scholarly journals Grouting Technique for Gob-Side Entry Retaining in Deep Mines

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Xianyang Yu ◽  
Zhihong Sun ◽  
Min Deng ◽  
Jinlin Xin
Keyword(s):  
Bearing Capacity ◽  
Research Result ◽  
Surrounding Rock ◽  
Coal Specimen ◽  
Rock Support ◽  
Induced Stress ◽  
Failure State ◽  
Fractured Coal ◽  
Bearing Structure

The retained rib displacement accounts for roughly 80% of rib-to-rib convergence in gob-side entry retaining in deep coal mines, which shows significant nonsymmetrical feature and long-term rheological phenomenon. Affected by mining-induced stress, cracks spread widely, and broken zones expand beyond the anchoring range. Without grouting and supplementary support in retained rib, the surrounding rock-support load-bearing structure will be in a postpeak failure state, and the anchoring force of the bolting system will be greatly attenuated. After grouting, the compressive strength of grouting geocomposite specimen is significantly higher than the postpeak residual strength of the intact coal specimen, and it is partially restored compared to that of the intact coal specimen. The ductility of the fractured coal specimen increases after grouting, and it has stronger elasticity and plasticity. Broken rock block can become a whole with coordinated bearing capacity, and its stability is improved after grouting. The grouting technique could restore the integrity and strength of the fractured retained coal rib, repair the damaged bolting structure, and make the surrounding rock and supporting structure become an effective bearing structure again. The research result shows that it is feasible to restore the bearing capacity of the retained coal rib by grouting technique.

scholarly journals Instability Mechanism and Key Control Technology of Deep Soft Rock Roadway under Long-Term Water Immersion

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Wei Jing ◽  
Xu Wang ◽  
Pengwei Hao ◽  
Laiwang Jing ◽  
Weipei Xue
Keyword(s):  
Water Immersion ◽  
Soft Rock ◽  
Surrounding Rock ◽  
The Self ◽  
Instability Mechanism ◽  
Roadway Support ◽  
Soft Rock Roadway ◽  
Bearing Structure ◽  
Rock Roadway

More and more attention has been paid to the supporting problem of deep soft rock roadway floor with long-term water immersion in recent years. However, the existing soft rock roadway support technology rarely takes into account the influence of the immersion softening phenomenon of the roadway floor and the self-supporting structure characteristics of the surrounding rock on the stability of the surrounding rock at the same time, and the influence of the creep characteristics of rock on the deformation zone of the surrounding rock requires further research on the nature and division of the self-supporting structure of the surrounding rock. In response to the issues mentioned, based on the loading and unloading properties of the surrounding rock of the soft rock roadway, a new concept of the internal and external self-bearing structure was proposed. The fact of water-immersed mudstone softening in the soft rock roadway floor was revealed through the field practice, and the shape of the internal and external bearing structure was determined based on the in situ monitoring results. Then, the instability mechanism of the internal and external self-bearing structure of the surrounding rock was analyzed, the position of the critical control point was calculated, and the key control technology based on the method of controlling floor heave by using double-row anchor cables to control the deformation of the roadway sides was put forward. Finally, the field industrial test showed that this support technology can effectively control the deformation and failure of soft rock roadway in the case of water immersion on the floor. This work can provide a technical reference for similar roadway support designs.

A Research of Reinforcing Ingate in Shale-Laminated Sandstone

2011 ◽  
Vol 243-249 ◽  
pp. 2095-2099
Author(s):  
Wei Guo Qiao ◽  
Yan Xin Lv ◽  
Lie Chang Wei
Keyword(s):  
Rock Mass ◽  
Bearing Capacity ◽  
Coal Mine ◽  
Surrounding Rock ◽  
Term Stability ◽  
Long Term Stability ◽  
Deformation Test ◽  
At Home

The auxiliary shaft ingate of Pengzhuang Coal Mine deformed greatly with large roof fallings. Through the analysis of destruction, the ingate reinforcement schema is put up according to the engineering consolidation experience and the advanced consolidation experience at home and abroad. On the completion of the ingate project, the surrounding rock mass is stable without apparent deformation. The two-side and roof deformations are 4mm and 5mm respectively according to the convergence deformation test, improving the integrity and bearing capacity of the shaft and pipelines effectively. Thus the deformation of the surrounding rock mass is under control, guaranteeing the long-term stability of the roadway.

