International Symposium on Earth Resources Management and Environment

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Adaptation to future flooding in a lowland city - a case of Jakarta city
(Department of Earth Resources Engineering, University of Moratuwa, 2020-12) Kazama, S; Januriyadi, NF; Kure, K; Dissanayake, DMDOK; Dassanayake, ABN
Proceedings of ISERME 2020 ISERME 2020 104 Adaptation to Future Flooding in a Lowland City, - A Case of Jakarta City - *Kazama1 S, Januriyadi2 NF and Kure3 K 1Department of Civil and Environmental Engineering, Tohoku University, Japan 2Universitas Pertamina, Indonesia 3Toyama Prefectural University, Japan *Corresponding author – so.kazama.d3＠tohoku.ac.jp Abstract Hydrological model and inundation model are applied to Chilliun River Baisn including Jakarta City, capital of Indonesia to evaluate countermeasures as the adaptation in the future. For the future projection, rainfall data was made using 8 GCMs with statistic downscaling and bias correction. Future scenarios were prepared for land use change, land subsidence and 3 RCPs. Structural and non-structural countermeasures were evaluated as the adaptation for flooding. Only landuse change to 2050 increases 99% flood damage cost (almost double from current situation) and only land subsidence to 2050 increase 95% one. The combination of land use change and land subsidence makes 226% higher damage cost in 2050 than current one. This calculation shows the emphasis of both influences. Heavier downpour makes higher damage cost by flooding. Only future rainfall increases 77% and 99% on mean flood damage (annual expected damage costs) in around 2050 and 2100, respectively. However, the range of damage cost by each GCM is large and some models show the decrease of damage cost in 2050. The combination of land use, land subsidence and climate change shows 5 times damage cost to current situation.
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An alternative underground hoisting system for Kahatagaha underground graphite mine, Sri Lanka- a case study
(Division of Sustainable Resources Engineering, Hokkaido University, Japan, 2024) Ekanayake, E.M.K.B.; Dissanayake, K.G.T.D.; Iresha, H.; Elakneswaran, Y.; Dassanayake, A.; Jayawardena, C.
Hoisting systems used in underground mines are essential for the transportation of equipment, personnel, mined ore and thus for the productivity of an underground mine. It consists of various components in which there are shear wheels, winches, wire ropes, lift cages, carriage boxes and electric motors. The safety and reliability of the hoist depends on its design, therefore proper and accurate design of a hoist is essential. A properly designed hoisting system also supports to increase underground productivity as well. Kahatagaha underground graphite mine is the deepest underground graphite mine in Sri Lanka, where the deepest level is 2080 feet below from the surface. The main lift operates up-to 1130 feet level from the surface and there are 5 inclined winzes equipped with pneumatic winches and hanging wooden boxes with the support of wire ropes for hoisting or lowering men and material as hoisting method from 1130 feet level to 2080 feet step by step between main underground levels. This hoisting method is very primitive and it has many bottlenecks when going to increase underground production, productivity and safety. This paper aims to provide a solution for current hoisting system & it`s issues mentioned above and presents the benefits of proposed hoisting system for Kahatagaha underground graphite mine. In fact, a cost-effective and safe hoisting system is a great support for any underground mine so that the proposed design would be a good alternative against the primitive system still in operation.
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Analysing the Effect of Curing Temperature on Micro-annuli Formation in Existing Wellbore Cement Sheath for Underground Hydrogen Storage
(Department of Earth Resources Engineering, 2023-08-28) Thirukumaran, A; Perera, S
Cement is used in a wellbore to isolate the formation fluids from the adjacent geologic regions. However, the interfaces between cement and casing as well as cement and formation can develop into leakage conduits in the form of micro-annuli. The formation of micro-annuli is a result of poor bonding which can be related to differential stress asserted on the wellbore system due to the changes in temperature and pressure. Micro-annuli are a type of cement sheath failure that can lead to significant leakage depending on the type of fluid and geometry of the micro-annuli. Studies over the years have assumed and simplified the pore geometry to be homogenous and uniform. In contrast, recent studies have revealed the complex nature of the geometry of the micro-annuli. In this experimental work, effort was made to visualise the initial cement bonding in three-dimensional space. X-ray CT scanning was carried out on cylindrical composite samples prepared with sandstone and API class G ordinary Portland wellbore cement. The images were reconstructed and analysed using AVIZO. The effect of different curing temperatures is illustrated through the quantification of micro-annuli and by analysing their geometry.
