scholarly journals Effects of Water Immersion on the Long-Term Bearing Characteristics of Crushed Gangue in Goaf

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Ning Jiang ◽  
Dawei Yin ◽  
Junbiao Ma ◽  
Liu Han ◽  
Haiyang Pan ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Power Index ◽  
Axial Stress ◽  
Water Immersion ◽  
Test System ◽  
Crushed Rock ◽  
Grain Composition ◽  
Sandstone Sample ◽  
Creep Stage

To study the long-term bearing characteristics of crushed gangue in goaf under water immersion conditions, the creep test of the crushed gangue in the water immersion state was performed by using the self-developed large-scale deformation-seepage test system of crushed rock. The effects of the rock lithology, axial stress, and grain composition on the long-term bearing deformation characteristics and fractal characteristics of crushed gangue under water immersion were analysed. The results show that under certain conditions of axial stress and grain composition of the gangue, a greater uniaxial compressive strength of water-saturated rock corresponds to a greater deformation resistance of the rock, smaller strain and crushing expansion in the corresponding creep stage, and greater fractal dimension increments of the crushed gangue after compression, and the gangue will have more serious crushing. With identical grain compositions and with the increase in the axial stress in the creep stage, the strain increases, the crushing expansion decreases, the fractal dimension increments of the crushed gangue after compression increase, and the gangue will have more serious crushing. Under identical axial stress conditions, when the Talbol power index n is 0.5, the differentials of the strain and crushing expansion for the crushed sandstone sample in the creep stage are minimal. When n is 0.3 or 0.7, these quantities are basically equal. With the increase in the Talbol power index, the fractal dimension increments of the crushed sandstone sample during compression gradually increase, and the crushed sandstone sample will have more serious crushing.

scholarly journals Influence of Macrotexture and Microtexture on the Skid Resistance of Aggregates

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Bowen Guan ◽  
Jiayu Wu ◽  
Chao Xie ◽  
Jianhong Fang ◽  
Haile Zheng ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Correlation Analysis ◽  
Surface Treatment ◽  
Critical Point ◽  
Friction Surface ◽  
Pearson Correlation ◽  
Correlation Coefficients ◽  
Skid Resistance ◽  
Mean Square

This article intends to study the influence of macrotexture and microtexture on the skid resistance of four types of aggregates. For this purpose, fractal dimension (D), root mean square height (Rq), and Polished Stone Value (PSV) were tested. The Pearson correlation coefficients between PSV and D or Rq in the interval of different polishing cycles were calculated and analyzed with correlation analysis. The relationships between PSV and Rq were also established. The results showed that the PSV development was approximately divided into 3 stages including accelerated attenuation stage, decelerated attenuation stage, and stabilization stage. There is a critical point of the entire polishing cycles. When the number of the polishing cycles exceeds this critical point, microtexture replaces macrotexture to play a major role in the skid resistance of aggregates. In the accelerated attenuation stage, macrotexture plays a major role in the skid resistance of aggregates. In the decelerated attenuation stage and stabilization stage, microtexture gradually plays a major role in the skid resistance of aggregates. Because of roughest microtexture in the stabilization stage, bauxite can provide the highest levels of skid resistance for high friction surface treatment over the long-term period.

scholarly journals Conceptual study for long-term monitoring of chemotherapeutic induced cell reactions by ESPI

2018 ◽  
Vol 85 (2) ◽  
pp. 111-118
Author(s):  
Josefine Johanna Gottschalk ◽  
Carsten Stollfuß ◽  
Kai-Henning Lietzau ◽  
Andreas H. Foitzik ◽  
Maria Richetta
Keyword(s):  
Speckle Pattern ◽  
Test System ◽  
Cytotoxic Agents ◽  
Electronic Speckle Pattern Interferometry ◽  
Universal Approach ◽  
Individualized Drug Therapy ◽  
Conceptual Study ◽  
Adequate Measurement ◽  
Term Monitoring

Abstract During the last years, various approaches on an individualized drug therapy for benign cells have been researched. However, due to the complex topic a universal approach has not been found up until this point. Commonly, the effect of cytotoxic drugs on benign cells is in most cases the same compared to regular cells while the actual effect on patient still can't be predicted. In order to reduce unwanted side effects or unspecific drug reactions a test system for patients which allows to analyse the interaction between cytotoxic agents and the targeted cells is needed. Furthermore, this should also include an adequate measurement system which is capable to work in a natural environment and without any additional preparation. In terms of this work, a first proof of concept with different benign cells and cytotoxic agents is presented while monitoring the obtained displacement using electronic speckle pattern interferometry (ESPI).

