scholarly journals Elastic Modulus Calculation Model of a Soil-Rock Mixture at Normal or Freezing Temperature Based on Micromechanics Approach

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Hao Yang ◽  
Zhong Zhou ◽  
Xiangcan Wang ◽  
Qifang Zhang
Keyword(s):  
Composite Material ◽  
Elastic Modulus ◽  
Freezing Temperature ◽  
Calculation Model ◽  
Frozen Soil ◽  
Experimental Comparison ◽  
Mesoscopic Structure ◽  
Embedded Model ◽  
Single Inclusion ◽  
Rock Interface

Considering rock wrapped by soil in the mesoscopic structure of soil-rock mixture at normal temperature, a two-layer embedded model of single inclusion composite material was established to obtain the elastic modulus of soil-rock mixture. Given an interface ice interlayer attached between the soil and rock interface in the mesoscopic structure of soil-rock mixture at freezing temperature, a three-layer embedded model of double inclusion composite material and multistep multiphase micromechanics model was established to obtain the elastic modulus of a frozen soil-rock mixture. With the effect of structure pore with soil-rock mixture at normal temperature taken into consideration, its elastic modulus was calculated with the three-layer embedded model. An experimental comparison found that the predicted effect of the three-layer embedded model on the soil-rock mixture was better than that of the two-layer embedded model. The elastic modulus of soil-rock mixture gradually increased with the increase in rock content regardless of temperature. The increase rate of the elastic modulus of the soil-rock mixture increased quickly especially when the rock content is between 50% and 70%. The elastic modulus of the frozen soil-rock mixture is close to four times higher than that of the soil-rock mixture at a normal temperature.

scholarly journals Degradation of Mechanical Behavior of Sandstone under Freeze-Thaw Conditions with Different Low Temperatures

2021 ◽  
Vol 11 (22) ◽  
pp. 10653
Author(s):  
Jingwei Gao ◽  
Chao Xu ◽  
Yan Xi ◽  
Lifeng Fan
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Mechanical Behavior ◽  
Energy Absorption ◽  
Uniaxial Compressive Strength ◽  
Dynamic Strength ◽  
Freezing Temperature ◽  
P Wave ◽  
Freeze Thaw ◽  
P Wave Velocity

This study investigated the effects of freezing temperature under freeze-thaw cycling conditions on the mechanical behavior of sandstone. First, the sandstone specimens were subjected to 10-time freeze-thaw cycling treatments at different freezing temperatures (−20, −40, −50, and −60 °C). Subsequently, a series of density, ultrasonic wave, and static and dynamic mechanical behavior tests were carried out. Finally, the effects of freezing temperature on the density, P-wave velocity, stress–strain curves, static and dynamic uniaxial compressive strength, static elastic modulus, and dynamic energy absorption of sandstone were discussed. The results show that the density slightly decreases as temperature decreases, approximately by 1.0% at −60 °C compared with that at 20 °C. The P-wave velocity, static and dynamic uniaxial compressive strength, static elastic modulus, and dynamic energy absorption obviously decrease. As freezing temperature decreases from 20 to −60 °C, the static uniaxial compressive strength, static elastic modulus, dynamic strength, and dynamic energy absorption of sandstone decrease by 16.8%, 21.2%, 30.8%, and 30.7%, respectively. The dynamic mechanical behavior is more sensitive to the freezing temperature during freeze-thawing cycling compared with the static mechanical behavior. In addition, a higher strain rate can induce a higher dynamic strength and energy absorption.

scholarly journals Artificial Frozen Soil Bending Test and Bending Property

2020 ◽  
Vol 165 ◽  
pp. 03028
Author(s):  
Liu Tao ◽  
Huang Zhi ◽  
Zheng Zhigang ◽  
Hong Shaoyou ◽  
Li Jia ◽  
...  
Keyword(s):  
Earth Pressure ◽  
Bending Moment ◽  
Freezing Temperature ◽  
Test Methods ◽  
Frozen Soil ◽  
Bending Test ◽  
Frozen Soils ◽  
Temporary Support ◽  
Artificial Freezing ◽  
Ground Method

Artificial freezing ground method has been widely used in tunnels, metro and other projects, in the connecting passage in metro, the artificial frozen soil wall, which is formed by artificial freezing method, is often used as temporary support. The artificial frozen soil wall is in the joint action of pressure and bending moment, for it takes the upper pressure and lateral earth pressure at same time, so there may be tensile stress in the profile, which may cause brittle failure. At present, some scholars have carried out researches on the tensile strength with different test methods, but they are insufficiency and have a certain difference in stress state between the specimen and the actual support structure. A bending test instrument was designed and manufacture, which satisfies the code’s requirements, and reduces the error caused by poor contact between the specimen and loading device. Bending test on artificially frozen soils was launched using this instrument, and the test on influence law of moisture content and freezing temperature on artificially frozen soils’ strength was also launched. The conclusions can provide a reference for design and construction.

scholarly journals Energy Absorption Characteristics of Frozen Soil Based on SHPB Test

