Response ◽  
Test Results ◽  
Stress Strain ◽  
Compaction Factor

To study the influence of osmotic pressure on the uniaxial compression mechanical properties of limestone, uniaxial compression tests were carried out on limestone specimens under different osmotic water pressure. The test results show that with the increase of osmotic pressure, the closure strain, yield strain and peak strain of limestone gradually increase, while the closure stress, yield stress, peak stress and elastic modulus gradually decrease. To describe the stress-strain response of limestone during uniaxial compression failure, the concepts of compaction factor and osmotic pressure influencing factor were proposed, and a constitutive model of rock compaction stage was established by integrating the relationship between the compaction factor and osmotic pressure influencing factor and the tangent modulus of compaction section. On this basis, combining the continuum damage mechanics theory, and assuming that the rock micro-unit strength obeys the compound power function distribution, a constitutive model reflecting the uniaxial compression mechanical properties of rock under osmotic pressure was established by the statistical method. The rationality of the model was verified using the results of the uniaxial compression test of limestone under different osmotic pressures. The results show that the test results under different osmotic pressures are in good agreement with the theoretical curves, and the model in this paper can reflect the stress-strain response of limestone before its failure under different osmotic pressures.

scholarly journals Study on Statistical Damage Theory Model of Tailings in a Metal Ore under the Action of Moisture Absorption and Dehumidification Circulation

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Bing Cao ◽  
Hua Wei ◽  
Mei-Qi Dou ◽  
Lin Hu ◽  
Yao-hui Guo
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Moisture Absorption ◽  
Physical And Mechanical Properties ◽  
Theory Model ◽  
Hunan Province ◽  
Test Results ◽  
Damage Constitutive Model ◽  
Damage Theory ◽  
Statistical Damage

In order to explore the variation law of mechanical properties of tailing sand of a metal ore in Hunan Province under the action of moisture absorption and dehumidification circulation, based on the indoor triaxial test results of tailing sand, this paper introduces the statistical damage theory, combined with the physical and mechanical properties of tailing sand, and studies the elastic-plastic mechanical properties of tailing sand on the basis of the Lemaitre strain equivalent theory. Giving full consideration of the change of tailing sand’s pore and volume in the deformation process, an improved statistical damage constitutive model is proposed; it can reflect that the residual strength of tailings after the peak value still has bearing capacity under the action of dry wet circulation. Compared with the results of indoor triaxial consolidation undrained test, this constitutive model is more reliable.

scholarly journals Damage Strengthening Constitutive Model of Cemented Paste Backfill

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Kangli Cheng ◽  
Bingbing Tu ◽  
Lang Liu ◽  
Bo Zhang ◽  
Huafu Qiu
Keyword(s):  
Constitutive Model ◽  
Uniaxial Compression ◽  
Strain Curve ◽  
Cemented Paste Backfill ◽  
Test Results ◽  
Stress Strain ◽  
Filling Materials ◽  
Paste Backfill ◽  
Damage Constitutive Model ◽  
Ucs Test

In order to consider the influence of mesoscopic characteristics of materials on the constitutive model of cemented paste backfill (CPB), the uniaxial compression variables and the damage constitutive model, considering the influence of porosity and pore size of filling materials, were derived based on the strain equivalence principle and Weibull probability distribution function. The nuclear magnetic resonance (NMR) tests and unconfined compression strength (UCS) tests were carried out on 8 groups of CPB specimens with different slurry concentrations and cement-tailings ratios. Then, the expression of damage strengthening coefficient is determined, and the stress-strain curves measured by the theoretical model were compared with the experimental ones. The results show that the uniaxial compression constitutive model proposed is in good agreement with UCS test results and can effectively describe the damage evolution law and the development process of stress-strain curve of CPB under uniaxial compression. The 28-day compressive strength of CPB can reach 8 MPa, the residual strength is about 1∼2 MPa, the elastic modulus is about 200∼2000 MPa, and the porosity is about 3∼5%. The CPB with slurry concentration of 74% and 76% and cement-tailings ratio of 1 : 4 and 1 : 6 is more reasonable, and the relevant mechanical parameters are more stable.