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Analysis of beachrock samples along Southern and Western coasts of Sri Lanka by spectroscopic methods
(Department of Earth Resources Engineering, 2019-08) Edirisooriya, KVUI; Thilakarathna, MADP; Vijitha, T; Dassanayake, ABN; Jayawardena, CL; Dissanayake, DMDOK; Samaradivakara, GVI
Beachrocks are sedimentary structures commonly observed where there is warm sea water in tropical and subtropical regions as a result of cementation by CaCCb of coastal sediments in the tidal zone. Comprehensive studies have been carried out to determine the formation mechanisms of beachrocks specially Japan to improve an alternative countermeasure against erosion by man-made rocks. When focusing on formation mechanism of beachrocks elemental and mineralogical composition is vital. Considering this important application, we used spectroscopic techniques to understand composition of beachrocks in southern coastal region between Ahangama to Kaikawala and Uswetakeiyawa in the western coastal region of Sri Lanka. The presence of minerals in beach rock samples in southern coast were identified by FT-IR spectroscopic technique. The constituents of minerals present in the beach rocks are further confirmed by XRD technique. Elemental concentrations of beach rock samples have been analyzed using technique of WDXRF spectrometry. Uswetakeiyawa beachrock was mainly analyzed by using EDX in SEM. Beachrocks in southern coasts is comprise higher percentage of Aragonite which is the polymorph of CaCCb, frequently founded in most of the sites in the world. Further the composition shown similarities with Indian (Tiruchendru) and Japan (Okinawa) beachrock occurrences. Comparative to the composition of southern coast beachrock, XRD analysis did not indicate any CaC03 polymorphs Uswetakeyyawa, beachrocks. Instead it indicated the presence of Kutnohorite (Ca(Mn,Mg,Fe)(C03)2).
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Analysis of efficiency and impact by deck charging patterns on rock blasting at Aruwakkalu Limestone Quarry, Sri Lanka
(Department of Earth Resources Engineering, 2023-08-28) Surangani, RKH; Shanthilal, S; Sandaruwan, DLCD; Chaminda, SP; Samarakoon, KGAU; Senarathna, TMB
There is a potential to enhance both the efficiency and the quantity of explosives in limestone excavation utilising deck charge patterns in the Aruwakkalu limestone quarry in Sri Lanka. To achieve this a series of combinations with ANFO and deck charge patterns were simulated using a numerical analysis software named JKSimblast – 2D bench. This study entails simulating and validating the existing blasting geometry in the rock blasting practice. The fragmentation curves of the real world blast events were analysed and plotted using an AI platform called “Streyos”. Subsequently, the blasting geometry was optimised by adjusting the spacing and burden with different charge amounts. A comparison was made between the explosive energy distribution figures of the simulated blast with optimised blasting geometry and the deck charging blast series. To simulate the limestone condition for the rock mass, throughout different simulations, the rock specific gravity (SG) was defined as 2.6. Optimised spacing and burden for a 10.3 m deep and 72 mm diameter blast hole pattern were found as 2.9 m and 2.4 m respectively, ensuring favourable conditions with controlled ground vibration (5 mms-1) and air blast overpressure (120 dB). The optimal configuration for minimising boulder formation in the upper section of the hole was 23.17 kg of ANFO quantity per hole with a two-charge deck pattern.
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Analysis of ground-borne vibrations due to piling operations and risk zonation
(Department of Earth Resources Engineering, 2019-08) De Seram, PSPSW; Indika, LGV; Athapattu, AMHSM; Samaradivakara, GVI; Hemalal, PVA; Dissanayake, DMDOK; Samaradivakara, GVI
Due to paucity of land for construction and the highest valuableness of lands in urban areas, construction activities are broadly carried out neighboring to existing buildings. Pile driving is the most common foundation technique used to transfer the load ol a building or a structure to the hard layer of soil or rock. These activities am source of ground vibrations affecting human life as well as existing buildings or structures. Ground-borne vibration and noise levels have been monitored at a pre-cast piling site closer to the Thermal Power Station at Kerawalapitiya using a blast vibration monitoring instruments in this study. The main objective of this research is to produce the risk zonation to the surrounding humans, buildings and infrastructures from the pile driving location. Nuisance to human and comfort level of workers are analysed as per British and ISO standards respectively, and possible damages to existing buildings and structures are discussed according to Swedish and Indian Standards, in this study.
