scholarly journals Modelling Hydration Swelling and Weakening of Montmorillonite Particles in Mudstone

Processes ◽  
2019 ◽  
Vol 7 (7) ◽  
pp. 428 ◽  
Author(s):  
Changlun Sun ◽  
Guichen Li ◽  
Yuantian Sun ◽  
Jintao He ◽  
Haoyu Rong
Keyword(s):  
Compressive Strength ◽  
Water Content ◽  
Uniaxial Compressive Strength ◽  
Underground Water ◽  
Experimental Results ◽  
Microscopic Structure ◽  
Compression Tests ◽  
Stress Changes ◽  
Mineral Components ◽  
Compaction Stress

It is of paramount importance to understand the hydration swelling and weakening properties of clay minerals, such as montmorillonite, to determine their mechanical responses during deep underground argillaceous engineering. In this study, the mineral components and microscopic structure of mudstone were characterised using X-ray powder diffraction and field-emission scanning electron microscopy. Experimental schemes were devised to determine the properties of mudstone under the influence of underground water and stress; these involved compacting montmorillonite particles with various water contents and conducting uniaxial compression tests. Experimental results demonstrated that compaction stress changes the microscopic structure of the montmorillonite matrix and affects its properties, and stress independency was found at particular water and stress conditions. Two equations were then obtained to describe the swelling and weakening properties of the montmorillonite matrix based on the discrete element method; further, the hydration swelling equation represents the linear decrease in the density of the montmorillonite matrix with an increase in the water content. It was also determined that the water dependency of uniaxial compressive strength can be described by negative quartic equations, and the uniaxial compressive strength of the montmorillonite matrix is just 0.04 MPa with a water content of 0.6. The experimental results are in good agreement with the calculated solutions and provide an important experimental basis to the understanding of the mechanical properties of montmorillonite-rich mudstones under the influence of underground water and stress.

scholarly journals Analysis of the Influencing Factors of FDM-Supported Positions for the Compressive Strength of Printing Components

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4008
Author(s):  
Zhengkai Feng ◽  
Heng Wang ◽  
Chuanjiang Wang ◽  
Xiujuan Sun ◽  
Shuai Zhang
Keyword(s):  
Compressive Strength ◽  
Stress Intensity ◽  
Influencing Factors ◽  
Fused Deposition Modeling ◽  
Experimental Results ◽  
Compression Tests ◽  
Suspended State ◽  
Fused Deposition ◽  
Deposition Modeling ◽  
Reference Experiment

Fused deposition modeling (FDM) has the advantage of being able to process complex workpieces with relatively simple operations. However, when processing complex components in a suspended state, it is necessary to add support parts to be processed and formed, which indicates an excessive dependence on support. The stress intensity of the supported positions of the printing components can be modified by changing the supporting model of the parts, their density, and their distance in relation to the Z direction in the FDM printing settings. The focus of the present work was to study the influences of these three modified factors on the stress intensity of the supporting position of the printing components. In this study, 99 sets of compression tests were carried out using a position of an FDM-supported part, and the experimental results were observed and analyzed with a 3D topographic imager. A reference experiment on the anti-pressure abilities of the printing components without support was also conducted. The experimental results clarify how the above factors can affect the anti-pressure abilities of the supporting positions of the printing components. According to the results, when the supporting density is 30% and the supporting distance in the Z direction is Z = 0.14, the compressive strength of the printing component is lowest. When the supporting density of the printing component is ≤30% and the supporting distance in the Z direction is Z ≥ 0.10, the compressive strength of printing without support is greater than that of the linear support model. Under the same conditions, the grid-support method offers the highest compressive strength.

scholarly journals Plane-Strain Compressive Strength of Columnar-Grained and Granular-Snow Ice

1977 ◽  
Vol 18 (80) ◽  
pp. 505-516 ◽  
Author(s):  
R. Frederking
Keyword(s):  
Compressive Strength ◽  
Strain Rate ◽  
Failure Mechanism ◽  
Plane Strain ◽  
Uniaxial Compressive Strength ◽  
Ice Cover ◽  
Anisotropic Structure ◽  
Compression Tests ◽  
Isotropic Structure ◽  
Plane Strain Case

Abstract An ice cover impinging on a long straight structure is assumed to be under a condition of plane strain. A technique is described for performing plane-strain compression tests, and results are presented for the strain-rate dependence of strength. The plane-strain compressive strength of ice having anisotropic structure (columnar-grained ice) is at least two and a half times the uniaxial compressive strength, whereas the plane-strain compressive strength of ice having an isotropic structure (granular-snow ice) is at most 25% greater than the uniaxial case. The greater plane-strain compressive strength of columnar grained ice when the loading and confining directions are in the plane of the ice cover, can be attributed to its anisotropic structure, which leads to a different failure mechanism for the plane-strain case.

