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Utilization of Coal Ash as a Barrier Material for Radioactive Waste Disposal

Journal of Geoscience and Environment Protection 2015年第4期3卷 31-43页

作者： Takashi Sasaoka wahyudi sugeng Hideki Shimada Department of Earth Resources Engineering Kyushu University Fukuoka Japan

About 10% of total electricity (386 MkW) was generated by nuclear power plants in the world (2014) and about 58,400 tons of uranium has been mined in uranium mines annually. A plenty of radioactive waste material is produced from uranium mines and nuclear power plants. The wastes must be disposed or stored safely for a long term. Because if they leak and/or move from disposal or storage sites due to air/groundwater flow, then a serious environmental pollution can occur. Hence, multi-layer system has been proposed and employed in order to seal off these radioactive waste materials from biosphere. Basically, bentonite is now used for establishing one of absorbing and sealing layers in this system. However, the amount of high quality bentonite is very limited and in some cases it is hard to be obtained. On the other hand, a great deal of refuse from coal burning plants is produced every year and the amount of it is expected to be higher each year especially in developing countries. More than half of coal ash is utilized and the remaining is disposed at the disposal sites. However, the life of the disposal site is limited and it is difficult to find a new disposal site. It is requested that the percentage of the utilization of the coal ash be increased in every field. From the above two points of view, a fly ash-based barrier system is considered in this research and this paper discusses the applicability of fly ash as a content of barrier material. Based on the results of a series of laboratory tests, it can be concluded that fly ash has a potential for use in the buffer material as the bentonite is substituted.

关键词： Utilization of Coal Ash Radioactive Waste Disposal Bentonite Laboratory Tests

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Feasibility of Chain Conveyor Cutter for Ocean Disposal Site＇s Construction

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Journal of Geological Resource and Engineering 2017年第4期5卷 169-177页

作者： Hideki Shimada sugeng wahyudi Takashi Sasaoka Akihiro Hamanaka Shizuo Ikuta Department of Earth Resources Engineering Kyushu University Fukuoka 819-0395 Japan Land Creative Co. Ltd Omuta 837-0927 Japan

The concept of ocean disposal site is proven technology. One of the most concerns in ocean disposal site is the leakage ofpollutants into the ocean from waste materials. In order to prevent its happening, technically, a vertical impermeable wall is constructedaround the disposal site. However, the conventional method fails to guarantee zero leakage due to method＇s limitation. This paperpresents the use of CCC （chain conveyor cutter） method to construct vertical impermeable wall. The feasibility of CCC for oceandisposal site is evaluated by means of pollutant dispersion model, and moreover, the result is compared with conventional method. Theresult indicates that the CCC method is technically feasible for ocean disposal site＇s construction. Additionally, this method showsbetter as for technique and economic point of view than that of the conventional method. One of advantage of CCC method is the abilityto construct homogeneous wall in regard to strength and permeability, which cannot be found in the conventional ocean disposaltechnology.

关键词： Chain conveyor cutter ocean disposal soil improvement.

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Numerical Study on Effect of Longwall Mining on Stability of Main Roadway under Weak Ground Conditions in Indonesia

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Journal of Geological Resource and Engineering 2017年第3期5卷 93-104页

作者： Phanthoudeth Pongpanya Takashi Sasaoka Hideki Shimada Akihiro Hamanaka sugeng wahyudi Department of Earth Resources Engineering Faculty of Engineering Kyushu University 744 Motooka Nishi-ku Fukuoka-shi819-0395 Japan Department of Mining Engineering Faculty of Engineering National University of Laos Lao-Thai Friendship Road Vientiane3166 Lao PDR

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Countermeasure Method for Stope Instability in Crown Pillar Area of Cut and Fill Underground Mine

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International Journal of Geosciences 2016年第3期7卷 280-300页

作者： Tri Karian Hideki Shimada Takashi Sasaoka sugeng wahyudi Deyu Qian Budi Sulistianto Department of Earth Resources Engineering Kyushu University Fukuoka Japan Department of Mining Engineering Institut Teknologi Bandung Bandung Indonesia

