Continuous-discrete coupling-based stability study of surrounding rock of limestone roadway in acid environment

2019 ◽  
Vol 12 (9) ◽  
Author(s):  
Zu-Liang Zhong ◽  
Xiang-Xiang Hu ◽  
Wei-Kun Luo ◽  
Yuqi Ren
Keyword(s):  
Stability Study ◽  
Surrounding Rock ◽  
Acid Environment

scholarly journals The Research on Stability of Surrounding Rock in Gob-side Entry Driving in Deep and Thick Seam

2021 ◽  
Author(s):  
jianjun SHI ◽  
Feng Jicheng ◽  
Peng Rui ◽  
Zhu Quanjie
Keyword(s):  
Stability Study ◽  
Surrounding Rock ◽  
Support Pressure ◽  
Thick Coal Seam ◽  
Thick Seam ◽  
Working Face ◽  
Pressure Area ◽  
Roadway Support ◽  
The Stability ◽  
Bolt Steel

Abstract The gob-side entry driving is driving in low pressure area, which bears less support pressure and is easy to maintain, so it is widely used. Taking the gob-side entry driving in thick coal seam of Dongtan Coal Mine as an example, the reasonable size of pillar and the section of roadway are numerically simulated by combining numerical with measurement, and the roadway support is designed. According to the distribution of lateral stress in working face, eight pillars of different sizes are designed. By simulating and comparing the stress distribution of surrounding rock and the development range and shape of plastic zone in different positions, the pillar size of gob-side entry driving is optimized to be 4.5m. According to the results of optimization of roadway section, the section of straight wall semi-circular arch roadway is adopted. According to the analysis, the roadway is supported by bolt + steel mesh + anchor cable. By observing the stability of roadway, it provides experience for the stability study of roadway the gob-side entry driving with small pillar in thick seam.

Stability Study of a Pumped Storage Power Station's Underground Powerhouse

2013 ◽  
Vol 353-356 ◽  
pp. 1635-1638
Author(s):  
Hui Huang ◽  
Guang Ming Ren
Keyword(s):  
Finite Element ◽  
Rock Mass ◽  
Calculation Model ◽  
Stability Study ◽  
Surrounding Rock ◽  
Underground Powerhouse ◽  
Rock Mass Strength ◽  
Primary Stress ◽  
Finite Element Software ◽  
Pumped Storage

In this paper, we use ANSYS finite element software to establish calculation model of the underground powerhouse and FLAC3D to calculate the model in different excavation stages. The purpose of calculation is to predict the surrounding rock displacement after excavation for the reference and evaluation of surrounding rock anchoring and rock mass strength on the basis of the computed result of primary stress and displacement.

Deformation and Stability Study of PBA Extension Method Based on Air Defense Tunnel

2012 ◽  
Vol 204-208 ◽  
pp. 1347-1355
Author(s):  
Jian Jia ◽  
Shun Hua Zhou ◽  
Xi Ping Yao ◽  
Chen Shen
Keyword(s):  
Internal Force ◽  
Stability Study ◽  
Surrounding Rock ◽  
Surface Settlement ◽  
Ground Settlement ◽  
Ground Displacement ◽  
Air Defense ◽  
Surrounding Rock Pressure ◽  
Unloading Effect

Jiaohua Square Station of Harbin Metro Line 1 is built by PBA method with the existence of No. 7381 air defense tunnel. In order to control the ground settlement during PBA construction, numerical model is performed to analyse the surrounding rock pressure, plastic zone and structure internal force. The result shows the lower pilot headings have stronger impact on existing tunnel than the upper ones in that the lower ones get the loading effect while the upper ones the unloading effect. The internal force of air defense tunnel and ground displacement can be well controlled by reducing the area of lower pilot headings at the stages of pilot heading excavation, but the final surface settlement is unqualified. The scheme of lower big pilot heading in part with the support of portal frame meets the requirement of surface settlement. The in-situ surface settlement and the vault settlement of defense tunnel are essentially consistent with numerical results.

