scholarly journals Experimental Investigation on the Evolution of Damage and Seepage Characteristics for Red Sandstone under Thermal-mechanical Coupling Conditions

2021 ◽  
Author(s):  
Haopeng Jiang ◽  
Annan Jiang ◽  
Fengrui Zhang
Keyword(s):  
High Temperature ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Effect Of Temperature ◽  
Permeability Evolution ◽  
Red Sandstone ◽  
Permeability Characteristics ◽  
Mechanical Coupling ◽  
Coupling Conditions ◽  
Rock Stability

Abstract Rock masses in underground space usually experience the coupling of high-temperature field, stress field and seepage field, which gives them complex mechanical behavior and permeability characteristics. In order to study the mechanical properties and permeability characteristics of red sandstone under different temperature environments, a seepage test under high temperature and triaxial compression is carried out based on the RLW-2000 multi-field coupling tester. The results show that the plastic flow of red sandstone at the stress peak under the same temperature is more obvious with the increase of confining pressure. In addition, as the confining pressure gradient increases, the permeability decreases and the trend becomes slower. And the higher the operating temperature, the easier to produce seepage channels inside the rock sample. The development of fissures is rapidly developed under the effect of temperature, so the seepage channels are widened and increased, and the permeability is greatly increased. The constitutive model of rock statistical damage considering the interaction of high temperature and osmotic pressure was constructed based on the experimental data and combining theoretical methods to reveal the characteristics of permeability evolution induced by thermal damage of rocks. The research results can be used as a reference for monitoring rock stability during geological engineering projects involving thermal-seepage-stress coupling conditions.

Study on Constitutive Mode of Three Typical Rocks Based on Triaxial Compression Test

2012 ◽  
Vol 170-173 ◽  
pp. 322-326
Author(s):  
Kui Chen ◽  
Ren Hua Yang ◽  
Tao Xu ◽  
Ya Jing Qi
Keyword(s):  
Residual Strength ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Digital Design ◽  
Peak Strength ◽  
Design Parameters ◽  
Stress Strain ◽  
Red Sandstone ◽  
Constitutive Mode ◽  
Shield Machine

In order to study the relationship between the design parameters of the shield machine and the strength of rock, the behaviours of rocks under the conventional triaxial compression, the complete stress-strain curves under different confining pressures of three typical rocks, i.e. granite, limestone and red sandstone, were taken out for analysis. From the curves, the values of elastic modulus E and Poisson's ratio μ were gained and the relationships between the following parameters were figured out, which are peak strength versus confining pressure, residual strength versus confining pressure, strain at peak strength versus confining pressure, and strain at residual strength versus confining pressure. According to the values and relationships, the complete stress-strain curves were divided into three parts. For each part, a constitutive equation was established by using the strain softening trilinear elastic-brittle-plastic constitutive model, and all the related parameters in the constitutive equations were also presented, which provide a theoretical foundation for the digital design of the cutter head and cutters of Shield machine.

scholarly journals Mechanical behavior investigation of Longmaxi shale under high temperature and high confining pressure

2019 ◽  
Vol 23 (3 Part A) ◽  
pp. 1521-1527
Author(s):  
Hui-Jun Lu ◽  
Dong-Feng Hu ◽  
Ru Zhang ◽  
Cun-Bao Li ◽  
Jun Wang ◽  
...  
Keyword(s):  
High Temperature ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Bedding Plane ◽  
Brittleness Index ◽  
Tensile Fracture ◽  
Pressure Condition ◽  
Failure Patterns ◽  
Longmaxi Shale ◽  
High Confining Pressure

Triaxial compression tests are conducted on Longmaxi shale under high temperature and high confining pressure condition corresponding to a depth of 3000 m for two typical bedding plane orientations (0? and 90?). It is found that the crack initiation stresses and crack damage stresses of the Longmaxi shale specimens with different vein orientations are different, reflecting that the inclination of the bedding plane has a non-negligible influence on the microcrack initiation and propagation. In addition, the brittleness index of the Longmaxi shale with a bedding plane orientation of 90? is greater than that with an orientation of 0?, which confirmed that the brittleness index is related to the structural orientation under a high temperature and high confining pressure condition. Concerning the failure patterns, both the shear and tensile fracture modes has been observed.

scholarly journals Experimental Study on Seepage Characteristics of Fractured Rock Mass under Different Stress Conditions