Structural Characteristics and Stability of the Aggregates in the Orchard Soils with Different Cultivation Years in Northern China

2013 ◽  
Vol 864-867 ◽  
pp. 2569-2576
Author(s):  
Wen Li Liu ◽  
Jing Gui Wu ◽  
Xin Yu Zhao
Keyword(s):  
Fractal Dimension ◽  
Structural Characteristics ◽  
Northern China ◽  
Soil Bulk Density ◽  
Annual Growth ◽  
Annual Average ◽  
Average Decrease ◽  
Increasing Trend ◽  
Orchard Soils

With dry sieving and wet sieving methods, we studied the distribution characteristics and stability of the aggregates in the typical orchard soils with different cultivation years in northern China under long-term freezing-thawing conditions. The results show that: the contents of the aggregates with particle size above 10 mm or between 0.25 and 10 mm are significantly increased with cultivation years and annual growth rates were respectively 1.28% and 0.078%. Fractal dimension in the orchard soils was gradually decreased and lower than that in uncultivated area near the orchard in corresponding cultivation year. MWD of orchard soils shows annual increasing trend of 0.76%. The content of the water stable macro aggregates in orchard soils was increased with the cultivation years and was about 11.65%-20.18% higher than that of uncultivated soils near the orchard. Average annual growth of orchard soils was 0.37%. Fractal dimension was decreased year by year on the water stable macro aggregates. MWD of the water stable macro aggregates was significantly greater than that of uncultivated soils near the orchard and increased with cultivation years. Aggregate destruction rate was gradually decreased to 31.61% of that in the 60th year and annual average decrease rate was 0.91%. Soil bulk density was gradually decreased.

scholarly journals Subcutaneous Implants of Buprenorphine-Cholesterol-Triglyceride Powder in Mice

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
L. DeTolla ◽  
R. Sanchez ◽  
E. Khan ◽  
B. Tyler ◽  
M. Guarnieri
Keyword(s):  
Clinical Pathology ◽  
Test System ◽  
Clinical Observations ◽  
Safety Test ◽  
Term Delivery ◽  
Low Toxicity ◽  
Animal Safety ◽  
Higher Doses ◽  
Drug Implants

Subcutaneous drug implants are convenient systems for the long-term delivery of drugs in animals. Lipid carriers are logical tools because they generally allow for higher doses and low toxicity. The present study used an US Food and Drug Administration Target Animal Safety test system to evaluate the safety of a subcutaneous implant of a cholesterol-triglyceride-buprenorphine powder in 120 BALB/c mice. Mice were evaluated in 4- and 12-day trials with 1- and 5-fold doses of the intended 3 mg/kg dose of drug. One male mouse treated with three 3 mg/kg doses and surgery on days 0, 4, and 8 died on day 9. The cause of death was not determined. In the surviving 119 mice there was no evidence of skin reaction at the site of the implant. Compared to control animals treated with saline, weight measurements, clinical pathology, histopathology, and clinical observations were unremarkable. These results demonstrate that the lipid carrier is substantially safe. Cholesterol-triglyceride-drug powders may provide a valuable research tool for studies of analgesic and inflammatory drug implants in veterinary medicine.

True Stress and Shakedown Analysis of Pressure Vessel which under Cyclic Loading to Plastic Deformation

2014 ◽  
Vol 590 ◽  
pp. 8-12
Author(s):  
Xiao Liang Jia ◽  
Yi Liang Zhang ◽  
Jing Wang ◽  
Chun Bo Wang
Keyword(s):  
Plastic Deformation ◽  
Constitutive Model ◽  
Pressure Vessel ◽  
Axial Stress ◽  
Water Pressure ◽  
True Strain ◽  
Test System ◽  
True Stress ◽  
Plastic Shakedown ◽  
The Relationship

