Browsing by Author "Hemalal, PVA"

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7th National Conference on Earth Resources Management (Pre Text)
(Department of Earth Resources Engineering, 2013-07) Hemalal, PVA
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8th National Conference on “Earth Resources Management” [Pre Text]
(Department of Earth Resources Engineering, 2014) Hemalal, PVA
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An alternative mitigation method for Gerandi-Ella reactivated landslide
(Department of Earth Resources Engineering, 2015) Mampitiyaarachchi, CT; Ranathunga, RMIGNK; Rifad, MZM; Thathkalana, UMC; Abeysinghe, AMKB; Indrathilaka, HML; Premasiri, HMR; Weerawamakula, S; Hemalal, PVA
Gerandi-Ella, a former landslide area is currently under threat of reactivation. National Building Research Organization has implemented a surface and vertical well drainage system to stabilize it. However, vertical drainage system has failed,and an unexpected behavior of groundwater was observed due to presence of clay layers in the colluvium. An effective and economical alternative mitigation method is required to stabilize the area. A particular portion of the site,positioned such that it keeps the rest of the landslide mass intact, was chosen as the study area. Implementing a proper alternative mitigation methodto the study area may help to stabilize the landslide along with existing surface drainage system.Piezometric levels at two boreholes and rainfall data at the study area were analyzed. Stability analysis through the software SLOPE/W gave the current factor of safety as 0.965. A horizontal drain network with suitable design parameters was proposed to achieve a factor of safety of 1.206 by considering the effect of the matrix suction. A series of sand and gravel filled vertical holes capped with 100 cm clay layer are also proposed to expedite the water drawdown through impervious strata to horizontal drains.
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Analysing the relationship between skin and formation damage of an oil well (time depended)
(Department of Earth Resources Engineering, 2016-07) Ruwanpathirana, RS; Nagasinghe, RV; Welagedara, WWVP; Wickrama, MADMG; Senadhira, AMADM; Ratnayake, NP; Vijitha, AVP; Hemalal, PVA
The concept of skin and formation damage play a vital role in productivity of an oil well. The objective of this study is to introduce the effect of skin into the well flowing equation in transient state. The effect of formation damage zone on the well flowing pressure was introduced to the original solution of diffusivity equation by considering three scenarios. In the first scenario it was assumed that oil is flowing through the reservoir with average (effective) permeability. In the second scenario it was assumed that the oil is flowing with the permeability of reservoir till the boundary of formation damage zone and within the altered zone, oil is flowing with the permeability of damage zone. The third scenario is similar to the second scenario, however it was assumed that the oil is flowing within the altered zone with an average permeability. By considering the difference between calculated reservoir permeability for all three scenarios and assumed values, scenario three was selected as the most suitable way to introduce the effect of skin in to the well flowing equation in transient condition.
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Analysis of geological structures for road cut failures: a case study along Balangoda – Haputale main road
(Department of Earth Resources Engineering, 2016-07) Senarathna, CSS; Godaliyadda, DP; Disanayaka, KTD; Premasiri, HMR; Abeysinghe, AMKB; Weerawarnakula, S; Hemalal, PVA
This study is focused on the causes for the road cut failures and suggest a methodology to design road orientation to minimize cut failures considering geology of the rock present in the area. In the past few years, several road cut failures have been recorded in Sri Lanka and there are development plans to construct expressways in hilly areas of the country. Hence, this study is important to minimize and control road cut failures while designing road orientation in a scientific manner. Several of studies were carried out to find the relationship between rock properties of the slope and occurrence of cut failures. This study helps to create a forecasting model for different scenarios. In this study, in order to validate the outcomes, some software were used. “DipAnalyst 2.0” is one of them and is a slope stability analysis software, which is designed to perform kinematic analysis for rock slopes and also calculating factor of safety values for plane and wedge failures based on the limit equilibrium theory. In this study, we identified that rock of the study area mainly dip towards the road (dip direction is parallel to the road direction). It is the main cause for lot of failures.
