Experimental Study of the Creep Disturbance Effect and Acoustic Emission Characteristics of Mudstone with Different Moisture Contents

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Yongjiang Yu ◽  
Pengbo Wang ◽  
Shipeng Zhang ◽  
Jingjing Liu
Keyword(s):  
Acoustic Emission ◽  
Moisture Content ◽  
Soft Rock ◽  
Clear Understanding ◽  
Creep Failure ◽  
Soft Rocks ◽  
Moisture Contents ◽  
Accelerated Creep ◽  
The Stability ◽  
The Impact

It is important to have a clear understanding of the creep characteristics of water-rich soft rocks under a dynamic load and the evolution of cracks because soft rock roadways in deep mines are very sensitive to disturbances, and instability and damage can easily occur under the impact of disturbances such as mining and blasting. In this study, a self-developed disturbed creep test bench was used to conduct graded loading creep disturbance tests on mudstone specimens with different moisture contents. The results show that an increase in the moisture content leads to a significant increase in the creep failure strain of mudstone, and the accelerated creep rate is greatly accelerated. Moreover, as the moisture content increases, the type of mudstone creep disturbance failure gradually changes from accelerated creep failure to disturbance failure. By analyzing the acoustic emission (AE) characteristics of the mudstone creep disturbance tests, it was found that the increase in the moisture content greatly weakens the AE count and the accumulated energy. In each stage of disturbance, the AE signals jumped, and the stability was restored at the end of the disturbance. As the load increased, the specimen entered the accelerated creep stage, the AE signal increased exponentially, and the internal cracks expanded rapidly until failure occurred. It is of great significance to carry out creep disturbance experiments and to analyze the evolution of the internal cracks in specimens with different moisture contents to maintain the long-term stability of deep soft rocks.

scholarly journals Experimental Study on the Softening Characteristics of Sandstone and Mudstone in Relation to Moisture Content

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Gui-chen Li ◽  
Chong-chong Qi ◽  
Yuan-tian Sun ◽  
Xiao-lin Tang ◽  
Bao-quan Hou
Keyword(s):  
Moisture Content ◽  
Vertical Displacement ◽  
Surface Porosity ◽  
Shear Tests ◽  
Moisture Contents ◽  
Dynamic Finite Element ◽  
Rock Types ◽  
Underground Roadway ◽  
The Stability ◽  
Kinetics Of

The kinetics of fluid-solid coupling during immersion is an important topic of investigation in rock engineering. Two rock types, sandstone and mudstone, are selected in this work to study the correlation between the softening characteristics of the rocks and moisture content. This is achieved through detailed studies using scanning electron microscopy, shear tests, and evaluation of rock index properties during exposure to different moisture contents. An underground roadway excavation is simulated by dynamic finite element modeling to analyze the effect of moisture content on the stability of the roadway. The results show that moisture content has a significant effect on shear properties reduction of both sandstone and mudstone, which must thus be considered in mining or excavation processes. Specifically, it is found that the number, area, and diameter of micropores, as well as surface porosity, increase with increasing moisture content. Additionally, stress concentration is negatively correlated with moisture content, while the influenced area and vertical displacement are positively correlated with moisture content. These findings may provide useful input for the design of underground roadways.

Stability Analysis about the Impact of Soft Rock to the Underground Cavern Group

2013 ◽  
Vol 706-708 ◽  
pp. 560-564
Author(s):  
Yi Huan Zhu ◽  
Guo Jian Shao ◽  
Zhi Gao Dong
Keyword(s):  
Finite Element ◽  
Rock Mass ◽  
Stability Analysis ◽  
Soft Rock ◽  
Element Model ◽  
Underground Excavation ◽  
Power Station ◽  
Excavation Process ◽  
The Stability ◽  
The Impact

Soft rock is frequently encountered in underground excavation process. It is difficult to excavate and support in soft rock mass which has low strength, large deformation and needs much time to be out of shape but little time to be self-stabilized. Based on a large underground power station, finite element model analysis was carried out to simulate the excavation process and the results of displacement, stress and plasticity area were compared between supported and unsupported conditions to evaluate the stability of the rock mass.

