Study on Basic Mechanical Behaviors of Rocks at Low Temperatures

2006 ◽  
Vol 306-308 ◽  
pp. 1479-1484 ◽  
Author(s):  
Quan Sheng Liu ◽  
Guang Miao Xu ◽  
Yun Hua Hu ◽  
Xiaoxiao Chang
Keyword(s):  
Young’S Modulus ◽  
Low Temperatures ◽  
Friction Angle ◽  
Test Results ◽  
Mechanical Behaviors ◽  
Rock Engineering ◽  
Cold Regions ◽  
Red Sandstone ◽  
Different Temperatures ◽  
Compressive Tests

Basic mechanical behaviors of rocks at different temperatures and with different moistures are required to be investigated for studying and designing rock engineering in cold regions. In this paper, two typical rocks, i.e., red sandstone and shale sampled from Jiangxi and Hubei in China, respectively, are tested by uniaxial and triaxial compressive tests at different temperatures ranging from 20°C to -20°C and in dry and fully saturated states. The test results show the different behaviors of them. The values of the uniaxial and triaxial compressive strengths, Young’s modulus, cohesion, and friction angle, increase with the lowering of the testing temperatures, but the tendencies are different for these two kinds of rock.

scholarly journals A Thermomechanical Coupling Constitutive Model of Concrete Including Elastoplastic Damage

2021 ◽  
Vol 11 (2) ◽  
pp. 604
Author(s):  
Liang Li ◽  
Hongwei Wang ◽  
Jun Wu ◽  
Wenhua Jiang
Keyword(s):  
Constitutive Model ◽  
Yield Function ◽  
Strain Increment ◽  
Thermomechanical Coupling ◽  
Test Results ◽  
Mechanical Behaviors ◽  
Concrete Members ◽  
Different Temperatures ◽  
Simulation Results ◽  
Elastoplastic Damage

The thermomechanical coupling constitutive model of concrete is a critical subject for the theoretical investigation and numerical simulation of the mechanical behaviors of concrete members and structures at high temperature. This paper presents a thermomechanical coupling constitutive model for the description of the mechanical behaviors of concrete at different temperatures. The expression of the elastic strain increment is derived with the free energy function including the temperature variable. The expression of the plastic strain increment is derived from the yield function based on the Drucker–Prager strength criterion. The elastoplastic damage effect is included in this constitutive model. The damage variable is included in the yield function to consider the effect of the damage on the elastoplastic mechanical behaviors of concrete. The proposed constitutive model is validated by the comparison of the simulation results of the uniaxial compression tests of concrete at different temperatures with the corresponding test results. The simulation results accord well with the test results at different temperatures. This indicates that the proposed constitutive model can characterize the mechanical behaviors of concrete at different temperatures with considerable accuracy. The proposed constitutive model was applied to simulate an axially compressive concrete column. The simulation results are consistent with the essential mechanical response behaviors of concrete members at different temperatures.

scholarly journals Effect of Freeze-Thaw Cycles on the Mechanical Properties of Polyacrylamide- and Lignocellulose-Stabilized Clay in Tibet

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Haiping Shi ◽  
Zhongyao Li ◽  
Wenwei Li ◽  
Shaopeng Wang ◽  
Baotian Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Internal Friction ◽  
Unconfined Compressive Strength ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Test Results ◽  
Freeze Thaw ◽  
Original Strength ◽  
Compressive Tests

Laboratory freezing experiments were conducted to evaluate the effect of polyacrylamide (PAM) and lignocellulose on the mechanical properties and microstructural characteristics of Tibetan clay. Direct shear and unconfined compressive tests and field emission scanning electron microscopy analyses were performed on clay samples with different contents of stabilizers. The test results show that the addition of PAM can improve the unconfined compressive strength and cohesion of Tibetan clay, but an excessive amount of PAM reduces the internal friction angle. After several freeze-thaw cycles, the unconfined compressive strength and cohesion of samples stabilized by PAM decrease significantly, while the internal friction angle increases. Samples stabilized by PAM and lignocellulose have higher internal friction angles, cohesion, and unconfined compressive strength and can retain about 80% of the original strength after 10 freeze-thaw cycles. PAM fills the pores between soil particles and provides adhesion. The addition of lignocellulose can form a network, restrict the expansion of pores caused by freeze-thaw cycles, and improve the integrity of PAM colloids. It is postulated that the addition of a composite stabilizer with a PAM content of 0.4% and a lignocellulose content of 2% may be a technically feasible method to increase the strength of Tibetan clay.

scholarly journals Rheological Evaluation of Modified Bitumen by EVA and Crumb Rubber Using RSM Optimization

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Mohamad H. Dehnad ◽  
Behrouz Damyar ◽  
Hossein Z. Farahani
Keyword(s):  
Low Temperatures ◽  
Ethylene Vinyl Acetate ◽  
Crumb Rubber ◽  
Test Results ◽  
Modified Bitumen ◽  
Rsm Optimization ◽  
Different Temperatures ◽  
Creep Stiffness ◽  
Optimal Values ◽  
High And Low Temperatures

