Study on the mechanical properties and damage constitutive model of frozen weakly cemented red sandstone

The constitutive model of rock is closely connected with the mechanical properties of rock. To achieve a more accurate quantitative analysis of the mechanical properties of rock after the action of freeze-thaw cycles, it is necessary to establish the constitutive models of rock subjected to freeze-thaw cycles from the view of rock damage. Based on the assumption of rock couple damage, this study established a statistical damage constitutive model of rock subjected to freeze-thaw cycles by combining the lognormal distribution, which is commonly used in engineering reliability analysis, and the strain strength theory. Then, the coordinates and derivative at the peak of the stress-strain curve of the rock after the action of freeze-thaw cycles were obtained through experiments to solve the statistical distribution parameters με and S of the model, whereafter, the theoretical curves by the established model were compared with the experimental curves to verify the validity of it, which shows a great agreement. Finally, the sensitivity analysis of the statistical distribution parameters was implemented. The results indicate that με reflects the strength of the rock, which shows a positive relation, and S stands for the brittleness of the rock, which shows a negative relation.

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

Mathematics ◽

10.3390/math9243264 ◽

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.

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Study on the Mechanical Properties and Damage Constitutive Model of Hybrid Fibre-Reinforced EPS Lightweight Aggregate Concrete

Tehnicki vjesnik - Technical Gazette ◽

10.17559/tv-20190428142148 ◽

2020 ◽

Vol 27 (6) ◽

Keyword(s):

Mechanical Properties ◽

Constitutive Model ◽

Lightweight Aggregate ◽

Lightweight Aggregate Concrete ◽

Aggregate Concrete ◽

Hybrid Fibre ◽

Damage Constitutive Model

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A Damage Constitutive Model of Red Sandstone under Coupling of Wet-Dry Cycles and Impact Load

Shock and Vibration ◽

10.1155/2019/7692424 ◽

2019 ◽

Vol 2019 ◽

pp. 1-12 ◽

Cited By ~ 2

Author(s):

Bin Du ◽

Haibo Bai

Keyword(s):

Constitutive Model ◽

Dynamic Stress ◽

Loading Rate ◽

Impact Load ◽

Coupling Effect ◽

Dynamic Compression ◽

Dominant Role ◽

Stress Strain ◽

Red Sandstone ◽

Damage Constitutive Model

In the engineering fields of mining, tunneling, slopes, and dams, rocks are usually subject to the coupling effect of impact load and wet-dry cycles. The deformation rule of rocks under the coupling effects is a symbolic mechanical property, which lays the foundation for the design and evaluation in the rock engineering. In this paper, the coupling damage was classified as mesodamage induced by wet-dry cycles and macrodamage induced by impact load, and the loading rate effect was considered as the load damage. Besides, a constitutive model of coupling damage was concluded based on Lemaitre’s strain equivalent assumption. Consequently, the validity of the model was verified by a series of dynamic compression tests of red sandstone. Results indicated that the proposed damage constitutive model can definitely describe the dynamic stress-strain curves of red sandstone after wet-dry cycles and impact load. The evolution of coupling damage curves showed that wet-dry cycle damage plays a dominant role in the elastic deformation stage, while the yield failure stage is controlled by the load damage in which the loading rate cannot be ignored. Parametric study was also performed to analyze the effect of parameters on dynamic stress-strain curves. The proposed mode has the simple and reliable operation with few parameters and can efficiently predict the long-term deformation behavior of rocks subject to multiple wet-dry cycles.

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

Periodica Polytechnica Civil Engineering ◽

10.3311/ppci.15313 ◽

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.

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Behavior of Chinese Dahurian Larch Wood after High-Temperature Exposure: Degradation of Mechanical Properties and Damage Constitutive Model

Advances in Materials Science and Engineering ◽

10.1155/2018/8614740 ◽

2018 ◽

Vol 2018 ◽

pp. 1-10

Author(s):

Qifang Xie ◽

Lipeng Zhang ◽

Zhenglei Yang ◽

Long Wang ◽

Yaopeng Wu

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Compressive Strength ◽

Shear Strength ◽

Constitutive Model ◽

Elevated Temperatures ◽

Dahurian Larch ◽

Water Cooling ◽

Residual Compressive Strength ◽

Damage Constitutive Model

Wood has been extensively used in Chinese ancient buildings, and it is important to clearly understand the mechanical properties of wood after exposure to elevated temperatures. In this paper, three kinds of tests with 102 clear wood specimens fabricated with Chinese Dahurian larch for each kind of test were conducted. The residual compressive strength, tensile strength, and shear strength parallel to grain of specimens after exposure to different temperatures (100°C, 150°C, 200°C, and 250°C) with various exposure times (15 min, 30 min, and 45 min) and different cooling methods (natural cooling and water cooling) were obtained. Results indicate that exposure to elevated temperatures causes great degradation of compressive strength, tensile strength, and shear strength parallel to grain. When the exposure temperatures exceed 200°C, the relative compressive strength, tensile strength, and shear strength parallel to grain decrease greatly with the increase of exposure time. The residual compressive strength, tensile strength, and shear strength of specimens after water cooling are lower than that after natural cooling. Exposure temperatures also have a great impact on the weight loss and color change of wood. Based on the test data, degradation models for the residual compressive strength, tensile strength, and shear strength of wood were developed. Furthermore, the damage constitutive model of compressive (CDMC) and tensile (CDMT) parallel to grain was established and validated reasonably by tests.

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

Geofluids ◽

10.1155/2020/8892904 ◽

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.

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Damage constitutive model of stratified cemented backfill based on coupling macroscopic and mesoscopic deformations

E3S Web of Conferences ◽

10.1051/e3sconf/202019405024 ◽

2020 ◽

Vol 194 ◽

pp. 05024

Author(s):

Yanan Tang ◽

Weidong Song ◽

Jianxin Fu

Keyword(s):

Mechanical Properties ◽

Constitutive Model ◽

Compressive Load ◽

Strain Curve ◽

Strength Distribution ◽

Stress Strain ◽

Strain Relationship ◽

Damage Constitutive Model ◽

Stratified Structure ◽

Relationship Of

The mechanical properties and stress-strain relationship of cemented backfills with different stratified structure have a direct effect on the mining-filling cycle and the mining of adjacent pillars. To obtain the stress-strain evolution curves, the uniaxial compressive strength tests were performed on backfills with stratified numbers of 0, 1, 2 and 3. The deformation of stratified backfill under the compressive load is regarded as a compound of closed deformation of the macroscopic stratified structure and elastic deformation of material. The damage constitutive model of cemented backfills with different stratified structure are established by considering the influence of compacted section. Comparative analysis reveals that the calculated curve based on the established sectional damage constitutive model conforms well to the trial curve. The maximum closed strain of the structural plane has a more significant effect on the mechanical properties of backfill. In the Weibull distribution, with the increase of the parameter m, the peak strength of backfill gradually increases and then reaches to a certain value, and the stress-strain curve gradually becomes steeper, which shows that m is a reflection of the concentration level of micro-unit strength distribution in the backfill..

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