scholarly journals Experimental Investigation on the Mixture Ratio and Diffusion Performance of Grouting Materials for Water Bursting Prevention in Coal Mines

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Huiqing Lian ◽  
Haiyang Yi ◽  
Zhenxue Dai ◽  
Junwen Yang ◽  
Zhenxing Ji ◽  
...  
Keyword(s):  
Setting Time ◽  
Coal Mines ◽  
Hydraulic Pressure ◽  
Performance Tests ◽  
Diffusion Distance ◽  
Mixture Ratio ◽  
Drainage Rate ◽  
Grouting Materials ◽  
Water Bursting ◽  
And Diffusion

Grouting is a common and important technique for water bursting prevention in coal mines; the success of grouting in coal mines depends highly on the flowability of grouting materials and the strength of the hardened body as well. In this paper, a series of performance tests, in terms of the water-cement ratio, viscosity, drainage rate, presetting time, final setting time, compressive strength, and permeability were conducted on the cement-fly ash-based grout at various mixture ratios. The evolution of these performances versus different mixture ratios was analyzed; targeting at the reasonable flowability and hardened strength of grouting materials, an optimized mixture ratio was recognized for water bursting prevention in coal mines. Furthermore, the diffusion experiments of optimized grout material were designed taking into account the influence of confining and hydraulic pressure in the porous medium. As a result, the confining and hydraulic pressures have a linear negative correlation with the diffusion distance of grout materials. These results have guiding significance to water bursting prevention in coal mines.

scholarly journals Tests Research on Grouting Materials of Waste-Concrete-Powder Cement for Goaf Ground Improvement

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Zhilin Dun ◽  
Mengqi Wang ◽  
Lianwei Ren ◽  
Zhiyuan Dun
Keyword(s):  
Ground Improvement ◽  
Setting Time ◽  
X Ray Diffraction ◽  
Microscopic Mechanism ◽  
Water Separation ◽  
Separation Ratio ◽  
Waste Concrete ◽  
Performance Indexes ◽  
Mixing Proportion ◽  
Grouting Materials

Waste concrete powder (WCP) is proposed to replace part of the cement to seek environmentally friendly grouting materials for ground improvement in mine goaf. The optimal mixing proportion was selected based on the performance indexes of the water-separation ratio, stone rate, viscosity, setting time, and compressive strength. X-ray diffraction (XRD) and scanning electron microscopy (SEM) tests were also conducted to analyze mineralogical phases and investigate the microscopic mechanism. Test results show that the slurry prepared by the substitution rate of 70% and adding 0.05% water-reducing agent meets well the requirements of ground grouting in mine goaf. The WCP produced by grinding mainly exerts microaggregate effect in the slurry due to low activity. A lot of pores on the surface of WCP were shown by SEM which can absorb the water in the slurry and increase the stone rate. The WCP application for ground grouting in mine goaf can not only recycle WC but also provide new grouting materials for goaf ground.

scholarly journals Optimization and Hydration Mechanism of Composite Cementing Material for Paste Filling in Coal Mines

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Jinxiao Liu ◽  
Wenxin Li ◽  
Feng Zhang ◽  
Xinguo Zhang ◽  
Lianjun Chen ◽  
...  
Keyword(s):  
Early Stage ◽  
Uniform Design ◽  
Setting Time ◽  
Coal Mines ◽  
Hydration Products ◽  
Hydrated Calcium Silicate ◽  
Sulphoaluminate Cement ◽  
Final Setting Time ◽  
Early Strength ◽  
Cementing Material