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Analysis of physical and mineralogical properties of aggregate on strength and durability of asphalt concrete
(Department of Earth Resources Engineering, 2018-08) Lakshan, LPS; De Silva, SHSN; Kapilaratne, RDMCLB; Chaminda, SP; Jayawardena, CL; Abeysinghe, AMKB; Samaradivakara, GVI
Asphalt is made by mixing aggregates, filler and binder materials together according to pre-determined ratios. Out of the total asphalt weight, 94% to 95% consists of aggregate. It is not surprising that the performance of asphalt concrete mixtures is influenced by the properties of their aggregate blends, such as gradation, shape (angularity and elongation), texture (roughness) and mineralogy. In asphalt concrete, numerous studies have related gradation, shape, and texture of the aggregate to durability , workability , shear resistance, tensile strength, stiffness, fatigue response, rutting susceptibility, and optimum binder content of the mixtures. However, a few has described about the influence of mineralogy on characteristics of asphalt. This research has been carried on to make an effort to fill that gap between the aggregate mineralogical properties and the characteristics of asphalt concrete. Under the research, a number of representative aggregate samples were collected from different quarry sites which are currently used in the process of manufacturing asphalt all over the country. The samples were subjected to a series of tests in order to determine both physical and mineralogical properties. Marshall stability and flow values of the asphalt mixtures were determined to assess the properties of asphalt made using the collected aggregates. Finally, using test results, an analysis was conducted followed by the conclusions made using the test results, a set of recommendations were proposed.
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Analysis of Sri Lankan petroleum fiscal system - petroleum resources agreement - 2007
(Department of Earth Resources Engineering, 2019-08) Jayamal, KC; Fernando, CR; Niroshan, WKD; Wickrama, MADMG; Dissanayake, DMDOK; Samaradivakara, GVI
Economic structure of the World Oil and Gas Industry significantly differs from other industries due to the greater risk and uncertainties associated with the industry. Petroleum fiscal regime of a county defines the set of laws, regulations and agreements related to petroleum exploration and production. Since Sri Lankan basins are not much known to the petroleum world, attraction of technically and - economically capable International Oil Companies for the investment is highly dependent on the Sri Lankan petroleum fiscal terms. The main objective of the study is to analyze the existing Sri Lankan petroleum fiscal systems. Fiscal model created w i t h the MS Excel according to the terms defined i n 2007 was used to calculate cash flow of government and contractor, contractor and government takes, IIR value and payback period i n dynamic envirormient conditions. Behaviour of above parameters under three variable conditions (by varying price of oil, reservoir size and life span of the project) were used to decide the attractiveness of the fiscal system. Results show that contactor share is decreasing i n un-favourable conditions w i t h the terms defined i n 2007 fiscal system.
