scholarly journals Research on the energy evolution characteristics and the failure intensity of rocks

2020 ◽  
Vol 30 (5) ◽  
pp. 705-713
Author(s):  
Lin Gao ◽  
Feng Gao ◽  
Zhizhen Zhang ◽  
Yan Xing
Keyword(s):  
Energy Evolution ◽  
Evolution Characteristics ◽  
Failure Intensity

scholarly journals Experimental Study on Dynamic Mechanical Properties and Energy Evolution Characteristics of Limestone Specimens Subjected to High Temperature

2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Qi Ping ◽  
Chuanliang Zhang ◽  
Haipeng Su ◽  
Hao Zhang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
High Temperature ◽  
Incident Energy ◽  
Dynamic Mechanical Properties ◽  
Energy Evolution ◽  
Strain And Strain Rate ◽  
Evolution Characteristics ◽  
Dynamic Compressive Strength

To study the effect of high temperature on the dynamic mechanical properties and energy evolution characteristic of limestone specimens, the basic physical parameters of limestone specimens that cool naturally after experiencing high temperatures of room temperature (25°C), 200°C, 400°C, and 600°C were tested. In addition, compression tests with 6 impact loading conditions were conducted using SHPB device. The changes of basic physical properties of limestone before and after temperature were analyzed, and the relationship among dynamic characteristic parameters, energy evolution characteristics, and temperature was discussed. Test results indicated that, with the increase of temperature, the surface color of specimen changed from gray-black to gray-white, and its volume increased, while the mass, density, and P-wave velocity of specimen decreased. The dynamic compressive stress-strain curve of limestone specimens after different high-temperature effects could be divided into three stages: elasticity stage, yield stage, and failure stage. Failure mode of specimen was in the form of spalling axial splitting, and the degree of fragmentation increased with the increase of the temperature and incident energy. With the increase of the temperature, the reflection energy, the absorption energy, the dynamic compressive strength, and dynamic elastic modulus of rock decreased, while its transmission energy, the dynamic peak strain, and strain rate increased. The dynamic compressive strength, dynamic elastic modulus, dynamic strain, and strain rate of limestone specimens all increased with the increase of incident energy, showing a quadratic function relationship.

scholarly journals The Effect of Confining Pressure and Water Content on Energy Evolution Characteristics of Sandstone under Stepwise Loading and Unloading

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Shuren Wang ◽  
Paul Hagan ◽  
Yanhai Zhao ◽  
Xu Chang ◽  
Ki-Il Song ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Water Content ◽  
Elastic Energy ◽  
Strain Energy ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
Energy Evolution ◽  
Evolution Characteristics ◽  
Loading And Unloading ◽  
Stepwise Loading

To investigate the mechanical properties and energy evolution characteristics of sandstone depending on the water contents and confining pressure, the uniaxial and triaxial tests were conducted. The test results show that the strain energy was stored in the sandstone samples at the prepeak stage, and that is suddenly released when the failure occurred, and energy dissipation is sharply increased at the postpeak stage. The damage and energy dissipation characteristics of the samples are observed clearly under the stepwise loading and unloading process. The critical strain energy and energy dissipation show a clear exponential relationship. The critical elastic energy decreases linearly as the water content increases. As the confining pressure increases, the critical elastic energy of the samples transforms from linear to exponential. The concept of energy enhancement factor is proposed to characterize the strengthening effect induced by the confining pressure on the energy storage capacity of the rock samples. The energy evolution of the sandstone samples is more sensitive to the confining pressure than that of the water content.

scholarly journals Experimental Study on Thermal Damage and Energy Evolution of Sandstone after High Temperature Treatment

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Rong-rong Zhang ◽  
Lai-wang Jing ◽  
Qin-yong Ma
Keyword(s):  
Strain Energy ◽  
Thermal Damage ◽  
Peak Stress ◽  
Temperature Treatment ◽  
P Wave ◽  
High Temperature Treatment ◽  
Energy Evolution ◽  
P Wave Velocity ◽  
Total Input ◽  
Evolution Characteristics