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Ma Haifeng ◽  
Yao Fanfan ◽  
Niu Xin’gang ◽  
Guo Jia ◽  
Li Yingming ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Permeability Coefficient ◽  
Fractured Rock ◽  
Axial Strain ◽  
Strain Curve ◽  
Confining Pressure ◽  
Strain Effect ◽  
Permeability Evolution ◽  
Hoop Strain ◽  
Permeability Characteristics

In order to obtain the mechanical behavior and permeability characteristics of coal under the coupling action of stress and seepage, permeability tests under different confining pressures in the process of deformation and destruction of briquette coal were carried out using the electrohydraulic servo system of rock mechanics. The stress-strain and permeability evolution curves of briquette coal during the whole deformation process were obtained. The mechanical behavior and permeability coefficient evolution response characteristics of briquette coal under stress-seepage coupling are well reflected. Research shows that stress-axial strain curve and the stress-circumferential strain curve have the same change trend, the hoop strain and axial strain effect on the permeability variation law of basic consistent, and the permeability coefficient with the increase of confining pressure and decreases, and the higher the confining pressure, the lower the permeability coefficient, the confining pressure increases rate under the same conditions, and the permeability coefficient corresponding to high confining pressure is far less than that corresponding to low confining pressure. The confining pressure influences the permeability of the briquette by affecting its dilatancy behavior. With the increase of the confining pressure, the permeability of the sample decreases, and the permeability coefficient decreases with the increase of the confining pressure at the initial stage, showing a logarithmic function. After failure, briquette samples show a power function change rule, and the greater the confining pressure is, the more obvious the permeability coefficient decreases.

Mechanical and permeability characteristics of rock under hydro-mechanical coupling conditions

2015 ◽  
Vol 73 (10) ◽  
pp. 5987-5996 ◽  
Author(s):  
Lu Wang ◽  
Jian-feng Liu ◽  
Jian-liang Pei ◽  
Hui-ning Xu ◽  
Yu Bian
Keyword(s):  
Permeability Characteristics ◽  
Mechanical Coupling ◽  
Coupling Conditions

Study on the Engineering Properties of Saturated Red Sandstone

2014 ◽  
Vol 638-640 ◽  
pp. 589-593
Author(s):  
Hong Yi Wang ◽  
Wu Xiu Ding ◽  
Jin Jin Yang
Keyword(s):  
Construction Projects ◽  
Elasticity Modulus ◽  
Triaxial Compression ◽  
Mechanical Damage ◽  
Confining Pressure ◽  
Peak Strength ◽  
Engineering Properties ◽  
Compression Tests ◽  
Red Sandstone ◽  
Slope Excavation

Red sandstone with a strong water softening can cause difficulties of construction projects, especially for slope excavation and support engineering. Therefore, the study on the engineering properties of saturated red sandstone has a important meaning. The mechanical parameters of saturated red sandstone are obtained by the triaxial compression tests. The test results indicate that the ralations between peak strength, elasticity modulus and confining pressure for the saturated specimens are similar with the natural specimens, that is, with the increasing of confining pressure, the peak strength and the elasticity modulus will increase, but the growth rate becomes slowly. Under the same confining pressure, the peak strength and the elasticity modulus of saturated specimen are more smaller than the natural one. The mechanical damage caused by water recedes when the confining pressure increases, so for the geotechnical engineering with larger influence of water, the increasement of confining pressure by the supporting structures is conducive to the stability of rock mass. The research results will provide a theoretical basis for the red sandstone engineering.

Experimental Investigation of the Influence of the Adsorption Gas on the Permeability Characteristics of the Coal Containing Gas

2012 ◽  
Vol 616-618 ◽  
pp. 190-196
Author(s):  
Deng Ke Wang ◽  
Jian Ping Wei ◽  
Le Wei ◽  
Heng Jie Qin
Keyword(s):  
Coal Sample ◽  
Gas Adsorption ◽  
Triaxial Compression ◽  
Axial Loading ◽  
Experimental System ◽  
Confining Pressure ◽  
Gas Pressure ◽  
Permeability Characteristics ◽  
Gas Seepage ◽  
Loading Case