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Analysis of subsurface strata of Colombo and Gampaha districts of Sri Lanka, based on geotechnical investigation data
(Division of Sustainable Resources Engineering, Hokkaido University, Japan, 2024) Karunarathna, K.S.S.; Wasana, N.W.A.P.; Bandara, M.G.K.M.; Ranathunga, R.M.IG.N.K.; Samaradivakara, G.V.I.; Iresha, H; Elakneswaran, Y; Dassanayake, A; Jayawardena, C
The subsurface exploration for geotechnical engineering applications in Sri Lanka is mainly based on borehole investigations. Several leading geotechnical engineering companies in the country have already done more than a couple of thousands of subsurface investigations for small- and large-scale civil engineering projects. Even though project-wise subsurface information is available, integration of available subsurface data in proximity, and development of subsurface three-dimensional (3D) models can hardly be seen in the country. This has been a significant disadvantage in the cost and planning of large-scale new investigation projects. Due to lack of information, most of the projects start even without knowing the tentative bedrock level of the area. Hence, in investigation cost estimations, pricing for most of the items is recorded as “rate-only”, hence the total cost could immensely be higher than the available budget with the client. However, if 3D modelling of subsurface strata can be done area-wise, based on already available borehole data, such uncertainties could be minimized. In this research, more than a thousand subsurface investigation reports were reviewed; data were recorded and analysed targeting to interpret the subsurface of the western province of Sri Lanka, and to develop a 3D subsurface model for the same. However, scattered data had to be excluded in data analysis, and eventually, the study was confined to Colombo and Gampaha districts, in which more than sufficient data could be found. By using interpolation methods, surface strata were interpreted in between borehole locations by matching similar geological features. In addition, artificial neural networks were used to forecast borehole data in exceptional cases for a few locations. This helped to improve the spatial coverage and accuracy of the 3D model developed by means of “Surfer” software. The 3D model developed for the study area well demonstrates the subsurface strata and facilitates taking of cross sections in any direction within minutes. Hence, the findings of this research will enhance the outcome of general geotechnical investigation practice in Sri Lanka. This will also be immensely beneficial in planning and budgeting of future large-scale geotechnical investigation projects, more accurately than in the past, saving energy and time.
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Analysis of topographic effects on tea yield in Sri Lankan tea estates using geomatics
(Department of Earth Resources Engineering, 2023-07-28) Randima, KAC; Malinga, DIGS; Kalpana, TMJ; Chaminda, SP
This research paper investigates the potential impact of hill shade on tea yield at the Dambatenne tea estate using unmanned aerial vehicles (UAVs). Drones were used to take high-resolution aerial photos of the location that was selected. The data were processed using Pix4D software to generate accurate 3D surface models, ortho mosaic maps, and vegetation indices. Additionally, the main goal of this study was to evaluate the impact of hill shade on tea yield. By analysing the obtained data, including vegetation indices derived from the multispectral imagery, the correlation between hill shade and tea yield was examined. Various mapping techniques and statistical analyses were employed to investigate this relationship. The findings suggested that there may be a relationship between hill shade and tea yield and that different levels of shading brought on by topographic characteristics may influence the development and production of tea. The findings from this research contribute to the understanding of how hill shade affects tea yield and provide insights for sustainable tea estate management practices. The results of this study are significant for tea estate owners and managers, as it highlights the importance of considering hill shade factors in optimizing tea cultivation and maximising yield.
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Analyzing the seasonal variation of groundwater characteristics in the Attanagalu Oya basin
(Department of Earth Resources Engineering, 2019-08) Athukorala, DRM; Kohilan, C; Danushka, U; Jayarathna, WHDP; Chaminda, SP; Dassanayake, ABN; Hewavidana, SM; Dissanayake, DMDOK; Samaradivakara, GVI
Gampaha district which has the second largest population in the country consists of many industrial establishments and residential areas. Attanagalu Oya Basin which almost entirely the Gampaha district is a major hydrologic feature in determining the seasonal variations of groundwater characteristics in the region. In this study, the groundwater characteristics in the Attanagalu Oya Basin analyzed both quantitatively and qualitatively to identify variations in the pre and post monsoon periods. The qualitative parameters such as pH, conductance, turbidity, calcium, magnesium, nitrate, phosphorous, ferrous, and heavy metal concentrations were analyzed for samples taken throughout the entire basin for the two time periods: pre and post monsoons. The groundwater quantity variations were observed through data loggers and field surveys of water wells. These recorded values were used to model the groundwater resources in the region using two numerical models, MODFLOW by USGS and a self-written Fortran code. The qualitative and quantitative variations were then analyzed spatially and temporally to correlate with the upstream to downstream flow and the monsoonal recharge. The possible reasons for the observed trends and variations were also studied to provide recommendations for the sustainable management of the groundwater resources in the Attanagalu Oya Basin.