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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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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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Assessment of environmental impacts resulting from ground vibrations due to piling activities and railway transport
(Department of Earth Resources Engineering, 2018-08) Piyarathna, HDAM; Godagama, GWADC; Maduranga, THT; Hemalal, PVA; Samaradivakara, GVI; Samaradivakara, GVI; Dharmaratne, PGR; Abeysinghe, AMKB; Samaradivakara, GVI
With the development of the country's economy, industrial activities close to urbanized areas have inceased tremendously. These activities are sources of ground vibrations impacting on human life. Resulting annoyance conditions near residential areas and possible human response to ground vibrations have been investigated in this study. Ground vibration have been monitored at precast pile driving sites and at a location close to Panadura-Moratuwa railway line using an A4-channel seismograph. Human perception and disturbance conditions associated with each location is discussed with the criteria given in British Standards. According to the ground vibrations levels measured at the piling site, up to 55 m distance from pile driving locations perceptible level of ground vibrations have been occurred thus caving annoyance to occupants. Zone with adverse comments, extends up to 37 m from the pile and adverse comment possible zone extend up to 50 m from the pile when using pile diver and piles with given specifications. According to ground vibration levels near the railway track, occupants in residential areas will experience annoyance as residential area contains ground vibrations in perceptible amount. Up to 27 m distance from the railway track, ground vibrations levels were measured up to a level of making complaints regarding annoyance made by train.The trench already existed near the railway track (parallel to the rail way track) is capable of reducing ground vibration levels up to 40%.
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Characterization of beach sand deposits with heavy minerals using geo-physical techniques
(Department of Earth Resources Engineering, 2015-07) Angammana, UHBIU; Gunasingha, ULDDM; Gunawardana, RA; Srilal, KGC; Ranaweera, KVDNP; Abeysinghe, AMKB; Weerawarnakula, S; Premasiri, HMR; Hemalal, PVA
Mineralogical analysis through physical concentration and microscopic studies of beach sand is one of the most accurate methods in the determination of percentages of constituent heavy minerals of beach sand. However, in this study a magnetic survey method was tested as a field method to separate magnetic minerals from non-magnetic minerals in beach sand. The main objective of this study is to find out a relationship between magnetic survey data and heavy mineral composition data of beach sand. Beaches at Panadura and Beruwala were selected for the magnetic surveys, owing to their dominance of heavy mineral bearing beach sand. Samples were also taken adequately and systematically from each beach, and were analysed at the mineral laboratory. The iso-dynamic magnetic separator was used to separate the magnetic heavy minerals. ArcGIS software and geo-statistical and normal statistical analyses were used to build the relationship between magnetometer survey data and mineral composition data. analysis was not observed a significant relationship between magnetic survey data and mineral composition data. However, According to the geographically weighted regression (GWR)
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Critical analysis of safety aspects of an underground graphite mine with reference to Bogala mines
(Department of Earth Resources Engineering, 2015-07) Karunarathne, KVP; Piyasena, DT; Marino, IJ; Sarvakaran, S; Hemalal, PVA; Dharmaratne, PGR; Hemalal, PVA
Trend analysis of occurrence of mine accidents was proposed to assess the risks associated with occurrence of underground accidents and human health in order to manage and control measures and support decision making. It provides the right balance between different concerns, such as safety and costs. For this purpose, information collected from Bogala graphite Lanka PLC located at Aruggammana in Kegalle district, Sri Lanka, was used to manage the risks affecting the health and safety of the miners. In order to categorize the data, various hazardous activities were identified and classified under eleven categories: Scaling, Hammering, Supporting, Lifting of weights, Drilling, Graphite transportation, Loading, Mucking, Machine/tool operating, Machine/tool repairing. The ranking process is accomplished by analyzing the past accident records. Further, four critical groups of body parts with different illnesses were obtained. These groups were; eye, limbs, back, head. From these groups, the most common injuries with the highest level of occurrence are sprains, cuts, bruises and contusions. According to the results, the proposed methodology can be a reliable technique for management of mine hazards and coping with uncertainties affecting the health and safety of miners when performance ratings are imprecise. The proposed recommendations can be primarily designed to identify potential hazards and help in taking appropriate measures to minimize or remove the risks before accidents occur in future mining activities in Bogala mines.