Strategies to Protect Hematopoietic Stem Cells from Culture-Induced Stress Conditions

2020 ◽  
Vol 15 ◽  
Author(s):  
Fatima Aerts-Kaya
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Ex Vivo ◽  
Stress Conditions ◽  
Stress Factors ◽  
Hematopoietic Stem ◽  
Induced Stress

: In contrast to their almost unlimited potential for expansion in vivo and despite years of dedicated research and optimization of expansion protocols, the expansion of Hematopoietic Stem Cells (HSCs) in vitro remains remarkably limited. Increased understanding of the mechanisms that are involved in maintenance, expansion and differentiation of HSCs will enable the development of better protocols for expansion of HSCs. This will allow procurement of HSCs with long-term engraftment potential and a better understanding of the effects of the external influences in and on the hematopoietic niche that may affect HSC function. During collection and culture of HSCs, the cells are exposed to suboptimal conditions that may induce different levels of stress and ultimately affect their self-renewal, differentiation and long-term engraftment potential. Some of these stress factors include normoxia, oxidative stress, extra-physiologic oxygen shock/stress (EPHOSS), endoplasmic reticulum (ER) stress, replicative stress, and stress related to DNA damage. Coping with these stress factors may help reduce the negative effects of cell culture on HSC potential, provide a better understanding of the true impact of certain treatments in the absence of confounding stress factors. This may facilitate the development of better ex vivo expansion protocols of HSCs with long-term engraftment potential without induction of stem cell exhaustion by cellular senescence or loss of cell viability. This review summarizes some of available strategies that may be used to protect HSCs from culture-induced stress conditions.

Three Dimensional Numerical Analyses of Bridge Piled-Raft Foundation under Riverbed Erosion

2012 ◽  
Vol 178-181 ◽  
pp. 2373-2377 ◽  
Author(s):  
Wen Tsung Liu ◽  
Yi Yi Li
Keyword(s):  
Bearing Capacity ◽  
Three Dimensional ◽  
Fem Analysis ◽  
Bridge Piers ◽  
Piled Raft Foundation ◽  
River Erosion ◽  
Dimensional Finite Element ◽  
The Face ◽  
Three Dimensional Finite Element

From the 921 earthquake to the major typhoons, including the Morakot typhoon, they damaged original landscape of rivers in Taiwan. In recent years, it alleged that abutment bridge exposed to the most serious security problems. Because of bridge piers in addition to the face of long-term river erosion, the flood on the pier will produce localized erosion near the bridge. The pier will be due to inadequate bearing capacity, resulting in subsidence, displacement, bridge version accompanied by tilting and even caving. The river erosion of soil around the piers deposits and production of contraction will often reduce the bearing capacity. Therefore, how to accurately estimate the scour depth, calculate piers to withstand water impact and analyses its stability for preventing injuries in the first place is the current pressing issues. In this study, three-dimensional finite element method (FEM) analysis program Plaxis 3D foundation is used. Polaris second bridge is selected for analysis. Based on local scouring of the model and various numerical variable conditions, the parameter of bridge pier is studied.

ANALISA LOGAM BESI (Fe) DI SUNGAI PASAR DAERAH BELANGWETAN KLATEN DENGAN METODE SPEKTROFOTOMETRI SERAPAN ATOM

2017 ◽  
Vol 2 (1) ◽  
pp. 39
Author(s):  
Rahmi Nurhaini ◽  
Arief Affandi
Keyword(s):  
Heavy Metals ◽  
Sampling Method ◽  
Research Result ◽  
The Body ◽  
Clean Water ◽  
Observational Method ◽  
The Mean ◽  
The Republic