The low early strength of materials for paste filling in mines caused by low early strength of composite cementing material has been a severe issue. In this study, the effects of sulphoaluminate cement and gypsum on strengths of composite cementing material were investigated experimentally by employing the constrained formulation uniform design. With the content of the sulphoaluminate cement below 14% and the content of the gypsum below 16%, the compressive strengths of composite cementing materials increased, especially early strength. However, the initial and final setting time does not meet the engineering requirements in this case. Optimization tests of composite additives demonstrated that H2BO3(0.3%) + Na2SO4(0.1%) and H2BO3(0.3%) + NaNO2(0.1%) were ideal setting retarding and early strengthening composite additives as they can both reduce the initial and final setting time and enhance compressive strengths of composite cementing material. Investigations by XRD and SEM revealed that the hydration products of composite cementing material were dominated by AFt (ettringite) at the early stage and by C-S-H (hydrated calcium silicate) gel + CH (calcium hydroxide) gel at the middle and late stages. The hydration products of ratio-optimized composite cementing material do not restrain each other due to the generation sequence. Instead, they grew interactively and were coupled, thus facilitating the growth of the hardened body. This study can provide references for optimization of composite cementing material for paste filling in coal mines.

The potential respiratory surfaces of a fish living in a historically polluted river

2020 ◽  
Vol 70 (1) ◽  
pp. 101-108
Author(s):  
André Luis da Cruz ◽  
Thiago Matos Prado ◽  
Laísa Peixoto Ramos ◽  
Wilfried Klein
Keyword(s):  
Metabolic Activity ◽  
Morphometric Analysis ◽  
Diffusion Barrier ◽  
Diffusion Distance ◽  
Polluted River ◽  
Atmospheric Air ◽  
Gill Structure ◽  
And Diffusion ◽  
Cutaneous Respiration

Abstract The acquisition of oxygen is fundamental for maintaining metabolic activity in fish, and most species obtain oxygen through aquatic gill respiration. Throughout evolution, different fish lineages have evolved secondary routes to obtain oxygen from atmospheric air, and the spinycheek sleeper, Eleotris pisonis, may be one example of such bimodal respiration. Gill structure and the top epithelium of the head of E. pisonis from the Subaé River (Santo Amaro, Bahia, Brazil) were evaluated morphometrically. The gills showed histopathologies, especially proliferation, which was prevalent on 35.6% of the filaments and on 13.7% of the lamellae, probably increasing the water-blood diffusion barrier of the lamellae to 5.48 ± 1.32 μm, similar to the air-blood diffusion distance of the skin (5.77 ± 1.72 μm). Quantitative morphometric analysis of histopathologies and diffusion distances could be considered as biomarkers, and also suggest the presence of cutaneous respiration as a possible strategy for aerial oxygen acquisition.

Dominant Texture and Diffusion Distance Manifolds

2009 ◽  
Vol 28 (2) ◽  
pp. 667-676 ◽  
Author(s):  
Jianye Lu ◽  
Julie Dorsey ◽  
Holly Rushmeier
Keyword(s):  
Diffusion Distance ◽  
And Diffusion

Vulnerability assessment of water bursting from Ordovician limestone into coal mines of China

2016 ◽  
Vol 75 (22) ◽  
Author(s):  
Yifan Zeng ◽  
Qiang Wu ◽  
Shouqiang Liu ◽  
Yanliang Zhai ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Vulnerability Assessment ◽  
Coal Mines ◽  
Ordovician Limestone ◽  
Water Bursting

Development of a New Type of Hydraulic Drilling Car Used in Coal Mine

2012 ◽  
Vol 522 ◽  
pp. 556-559 ◽  
Author(s):  
Ming Zhu Zhang ◽  
Yong Dai ◽  
Bo Guo
Keyword(s):  
Coal Mine ◽  
Coal Mines ◽  
Hydraulic Pressure ◽  
Directional Drilling ◽  
Coal Gas ◽  
Drilling Equipment ◽  
Underground Coal Mines ◽  
Safety Production ◽  
New Type ◽  
Structure Layout

Coal gas accident is the main threat to the safety production in coal mine,it needs a safe and efficient drilling equipment to detection and drainage in the gas area.At present,the equipments detect and drainage in underground coal mines are mainly fission rigs,which move time-consuming, and the efficiency of drilling is low.This paper introduces a new kind of full hydraulic drill car used in coal,it includes the integral design of the car, the structure layout, the drilling arm and the main parts of design ideas.The new drill carriage adopts the caterpillar vehicle structures,full hydraulic pressure drives,it can automatically change the drill rod, prevent bit-stuck device,can freely passage in the narrow roadway,arrived at the reservation of the drilling position and carries on the omni-directional drilling,it can meets various mine construction requirements, and it has a broad market prospect.