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Critical Evaluation of Blast- Induced Structural Damage Criteria for Buildings around Metal Quarries at Thudugala, Kaluthara
(2016-08-22) Hettiarachchi, MM; Priyasanka, IDP; Herath, HMWD; Mohanaruban, G; Dharmaratne, PGR; Hemalal, PVA
Quarrying can generate a number of on-site and off-site environmental effects as a result of blasting, excavation, crushing, screening, stockpiling and transport activities. Blasting is necessary for recovery of ore and production of aggregates in most underground and open cut mines, as well as in quarries. However, blasting can cause noise and ground vibration, which can have an impact upon nearby structures and people living close by. Hence, proper control of blasting practices is necessary to ensure both the safety of employees and the protection of the community from adverse effects. In Thudugala, in Kaluthura district, people those who are living close to quarries are highly subjected to these effects due to quarry blasting. In these circumstances, it was decided to conduct a research into the ground vibration impact in the area. Due to complexity of structures ranging from wattle-and-daub structures which do not have proper foundations to those built with good foundations, the applicability of single criteria of 5 mm/sec PPV level of vibration which is currently being used in Sri Lanka is inadequate. It is also noted that the above vibration criteria has been adopted in Sri Lanka without a proper theoretical foundation. In this research program, the propagation of cracks due to the blasting was assessed at the initial stage of the project. At the final stage, the optimum PPV values will have to be found for different types of structures by constructing them. In this area soil overburden is less. Therefore most of the structures have been constructed on rock. When blasting takes place, rock tends to vibrate and the intensity perceived is very high. Therefore crack propagation is high in these particular structures. It is also noticed that the cracks have further developed between the period between pre-blast crack survey and post-blast crack survey. It is due to large number of un-monitored blasts that have been conducted during that period. Therefore to solve this problem, it is recommended to carry out continuous monitoring of blasts.
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Critical evaluation of blast- induced structural damage criteria for buildings around metal quarries at Thudugala, Kaluthara
(Department of Earth Resources Engineering, 2016-07) Hettiarachchi, MM; Priyasanka, IDP; Herath, HMWD; Mohanaruban, G; Dharmaratne, PGR; Hemalal, PVA
Quarrying can generate a number of on-site and off-site environmental effects as a result of blasting, excavation, crushing, screening, stockpiling and transport activities. Blasting is necessary for recovery of ore and production of aggregates in most underground and open cut mines, as well as in quarries. However, blasting can cause noise and ground vibration, which can have an impact upon nearby structures and people living close by. Hence, proper control of blasting practices is necessary to ensure both the safety of employees and the protection of the community from adverse effects. In Thudugala, in Kaluthura district, people those who are living close to quarries are highly subjected to these effects due to quarry blasting. In these circumstances, it was decided to conduct a research into the ground vibration impact in the area. Due to complexity of structures ranging from wattle-and-daub structures which do not have proper foundations to those built with good foundations, the applicability of single criteria of 5 mm/sec PPV level of vibration which is currently being used in Sri Lanka is inadequate. It is also noted that the above vibration criteria has been adopted in Sri Lanka without a proper theoretical foundation. In this research program, the propagation of cracks due to the blasting was assessed at the initial stage of the project. At the final stage, the optimum PPV values will have to be found for different types of structures by constructing them. In this area soil overburden is less. Therefore most of the structures have been constructed on rock. When blasting takes place, rock tends to vibrate and the intensity perceived is very high. Therefore crack propagation is high in these particular structures. It is also noticed that the cracks have further developed between the period between pre-blast crack survey and post-blast crack survey. It is due to large number of un-monitored blasts that have been conducted during that period. Therefore to solve this problem, it is recommended to carry out continuous monitoring of blasts.
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Critical evaluation of current environmental comfort conditions of Bogala underground
Lasantha, MML; Thushath, T; Somarathne, KGMS; Hemalal, PVA; Dharmaratne, PGR; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y
Ventilation is a basic part of all underground mine operations as fresh, cool air is required to remove stale, affected air from the workings. The inadequate ventilation often is the cause of lower worker efficiency leading to decreased productivity and increased accident rates. This study focuses on the evaluation of environmental comfort conditions in Bogala Underground, a medium-depth underground graphite mine located in Aruggammana, Sri Lanka. A detailed ventilation survey was carried out taking measurements of dry bulb temperatures, wet bulb temperatures, Dry Kata and Wet Kata thermometer values, air velocities, surface air temperature and barometric pressures at strategic points covering the entire mine. All results were compared with corresponding standard values which describe the standard conditions to be met for working underground. Recommendations were made to improve the present environmental comfort conditions by installing auxiliary fans in stopes where necessary which will enhance the immediate mine environment contributing to health and safety aspects of the underground working environment.