Iron (Fe) is one of many heavy metals that is corrosive resistant, dense, and has a low melting point. If accumulated in the body, the metal can cause some medical conditions, such as irritation to skin and eyes, breathing problems, and in the long term, cancer. This research aims to know generally the spread of metallic iron (Fe) in the river Pasar in Belangwetan, Klaten. This study was conducted using an observational method in which researchers did not examine the effects of interventions. Sampling was done using purposive sampling method taken from three points, namely the upper, middle, lower. Determination of iron levels by Atomic Absorption Spectrophotometer (AAS) obtained a positive result, and the data was processed using SPSS to determine the Mean and Standard Deviation. Of the research result, it could be known the Mean score was 2.33 ppm and SD was 0.0352. The result of this research indicated that the levels of iron in the river Pasar in Belangwetan were 2.33 ppm. It means that the levels violate the regulation of the Minister of Health of the Republic of Indonesia, which is not more than 1mg/L (1ppm) in the clean water

scholarly journals Callus growth and ion composition in response to long-term NaCl-induced stress in two sugarcane (Saccharum sp.) cultivars

2017 ◽  
Vol 8 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Errabii Tomader ◽  
Bernard Gandonou Christophe ◽  
Bouhdid Samira ◽  
Abrini Jamal ◽  
Skali-Senhaji Nadia
Keyword(s):  
Callus Growth ◽  
Ion Composition ◽  
Induced Stress ◽  
Saccharum Sp

Strength Assessments of Concrete-Filled Steel Tubular Support of Soft Rock Roadway

2013 ◽  
Vol 838-841 ◽  
pp. 1884-1890 ◽  
Author(s):  
Guang Long Qu ◽  
Yan Fa Gao ◽  
Liu Yang ◽  
Bin Jing Xu ◽  
Guo Lei Liu ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Coal Mine ◽  
Soft Rock ◽  
Surrounding Rock ◽  
Flexural Performance ◽  
Laboratory Test Results ◽  
Different Types ◽  
Soft Rock Roadway ◽  
Core Concrete ◽  
Rock Roadway

Compared with I-shaped and U-shaped supports in soft rock roadway, concrete-filled steel tubular (CFST) support, as a new supporting form, has stronger bearing capacity with reasonable price. So it is becoming more and more popular in roadway supporting of coal mine in China. In this article, the surrounding rock in soft rock roadway was classified into three different types: hard rock in deep coal mine, soft surrounding rock, extremely soft surrounding rock. And, according to the characteristics of deformation failure of the CFST support and the surrounding rock in the industrial tests, three different strength assessments, including assessment of axial compressive strength, assessment of lateral flexural performance, assessment of hardening rate of core concrete, were proposed through mechanical analysis and laboratory tests for the three different types of the surrounding rock, respectively. Moreover, aimed to insufficient flexural strength of the support or low hardening rate of the core concrete in some of the roadway supporting, strengthening lateral flexural performance or making early strength concrete was necessary for the above unfavorable situations. The laboratory test results showed that the ultimate bearing capacity for the CFST support with φ194*8mm of steel tube reinforced by φ38mm round steel was 31% greater than that of the unreinforced one, 177% greater than that of the U-shaped one with equivalent weight per unit length.

scholarly journals PENGARUH GLOBALISASI KEPADATAN PENDUDUK DAN PERTUMBUHAN EKONOMI TERHADAP DEGRADASI LINGKUNGAN DI INDONESIA

2020 ◽  
Vol 2 (4) ◽  
Author(s):  
Safriwan Safriwan ◽  
Idris Idris
Keyword(s):  
Population Density ◽  
Environmental Degradation ◽  
Research Result ◽  
Short Term ◽  
Method Error ◽  
Negative Effect ◽  
Economic Institute ◽  
Carbon Project ◽  
Positive Effect

Abstract : The study describes the effects on globalization population density andeconomic growth on environmental degradation in Indonesia. This research uses a timeseries data from year 1971 - 2017, with method Error Correction Model (ECM). Datasources from Global Carbon Project, KOF Swiss Economic Institute, and WorldBank. Research result explain that (1) Globalization in long term has a insignificantpositive effect on environmental degradation in Indonesia, but short term globalizationhas a insignificant negative effect on environmental degradation in Indonesia (2)Population density in long term has a significant positive , and short term has ainsignificant positive effect on environmental degradation in Indonesia (3) Economicgrowth in long and short term has a significant positive effect on environmentaldegradation in Indonesia.Keywords : Environmental Degradation, Globalization Population Density AndEconomic Growth.

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