Study on Damage of Rock Samples with Single-Hole under Uniaxial Compression Condition

2012 ◽  
Vol 446-449 ◽  
pp. 3810-3813
Author(s):  
Bing Xie ◽  
Huai Feng Tong ◽  
Xiang Xia
Keyword(s):  
Compressive Strength ◽  
Uniaxial Compression ◽  
Uniaxial Compressive Strength ◽  
Particle Flow ◽  
Particle Flow Code ◽  
Compression Tests ◽  
Rock Samples ◽  
Single Hole ◽  
Compression Condition

Numerical specimens with single-hole is established by particle flow code PFC2D and uniaxial compression tests are conducted. Studies have shown that uniaxial compressive strength of specimen with single hole is less than complete specimens. As the holes move to the end of specimen, the uniaxial compressive strength first increases and then tends to decrease.

scholarly journals Plane-Strain Compressive Strength of Columnar-Grained and Granular-Snow Ice

1977 ◽  
Vol 18 (80) ◽  
pp. 505-516 ◽  
Author(s):  
R. Frederking
Keyword(s):  
Compressive Strength ◽  
Strain Rate ◽  
Failure Mechanism ◽  
Plane Strain ◽  
Uniaxial Compressive Strength ◽  
Ice Cover ◽  
Anisotropic Structure ◽  
Compression Tests ◽  
Isotropic Structure ◽  
Plane Strain Case

AbstractAn ice cover impinging on a long straight structure is assumed to be under a condition of plane strain. A technique is described for performing plane-strain compression tests, and results are presented for the strain-rate dependence of strength. The plane-strain compressive strength of ice having anisotropic structure (columnar-grained ice) is at least two and a half times the uniaxial compressive strength, whereas the plane-strain compressive strength of ice having an isotropic structure (granular-snow ice) is at most 25% greater than the uniaxial case. The greater plane-strain compressive strength of columnar grained ice when the loading and confining directions are in the plane of the ice cover, can be attributed to its anisotropic structure, which leads to a different failure mechanism for the plane-strain case.

Influence of Adding Lime Dust on Compressive Strength and Frost Resistance of Fly Ash Recycled Concrete

2013 ◽  
Vol 671-674 ◽  
pp. 1813-1816
Author(s):  
Xiang Hao Wu ◽  
Yong Xin Yao ◽  
Xing Wei Yin ◽  
Pan Yuan
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Frost Resistance ◽  
Sulfate Solution ◽  
Recycled Concrete ◽  
Experimental Results ◽  
Compression Tests ◽  
Concrete Compressive Strength ◽  
Recycle Concrete ◽  
The Right

The influence of part of fly ash replaced with lime dust on fly ash recycle concrete compressive strength and frost resistance is investigated by compression tests and rapid frost-thawing test. The experimental results show that part of fly ash replaced with lime dust will reduce the early compressive strength of the fly ash recycled concrete; the right amount of lime dust replacing fly ash can raise the latter compressive strength of fly ash recycled concrete, the best replacement proportion is 10%. The anti-frozen capacity of fly ash recycled concrete will reduce by replacing part of fly ash with lime dust, and the amplitude reduction of anti-frozen capacity of fly ash recycled concrete in seawater is greater than the amplitude reduction in sulfate solution and in freshwater.

scholarly journals Experimental study on creep characteristics of infiltrated coal-rock under load

2021 ◽  
Author(s):  
Huimei Zhang ◽  
fuyu wang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Water Content ◽  
Uniaxial Compressive Strength ◽  
Stress Level ◽  
Water Infiltration ◽  
Creep Properties ◽  
Whole Process ◽  
Rock Creep ◽  
Coal Rock

Abstract For the water-rich zone in the coal tunnel rock body perennial suffer from water infiltration destabilization destruction problem.In this paper, the influence of stress level and infiltration time on the creep properties of coal-rock was systematically studied after the water infiltration test, scanning electron microscope(SEM), water content test, uniaxial compressive strength test and creep mechanical properties test.The whole process of coal-rock creep is described by Hooke's body, Kelvin body and damage elastic-plastic body, and the total damage variable was introduced to show the weakening effect of the coupling effect of stress and water infiltration on the creep properties of coal-rock.A creep constitutive model of coal rock damage considering the weakening effect of water infiltration was established, besides, the influence law of stress level and infiltration time on creep parameters of coal rock was analyzed.The study shows that coal rocks underwent a process from surface drying and shrinkage to water absorption and swelling to water-filled infiltration damage in the infiltration test.With the increase of infiltration time, the water content of coal-rock tended to increase and eventually stabilizes, while the uniaxial compressive strength gradually decreased.With the increase of stress level and infiltration time, the stable creep strain of coal-rock kept increasing which accelerated creep advance, and its internal damage continued to accumulate and eventually led to destabilization damage.At the same stress level, the creep parameter E0 showed a tendency to increase and then decreased with the increase of infiltration time, while E1, η1, tF, E2 and ν continued to decrease.Combined with the microstructural changes of coal rocks in the water infiltration process, the change law of mechanical properties of infiltrated coal-rock and the intrinsic softening mechanism were revealed.Comparing the theoretical model of infiltrated coal rock creep with the experimental data, the model developed in this paper reflected the whole process of infiltrated coal-rock creep deformation and damage, and can characterize the influence of infiltration time and stress level on coal-rock creep properties, which verified the reasonableness of the model.