Thermal damage and energy evolution characteristics in process of impact failure of sandstone after high temperature treatment were studied by split Hopkinson pressure bar (SHPB) system. The ultrasonic P-wave velocity, density, porosity, peak stress, ET/E0, thermal damage, fracture, and energy evolution characteristics of sandstone with temperature during the experimental process were explored. Results show that, with the increase of temperature, the ultrasonic P-wave velocity and density decrease, while the porosity increases. It is found that the peak stress and ET/E0 decrease with the increase of temperature, and the decreasing trend is fitted with the simple cubic equation. Above 600°C, dynamic peak stress and ET/E0 decrease rapidly. The thermal damage of rock increases with the increase of temperature, which is in accordance with the logistic curve model. The thresholds of damage strain energy release rate are 200°C and 800°C in this research. Its total input strain energy decreases with the increase of processing temperature and decreases sharply when the temperature is over 600°C. The variation of total input strain energy has small change at the range from 400°C to 600°C.

scholarly journals Energy Accumulation and Dissipation of Coal with Preopening under Uniaxial Loading

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xin Wei ◽  
Hao Hu ◽  
Yang Li
Keyword(s):  
Simulation Method ◽  
Particle Simulation ◽  
Energy Evolution ◽  
Coal Specimen ◽  
Energy Accumulation ◽  
Evolution Characteristics ◽  
Optimal Value ◽  
Storage Limit ◽  
Particle Simulation Method ◽  
Energy Accumulation And Dissipation

Energy accumulation and dissipation play an important role during the entire process of rock failure. Some flaws, such as preexisting holes, will influence energy accumulation and dissipation. In order to investigate the energy evolution of coal specimen with preexisting holes under uniaxial compression through numerical approaches, the particle simulation method was used in numerical simulations. In this paper, the energy evolution of coal specimen was theoretically analyzed, and the influence of different hole arrangement, such as diameter, spacing, angle, and number, on the evolution characteristics of energy was also discussed. At the same time, the arrangement of the artificial boreholes for preventing the rockburst was explored. The results show that, compared with the intact coal specimen, the change of diameter, spacing, angle, and the number of holes weakened the coal specimen’s capacity to store energy and release strain energy. When the diameter, the vertical distance, and relative angle of preexisting holes were 15 mm, 10∼15 mm, and 60°, respectively, the energy storage limit reached optimal value. For arrangement of the artificial boreholes, the diameter, spacing, and angle can be designed on the basis of those optimal values. This study has a guiding significance in designing the arrangement of the artificial boreholes for mitigation of rockburst.

Deformation Damage and Energy Evolution Characteristics of Coal at Different Depths

2018 ◽  
Vol 52 (5) ◽  
pp. 1491-1503 ◽  
Author(s):  
Zhaopeng Zhang ◽  
Heping Xie ◽  
Ru Zhang ◽  
Zetian Zhang ◽  
Mingzhong Gao ◽  
...  
Keyword(s):  
Energy Evolution ◽  
Evolution Characteristics ◽  
Different Depths

scholarly journals Influence of Loading Rate on the Energy Evolution Characteristics of Rocks under Cyclic Loading and Unloading

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 4003
Author(s):  
Jielin Li ◽  
Liu Hong ◽  
Keping Zhou ◽  
Caichu Xia ◽  
Longyin Zhu
Keyword(s):  
Cyclic Loading ◽  
Loading Rate ◽  
Energy Evolution ◽  
Dissipation Energy ◽  
Loading Rates ◽  
Cyclic Loading And Unloading ◽  
Evolution Characteristics ◽  
Increasing Trend ◽  
Loading And Unloading ◽  
Fast Increase

To analyse the effect of loading rate on the energy evolution of rocks under cyclic loading and unloading, tests on saturated limestone were conducted at loading rates of 0.15, 0.2, and 0.3 mm/min, and the evolution characteristics of plastic, elastic, dissipation, and input energies were examined under different loading rates. The results indicated that the plastic strain in the entire test was directly proportional to the loading rate. In addition, strength, residual stress, plastic energy, and dissipation energy under residual resistance were inversely proportional to the loading rate. The plastic strain exhibited a decreasing–stabilising–increasing trend, and the smaller loading rate delayed the “increasing” trend. The increasing extent of each energy exhibited the following trend: input > elastic > plastic > dissipation energy. Furthermore, the first three types of energy exhibited a slow–fast–slow–fast increase trend. The dissipation energy exhibited a fast–steady–fast–slow–fast increase trend. Additionally, the elastic energy index exhibited a large increase–steady increase–decrease trend, which was proportional to the loading rate. The damping ratio exhibited a decrease–increase–decrease–increase–decrease trend which was proportional to the loading rate in the compaction stage and inversely proportional to the plastic stage.

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.

Sign in / Sign up

Export Citation Format

Share Document