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analyzing the temporal variation of groundwater level in Attanagalu oya basin using numerical models
(Department of Earth Resources Engineering, University of Moratuwa, 2020-12) Vinu, I; Udayanga, RMK; Chaminda, SP; Dassanayake, ABN; Dissanayake, DMDOK; Dassanayake, ABN
Scarcity for drinking water becomes one of the enormous threats around the world due to the increase in population, climatic fluctuation and pollution. Sri Lanka is considered as a country with little or no water scarcity when reckoning the whole country as one unit. However, several local regions have been identified with temporal water scarcity. Attanagalu Oya basin which covers almost the entire Gampaha district is a major hydrologic feature in determining the groundwater characteristics of the region. In this study, the temporal groundwater variation of the Attanagalu Oya basin was quantitatively analyzed. Using the data obtained from data loggers and field surveys, a numerical model for the groundwater in the basin was designed by using two software modelling approaches, a self-written Fortran code and Visual MODFLOW by USGS. Fortran code is mainly used for runoff modelling and Visual MODFLOW is for subsurface modelling. The quantitative variation obtained from the model was then examined temporally and spatially to correlate the upstream to downstream flow and monsoonal recharging impacts. The possible reasons for the observed deterioration and variations in the groundwater quantity can be contemplated as keys to providing recommendations for sustainable management of the groundwater resources in the basin.
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Applicability of a neural network model for forecasting ground vibrations in opencast mining
(Department of Earth Resources Engineering, 2018-08) Dassanayake, SM; Dushyantha, NP; Jayawardena, CL; Abeysinghe, AMKB; Samaradivakara, GVI
Ground vibration and air-blast over pressure are two significant undesirables, among many environmental risks, in open-pit mining . Gaining control over the ground vibrations generated by rock blasts had been difficult mainly due to the complexities involved with local geology and properties of the blast. Accordingly, existing empirical equations are only capable of making vague approximations on the vibration frequencies based on site-specific parameters and attenuation factor. Therefore, the available models cannot be generalized to different geo-mining environments to obtain sufficiently reliable forecasts for ground vibration and airblast overpressure. Hence, this study attempts to employ an Artificial Neural Network (ANN) based feed-forward back-propagation algorithm to train a model, using a supervised learning technique to forecast possible ground v i b r a t i on frequencies. The main in-put parameters included in the model are noise level, number of boreholes per single blast, depth and diameter of a borehole, charge per hole, number of delays of the Electric Detonators (ED) in a single blast, burden and spacing. Airblast overpressure and the ground vibration levels will be the output by ANN model. The model was validated using 50 datasets, which were obtained from a quarry site. After adequate training, the model can determine Peak Particle Velocity (PPV) and frequency of Ground Vibrations (GV) for new input parameters with a statistically significant confidence level.
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Applicability of GPR technique for earthen dam failures
(Department of Earth Resources Engineering, 2023-08-28) Arunapriya, GGDPI; Liyanage, AGSI; Kishanth, S; Premasiri, HMR; Ratnayake, NP; Abeysinghe, AMKB
A dam is a structure constructed across a river or stream to store water upstream from the obstruction. Dams are susceptible to damage for various reasons, which can lead to many catastrophic disasters. Therefore, identifying the dam's structural failures prior to a disaster is crucial. Drilling can be used for dam failure identification. But it is costly and destructive. Integrated geophysical methods have always helped in identifying subsurface features. In the current investigation, the applicability of ground penetrating radar (GPR) to detect potential failures in earthen dams was assessed. The Uyanwatta Lake earthen dam was selected as the study area during this investigation, considering the reported water leakage in this dam. A GPR survey was conducted with 100 MHz and 300 MHz antennas along five survey paths. Those are the top of the dam, 1.5 m below the top of the dam, and three distinct paths for the lake's spill. During the interpretation process, clay layers, fractured zones, gravel layers, and water seepage areas were identified. Those water leakage areas indicate that there has been a leak in the dam. Those results were compared with exploratory drill hole data from the Uyanwatta Lake Dam. Drill hole data has only presented information about the rock types present in the dam. But GPR data was able to provide information on loose sediments in the shallow depths of the dam as well. That indicates GPR data has the potential to provide additional information related to earthen dams.