The aim of this study is to discuss the plastic shakedown and true stress of the cyclically loaded pressure vessel. A thin-walled cylinder pressure vessel is made according to actual working state and a water pressure test system is built. The vessel is loaded to different strain levels of plastic deformation first. Then it is loaded cyclically to shakedown state. The relationship between plastic strain and shakedown range is given based on numerous experiments. The constitutive model of the true stress-true strain of the vessel is obtained. The experimental results show that the ratcheting obviously occurred when the vessel is cyclically loaded to plastic deformation. The true stress-strain constitutive model which is presented in this paper can show appropriately the constitutive relation of the vessel when it is under multi-axial stress state. The application of uniaxial shakedown constitutive model has been demonstrated in this study.

On the Interrupted Creep Test Under Low Stress Levels for the Power Law Parameter Extraction

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Bin Yang ◽  
Fu-Zhen Xuan ◽  
Wen-Chun Jiang
Keyword(s):  
Creep Strain ◽  
Stress Level ◽  
Creep Test ◽  
Creep Deformation ◽  
Parameter Extraction ◽  
Tertiary Creep ◽  
Secondary Creep ◽  
Creep Stage ◽  
Strain Data

Abstract Low stress interrupted creep test, as an interim compromise, can provide essential data for creep deformation design. However, there are no clear guidelines on the characterization of the terminating time for interrupted low-stress creep test. To obtain a suitable terminating time in terms of economy and effectiveness, long-term creep strain data of 9%Cr steels are collected from literatures and their creep deformation characterization is analyzed. First, the variations of normalized time and strain of each creep stage with the stress level are discussed. Then, the effect of the terminating time on final fitted results of Norton–Bailey equation is estimated. Third, the relationship between demarcation points at different creep stages and minimum/steady-state creep rate is analyzed. The results indicate that when the creep rupture life is considered as an important factor for creep design, the tertiary creep stage is of greatest significance due to the largest life fraction and creep strain fraction at low stress level. However, the primary and secondary creep stages are of great significance for design due to their larger contribution to 1% limited creep strain. And the long-term secondary creep data could be extrapolated by combining the primary creep strain data obtained from interrupted creep tests with the time to onset of tertiary creep derived from a similar Monkman–Grant relationship.

scholarly journals A More Realistic Study on the Mechanical Properties of CFRC Composite Grouting Material under a Long-Term Water Immersion Process

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Yao Xiao ◽  
Huafeng Deng ◽  
Jianlin Li ◽  
Eleyas Assefa
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Carbon Fiber ◽  
Water Immersion ◽  
Fiber Content ◽  
Grouting Material ◽  
Bonding Properties ◽  
Grouting Materials ◽  
Dam Foundations

The long-term effect of water immersion on the mechanical properties of CFRC composite grouting materials was studied by using five different carbon fiber contents (0, 0.25%, 0.50%, 0.75%, and 1.00%). The direct shear and long-term immersion tests were performed based on the specified and optimum values of carbon fiber content, respectively. The results showed the following: (1) the application of carbon fiber significantly improved the shear resistance of CRFC composite grouting material by using “reinforcing” and “anchoring” actions. The shear strength of the specimen was increasing by 5.66%∼43.41% when the carbon fiber content increased from 0.25% to 1.00%. After a comprehensive analysis, the optimum carbon fiber content was found to be 0.75%. (2) The degradation in the compressive and tensile strength of CRFC composite specimens exhibited a consistent trend (i.e., a steep gradient was gradually followed by a gentle slope) under a long-term water immersion process. About 90% of the total degradation in the compressive and tensile strength has occurred in 90 immersion days (i.e., 16.05% and 18.45%, respectively). In comparison, the degradation in the tensile strength (20.05%) was slightly higher than the compressive strength (18.16%). (3) Under the long-term water immersion process: the properties of the specimens were gradually deteriorating, the carbon fibers were gradually reaching a fatigue stage, and the bonding properties of carbon fiber was decreasing, which resulted in a reduction in the compressive and tensile strength. The uniaxial compression failure mode changed from brittle to ductile, and the development of local failure was very noticeable. Based on the findings of this paper, groundwater has a significant impact on the mechanical properties of grouted rock mass such as dam foundations and abutments. Therefore, the degradation in the grouting materials has to be considered in practical cases.

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