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Evaluating Rock Mass Properties of Vipingo Coral Limestone Quarry Based on a Modified Geological Strength Index (GSI) and State of Karstification

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Open Journal of Geology 2022年第1期12卷 57-79页

作者： Joan Atieno Onyango Takashi Sasaoka Hideki Shimada Akihiro Hamanaka dyson moses Dintwe Tumelo Earth Resources Engineering Department Kyushu University Fukuoka Japan Mining Materials and Petroleum Engineering Department Jomo Kenyatta University of Agriculture and Technology Nairobi Kenya

The process of evaluating rock mass strength requires that major structural features such as joints that influence rock strength are considered. In carbonate rock masses, however, the strength of the rock mass is largely dependent on intact rock strength and structural features play a secondary role. Laboratory experiments on porous rock have shown that intact rock strength reduces with increasing porosity, which has a direct effect on the rock mass strength. Rock porosity has however not been well accounted for in rock mass characterization methods currently in use. This research applies the modified GSI method for carbonate rock masses which is based on a combination of GSI and total porosity. The main aim is to quantify the GSI with respect to rock porosity which is a direct indicator of the state of karstification, as an inherent feature that affects rock mass strength. An empirical equation is proposed whereby the GSI as observed in the field is modified by a natural log of the value of porosity, giving rise to a modified GSI (GSIm). The GSIm together with laboratory properties of rock is used to determine the properties of Vipingo coral limestone from RocLab software. A deterministic parametric slope stability analysis is done using the finite element software Phase 2 with the rock mass properties as input parameters. The analysis results point to a direct dependence of the slope stability on slope angle, slope height and rock mass strength of the lithological unit. The graphs make a useful design guide for slopes engineered in this type of rock mass.

关键词： Carbonates Karstification Porosity Rock Mass Strength Slope Stability Weak Rock

Rock Slope Stability Analysis by Using Integrated Approach

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World Journal of Engineering and Technology 2020年第3期8卷 405-428页

作者： dyson moses Hideki Shimada Takashi Sasaoka Akihiro Hamanaka Tumelo K. Dintwe Sugeng Wahyudi Department of Earth Resources Engineering Faculty of Engineering Kyushu University Fukuoka Japan

Slope stability assessment is an essential aspect of mining and civil engineering. In this study, Songwe open-pit mine in Malawi was investigated to establish possible pit slope instability. In performing the analysis, an integrated approach entailing rock mass characterisation, kinematic and numerical methods were applied. Based on rock mass classification system, Songwe Hill carbonatite rock mass is characterised as a good rock but still it possesses numerous random discontinuities that present a complex challenge in geotechnical engineering. Dip 6.0 software was used in carrying out kinematic analysis based on the attributes of discontinuities. The results show that there is a 16% likelihood of planar failure in the divided slope sections of the planned pit. Thus, slope angle optimisation to 41° has been proposed as a counter-measure to minimise the potential risk of planar failure. At the optimised angle, the risk of planar failure could be reduced by 44%. On the other hand, wedge failure was found to be improbable since no joint intersections were found in the critical zone of potential failure. For numerical analysis, finite element code was applied using FLAC3D 5.0 application. The results demonstrate that overall slope angle of 41° would offer a favourable balance between safety and mining economics as mining operations progress to deeper horizons thereby avoiding a costly push back solution due to instability.

关键词： Songwe Hill Carbonatite Kinematic Analysis Numerical Analysis Slope Stability

Effects of Sublevel Open Stope Underground Mining on Surface and Open Pit Slopes

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Journal of Geoscience and Environment Protection 2021年第1期9卷 121-131页

作者： Tumelo K. M. Dintwe Takashi Sasaoka Hideki Shimada Akihiro Hamanaka dyson moses Sifei Liu Fanfei Meng Department of Earth Resources Engineering Kyushu University Fukuoka Japan China University of Science and Technology Xuzhou China

Underground mining is an economically viable option for exploiting ore reserves deemed uneconomic after open pit mining. However, underground development can have adverse effects on the above existing open pit slope walls. As a goal of this paper, identification and assessment of potential slope instabilities prior to underground development is crucial for safe and sustainable mining. Towards goal achieving, this paper gives a comprehensive parametric study to investigate the influence of sublevel open stope (SLOS) underground mining on the surface and open pit slope walls. By means of numerical simulation, the SLOS design is tried against the existing open pit followed by adjustments of important slope parameters which are overall slope height (OSH) and overall slope angle (OSA). We found that underground mining may induce slope failure, particularly on the hangingwall side of the pit. Subsidence is prominent on the hanging wall and the surface, whereas, the uplift dominates the footwall and pit bottom. Pit wall closure is observed during underground mining. Although the assigned dimensions in the parametric study show a negligible effect of OSH and OSA, the high OSH experience low subsidence in comparison with low OSH. Overall, the results demonstrate that the slope walls on the hanging wall side are mostly affected by the underground mining and high-stress concentration prevails near slope toes and pit bottom. Additionally, slope deformation decrease from pit bottom towards the slope crest and surface. The results of this study add knowledge to open pit and underground mining interaction.

