scholarly journals Experimental Study on the Mechanical Properties of Sandstone under the Action of Chemical Erosion and Freeze-Thaw Cycles

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Lizhuang Cui ◽  
Nan Qin ◽  
Shuai Wang ◽  
Xuezhi Feng
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Triaxial Compression ◽  
Rock Properties ◽  
Chemical Solution ◽  
Compression Tests ◽  
Chemical Erosion ◽  
Freeze Thaw ◽  
The Impact

In order to study the mechanical properties of sandstone under the coupling action of chemical erosion and freeze-thaw cycles, the fine-grained yellow sandstone in a mining area in Zigong, China, is collected as the research object. The changes in mechanical properties of yellow sandstone under the coupling action of chemical solution erosion and freeze-thaw cycles are analyzed based on uniaxial compression tests (UCTs) and triaxial compression tests (TCTs). The results show that, with the increase in freeze-thaw cycles, the compressive strength, elastic modulus, and cohesion of the sandstone samples decrease with varying degrees. Under constant freeze-thaw cycles, the most serious mechanical properties of degradation are observed in acidic solution, followed by alkaline solution and neutral solution. Under different confining pressures, the compressive strength and elastic modulus of the sandstone samples decrease exponentially with the increase in freeze-thaw cycles. Under the action of the chemical solution erosion and freeze-thaw cycles, the internal friction angle fluctuates around 30°. For the cohesion degradation, 35.4%, 29.3%, and 27.2% degradation are observed under acidic, alkaline, and neutral solutions. Nuclear magnetic resonance imaging shows that the chemical erosion and freeze-thaw cycles both promote the degradation of rock properties from surface to interior; after 45 freeze-thaw cycles, the mechanical properties drop sharply. To properly design rock tunneling support and long-term protection in the cold region, the impact of both freeze-thaw cycles and chemical erosion should be considered.

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 Influence of Water Pressure on the Mechanical Properties of Concrete after Freeze-Thaw Attack under Dynamic Triaxial Compression State

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Ruijun Wang ◽  
Yan Li ◽  
Yang Li ◽  
Fan Xu ◽  
Xiaotong Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Strain Rate ◽  
Water Pressure ◽  
Mass Loss Rate ◽  
Triaxial Compression ◽  
Ultimate Compressive Strength ◽  
Peak Strain ◽  
Freeze Thaw ◽  
Dynamic Triaxial Compression

This study aims at determining the effect of water pressure on the mechanical properties of concrete subjected to freeze-thaw (F-T) attack under the dynamic triaxial compression state. Two specimens were used: (1) a 100 mm × 100 mm × 400 mm prism for testing the loss of mass and relative dynamic modulus of elasticity (RDME) after F-T cycles and (2) cylinders with a diameter of 100 mm and a height of 200 mm for testing the dynamic mechanical properties of concrete. Strain rates ranged from 10−5·s−1 to 10−3·s−1, and F-T cycles ranged from 0 to 100. Three levels of water pressure (0, 5, and 10 MPa) were applied to concrete. Results showed that as the number of F-T cycles increased, the mass loss rate of the concrete specimen initially decreased and then increased, but the RDME decreased. Under 5 MPa of water pressure and at the same strain rate, the ultimate compressive strength decreased, whereas the peak strain increased with the increase in the number of F-T cycles. This result is contrary to the variation law of ultimate compressive strength and peak strain with the increase in strain rate under the same number of F-T times. With the increase in F-T cycles or water pressure, the strain sensitivity of the dynamic increase factor of ultimate compressive strength and peak strain decreased, respectively. After 100 F-T cycles, the dynamic compressive strength under all water pressure levels tended to increase as the strain rate increased, whereas the peak strain decreased gradually.

scholarly journals Degradation of Roller-Compacted Concrete Subjected to Freeze-Thaw Cycles and Immersion in Potassium Acetate Solution

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Wuman Zhang ◽  
Jingsong Zhang ◽  
Shuhang Chen ◽  
Sheng Gong
Keyword(s):  
Mechanical Properties ◽  
Weight Loss ◽  
Compressive Strength ◽  
Impact Energy ◽  
Impact Test ◽  
Potassium Acetate ◽  
Acetate Solution ◽  
Freeze Thaw ◽  
Roller Compacted Concrete ◽  
The Impact

Two sets of roller-compacted concrete (RCC) samples cured for 28 days were subjected to freeze-thaw (F-T) cycles and immersion in laboratory conditions. F-T cycles in water and water-potassium acetate solution (50% by weight) were carried out and followed by the flexural impact test. The weight loss, the dynamic elastic modulus (Ed), the mechanical properties, and the residual strain of RCC were measured. The impact energy was calculated based on the final number of the impact test. The results show that the effect of F-T cycles in KAc solution on the weight loss and Ed of RCC is slight. Ed, the compressive strength, and the flexural strength of RCC with 250 F-T cycles in KAc solution decrease by 3.8%, 23%, and 36%, respectively. The content (by weight) of K+ at the same depth of RCC specimens increases with the increase of F-T cycles. The impact energy of RCC specimens subjected to 250 F-T cycles in KAc solution decreases by nearly 30%. Microcracks occur and increase with the increase of F-T cycles in KAc solution. The compressive strength of RCC immersed in KAc solution decreases by 18.8% and 32.8% after 6 and 12 months. More attention should be paid to using KAc in practical engineering because both the freeze-thaw cycles and the complete immersion in KAc solution damage the mechanical properties of RCC.