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Applicability of ground penetration radar (GPR) technique to optimize soil Nail Wall designs
Lasan, HLI; Weerasekara, MN; Prashanth, S; Abeysinghe, AMKB; Premasiri, HMR; Samaradivakara, GVI; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y
Soil nailing is used to stabilize existing natural slopes or excavations using soil reinforcement technique. Due to lack of information on ground profiles and thickness of soil layers, the required soil nail lengths cannot be determined in advance, for most of the steep slopes. Furthermore, the cost of drilling in fresh rock is much higher than the cost of drilling in soft soil and weathered rock. Without proper information on the depth at which the fresh rock is found, a cost-effective soil nail wall design cannot be finalized. This research was focused on studying the methods that can be used for soil nail wall design optimization by applying Ground Penetration Radar (GPR). The study was carried out on an unstable slope near Nursing Training School located in Kandy in the central part of Sri Lanka.The physical properties of soil were determined by direct shear tests, and stability analysis was done by means of “Slope-W” software. GPR techniques were also used in this study. The investigation results showed that the existing slope is unstable, and necessary to be protected. Further, it was identified that the basement rock cannot be encountered at already designed depths of the soil nails, which was subcequently proven as correctbased on data from ongoing drilling for soil nail installations. With the precise knowledge about the underground geological structure using GPR technique, the drilling cost, nail transporting cost, nail off cutting time to complete the total work can be reduced.
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Applicability of pre-heating techniques for recovery of garnet from garnet biotite gneiss
Jayakodi, JDSU; Weliwita, BY; Nishanthan, SS; Samaradivakara, GVI; Abeysinghe, AMKB; Rohitha, LPS; Vijitha, AVP; ; ; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y
In mineral processing industry, the highest energy is consumed by crushing and grinding operations. However, if we can initiate micro cracks in the hard rock pieces in advance, we should be able to reduce the crushing energy and liberate useful minerals economically. Various pre-heating techniques have been tried by the scientists around the world to liberate minerals from rocks. In this investigation, pre-heating techniques were used to liberate Garnet from Garnet Biotite Gneiss. The market price of Garnet varies with the particle size. Hence, the samples were crushed and sized into industry needed three size fractions: (+250-850) μm, (+180-250) μm and (-180) μm. Afterwards, by means of Wilfley Table, Garnet was separated from rocks. Final Garnet recovery percentage was recorded for different temperatures. Furthermore, energy calculation was done for each sample to get an idea about the power consumption. It was observed that the crushing strength decreases with the temperature increment and it has been proven by identifying propagation of micro cracks in thin sections, prepared from rock samples pre-heat treated in Muffle Furnace and Microwave Oven. The analysis reveals that the preheat treated and quenched samples give higher Garnet recovery than Garnet recovered from as-received samples of Garnet rich Biotite Gneiss.
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Applicability of pre-heating techniques for recovery of minerals from rocks
(Department of Earth Resources Engineering, 2018-08) Dasanayake, RB; Jatheesan, N; Nissanka, NACM; Samaradivakara, GVI; Abeysinghe, AMKB; Rohitha, LPS; Abeysinghe, AMKB; Samaradivakara, GVI
In mineral processing industry, liberating of minerals is the most important involvement because it can enhance the purity of the mineral. However, if we can initiate micro-cracks in rock pieces in advance to these operations, it would be more economically viable. Hence, there is a trend i n the world to investigate less energy-consuming methods for propagating micro cracks within rock grains. Previous studies show that preheating techniques such as heating in muffle furnace, microwave preheating can enhance micro-cracks propagation in rocks and samples. Microwaves have several advantages over standard heat application methods namely that they heat only "responsive" phases. Microwaves also heat considerably faster than conventional heating methods as the heating on radiation and conduction heat transfer mechanisms. Therefore, in this scientific investigation, we applied microwave pre-heating technique to liberate Garnet from Garnet Biotite Gneiss for which samples were collected from Boulder Mix Pvt. Ltd quarry in Meepe. To create a weak zone i n between graphite and its gangui rock in graphite bearing rocks which were collected from Bogala Mines in Aruggammana have also tested. Industrial price of garnet vary w i t h the particle size. In general, higher the particle size, higher w i l l be the value. Hence, the recovery of Garnet in this study was considered focused on industry needed particle size which is less than 850 |xm. The analysis revealed that there is a possibility to produce low cost garnet sand which is cheaper than i n the international market with high purity, by means of microwave technology,. Also it is proved that creating a weak zone along the grain boundary of graphite and its gangue rock is possible w i t h microwave pre-heating.