关键词： Open Pit-Underground Interaction Slope Stability Underground Mining Subsidence

Study of Internal Waste Dump-Induced Shear Stress Behavior on Pit-Slope

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Journal of Geoscience and Environment Protection 2020年第4期8卷 71-86页

作者： Sugeng Wahyudi Hideki Shimada Takashi Sasaoka Akihiro Hamanaka Tsedendorj Amarsaikhan Pisith Mao Tumelo K. M. Dintwe dyson moses Department of Earth Resources Engineering Kyushu University Fukuoka Japan Mining Research and Design Center Mongolian University of Science and Technology Sukhbaatar Mongolia

Regardless of beneficial associated with internal waste dump (IWD) method, practices of this method within boundaries of pit-slope have some serious problems on stability issues due to this area is zone of potential failure. This zone is known as dynamic reactive zone which is easy to deform by external force, and inherent dangers of failure posing a threat to slope. Therefore, it is paramount to study the induced shear stress behavior in this zone particularly when IWD method is adopted within this zone. In this paper, a numerical study for investigating IWD-induced shear stress behavior has been carried out using Finite Element Method (FEM) with Strength Reduction approach. Different scenarios as per pit-slope depths, IWD heights and buffer zone lengths have been accounted and simulated using PHASE 2 to understand changes in induced shear stress imposed on the pit-slope. It is found that shear stress imposed on pit slope seems change dramatically with increasing IWD height for case of buffer zone length is less than 100-m-long.

关键词： Slope Stability Internal Waste Dump Shear-Stress Numerical Simulation

Squamous cell cancer of the rectum

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World Journal of Gastroenterology 2009年第35期15卷 4380-4386页

作者： Tara dyson Peter V Draganov Department of Gastro-enterology Hepatology and NutritionUniversity of Florida 1600 SW Archer RdRoom HD 602PO Box 100214 GainesvilleFlorida 32610United States

Squamous cell carcinoma of the rectum is a rare *** appears to be associated with chronic inflammatory conditions and *** clear association seen between Human Papilloma Virus and various squamous cancers has not been firmly established for the squamous cell cancer of the rectum. The presentation is nonspecific and patients tend to present with advanced stage *** relies on endoscopic examination with biopsy of the *** from squamous cell cancer of the anus can be difficult,but can be facilitated by immunohistochemical staining for *** of the cancer with endoscopic ultrasound and computed tomography provides essential information on prognosis and can guide *** present,surgery remains the main therapeutic option;however recent advances have made chemoradiation a valuable therapeutic addition. Squamous cell carcinoma of the rectum is a distinct entity and it is of crucial importance for the practicing Gastroenterologist to be thoroughly familiar with this *** to adenocarcinoma of the rectum and squamous cell cancer of the anal canal,squamous cell carcinoma of the rectum has different epidemiology, etiology,pathogenesis,and prognosis but,most importantly,requires a different therapeutic approach. This review will examine and summarize the available information regarding this disease from the perspective of the practicing gastroenterologist.

关键词： Rectal cancer Squamous cell cancer Endoscopic ultrasound Chemoradiation Surgery

The rise of 3D cellular spheroids: efficient culture via upward growth from a superamphiphobic surface

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National Science Review 2019年第6期6卷 1068-1069页

作者： Paul J.dyson Institut des Sciences et Ingénierie Chimiques Ecole Polytechnique Fédérale de Lausanne

Cell culture assays are extensively used in drug discovery and development programs, biomedical research, and in many others areas of science. Currently,2D monolayer cellular assays serve as the gold standard. However, while they provide seemingly indispensable information on drug activity, it is estimated that of the putative drug candidates selected

关键词： The rise of 3D cellular spheroids efficient culture via upward growth from a superamphiphobic surface

Colorectal cancer in inflammatory bowel disease:What is the real magnitude of the risk?

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World Journal of Gastroenterology 2012年第29期18卷 3839-3848页

作者： Jessica K dyson Matthew D Rutter Gastroenterology North Tyneside General HospitalRake LaneNorth ShieldsTyne and Wear NE29 8NHUnited Kingdom University Hospital of North Tees Hardwick RoadStockton TS19 8PEUnited Kingdom