scholarly journals Effect of Dry-Wet Cycling on the Mechanical Properties of Rocks: A Laboratory-Scale Experimental Study

Processes ◽  
2018 ◽  
Vol 6 (10) ◽  
pp. 199 ◽  
Author(s):  
Xiaojie Yang ◽  
Jiamin Wang ◽  
Dinggui Hou ◽  
Chun Zhu ◽  
Manchao He
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Uniaxial Compressive Strength ◽  
Open Pit ◽  
Rock Surface ◽  
Periodic Action ◽  
Rock Interaction ◽  
The Impact ◽  
Water Rock Interaction

Taking Nanfen open-pit iron mine in Liaoning Province as the engineering background, this study analyzes the effect of water-rock circulation on the mechanical properties of rock through a combination of macro-mechanical experiments and microstructure tests in the laboratory. Uniaxial compression experiments and acoustic wave tests are used to determine the degradation law of the mechanical properties of chlorite under the periodic action of water. The experimental results show that dry-wet cycles have a continuous and gradual effect on the rock sampled: Its uniaxial compressive strength, elastic modulus, and acoustic velocity all decrease gradually with an increase in the number of cycles. After 15 wet-dry cycles, the uniaxial compressive strength and elastic modulus of the rock decreased by 34.21% and 44.63%, respectively. Electron microscope scans of the rock indicate that the particle size, characteristics, and pore distribution at the rock surface had changed significantly after water-rock interaction. Finally, a drainage system and sliding force monitoring devices have been arranged at the mine site that can effectively reduce the impact of water-rock interaction on the stability of the mine. This combination of macro-experiments and micro-analysis allowed the weakening effect of dry-wet cycles on slope rock to be studied quantitatively, providing a theoretical reference for stability evaluation in geotechnical engineering.

The Application of Coreless Inductors for Displacement Measurements in Laboratory Investigations of Rock Properties

2014 ◽  
Vol 59 (4) ◽  
pp. 1033-1050
Author(s):  
Janusz Nurkowski
Keyword(s):  
Temperature Compensation ◽  
Measurement Accuracy ◽  
Triaxial Compression ◽  
Rock Properties ◽  
Variable Pressure ◽  
Compression Tests ◽  
Rock Samples ◽  
Laboratory Investigations ◽  
The Impact ◽  
Triaxial Compression Tests

Abstract The paper presented the coreless inductive sensor, its construction and principle of operation. The impact of temperature on the outcome of a measurement performed with the inductor was discusses, together with the possibility of temperature compensation of the inductor’s performance. Subsequently, the reasons for limited measurement accuracy and resolution were discussed, particularly under the variable pressure in the order of some hundreds MPa. Two types of such sensor were presented: a sensor for measuring linear strains, e.g. during compressibility measurements, and an sensor for measuring circumferential strains during triaxial compression tests. Additionally, the manners of fixing the sensor on rock samples were presented. Finally, some examples of the sensor application were shown, together with the results of measurements of deformations of rock samples - especially in cases when resistance gauges cannot be used, and the samples are subjected to a load in the uniaxial and triaxial system, under the hydrostatic pressure of up to 400 MPa and the normal one.

Impact Resistant Behavior of RC Beam Damaged by Freeze-Thaw Action

2016 ◽  
Vol 711 ◽  
pp. 745-750
Author(s):  
Yusuke Kurihashi ◽  
Maki Mizuta ◽  
Akinori Shimata ◽  
Norimitsu Kishi
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Frost Damage ◽  
Rc Beam ◽  
Input Energy ◽  
Rc Beams ◽  
Freeze Thaw ◽  
Weight Impact ◽  
Falling Weight ◽  
The Impact

In this study, in order to investigate the impact resistant behavior of RC beams damaged by freeze-thaw action, falling-weight impact tests for RC beams were conducted taking with/without frost damage as variable. The RC beam used in this study has been damaged by accelerated freeze-thaw cycling. From this experiment, following results were obtained: 1) Elastic modulus and compressive strength of the concrete were decreased due to freeze-thaw action; 2) In the case of damaged beam, many fine cracks were occurred in small input energy; and 3) Deflections of damaged beam was larger than that of non-damaged beam at the same weight-falling height.