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Applicability of tunnel muck as an alternative for fine aggregates in cement concrete
(Department of Earth Resources Engineering, University of Moratuwa, 2021-12) Ariyasena, HHS; Sampath, BA; Wickramasooriya, MDJP; Dissanayake, DMDOK; Jayawardena, CL
One of the recent applications of Tunnel boring Machines (TBM) in Sri Lanka is Uma Oya Multipurpose Development Project (UOMDP). During rainy periods, the washed tunnel muck particles sediment in low agricultural lands forming infertile soil. It mainly affects the agricultural sector in the respective area of the country. Therefore, it appears that there is a need to study the reuse of the tunnel muck as an alternative for sand which is a very expensive construction material these days, or any other field as a useful material in an effective manner. The objective of this study is to determine the applicability of tunnel muck as an alternative for sand in concrete as fine aggregate. The material properties of tunnel muck were analysed. Water absorption and workability were higher in the concrete mixed with tunnel muck because the tunnel muck particles are finer than normal sand particles. It was observed that there was a slight decrease in the compressive strength of the concrete casted with tunnel muck. However, the compressive strength could be increased with higher cement content in the concrete. Furthermore, the mix designs with adjusted values were proposed for the concrete mixed with tunnel muck as fine aggregates.
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Application of emulsion explosive and comparative study on water-gel explosives for rock quarrying in Sri Lanka
Dharmaratne, PGR; Hemalal, PVA; Rohitha, LPS; Herath, B; ; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y
Dynamite has been the premier and the only high explosive used for mining and construction activities in Sri Lanka for a long period of time. Negative environmental impacts, effect on health and security hazards led to the Government of Sri Lanka (GOSL) to issue directives to find a suitable substitute for Dynamite. Subsequently, Water-Gel explosive was introduced in the year 2011. The poor performance of Water-Gels in wet conditions and it’s low Velocity of Detonation encouraged the use of Emulsion explosives. This research was focused on performing a comparative study of the performance of both Water-Gels and Emulsion explosives by analysis of the ground vibration and the blast air over pressures. The methodology adopted was to conduct ten blasts at one single metal quarry site keeping all other parameters constant. Blasting tests were performed using Emulsion explosives and Water-Gel explosives and the resulting ground vibration and Air-Blast overpressures were measured with Blastmate 111model for each blast. Calculation of mean fragmentation was done and particle size distribution based on photographic evidence of each blast was analyzed. Analysis was carried out demarcating the resultant production pile of aggregates covering a cleared zone. Grid lines inserted on the muck pile facilitated particle counting using photographs and calculating the mean fragmentation.
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Application of GPR to identify carbonate rock cavities related to ground subsidence in Matale, Sri Lanka
(Department of Earth Resources Engineering, 2018-08) De Silva, MSTL; Chiyamvarnan, K; Niroshini, R; Abeysinghe, AMKB; Jayawardena, CL; Abeysinghe, AMKB; Samaradivakara, GVI
Cavity formation within the rocks result in ground subsidence in the regions where carbonate rocks are predominantly present. Identification of ground subsidence potential areas and the probability of such incidents is a challenge without detailed information about the subsurface. Dorakumbura in Matale, Sri Lanka is one such area which faced multiple ground subsidence incidents that demands the investigation of subsurface profile. This study uses Ground Penetrating Radar (GPR) to locate the subsurface cavities in order to create a cavity profile for the Dorakumbura area using 1D and 2D trace analysis of the radargrams. Cavities were identified and analyzed and the results reveal the existence of cavities mostly below the depth of 15 m. Comparison of GPR survey results with the well log data in the region was equivalent. The same methodology is expected to be used in similar regions to identify the presence of cavities which can result in future ground subsidence. It can also assist in suitable site selection without ground subsidence hazards, for the construction and development activities in regions underlying carbonate rocks in Sri Lanka.