The association between inflammatory bowel disease(IBD) and colorectal cancer(CRC) has been recognised since 1925 and still accounts for 10%-15% of deaths in ***-associated CRC(IBD-CRC) affects patients at a younger age than sporadic *** prognosis for sporadic CRC and IBD-CRC is similar,with a 5-year survival of approximately 50%.Identifying at risk patients and implementing appropriate surveillance for these patients is central to managing the CRC risk in *** increased risk of colorectal cancer in association with IBD is thought to be due to genetic and acquired *** link between inflammation and cancer is well recognised but the molecular biology,immune pathobiology and genetics of IBD-CRC are areas of much ongoing *** review examines the literature relating to IBD-CRC,focusing on the incidence of IBD-CRC and examining potential risk factors including age at diagnosis,gender,duration and extent of colitis,severity of inflammation,family history of sporadic CRC and co-existent primary sclerosing cholangitis(PSC).Confirmed risk factors for IBD-CRC are duration,severity and extent of colitis,the presence of co-existent PSC and a family history of *** is insufficient evidence currently to support an increased frequency of surveillance for patients diagnosed with IBD at a younger ***-based guidelines advise surveillance colonoscopy for patients with colitis 8 to 10 years after diagnosis,with the interval for further surveillance guided by risk factors(extent of disease,family history of CRC,post-inflammatory polyps,concomitant PSC,personal history of colonic dysplasia,colonic strictures).There is a move away from using random colonic biopsies towards targeted biopsies aimed at abnormal areas identified by newer colonoscopic techniques(narrow band imaging,chromoendoscopy,confocal microendoscopy).

关键词： Colorectal cancer Inflammatory bowel disease Ulcerative colitis Crohn's disease Risk

Coupled Eulerian-Lagrangian simulation of a modified direct shearapparatus for the measurement of residual shear strengths

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第5期13卷 1113-1123页

作者： Luke Tatnell Ashley P.dyson Ali Tolooiyan GHD Group Pty.Ltd. TraralgonVIC3844Australia School of Engineering University of TasmaniaHobartTAS7001Australia

The simulation of large-strain geotechnical laboratory tests with conventional Lagrangian finite element method(FEM)techniques is often problematic due to excessive mesh *** multiple reversal direct shear(MRDS)test can be used to measure the residual shear strength of soils in a laboratory ***,modelling and simulation generally require advanced numerical methods to accommodate the large shear strains concentrated in the shear *** reality,when the standard direct shear(DS)apparatus is used,the MRDS method is prone to two major sources of measurement error:load cap tilting and specimen *** sources of error make it difficult or even impossible to correctly determine the residual shear *** paper presents a modified DS apparatus and multi-reversal multi-stage test method,simulated using the coupled Eulerian-Lagrangian(CEL)method in a finite element *** method was successful in evaluating equipment and preventing both load cap tilting and specimen loss,while modelling large-deformation behaviour that is not readily simulated with the conventional FEM or arbitrary Lagrangian-Eulerian(ALE)***,a modified DS apparatus was created for the purpose of analysing mixtures of organic materials found in an Australian *** results obtained from the modified DS CEL model in combination with laboratory tests show a great improvement in the measured residual shear strength profiles compared to those from the standard *** modified DS setup ensures that accurate material residual shear strengths are calculated,a factor that is vital to ensure appropriate soil behaviour is simulated for numerical analyses of large-scale geotechnical projects.

关键词： Coupled Eulerian-Lagrangian(CEL)simulation Residual shear strength Multi-stage Direct shear(DS) Organic content Cohesive soil

Bacterial diversity and distribution in the southeast edge of the Tengger Desert and their correlation with soil enzyme activities

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Journal of Environmental Sciences 2012年第11期24卷 2004-2011页

作者： Wei Zhang Gaosen Zhang Guangxiu Liu Zhibao Dong Tuo Chen Manxiao Zhang Paul J.dyson Lizhe An Key Laboratory of Desert and Desertification Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of SciencesLanzhou 730000China School of Life Sciences Lanzhou UniversityLanzhou 730000China Institute of Life Science College of MedicineSwansea UniversitySwansea SA28PPUK

The nature of microbial communities and their relation to enzyme activities in desert soils is a neglected area of investigation. To address this, the bacterial diversity and distribution and soil physico-chemical factors were investigated in the soil crust, the soil beneath the crust and rhizosphere soil at the southeast edge of the Tengger Desert, using the denaturing gradient gel electrophoresis of 16S rRNA genes amplified by the polymerase chain reaction. Phylogenedc analysis of the sequenced DGGE bands revealed a great diversity of bacteria. The Proteobacteria, consisting of the α, β, and γsubdivisions, were clearly the dominant group at all depths and in rhizosphere soil. Analysis of the enzyme activities indicated that the rhizosphere soil of Caragana korshinskii exhibited the highest protease and polyphenol oxidase activities, and in the soil crust there were increased activities of catalase, urease, dehydrogenase and sucrase. The bacterial community abundance closely correlated with soil enzyme activities in different soils. The presence of Cyanobacteria correlated with significant increases in protease, catalase and sucrase in the soil crust, and increased urease in the rhizosphere soil of Artemisia ordosica. The occurrence of Acidobacteria was associated with significant increases in urease, dehydrogenase, and sucrase in the rhizosphere soil of C. korshinski. The presence of γ-Proteobacteria correlated with a significant increase in polyphenol oxidase in the rhizosphere soil ofA. ordosica. The study indicated a close relationship between the soil bacterial community and soil enzymes, suggesting the necessity of further investigations into bacterial function in this desert ecosystem.

关键词： Tengger Desert DGGE 16S rRNA bacterial community soil enzyme