scholarly journals Breakage Susceptibility of Wheat and Triticale Seeds Related to Moisture Content and Impact Energy

2012 ◽  
Vol 45 (3) ◽  
pp. 5-13
Author(s):  
F. Shahbazi ◽  
A Dowlatshah ◽  
S. Valizadeh
Keyword(s):  
Moisture Content ◽  
Impact Energy ◽  
Mechanical Damage ◽  
Moisture Contents ◽  
Seed Damage ◽  
Significant Difference ◽  
Impact Energies ◽  
The Impact ◽  
Content Range ◽  
Wheat Seeds

Abstract Mechanical damage of seeds due to harvest, handling and other process is an important factor that affects the quality and quantity of seeds. Seed damage result in lower grain value, storability problem, and reduced seed germination and seedling vigor and subsequent yield of crops. The objective of this research was to determine the effects of moisture content and impact energy on the breakage susceptibility of wheat and triticale seeds. The experiments were conducted at five moisture contents of 7.5, 12, 17, 22 and 27% w.b. and at the impact energies of 0.05 and 0.1 J. The percentage of breakage of both wheat and triticale seeds increased as impact energy increased. The analysis of variance showed that there was a significant difference between breakage susceptibility of wheat and triticale seeds at the 1% probability level. Triticale seeds had more breakage than wheat seeds. For both wheat and triticale seeds as the moisture content of the seeds increased, the amount of the percentage breakage of seeds decreased as a polynomial. The average values of percentage breakage of wheat seeds decreased from 43.81 to 19.88% as the moisture content increased from 7.5 to 27%. Over this same moisture content range the percentage breakage of triticale seeds varied from 81.34 to 37.77%. Below the moisture contents of 17% for the wheat and 22% for the triticale the percentage breakage of seeds increased dramatically.

scholarly journals Effect of Machine Clearance and Maize Moisture Contents on Mechanical Parameters For Local Shelling Machine

2021 ◽  
Vol 910 (1) ◽  
pp. 012016
Author(s):  
Salih K. Alwan Alsharifi ◽  
Aleawi A Ghali ◽  
Hussein R. Nayyef
Keyword(s):  
Moisture Content ◽  
Factorial Experiment ◽  
The Other ◽  
Mechanical Parameters ◽  
Moisture Contents ◽  
Randomized Design ◽  
Grain Moisture ◽  
The Impact ◽  
Corn Grain

Abstract The impact of local thresher machine on maize Syn12 cultivar was tested at two CL - 0.5, and 0.7 mm at three ranges of MOI - 16%, 18%, and 21%. The experiments were conducted in a factorial experiment under a complete randomized design with three replications. The CL- 0.7 mm was significantly more than CL -0.5 mm in all studied parameters. While the corn grain moisture content at a range of 16% was significantly superior compared to the other ranges (18 and 21%) in all parameters. For the CL -0.7mm and MOI 16%, the PP,PR,TE,BR,PCG,WG and GC were 1.566 t.hr-1and 1.715 t.hr-1, 9.155 Kw and 9.028 Kw, 86.009% and 89.587%; 3.228% and 3.064%;2.184% and 2.013; 81.14% and 81.69%and 90.743% and 91.587%, respectively.

scholarly journals Investigation of Energy Mechanism and Acoustic Emission Characteristics of Mudstone with Different Moisture Contents

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Jingdong Jiang ◽  
Jie Xu
Keyword(s):  
Acoustic Emission ◽  
Moisture Content ◽  
Total Energy ◽  
Failure Time ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Development Stage ◽  
Dissipated Energy ◽  
Deformation And Failure ◽  
Moisture Contents