INVESTIGATION OF BEE BREAD AND DEVELOPMENT OF ITS DOSAGE FORMS

2014 ◽  
Vol 21 (1) ◽  
pp. 16-22 ◽  
Author(s):  
Ilze Barene ◽  
Irena Daberte ◽  
Sanita Siksna
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Potato Starch ◽  
Microscopic Analysis ◽  
Stability Study ◽  
Ion Concentration ◽  
Wet Granulation ◽  
Hydrogen Ion Concentration ◽  
Bee Bread ◽  
Layer Chromatography

The aim of the study. The objective of this study was to investigate microscopic, physical and chemical properties of bee bread collected in three regions of Latvia in order to compare the quality and to investigate the possibility of producing granules containing bee bread. Material and methods. Microscopic analysis of bee bread samples was performed. Plant herbaria, special literature and internet sources were used for identification of pollen. Thin layer chromatography was used for identification of carotenoids and flavonoids. Granules were prepared by wet granulation method. Lactose, calcium lactate, calcium carbonate, potato starch and purified water were used as excipients. Appearance, loss on drying, pH of aqueous solution and content of carotenes were estimated. Results. Microscopic analysis showed mostly native pollen identified as willow pollen. Beta-carotene identified and 2 carotenoids found by thin layer chromatography. Two zones of flavonoids found on chromatograms at day light and 6 zones at ultra violet light. The comparison of bee bread samples of 3 regions of Latvia showed insignificant differences in appearance and consistency, hydrogen ion concentration 3.93–4.23, loss on drying 7.72–11.07 %; content of carotenes calculated to bcarotene 6.77–9.35 mg%. Stability study of bee bread samples showed greater changes after storage at 40ºC temperature. All compositions of granules showed appropriate appearance and flowability. Quality of granules: loss on drying 5.48–13.5%, content of carotenes calculated to b-carotene 5.77–6.75 mg%. Conclusions. Pollen of willow can be considered as an indicator of the origin of bee bread in Latvia. Bee bread samples of three regions of Latvia have insignificant differences in physical, chemical parameters.

Influence exerted by underground excavation shape and by effective stresses on the formation of a tensile strain zone at a depth greater than 1 km

2020 ◽  
pp. 67-75
Author(s):  
Van Min Nguyen ◽  
V. A. Eremenko ◽  
M. A. Sukhorukova ◽  
S. S. Shermatova
Keyword(s):  
Rock Mass ◽  
Cross Sections ◽  
Tensile Strain ◽  
Rock Fracture ◽  
Strain Analysis ◽  
Surrounding Rock ◽  
Underground Excavation ◽  
Secondary Stress ◽  
Principal Stresses ◽  
Mining Depth

The article presents the studies into the secondary stress field formed in surrounding rock mass around underground excavations of different cross-sections and the variants of principal stresses at a mining depth greater than 1 km. The stress-strain analysis of surrounding rock mass around development headings was performed in Map3D environment. The obtained results of the quantitative analysis are currently used in adjustment of the model over the whole period of heading and support of operating mine openings. The estimates of the assumed parameters of excavations, as well as the calculations of micro-strains in surrounding rock mass by three scenarios are given. During heading in the test area in granite, dense fracturing and formation of tensile strain zone proceeds from the boundary of e ≥ 350me and is used to determine rough distances from the roof ( H roof) and sidewalls ( H side) of an underground excavation to the 3 boundary e = 350me (probable rock fracture zone). The modeling has determined the structure of secondary stress and strain fields in the conditions of heading operations at great depths.

Acyclovir Loaded Solid Lipid Nanoparticle Based Cream: A Novel Drug Delivery System

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
EL- Assal I. A. ◽  
Retnowati .
Keyword(s):  
Drug Delivery ◽  
Drug Release ◽  
Antiviral Agent ◽  
Study Drug ◽  
Particle Size Analysis ◽  
Stability Study ◽  
Size Analysis ◽  
Solid Lipid ◽  
Dermal Delivery

Objective of the present investigation was enthused by the possibility to develop solid lipid nanoparticles (SLNs) of hydrophilic drug acyclovir. Also study vitro and vivo drug delivery. Methods: Drug loaded SLNs (ACV-SLNs) were prepared by high pressure homogenization of aqueous surfactant solutions containing the drug-loaded lipids in the melted or in the solid state with formula optimization study (Different lipid concentration, drug loaded, homogenization / stirring speed and compritol 888ATO: drug ratio). ACV - SLN incorporated in cream base. The pH was evaluated and rheological study. Drug release was evaluated and compared with simple cream- drug, ACV – SLN with compritol 888ATO and marketed cream. The potential of SLN as the carrier for dermal delivery was studied. Results: Particle size analysis of SLNs prove small, smooth, spherical shape particle ranged from 150 to 200 nm for unloaded and from 330 to 444 nm for ACV loaded particles. The EE% for optimal formula is 72% with suitable pH for skin application. Rheological behavior is shear thinning and thixotropic. Release study proved controlled drug release for SLNs especially in formula containing compritol88 ATO. Stability study emphasized an insignificant change in SLNs properties over 6 month. In-vivo study showed significantly higher accumulation of ACV in stratum corneum, dermal layer, and receptor compartment compared with blank skin. Conclusion: AVC-loaded SLNs might be beneficial in controlling drug release, stable and improving dermal delivery of antiviral agent(s).

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