scholarly journals Study on the Tri-axial Time-Dependent Deformation and Constitutive Model of Glauberite Salt Rock under the Coupled Effects of Compression and Dissolution

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1797
Author(s):  
Mengtao Cao ◽  
Shunde Yin
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Ct Scan ◽  
Time Dependent ◽  
Solid Skeleton ◽  
Micro Ct ◽  
Salt Rock ◽  
Hydraulic Connection ◽  
Infiltration Pressure ◽  
Damage Constitutive Model

Solution mining for glauberite salt rock is a long-term process that takes several years to several decades. Therefore, deposit deformations and subsidence of ground surfaces are time-dependent deformation problems that should consider the effect of water dissolution. In order to investigate the time-dependent deformation characteristics of glauberite salt rock, tri-axial time-dependent deformation tests were conducted under the condition of 4 MPa confining pressure and 5 MPa axial pressure with infiltration pressures of 3, 2, 1, and 0 MPa, respectively, and the micro-CT scan system was used to scan the glauberite specimens before and after the experiment in order to study the fracture evolution inside the specimen, and a damage constitutive model was established to fit the time-dependent deformation curves based on the damage mechanics and effective stress principle. To simulate the solution mining process, the time-dependent deformation process of glauberite salt rock was divided into three stages: hydraulic connection stage, water-saturated stage, and drainage stage. The results demonstrate that the hydraulic connection time for glauberite salt rock decreases with increasing infiltration pressure. The time-dependent deformations of the specimens at the hydraulic connection and saturated-water stages are significantly affected by the effective stress and continual mineral dissolution. At the drainage stage, the softening degree of the solid skeleton mechanical properties, which is caused by the dissolution effect and infiltration pressure loading history, decides the deformation of glauberite salt rock. In addition, the degree of softening inside glauberite salt rock caused by dissolution becomes more severe with increasing infiltration pressure using the micro-CT scan technology. Lastly, the time-dependent damage constitutive model is able to describe the tri-axial time-dependent deformation behavior of glauberite salt rock, and the variations of time-dependent deformation parameters further indicate the damage evolution of the solid skeleton mechanical properties of glauberite caused by infiltration pressure and dissolution effect.

scholarly journals Creep Properties and Constitutive Model of Salt Rock

2021 ◽  
Vol 2021 ◽  
pp. 1-29
Author(s):  
Qiang Zhang ◽  
Zhanping Song ◽  
Junbao Wang ◽  
Yuwei Zhang ◽  
Tong Wang
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Effect Of Temperature ◽  
Creep Process ◽  
Underground Storage ◽  
Self Healing ◽  
Salt Rock ◽  
Creep Properties ◽  
Term Operation ◽  
Rock Creep

Due to the advantages of low porosity, low permeability, high ductility, and excellent capacities for creep and damage self-healing, salt rock is internationally considered as the ideal medium for underground storage of energy and disposal of radioactive waste. As one of the most important mechanical properties of salt rock, creep properties are closely related to the long-term operation stability and safety of salt rock underground storage cavern. A comprehensive review on the creep properties and constitutive model of salt rock is put forward in this paper. The opinions and suggestions on the research priority and direction of salt rock's mechanical properties in the future are put forward: (1) permeability variation of salt rock under the coupling effect of temperature and stress; (2) damage mechanism and evolution process under the effect of creep-fatigue interaction and low frequency cyclic loading; (3) microdeformation mechanisms of salt rock and the relationship between microstructure variations and macrocreep behavior during creep process; (4) the establishment of the creep damage constitutive model with simple form, less parameters, easy application, and considering the damage self-healing ability of salt rock simultaneously.

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