Characteristics of energy accumulation, evolution, and dissipation in conventional triaxial compression of mudstones with different moisture contents were explored. Stress-strain relations and acoustic emission (AE) characteristics of the deformation and failure of rock specimens were analyzed. The densities and rates of stored energy, elastic energy, and dissipated energy under different confining pressures were confirmed. The results demonstrated that the growth rate of absorbed total energy decreases with the increase of moisture content, indicating that the higher the moisture content is, the less the total energy mudstone samples absorb. The dissipated energy of the soaking sample, by contrast, has the first increase speed, and natural sample comes second at the beginning. When entering the crack stable development stage, the dry sample has the fastest growing rate of dissipated energy, meaning that dissipated energy used for crack propagation gradually decreases with the increase of moisture content. The AE signals significantly enhance at the initial compression stage and plastic deformation stage with the moisture content decreasing. The AE location events at the failure moment decrease as the moisture content increasing. The time that the maximum AE even rate appears is slightly lagged behind the macroscopic failure time, and the AE even rates increase with the decrease of confining pressure. The above results indicate that the water erosion process on rock reduces the cohesive energy and cohesive force, destroys the micromechanical structure, and minimizes the energy states of rock.

scholarly journals The Effect of Sorbitol and Conservation Period on The in Vitro Evolution of Solanum Tuberosum L. Plantlets

2012 ◽  
Vol 45 (3) ◽  
pp. 79-86
Author(s):  
Iustina Brînduşa Ciobanu ◽  
Dana Constantinovici
Keyword(s):  
Moisture Content ◽  
Impact Energy ◽  
Solanum Tuberosum L ◽  
Mechanical Damage ◽  
Moisture Contents ◽  
Significant Difference ◽  
Impact Energies ◽  
The Impact ◽  
Wheat Seeds

Abstract Mechanical damage of seeds due to harvest, handling and other process is an important factor that affects the quality and quantity of seeds. Seed damage result in lower grain value, storability problem, and reduced seed germination and seedling vigor and subsequent yield of crops. The objective of this research was to determine the effects of moisture content and impact energy on the breakage susceptibility of wheat and triticale seeds. The experiments were conducted at five moisture contents of 7.5, 12, 17, 22 and 27% w.b. and at the impact energies of 0.05 and 0.1 J. The percentage of breakage of both wheat and triticale seeds increased as impact energy increased. The analysis of variance showed that there was a significant difference between breakage susceptibility of wheat and triticale seeds at the 1% probability level. Triticale seeds had more breakage than wheat seeds. For both wheat and triticale seeds as the moisture content of the seeds increased, the amount of the percentage breakage of seeds decreased as a polynomial. The average values of percentage breakage of wheat seeds decreased from 43.81 to 19.88% as the moisture content increased from 7.5 to 27%. Over this same moisture content range the percentage breakage of triticale seeds varied from 81.34 to 37.77%. Below the moisture contents of 17% for the wheat and 22% for the triticale the percentage breakage of seeds increased dramatically.

The Relation between Moisture Content and Share Strength of Swelling Soft Rock in the North of Xianfeng Town Open-Cast Coal

2014 ◽  
Vol 971-973 ◽  
pp. 2168-2171
Author(s):  
Qing Shui Liu ◽  
Ying Hui Chen ◽  
Wen Lian Liu
Keyword(s):  
Shear Strength ◽  
Moisture Content ◽  
Soft Rock ◽  
Soil Mass ◽  
Soaking Time ◽  
The North ◽  
Disturbed Soil ◽  
Strength Tests ◽  
The Stability ◽  
Open Cast

We did sorts of shear strength tests in different moisture content conditions with amount of disturbed soil which was collected from the swelling soft rock in the north of xianfeng town open-cast coal. Furthermore, we analyzed the physical relationships between moisture content of the rock-soil mass and shear strength under different soaking time or different moisture content conditions. Finally, we find the shear strength of rock-soil mass drops along with the saturated degree of test specimen doubled and re-doubled. We get a conclusion that soaking of the rock-soil mass has a strong influence on the strength of rock-soil mass. The soaking of groundwater and surface water could soft the rock-soil mass, which plays an important role in controlling the stability of side slope, also in continuing slip deformation.

scholarly journals Properties of Crushed Red-Bed Soft Rock Mixtures Used in Subgrade

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Huayan Yao ◽  
Shanpo Jia ◽  
Wenning Gan ◽  
Zhenhua Zhang ◽  
Kunlin Lu
Keyword(s):  
Moisture Content ◽  
Resilient Modulus ◽  
Soft Rock ◽  
Road Construction ◽  
Absorption Capacity ◽  
Test Results ◽  
Soft Rocks ◽  
Red Bed ◽  
Compaction Degree ◽  
Physical And Mechanical Characteristics