Inhibition of thrombocyte aggregation during extracorporeal lung assist: a case report

Perfusion ◽  
2007 ◽  
Vol 22 (4) ◽  
pp. 293-297 ◽  
Author(s):  
Alois Philipp ◽  
Thomas Müller ◽  
Thomas Bein ◽  
Maik Foltan ◽  
Franz-Xaver Schmid ◽  
...  
Keyword(s):  
Blood Flow ◽  
Case Report ◽  
Gas Exchange ◽  
Acetylsalicylic Acid ◽  
Diffusion Distance ◽  
Thrombocyte Aggregation ◽  
Extracorporeal Lung Assist ◽  
End Products ◽  
Membrane Oxygenators ◽  
And Diffusion

Disclaimer: All authors declare that there are no beneficial arrangements with NovaLung® GmbH, Hechingen, Germany In extracorporeal lung assist, membrane oxygenators are used to improve gas exchange. Accumulations on the membranes of coagulation end products can increase resistance to blood flow and diffusion distance. Thus, functioning of the system can be impaired and, in extreme cases, lead to malfunction which may necessitate change out of the oxygenator. We describe a method that complements conventional continuous heparinisation with the administration of acetylsalicylic acid to inhibit thrombocyte aggregation. Perfusion (2007) 22, 293—298.

scholarly journals Experimental Study on the Influence of PVA Content on the Performance of Grouting Material in Deep Stope

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Bin Liu ◽  
Liming Yin ◽  
Juntao Chen ◽  
Ming Li ◽  
Daozeng Tang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Setting Time ◽  
Practical Significance ◽  
Peak Period ◽  
Grouting Material ◽  
Coupling Characteristics ◽  
Grouting Materials ◽  
And Control ◽  
Water Hazards

Based on laboratory experiments, the paper researches the effect of polyvinyl alcohol (PVA) content on the performance of fly ash-based cement grouting materials. The test results show that the addition of PVA has limited effect on the initial and final setting time and brings a certain but minor delay on the appearance of the hydration peak period. It enhances cement hydration during the hydration slow down period. The impermeability of PVA to the grouting material is obviously improved, and it increases with the growing amount of PVA content. PVA improves the flexural strength and compressive strength of the sample block to varying degrees, and the improvement on flexural strength is more obvious than that on the compressive strength. It has a significant effect on the mechanical properties of the grouting material and can effectively improve the rock mass’s hydraulic coupling characteristics. It also has great application value and practical significance for the prevention and control of water hazards in deep coal stopes.

scholarly journals Study of the Penetration and Diffusion Characteristics of Inorganic Solidified Foam in Rock Fractures

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Yi Lu ◽  
Tao Wang ◽  
Qing Ye
Keyword(s):  
Effective Diffusion ◽  
Rock Fractures ◽  
Prediction Formula ◽  
Diffusion Distance ◽  
Coal Fire ◽  
Diffusion Characteristics ◽  
Diffusion Pattern ◽  
The Right ◽  
Fluid Penetration ◽  
And Diffusion

To explore the penetration and diffusion law in coal and rock fractures when inorganic solidified foam (ISF) is used to prevent coal fire, the penetration experiment was conducted; the results showed that the penetration pressure fluctuates within a certain range and decreases with the diffusion distance. In theXYplane, the diffusion pattern presents an ellipsoid shape, and the diffusion area becomes increasingly large over time; in theXZplane, the foam fluid penetration changes from dense to loose in theXdirection and it does not undergo downward penetration and diffuses via its own weight in theZdirection; in theYZplane, it is loose on the left and dense on the right. The viscosity of ISF was tested and then the time-varying formula was fitted. The formula of the effective diffusion radius for foam fluid diffusing in the fracture channel was determined theoretically. The permeability coefficient and other related parameters were calculated in terms of the penetration pressure and diffusion time of two monitoring points. At last, the prediction formula of effective diffusion distance of foam fluid was verified with the remaining seven monitoring points and all the relative error of monitoring is within 10%.

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