A large number of laboratory experiments on the gas seepage characteristics by the self-developed gas-bearing coal triaxial compression experimental system and conducts the comparative analysis of the similarities and differences of the permeability among CO2, CH4 and N2. The results show that given the condition of constant gas pressure, the permeability of the coal sample decreases with the increase of the confining pressure; under the constant confining pressure, the permeability of the coal sample decreases with the increase of the gas pressure; gases of different adsorbabilities have different permeabilities. The stronger the gas adsorption is, the worse its permeability will be; in the axial loading case, the permeabilities of different gases all reduce firstly and increase afterward, showing the generally V-shaped variation law. The results are of certain theoretical values on the in-depth understanding of the migration law of the gas in coal seams.

scholarly journals Experimental Investigation of Thermal Cracking and Permeability Evolution of Granite with Varying Initial Damage under High Temperature and Triaxial Compression

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Xiangxi Meng ◽  
Weitao Liu ◽  
Tao Meng
Keyword(s):  
High Temperature ◽  
Critical Temperature ◽  
Waste Disposal ◽  
Sharp Increase ◽  
Triaxial Compression ◽  
Thermal Cracking ◽  
High Level Waste ◽  
Permeability Evolution ◽  
Initial Damage ◽  
High Level

Thermal cracking and permeability evolution of granite under high temperature and triaxial compression are the key to designing high-level waste disposal sites. In this paper, uniaxial compression tests of granite specimens with different axial compression are designed, and then a solid-head-designed coupling triaxial testing system is applied to study thermal cracking and permeability evolution of granite specimen with different damage at different inlet gas pressures (1, 2, 4, and 6 MPa) and temperatures (ranging from 100 to 650°C). The test results show that granite, nearly impermeable rocks, can show a striking increase of permeability by heating beyond the critical temperature. When the initial axial pressure is 60% or 70% of the uniaxial compressive strength, the growth of granite permeability exhibits three stages during 100∼650°C heating process. Permeability increases by two orders of magnitude, but it does not reach the maximum value (i.e., a network of interconnected cracks is not fully formed in the specimen). With increasing initial damage, permeability shows a sharp increase. Permeability increases by three orders of magnitude, it is in equilibrium state, and a network of interconnected cracks is fully formed in the specimen. Permeability of granite has a critical temperature at which permeability increases sharply. When the temperature is lower than the critical temperature, the magnitude of permeability is 10−18 m2 with a slight increase. When temperature is higher than the critical temperature, the magnitude of permeability is 10−15 m2 with a sharp increase. The critical temperature is related to the initial damage of specimen, and the critical temperature is smaller with the initial damage going larger. Therefore, studying thermal cracking and permeability evolution of granite with different initial damage under high temperature and triaxial compression is expected to provide necessary and valuable insight into the design and construction of high-level waste disposal structures.

scholarly journals Gas Permeability Change with Deformation and Cracking of a Sandstone under Triaxial Compression

2021 ◽  
Author(s):  
Yuan-Jian LIN ◽  
Jiang-Feng LIU ◽  
Tao CHEN ◽  
Shi-Jia MA ◽  
Pei-Lin WANG ◽  
...  
Keyword(s):  
Gas Permeability ◽  
Axial Stress ◽  
Triaxial Compression ◽  
Gas Injection ◽  
Injection Pressure ◽  
Confining Pressure ◽  
Loading Path ◽  
Permeability Evolution ◽  
Axial Pressure ◽  
Triaxial Cell

Abstract In this paper, a THMC multi-field coupling triaxial cell was used to systematically study the evolution of gas permeability and the deformation characteristics of sandstone. The effects of confining pressure, axial pressure and air pressure on gas permeability characteristics were fully considered in the test. The gas permeability of sandstone decreases with increasing confining pressure. When the confining pressure is low, the variation of gas permeability is greater than the variation of gas permeability at high confining pressure. The gas injection pressure has a significant effect on the gas permeability evolution of sandstone. As the gas injection pressure increases, the gas permeability of sandstone tends to decrease. At the same confining pressure, the gas permeability of the sample during the unloading path is less than the gas permeability of the sample in the loading path. When axial pressure is applied, the axial stress has a significant influence on the permeability evolution of sandstone. When the axial pressure is less than 30 MPa, the gas permeability of the sandstone increases as the axial pressure increases. At axial pressures greater than 30 MPa, the permeability decreases as the axial pressure increases. Finally, the micro-pore/fracture structure of the sample after the gas permeability test was observed using 3D X-ray CT imaging.

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