Maintaining stability as well as optimizing recovery of crown pillar, a pillar separating surface area with the uppermost stope in overhand cut and fill underground mining method, is important. Failures in stope may lead to crown pillar failures and cause surface subsidence. Increasing crown pillar thickness will increase crown pillar stability yet reduce mining recovery because part of crown pillar is formed by ore body. Preventing stope failure is the key to maintain stability and optimize recovery of crown pillar. Therefore, it is important to study countermeasure method for stope failure especially in crown pillar area. An attempt has been made to investigate the effectiveness of various countermeasures for stope failure in crown pillar area by means of parametric study. The result shows active type support system is effective for supporting stope in high vertical stress condition while the passive one needs to be installed if the stope is opened in high horizontal stress condition. In general, more supporting capacity from both type support systems is needed if the stope is opened in more severe geological condition. Another countermeasures, sill pillar and surface pile, are introduced for stope instability in crown pillar and non-crown pillar area. Sill pillar is an abandoned slice of unstable stope based on stability analysis. Sill pillar is very effective to stabilize stope both in crown pillar and non-crown pillar area, especially for stope in high horizontal stress condition. Sill pillar application in model with stress ratio 2 can optimize 20 meter thickness of crown pillar into 5 meter. Another proposed countermeasure is surface pile. Surface pile can be installed from the surface to improve stability of crown pillar and stope. The most effective use of surface pile is found in simulation of model with stress ratio 0.75 where surface pile can optimize 15 meter thickness of crown pillar into 5 meter.

关键词： Crown Pillar Stope Stability Active and Passive Type Support System Sill Pillar Surface Pile

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Optimization of Dump Bench Configuration to Improve Waste Dump Capacity of Narynsukhait Open Pit Coal Mine

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International Journal of Geosciences 2018年第6期9卷 379-396页

作者： Tsedendorj Amarsaikhan Hideki Shimada sugeng wahyudi Takashi Sasaoka Akihiro Hamanaka Department of Earth Resources Engineering Kyushu University Fukuoka Japan

In next two years, the current waste dump of Narynsukhait coal mine is predicted insufficient to accommodate the overburden as limited of the waste dump capacity. Thus, redesigning waste dump is paramount to increase capacity of the dump in future. This paper describes current condition of waste dump of Narynsukhait coal mine and then discusses the optimization of waste dump geometry by analyzing the effect of different waste dump’s bench configuration on slope performance. Optimization of the geometry is carried out by investigating and comparing the performance of geometrical combinations of bench height, bench angles and number of safety berm by means of numerical modeling. The model shows that increasing height of bench is able to induce shear stress in the bench and may initiate bench instable. However, the shear stress can be limited by having safety berm and/or reducing bench angle to satisfy the stability criteria.

关键词： Waste Dump Bench Stability Bench Configuration Open Pit Coal Mine

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Stability Assessment of Open Stope under Overlaying Mined-Out Regions at Modi Taung Gold Mine, Myanmar

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International Journal of Geosciences 2018年第9期9卷 547-571页

作者： Naung Naung Takashi Sasaoka Hideki Shimada Akihiro Hamanaka sugeng wahyudi Mao Pisith Department of Earth Resources Engineering Kyushu University Fukuoka Japan No. 2 Mining Enterprise Ministry of Natural Resources and Environmental Conservation Nay Pyi Taw Myanmar

Stability assessment is one of the most important issues in mining ground control. Mine development and/or production instability can cause production delay, loss of reserves, as well as injury to miners. Within the scope of this study, a series of open stope’s instability under the influence of overlaying mined-out regions were carried out with different mining scenarios at Modi Taung gold mine which is operated by National Prosperity Gold Production Group Limited (NPGPGL) in Myanmar. NPGPGL has been developing stopes up to 150 m from the surface at Shwesin vein system, and the mining activities are going to continue to deeper levels to fulfill the ore mineral supply. Creating a new stope opening under overlaying mined-out regions is not easy considering the instability of mined-out regions can affect the stope. The instability of new stope opening is not only due to its own induced stress but also the strong influence by the mined-out regions situated on upper part of the stope. Therefore, the understandings of ground behaviors and failure mechanisms of new stope opening due to the influence of overlaying mined-out regions are paramount to be studied. This paper describes in detail the strength factor and failure zones under the overlaying mined-out regions with different mine conditions by using numerical simulations, 3D finite difference software (FLAC 3D).