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Critical evaluation of industrial mineral mining methods in Sri Lanka
(Department of Earth Resources Engineering, University of Moratuwa, 2021-12) Jeewandara, JTP; Senarathna, MKT; Wickramarathna, CH; Sirisena, KMW; Hemalal, PVA; Lasantha, MML; Dharmaratne, PGR; Chaminda, SP; Jayawardena, CL; Dissanayake, DMDOK; Jayawardena, CL
Sri Lanka is rich in industrial minerals, including graphite, apatite, ilmenite, rutile, quartz, feldspar, kaolin, apatite, garnet sand, mica, calcite, and dolomite. Even though lots of mining methods are used to extract such minerals, only limited studies have been carried out in Sri Lanka to evaluate mining methods by means of main mining principles, such as safety, economy, and efficiency. This study focuses on the Bogala graphite mine, a narrow vein medium depth underground mine, and Aruwakkalu limestone open pit mine. To evaluate the overhand cut and fill mining method in Bogala mine, Equivalent Linear Overbreak or Slough (ELOS), which is a useful measurement for quantifying the unplanned dilution in narrow vein mining, is used. The favourability of the underground mining method is evaluated for a particular mine site using Key Deposit Indicators (KDIs), and it provides the best suited underground mine based on characteristics of the ore body. The fracture system presence in the Bogala mine requires a good support system to ensure the safety of underground workers. The efficiency of the loading and hauling equipment in the Aruwakkalu mine site is evaluated by Match Factor (MF).
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Delineation of potential sites for gemstone mining in Kura Ganga catchment, Ratnapura: a GIS approach
(Department of Earth Resources Engineering, 2015-07) Jaliya, RGC; Thotahewa, AHTTB; Palihakkara, CR; Siriwardena, PRR; Premasiri, HMR; Dharmaratne, PGR; Chaminda, SP; Senanayake, IP; Hemalal, PVA
Sri Lanka has been known as 'Ratnadeepa', which translates to 'Island of gems' because of the precious natural gemstones found in its gravelly soil. Even though the gem industry in Sri Lanka extends back to ancient times, studies on patterns of gemstone occurrences were rare. However, identification of potential gem bearing lands can provide guidelines in mining and land valuation. This study was carried out to identify the potential lands for gemstone mining in Kuru Ganga catchment, Ratnapura, based on patterns of gemstone occurrences and mining cost using integrated geo-spatial technologies. Fieldwork was conducted to collect gravel samples from riverbanks and gem mines. The samples were subjected to microscopic analysis to trace potential gemstones. The results obtained were combined with the data gathered from gem mines and mapped on a GIS platform to identify the occurrence patterns. Mining cost at each sampling location was estimated based on depth to the gem bearing gravel layer, "illamaSubsequently, potential lands for feasible gemstone mining were delineated through a knowledgedriven weighted analysis. The results depict that the South Western region of the Kuru Ganga catchment encompasses the highest feasibility of gem mining while North Eastern region of the catchment has the least feasibility of gemstone mining based on mining cost and values of potential gem varieties in the area.
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Design of a low cost magnetic separator for local beach sand separation
(Department of Earth Resources Engineering, 2013-07) Boralugoda, BPD; Udowita, UGKPB; Sayanthan, K; Rohitha, LPS; Hemalal, PVA
Study had been carried out to identify beach sand minerals available locally. Principles, cost, and design feasibilities of industrially used magnetic separators were reviewed. As the best suit for requirements permanent drum magnetic separator was chosen. Software aided separator design was prepared based on reversed engineering concept, in the purpose of building fully functional prototype. Material selection was carried out. According to basic CAD drawing, prototype was built with necessary design adjustments. Magnetic drum is 20 cm (0) x 40 cm, which yields a magnetic force field nearly 0.1 T. Prototype proven to separate ferromagnetic minerals in beach sand. Flow rate is nearly 15 kg/hour. Recovery of magnetite in silica-magnetite mixture is about 50-60% in single batch process. Using drum direction of rotation opposite to flow direction, highly magnetic susceptible material was removed with a higher recovery.
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Designing and evaluating a casing program for petroleum wellbores
(Department of Earth Resources Engineering, 2013-07) Wijesinghe, KADR; Hewavitharana, TD; Mahsoom, MSM; Wickrama, MADMG; Senadhira, AMADM; Ratnayake, NP; Hemalal, PVA
Due to high operational and financial risks associated with the investments in the petroleum industry, all precautions are taken by the operators to achieve a safe and cost effective well completion. Casing design of a drilling program is a critical element which contributes greatly to safety and cost of the operation. The objective of this research was to develop a casing design program which enables the user to evaluate casing design proposed or implemented in a drilling campaign. The developed casing design program consists of sequential criteria to select casing setting depth and establish optimum casing strength. Knowledge on local pore pressure gradient and facture gradient are essential to select the casing setting depths. Since both the factors are regional stratigraphy dependants, casing setting depth selection was designed in the way it allows user to assign variables for these parameters. Developed casing design program was validated with the casing design done by Rahman, S. S and Chilingar, G. V(1995). Validation results shows that the casing design of Rahman and Chilingar and the casing design done with the use of developed program are having similar casing setting depths except in the case of conductor casing.