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Qin-yong Ma ◽  
Dong-dong Ma ◽  
Pu Yuan ◽  
Zhao-ming Yao
Keyword(s):  
Energy Absorption ◽  
Impact Loading ◽  
Soil Type ◽  
Incident Energy ◽  
Confining Pressure ◽  
Freezing Temperature ◽  
Frozen Soil ◽  
Absorbed Energy ◽  
Stress States ◽  
Absorption Characteristics

Dynamic compressive tests are performed in three frozen soil types under different stress states at freezing temperatures of −5°C and −15°C with impact loading pressures from 0.3 MPa to 0.6 MPa. The effects of frozen soil type, freezing temperature, impact loading pressures, and stress states on incident energy and energy absorption characteristics, such as absorbed energy and energy absorbency rate, are investigated. The experimental results show that most of the incident energy is reflected back to the incident bar, and incident energy linearly increases with the increase of impact loading pressures. Both absorbed energy and energy absorbency rate are found to be negatively correlated with freezing temperature, and there values under confining pressure state are larger than that under uniaxial condition. The effects of confining pressure on absorbed energy are quite different at different freezing temperatures. In addition, frozen soil type also affects absorbed energy and energy absorbency rate. Meanwhile, impact loading pressure shows an increased effect on the absorbed energy, but it has little effect on energy absorbency rate in the research.

Experimental Determination of the Poisson's Ratio and the Elastic Modulus of a Sand-Plastic Composite Material

2017 ◽  
Vol 6 (6) ◽  
pp. 292 ◽  
Author(s):  
Moro Olivier Boffoue ◽  
Brahiman Traore ◽  
Conand Honoré Kouakou ◽  
Kokou Esso Atcholi ◽  
Remy Lachat ◽  
...  
Keyword(s):  
Composite Material ◽  
Elastic Modulus ◽  
Experimental Determination ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Plastic Composite

Preparation of Environment-Friendly Composite from Waste Paper Fiber and Waste Collagen

2011 ◽  
Vol 71-78 ◽  
pp. 2978-2982
Author(s):  
Yin Fei Tan ◽  
Bin Liu ◽  
Peng Fei Li ◽  
Ming Bo Gu ◽  
Li Juan Wang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Composite Material ◽  
Elastic Modulus ◽  
Fiber Content ◽  
Waste Paper ◽  
Environment Friendly

Waste newspaper fiber was filled in the collagen cross-linked by glutaraldehyde. The effects of deinking fiber, glycerol dosage, glutaraldehyde dosage on the mechanical properties of composite were investigated. It is found that the deinking treatment increases the strength of the composite material. The composite has better mechanical properties under the preparing conditions as follows: waste newspaper fiber content 10%, glutaraldehyde dosage12.5%, glycerol dosage 12.5%, pH 9.7, 60°C for 2h. The tensile strength and elastic modulus are 4.98Mpa and 0.09Gpa, respectively.

Charge storage and mechanical properties of porous PTFE and composite PTFE/COC electrets

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
Wen-Ching Ko ◽  
Chien-Kai Tseng ◽  
Wen-Jong Wu ◽  
Chih-Kung Lee
Keyword(s):  
Mechanical Properties ◽  
Composite Material ◽  
Elastic Modulus ◽  
Surface Potential ◽  
Room Temperature ◽  
Base Material ◽  
Processing Method ◽  
Charge Storage ◽  
Ptfe Film ◽  
Potential Decay

AbstractRecent futuristic applications of flexible electret loudspeakers have garnered much interest for these novel loudspeakers. To increase the loudspeaker properties, a processing method was developed to improve the electret and mechanical properties of porous PTFE film. Taking a thin porous PTFE film as the base material, a cyclic olefin copolymer (COC) was coated to a base material to form a PTFE/COC composite film. Results show that the composite material improves the advantageous characteristics when used as an electret diaphragm for loudspeakers. By measuring the surface potential decay and the elastic modulus, properties of a standard porous PTFE film were compared to an improved composite PTFE/COC film. Experimental results showed that the composite PTFE/COC possess the following advantages: (1) 80% higher surface potential after 10 days at room temperature, (2) a better thermal resistance of charge storage, and (3) a 643% higher elastic modulus. Therefore, our novel composite material can be used to create a much improved electret diaphragm for flexible electret loudspeakers.

scholarly journals Theoretical Study and Numerical Simulation Research on the Effect of Coal-Rock Interface on Multistaged Fracturing in the Roof of Outburst Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Fan Zhang ◽  
Yang Tang
Keyword(s):  
Elastic Modulus ◽  
Coal Seam ◽  
Hydraulic Fracture ◽  
Mechanical Parameters ◽  
Multiple Fractures ◽  
Rock Stratum ◽  
Gas Drainage ◽  
Rock Interface ◽  
Coal Rock ◽  
Outburst Coal Seam