scholarly journals Experimental Study on the Influence of Moisture Content on the Mechanical Properties of Coal

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Mingxing Gao ◽  
Yongli Liu
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Moisture Content ◽  
Uniaxial Compressive Strength ◽  
Poisson’S Ratio ◽  
Triaxial Compression ◽  
Test System ◽  
Poisson's Ratio ◽  
Compression Tests

Water injection in coal seams will lead to the increase of moisture content in coal, which plays an essential role in the physical and mechanical properties of coal. In order to study the influence of moisture content on the mechanical properties of soft media, the forming pressure (20 MPa) and particle size ratio (0-1 mm (50%), 1-2 mm (25%), and 2-3 mm (25%)) during briquette preparation were firstly determined in this paper. Briquettes with different moisture contents (3%, 6%, 9%, 12%, and 15%) were prepared by using self-developed briquettes. Uniaxial and triaxial compression tests were carried out using the RMT-150C rock mechanics test system. The results show that the uniaxial compressive strength and elastic modulus of briquette samples increase first and then decrease with the increase of briquette water, while Poisson’s ratio decreases first and then increases with the increase of briquette water. When the moisture content is around 9%, the maximum uniaxial compressive strength is 0.866 MPa, the maximum elastic modulus is 1.385 GPa, and Poisson’s ratio is at the minimum of 0.259. The compressive strength of briquettes increases with the increase of confining pressure. With the increase of moisture content, the cohesion and internal friction angle of briquettes first increased and then decreased.

scholarly journals Effects of Cyclic Wetting-Drying Conditions on Elastic Modulus and Compressive Strength of Sandstone and Mudstone

Processes ◽  
2018 ◽  
Vol 6 (12) ◽  
pp. 234 ◽  
Author(s):  
Shiyuan Huang ◽  
Junjie Wang ◽  
Zhenfeng Qiu ◽  
Kai Kang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Uniaxial Compressive Strength ◽  
Strength Increase ◽  
Compression Tests ◽  
Wetting And Drying ◽  
Rock Stability ◽  
Degradation Rates ◽  
Degradation Degree

The influence of water on the mechanical properties of rock is vital for determining the rock stability when subjected to changes of water conditions. In this paper, a series of uniaxial compression tests were conducted to investigate effects of cyclic wetting and drying on the mechanical properties of sandstone and mudstone collected from Chongqing city, China. The results showed that both elastic modulus and uniaxial compressive strength of sandstone and mudstone were reduced by wetting and drying cycles, and that the degradation rate of the two mechanic parameters of mudstone was always larger than sandstone. The parameters, including water adsorption, degradation degree of elastic modulus, degradation degree of uniaxial compressive strength, increase with the increase of the wetting-drying cycles (N). The relationship between these three parameters and the value of N + 1 could be well fitted by logarithmic curves. The average degradation degree was also used to describe the degradation of per time wetting-drying cycles. It is found that the average degradation degree of elastic modulus and uniaxial compressive strength decrease with the increase of wetting-drying cycles. Moreover, the relationships between the mechanical properties and the porosity are presented, which can be fitted by linear curves. In the cyclic wetting-drying process, the elastic modulus and the uniaxial compressive strength decreased with the porosity increasing, and the degradation rates of sandstone mechanic parameters were higher than those of mudstone.

The effect of cross-section shape on deformation, damage and failure of rock-like materials under uniaxial compression from both a macro and micro viewpoint

2020 ◽  
Vol 29 (7) ◽  
pp. 1076-1099 ◽  
Author(s):  
Chunyang Zhang ◽  
Hang Lin ◽  
Caimou Qiu ◽  
Tingting Jiang ◽  
Jianhua Zhang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Uniaxial Compression ◽  
Uniaxial Compressive Strength ◽  
Cross Section ◽  
Peak Strength ◽  
Experimental Results ◽  
Cross Sectional ◽  
Damage And Failure ◽  
Section Shape

The mechanical properties of rock-like materials always attract the interest of many researchers. In this paper, we study the influence of specimen cross-section shape on uniaxial compressive strength as well as their deformation, damage and failure characteristics by uniaxial compression tests. The diameter and height of circular cross-section specimens are 50 and 100 mm, respectively, and the height and cross-sectional area of other specimens are equal to that of circular cross-sectional ones. Simulation and experimental results show that the cross-sectional shape has little effect on uniaxial compressive strength. Moreover, the effect on other mechanical properties is also very limited before the peak strength, such as stress–strain curve, rotation and motion of particles, contact damage and energy evolution of particles; however, it gradually becomes obvious after the peak strength. This is a very important feature, which affects the macroscopic form of failure of specimens and reflects the difference between failure surfaces. The shapes of failure surfaces obtained from numerical simulations are quite similar to the experimental results, which verify the reliability of numerical simulation results. Finally, the achievements can serve as a reference for related engineering issues.

Sign in / Sign up

Export Citation Format

Share Document