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Determination of depleted rock volume in open cast mines using photogrammetric techniques for the purpose of royalty calculation
(Department of Earth Resources Engineering, University of Moratuwa, 2021-12) Ariyarathne, RCDK; Samaraweera, SACV; Maduwantha, LSE; Insaf, MJM; Hemalal, PVA; Illankoon, IMTN; Dharmaratne, PGR; Chaminda, SP; Lasantha, MML; Dissanayake, DMDOK; Jayawardena, CL
In Sri Lanka, Geological Survey and Mines Bureau (GSMB) imposed royalty levy for aggregate production volume using an equation (indirect method) which utilises the quantity of explosives for the calculation. Since the equation resulted in higher deviations and the previous studies emphasise the advantages of photogrammetric 3-dimensional (3D) modelling (direct method) when determining production volume of bench blast, the present study focus on investigating its applicability to irregular faced dynamic quarry with uneven overburden. Pre and post 3D Digital Surface Models (DSMs) of the quarry were generated using the structure from motion (SFM) algorithm with Real-Time Kinematic (RTK) positioning system and Pix4D mapper software. Golden Software Surfer 16 was used to determine depleted rock volume as the difference between pre and post 3D DSMs. Results indicate a 5.50% deviation of the proposed method from true depleted rock volume determined by truck measurements due to uncleaned quarry face during the pre-Drone survey and unaccounted soil overburden removal. Presence of overburden while generating DSMs can be overcome by pile volume estimation of overburden and decreasing it from depleted rock volume when calculating production volume. GSMB equation calculated production deviate -32% from true production due to the unaccounted explosive amounts which contributed to the production and confirm the suitability of the proposed direct method (5.5% deviation) for determining the depleted rock volume in open-cast mines.
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Determination of percentage of mineral in beach sand using digital image processing techniques
(Department of Earth Resources Engineering, 2015-07) Abeyrathna, PMDGSK; Bandara, IMMS; Ranaweerasinghe, GA; Tharmakulasingham, K; Rohitha, LPS; Hemalal, PVA
Determination of percentage ofmineral is extremely important in beach sand mining industry. To select a site for extraction and processing heavy minerals it is important to assess the rough concentrations. The traditional methods are time consuming, costly, high labour intensive and difficult to handle the equipment. A method was developed to determine the percentage of minerals in raw sand by Digital Image Processing. HSV colour space was selected due to its wide range when compared to other colour spaces. Non over lapping samples were analyzed in this research. Most appropriate background was selected using colour analysis of HSV values. Background was differentiated from the minerals by using HSV values. By analyzing the pixels, area occupied by the minerals can be determined and using weight to area relationship, the weight percentage of minerals can be identified. Validation was carried out and using the statics accuracy was estimated. There are some limitations despite the benefits.
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Determination of the Specific Charge in Sri Lankan Quarrying Industry and Tunnelling Practice
(2015-08-14) Fainaz, MIM; Premathilaka, SDNN; Faslan, ACM; Gayan, WAMS; Gugathasan, N; Hemalal, PVA; Dharmaratne, PGR
At present, Sri Lanka is investheavily on the development of the country’s infrastructure., facilitating the vast demand for construction materials particularly, aggregate metals. Blast fragmentation is one of the most important aspects in open pit blasting. Blasted rock should be easily loaded and transported and the rock fragments should be adequately pre-conditioned (i.e. weakened) in order to reduce the energy requirements in down-stream processes such as, crushing and grinding. In Sri Lanka, the geological parameters of rocks vary throughout the island. Currently, there is a large number of metal quarries and mining activities operating all over the country, but the lack of optimum blasting practice and specific charge selection is a drawback to achieve the optimum benefits. In this research, an investigation on specific charge values have been carried out for the required level of fragmentation in quarrying industry and tunneling practice throughout Sri Lanka depending on geological parameters varying from region to region. Rock sample collection from various geological locations, determination of rock strength and hence, building-up a relationship between rock strength and specific charge values, experimentation of a fragmentation model have been carried out.