Multistaged fracturing in the roof of outburst coal seam is an efficient and creative technology for coalbed methane (CBM) drainage, which can effectively improve the permeability of coal seam. To reveal its mechanism of permeability enhancement, the effect of coal-rock interface on multistaged fracturing in the roof of outburst coal seam was simulated and discussed in this paper. Firstly, the lithological difference between outburst coal seam and roof was compared, and the concept and significance of multistaged fracturing in the roof of outburst coal seam were explained. Then, the mechanical conditions of multiple fractures in the roof traversing coal-rock interface were analyzed. The effects of mechanical parameters on multiple fractures were numerically simulated. The results indicated that fracturing borehole in adjacent rocks of outburst coal seam is much easier to drill and maintain gas drainage. Considering gas drainage efficiency and avoiding being blocked by coal fines, multistaged fracturing borehole is generally drilled in the stable rock stratum of roof. Whether the multiple fractures in the roof can traverse coal-rock interface is related to mechanical parameters of coal and rock, friction factor of coal-rock interface, angle between horizontal profile and coal-rock interface, cementing strength of coal-rock interface, minimum horizontal stress, and other factors. Higher fracturing fluid pressure contributes to propagating from the reservoir with low elastic modulus to the one with high elastic modulus for hydraulic fracture. Hydraulic fracture is more likely to propagate in the rock stratum with high brittleness index. The research results can improve multistaged fracturing theory and provide technological support for field test.

scholarly journals Research on the Temperature Field and Frost Heaving Law of Massive Freezing Engineering in Coastal Strata

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Chaochao Zhang ◽  
Dongwei Li ◽  
Junhao Chen ◽  
Guanren Chen ◽  
Chang Yuan ◽  
...  
Keyword(s):  
Temperature Field ◽  
Three Dimensional ◽  
Element Model ◽  
Freezing Temperature ◽  
Frozen Soil ◽  
Physical Parameters ◽  
Frost Heaving ◽  
Soil Frost ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

In this study, based on the background of massive freezing engineering in coastal strata, the thermal physical parameters and some freezing laws of soil were obtained through soil thermal physical tests and frozen soil frost heaving tests. When the freezing temperatures were −5°C, −10°C, −15°C, and −20°C, the frost heaving rates of the soil were 0.53%, 0.95%, 1.28%, and 1.41%, and the frost heaving forces of the soil were 0.37 MPa, 0.46 MPa, 0.59 MPa, and 0.74 MPa, respectively. In the range of test conditions, the frost heaving rate and the frost heaving force of the soil increased with the decrease of the freezing temperature, and the relationship was roughly linear with the temperature. The entire cooling process could be roughly divided into three stages: active freezing stage, attenuation cooling stage, and stability stage. The range of the frozen soil expansion did not increase linearly with the decrease of the freezing temperature, and there was a limit radius for the frozen soil expansion. A three-dimensional finite element model was established to simulate the temperature field and frost heaving of the soil under the on-site working conditions. The entire frost heaving process could be roughly divided into two stages. The calculated temperature values and the frost heaving force values were compared with the on-site measured values, and the results verified that the numerical calculation could accurately reflect the temperature field and frost heaving law of the formation.

Microstructure and life prediction model of steel slag concrete under freezing-thawing environment

2021 ◽  
Vol 10 (1) ◽  
pp. 1776-1788
Author(s):  
Yang Wen ◽  
Hui Sun ◽  
Shuaidong Hu ◽  
Guangmao Xu ◽  
Xiazhi Wu ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Mass Loss ◽  
Frost Resistance ◽  
Mass Loss Rate ◽  
Steel Slag ◽  
Quadratic Function ◽  
Northern China ◽  
Calculation Model ◽  
Dynamic Elastic Modulus ◽  
Resistance Durability

Abstract The goals of this paper are to study the frost resistance of steel slag concrete (SSC), research the damage mechanisms, and predict the service life of SSC in cold regions. First, the stability of steel slag (SS) was tested, and then SS samples with different treatment dosages were used as aggregates to replace natural aggregates of equal volumes in the preparation of C40 concrete. The microstructures of concrete and micro properties of cement hydration products were investigated in nanospace in this research. In addition, rapid frost resistance durability tests were carried out under laboratory conditions. The results revealed that the ordinary concrete (OC) exhibited a more serious damage phenomenon, and the mass loss and relative dynamic elastic modulus of OC were changed by 5.27 and 62.30%, respectively. However, with increases in the SS content, the losses in mass were lowered. Furthermore, the relative dynamic elastic modulus decreased less, and the frost resistance of the specimens was stronger. The range of mass loss rate was between 2.233 and 3.024%, and the relative dynamic elastic modulus range was between 74.92 and 91.09%. A quadratic function with a good fitting degree was selected to establish a freezing-thawing damage calculation model by taking the relative dynamic elastic modulus as the variable. Then, the freezing-thawing durability lifespan of concrete in the colder regions of northern China was successfully predicted by using the damage calculation model. The results of SSC20–60 showed the better frost resistance durability when the content of SS sand was 20% and the dosage of SS stone was 60%. Its frost resistance lifespan was more than twice that of OC, which demonstrated that SS as an aggregate could effectively improve the frost resistance lifespan of concrete to a certain extent.

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