In the present study, ethylene-vinyl acetate (EVA) and crumb rubber (CR) were used as bitumen modifiers. The experiment was designed by response surface methodology (RSM) at different levels of modifier additives based on the central composite design (CCD). Next, the Superpave protocol was followed to evaluate the modified bitumen performance at different temperatures compared with the unmodified bitumen. In this regard, to evaluate at high temperatures, a dynamic shear rheometer (DSR) test was performed, and G ∗ /sinδ index was examined on bitumen samples after aging. Besides, the bending beam rheometer (BBR) test was performed to evaluate the low-temperature behaviour of the modified bitumen according to the SHRP standard based on the creep stiffness and creep rate. The optimal combination of additives was evaluated using RSM and analysis of statistical values to improve the performance properties of bitumen at high and low temperatures. Moreover, based on the DSR and BBR test results, 5.6% of EVA and 3.9% of CR were selected as the optimal values for the modified bitumen behaviour at the high and low temperatures of the mixture.

scholarly journals Effect of Radiation on Topopah Spring Tuff Mechanical Properties

1996 ◽  
Vol 465 ◽  
Author(s):  
P. A. Berge ◽  
S. C. Blair
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Peak Strength ◽  
Test Results ◽  
Welded Tuff ◽  
Discernible Effect ◽  
And Control ◽  
Compressive Tests ◽  
Topopah Spring Tuff

ABSTRACTThe effect of radiation on the mechanical properties of Topopah Spring tuff was investigated by performing uniaxial compressive tests on irradiated and control samples of the tuff from the potential repository horizon at Yucca Mountain. Test results are presented, including stress-strain curves and peak strength and Young's modulus values. The results from this preliminary study show that for uncracked samples of Topopah Spring tuff, exposure to gamma radiation had no discernible effect on the unconfined compressive (peak) strength or the Young's modulus. However, results for samples that contained partially healed subvertical cracks indicate that exposure to radiation may reduce the strength and Young's modulus significantly. This is attributed to weakening of the cementing materials in the cracks and fractures of the samples that were irradiated. These results are preliminary, and additional studies are warranted to evaluate whether radiation weakens cementing materials in welded tuff.

Effect of temperature on behaviour of red clay–structure interface

2019 ◽  
Vol 56 (1) ◽  
pp. 126-134 ◽  
Author(s):  
Chunhong Li ◽  
Gangqiang Kong ◽  
Hanlong Liu ◽  
Hossam Abuel-Naga
Keyword(s):  
Temperature Effect ◽  
Conceptual Understanding ◽  
Friction Angle ◽  
Effect Of Temperature ◽  
Experimental Program ◽  
Test Results ◽  
Shear Strength Parameters ◽  
Red Clay ◽  
Strain Behaviour ◽  
Different Temperatures

This study presents the results of an experimental investigation conducted to assess the temperature effects on shear stress–strain behaviour and shear strength parameters of red clay and its interface with the geostructure under different normal stresses (50, 100, 200, and 400 kPa). A modified direct shear test apparatus, capable of handling temperatures up to 50 °C, was used in this study. The experimental program includes shearing the red clay and red clay–structure interface at different temperatures (2, 15, 38 °C) and after subjecting it to different heating–cooling cycles. The test results in this study and the previous studies in the literature indicated that the temperature has insignificant effects on the friction angle of clay and clay–structure interface. However, the temperature effect on the cohesion of clay and the adhesion between the clay and structure depends on the normal stress level and history. A new conceptual understanding for the possible temperature effect on the clay–structure interface was introduced in this study and it was used to interpret the different interface test results in the literature.

scholarly journals A Comparative Electrochemical and Morphological Investigation on the Behavior of NiCr and CoCr Dental Alloys at Various Temperatures

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 256
Author(s):  
Florentina Golgovici ◽  
Mariana Prodana ◽  
Florentina Gina Ionascu ◽  
Ioana Demetrescu
Keyword(s):  
Low Temperatures ◽  
Artificial Saliva ◽  
Electrochemical Stability ◽  
Morphological Investigation ◽  
Dental Alloys ◽  
Ion Release ◽  
Icp Ms ◽  
Different Temperatures ◽  
Good Concordance ◽  
Increasing Temperature

The purpose of our study is to compare the behavior of two reprocessed dental alloys (NiCr and CoCr) at different temperatures considering the idea that food and drinks in the oral cavity create various compositions at different pH levels; the novelty is the investigation of temperature effect on corrosion parameters and ion release of dental alloys. Electrochemical stability was studied together with morphology, elemental composition and ions release determination. The results obtained are in good concordance: electrochemistry studies reveal that the corrosion rate is increasing by increasing the temperature. From SEM coupled with EDS, the oxide film formed on the surface of the alloys is stable at low temperatures and a trend to break after 310K. ICP-MS results evidence that in accordance with increasing temperature, the quantities of ions released from the alloys immersed in artificial saliva also increase, though they still remain small, less than 20 ppm.