Slaking red-bed soft rocks are widely distributed in the south of Anhui Province, China, and several highways will go through this area. It is important to evaluate their physical and mechanical characteristics for the purpose of using this kind of soft rocks as materials for road construction. In this paper, the compacting tests, the resilient modulus tests, the California bearing ratio (CBR) tests, and permeability tests have been carried out on crushed red-bed soft rock mixtures. The test results showed that, for a given degree of compaction, the resilient modulus decreases linearly with the increase of moisture content. For a given moisture content, the resilient modulus and CBR values increase linearly with the increase of compaction degree, while the soaking swelling, water absorption capacity, and permeability coefficient decrease linearly. In other words, the strength and water stability are enhanced with the increase of the degree of compaction. The results demonstrate that the crushed red-bed soft rock mixtures can be directly used as materials for the highway construction by taking corresponding measures.

The initiation of fire spread in shrubland fuels recreated in the laboratory

2010 ◽  
Vol 19 (4) ◽  
pp. 512 ◽  
Author(s):  
Matt P. Plucinski ◽  
Wendy R. Anderson ◽  
Ross A. Bradstock ◽  
A. Malcolm Gill
Keyword(s):  
Moisture Content ◽  
Classification Tree ◽  
Fire Spread ◽  
Fuel Moisture ◽  
Shrub Layer ◽  
Moisture Contents ◽  
Layer Density ◽  
Live Fuel Moisture ◽  
Fuel Moisture Content ◽  
The Impact

Fire-prone shrub-dominated vegetation communities cover a considerable portion of Australia, including areas fringing urban development. Near urban interfaces, they are actively managed with prescribed fire to reduce the risk of wildfire (unplanned fire). Knowledge of the range of conditions that allow fires to spread or fail to do so is limited and can inconvenience fire managers when conducting prescribed burns. A series of experimental ignitions conducted in miniature shrublands reconstructed in the laboratory were used to investigate factors that influence ignition thresholds. The miniature shrublands were composed of foliage from the shrub Allocasuarina nana and were prepared over a range of moisture contents and densities. The impact of dead fuel within the aerial structure of the shrubs was also investigated, as was the presence and absence of wind and litter. The most important factors for spread initiation were identified using logistic regression analysis and classification tree modelling. The presence of litter, live fuel moisture content, shrub-layer density, presence of wind, and the amount and continuity of the dead elevated fuel were all found to influence spread sustainability. There was a negative interaction between shrub-layer density and live fuel moisture content, showing the effect of density to be less at higher moisture contents.

Effects of Absorbed Moisture Content on the Impact Response of Specially-Orthotropic Composite Plates

2019 ◽  
Author(s):  
Furqan Ahmad ◽  
Fethi Abbassi ◽  
Sajjad Miran
Keyword(s):  
Moisture Content ◽  
Composite Plates ◽  
Peak Force ◽  
Impact Response ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Constant Weight ◽  
Velocity Impact ◽  
Moisture Contents ◽  
The Impact

Abstract This paper addresses the hygroscopic effects on the impact response of specially-orthotropic carbon fiber reinforced polymer composite plates under low-velocity impact loading. The material used in this study is Toray T800/3900 which is consist of carbon fibers and epoxy resin. For different percentage of moisture content by weight in the composite plates, low-velocity impact tests were done by using the 8-ply unidirectional [UD] and cross-ply [CP] composite plates with newly designed mini-drop tower testing machine. To study the hygroscopic effects, specimens were impacted by constant weight of impactor (3.44 Kg) with fixed impact height of 0.70 m corresponding to 23.62 J impact energy. The experiments were carried out on plates with dimension of 125 mm × 125 mm × 1.5 mm for simply supported boundary conditions. All UD composite plates were broken into two parts, but the impactor bounces back after hitting the top layer of the CP composite plate for all conditions. The strength of the UD composite plates decreased with increase of moisture contents, but with the increased of moisture contents, a small change was observed in the peak force, time to peak force values and absorbed energy for the CP composite plates. The large size damage areas were observed for wet plates as compared to dry plates. Absorbed moisture contents also have effect on the impactor velocity and impactor displacement.

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