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.

scholarly journals Study on Long-Term Dynamic Mechanical Properties and Degradation Law of Sandstone under Freeze-Thaw Cycle

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Qingsong Pu ◽  
Junhong Huang ◽  
Fuling Zeng ◽  
Yi Luo ◽  
Xinping Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Strain Rate ◽  
Air Pressure ◽  
Freeze Thaw ◽  
Dynamic Mechanical ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Dynamic Compressive Strength

This study is based on the tunnel-face slope engineering of Dongfeng tunnel in Shanxi section of China’s Shuozhou-Huanghua Railway. The sandstone specimens in the perennial freeze-thaw zone of the slope were collected to carry out freeze-thaw cycle static physical mechanics test and split Hopkinson pressure bar (SHPB) dynamic mechanical test. Thus, the damage process of sandstone under freeze-thaw cycle and impact load is studied. Also, the dynamic compressive strength and dynamic elastic modulus of sandstone are analysed under different loading strain rates and freeze-thaw cycle based on LS-DYNA, a dynamic finite element program. The results showed that the dynamic compressive strength of sandstone subjected to multiple freeze-thaw cycles under 0.04 MPa air pressure has a greater damage ratio than that under 0.055 MPa and 0.07 MPa air pressure, which was more likely to cause damage to slope sandstone than in actual engineering; the dynamic compressive strength and elastic modulus of sandstone decrease greatly within a certain range of freeze-thaw cycles and loading strain rate, leading to significant deterioration. When the freeze-thaw cycle exceeded 200 times and the strain rate was greater than 200 s−1, the physical and mechanical properties of sandstone gradually tended to be stable.

scholarly journals An Experimental Study on Characteristics of Impact Compression of Freeze-Thawed Granite Samples Under Four Different States Considering Moisture Content and Temperature Difference

2021 ◽  
Author(s):  
Chunyang Zhang ◽  
Bo Ke ◽  
Chuanju Liu ◽  
Linmin Ding ◽  
Yixian Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Impact Strength ◽  
Influence Factor ◽  
Dynamic Elastic Modulus ◽  
Rock Masses ◽  
Impact Compression ◽  
Freeze Thaw ◽  
The Impact ◽  
Granite Samples

Abstract The mechanics of rock masses in cold regions have attracted the attention of researchers from all over the world, and the concern here is that the mechanical properties of rock masses are inevitably weakened under freeze-thaw cycles. In this paper, firstly, granite samples were subjected to different freeze-thaw cycles, after that, we dealt with the freeze-thawed samples considering four different states, such as saturated and frozen states, saturated and normal temperature states, dry and frozen states as well as dry and normal temperature states. The impact compression test was carried out by using the Split Hopkinson Pressure Bar (SHPB) device. Results show that the impact strength of granite samples deteriorates with the increase of freeze-thaw cycles in the same state, for samples in different states, although the number of freeze-thaw cycles is equal, the degree of deterioration of the impact strength is different. For freeze-thawed granite samples in the same state, the dynamic elastic modulus decreases with the increase of freeze-thaw cycles, and its degree of decrease is different for different states. Under the same freeze-thaw cycles, the deterioration of mechanical properties of granite samples is different in four different weather states, for example, the dynamic elastic modulus from large to small is generally as follows: saturated and frozen states, saturated and normal temperature states, dry and frozen states as well as dry and normal temperature states. Finally, the freeze-thaw influence factor is proposed to describe the damage of granite samples. All in all, it can be concluded that water and low temperature strengthen the influence of freeze-thaw cycles on the dynamic mechanical properties of granite samples.

scholarly journals Effect of Silica Fume and Polyvinyl Alcohol Fiber on Mechanical Properties and Frost Resistance of Concrete

Buildings ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 47
Author(s):  
Yan Tan ◽  
Ziling Xu ◽  
Zeli Liu ◽  
Jiuhong Jiang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Flexural Strength ◽  
Polyvinyl Alcohol ◽  
Silica Fume ◽  
Frost Resistance ◽  
Strength Test ◽  
Freeze Thaw ◽  
Polyvinyl Alcohol Fiber

To improve the mechanical properties and frost resistance of concrete, silica fume, and polyvinyl alcohol fiber compounded in concrete. The mechanical and frost resistance of concrete were comprehensively analyzed and evaluated for strength change, mass loss, and relative dynamic elastic modulus change by compressive strength test, flexural strength test, and rapid freeze-thaw test. The results showed that with the incorporation of silica fume and polyvinyl alcohol fiber, the compressive and flexural strengths of concrete were improved, and the decrease in mass loss rate and relative dynamic elastic modulus of concrete after freeze-thaw cycles were significantly reduced, which indicated that the compounding of silica fume and polyvinyl alcohol fiber improved the frost resistance of concrete. When the content of silica fume was 10% and the volume content of polyvinyl alcohol fiber was 1%, the comprehensive mechanical performance and frost resistance of concrete is the best. The compressive strength increased by 26.6% and flexural strength increased by 29.17% compared to ordinary concrete. Based on the test data, to study the macroscopic damage evolution of concrete compound silica fume and polyvinyl alcohol fiber under repeated freeze-thaw conditions. The Weibull distribution probability model and GM (1, 1) model were established. The average relative errors between the predicted and actual data of the two models are small and very close. It is shown that both models can reflect well the development of concrete damage under a freeze-thaw environment. This provides an important reference value and theoretical basis for the durability evaluation and life prediction of compound silica fume and polyvinyl alcohol fiber concrete in cold regions.

Sign in / Sign up

Export Citation Format

Share Document