关键词： Failure Zones FLAC 3D Open Stope Overlaying Mined-Out Regions Stability Assessment

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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

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Effects of Rock Mass Conditions and Blasting Standard on Fragmentation Size at Limestone Quarries

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Open Journal of Geology 2015年第5期5卷 331-339页

作者： Takashi Sasaoka Yoshiaki Takahashi wahyudi sugeng Akihiro Hamanaka Hideki Shimada Kikuo Matsui Shiro Kubota Department of Earth Resources Engineering Faculty of Engineering Kyushu University Fukuoka Japan Center of Environmental Science and Disaster Mitigation for Advanced Research Muroran Institute Technology Muroran Japan National Institute of Advanced Industrial Science and Technology Ibaraki Japan

The size distribution of fragmented rocks depends on not only the blasting standard but also the mechanical properties, joint system and crack density of rock mass. As, especially, the cracks in the rock mass are heavily developed at the limestone quarries in Japan, the joints and/or cracks in the rock mass have big impacts on the blasting effects such as the size of fragmented rocks. Therefore, if the joint system and/or crack density in the rock mass can be known and evaluated in quantity, the blasting operation can be done more effectively, efficiency and safety. However, the guideline for designing the appropriate blasting standard based on the rock mass condition such as mechanical properties, joint system and/or distribution of cracks, discontinuities, from the scientific point of view, has not been developed yet. Therefore, a series of blasting tests had been conducted in different mines and faces, geological conditions and blasting standards in order to know the impacts of each factor on the blasting effects. This paper summarizes the results of blasting tests and describes the impacts of rock mass conditions and blasting standard on the size of fragmented rocks.

关键词： Fragmentation Borehole Camera Mechanical Properties of Rock Mass Crack Density Blasting Standard

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Study on Prediction of Ground Vibration in Consideration of Damping Effect by Fragment in the Rock Mass

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Journal of Geoscience and Environment Protection 2018年第6期6卷 1-11页

作者： Yoshiaki Takahashi Takashi Sasaoka wahyudi sugeng Akihiro Hamanaka Hideki Shimada Tei Saburi Shiro Kubota Department of Earth Resources Engineering Faculty of Engineering Kyushu University Fukuoka Japan National Institute of Advanced Industrial Science and Technology (AIST) Ibaraki Japan

In modern mining industry, rock blasting is one of the essential working for rock breakage in terms of economic and efficient aspects. Blast-induced ground vibration may give serious impacts on wide range of surrounding environment, so it has to be paid much attention in the blasting process. Peak Particle Velocity (PPV) is one of the most important parameters related with blast-induced ground vibration. The prediction of PPV is very important in order to design an appropriate blasting standard and minimize its environmental impacts. However, general prediction equations and/or methods have not been developed yet because they do not consider the impact of rock mass and geological conditions. Therefore, in this paper, indoor tests, field tests and numerical simulation were conducted for assessing the effect of fragment in the rock mass on propagation behavior of ground vibration. In order to enable versatile vibration prediction at different sites with different blasting and geological condition, we investigated the differences in vibration behaviors due to blasting design, and the difference in geological condition. The result of a series of tests suggested that fragments in the rock mass related with the damping behavior of the blast-induced ground vibrations and more accurate prediction of the ground vibration (PPV) could be performed by considering fragment condition in the rock mass.

关键词： Blasting PPV Numerical Simulation LS-DYNA Fragment

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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

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