The Analysis of Stress Distribution of Hammer Bottom during Dynamic Compaction on Sandy Soil Foundation

2011 ◽  
Vol 250-253 ◽  
pp. 1460-1463
Author(s):  
Jian Qi Wu ◽  
Jian Hong Deng ◽  
Xiao Ping Wang
Keyword(s):  
Comparative Analysis ◽  
Stress Distribution ◽  
Sandy Soil ◽  
Field Monitoring ◽  
Dynamic Compaction ◽  
Dry Density ◽  
Test Results ◽  
Red Sandstone ◽  
Soil Foundation

Obtained stress distribution of hammer bottom according to the analysis of horizontal and vertical red sandstone fill dry density of the hammer bottom after dynamic compaction; affirmed the stress distribution situation of the hammer bottom through comparative analysis of the test results by laboratory and field monitoring.

Analysis of Fatigue Mechanical Behaviors of Welding Conformations in Orthotropic Steel Bridge Deck

2015 ◽  
Vol 1096 ◽  
pp. 562-566 ◽  
Author(s):  
Bo Yu ◽  
Tao Hong ◽  
Jian Zhang ◽  
Qing Yu Liang
Keyword(s):  
Fatigue Damage ◽  
Bridge Deck ◽  
Fatigue Tests ◽  
Steel Bridge ◽  
Test Results ◽  
Practical Application ◽  
Mechanical Behaviors ◽  
Homogeneous Test ◽  
Orthotropic Steel Bridge Deck ◽  
Damage Theory

Due to the superior structure style, orthotropic steel bridge deck has been getting more and more widely practical application. The static and fatigue tests of the orthotropic steel bridge deck models were carried out in this research paper, which presented the fatigue damage developing laws, compared the test results with homogeneous test results in existing documents, and according to the relative fatigue accumulative damage theory, the fatigue accumulative damage equations of the sectional specimen and the whole specimen are respectively studied.

scholarly journals The effects of environmental temperature on the properties of myofibrillar adenosine triphosphatase from various species of fish

1973 ◽  
Vol 133 (4) ◽  
pp. 735-738 ◽  
Author(s):  
Ian A. Johnston ◽  
Neil Frearson ◽  
Geoffrey Goldspink
Keyword(s):  
Low Temperatures ◽  
Half Life ◽  
Adenosine Triphosphatase ◽  
Environmental Temperature ◽  
Cold Water ◽  
Warm Water ◽  
Adenosine Triphosphatase Activity ◽  
Water Fish ◽  
Different Temperatures ◽  
Myotomal Muscle

1. Myofibrillar adenosine triphosphatase (ATPase) activities were measured for white myotomal muscle of 19 species of fish. 2. The activity was measured at different temperatures and after periods of preincubation at 37°C. 3. The inactivation half-life at 37°C depended on environmental temperature, increasing as the temperature increased. 4. Cold-water fish had higher myofibrillar adenosine triphosphatase activity at low temperatures than had warm-water fish. 5. The significance of these results is discussed.

scholarly journals CONSEQUENCES OF PRESOWING INFLUENCE OF LOW AND VARIABLE TEMPERATURES ON CARROT AND RADISH SEEDS

2019 ◽  
pp. 62-64
Author(s):  
S. R. Gasanov ◽  
S. A. Mammadova
Keyword(s):  
Low Temperatures ◽  
Raphanus Sativus ◽  
Seed Treatment ◽  
Growth And Yield ◽  
Average Weight ◽  
Vegetable Crops ◽  
Root Crops ◽  
Different Temperatures ◽  
Sowing Seed ◽  
The Impact

The study of the dynamics of plant growth and yield of vegetable crops (carrot variety Absheron winter (Daucus carota subsp. sativus (Hoffm.) Schьbl.) and radish variety Virovsky white (Raphanus sativus var.radicula Pers.)) was conducted in the field conditions after presowing exposure to different temperatures: I option – sowing of seeds exposed to low temperatures (for 15 days the swollen for 24 hours seeds were kept at a temperature of 0±1°С); Option II - sowing of seeds exposed to variable temperatures (for 5 days, the swollen for 24 hours seeds were exposed to variable temperatures of + 20°C (8 hours) and 0±1°C (16 hours) and then 10 days at a temperature of 0±1°C; K1 – sowing dry seeds; K2 – sowing soaked seeds. The impact on the seeds of low and variable temperatures caused an increase in growth processes, both in radish and carrot. Both studied crops showed a tendency to increase the yield to a greater extent when exposed to swollen seeds with variable temperatures. Thus, the average weight of radish crops exceeded the control variant by 47.1% and carrots by 27.6%. The yield of root crops per m2increased by 36.4% for radish and 30.0% for carrot. To increase the productivity of vegetable crops, we recommend using the studied methods of pre-sowing seed treatment in practice.

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