International Symposium on Earth Resources Management and Environment

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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 seasonal impacts on groundwater quantity and quality in upstream of Malwathu Oya Basin
Madhushankha, JML; Madhuwan, ARB; Menan, P; Chaminda, SP; Abeysinghe, AMKB; Jayawardena, CL; ; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y
Malwathu Oya Basin which covers 2350km2 located in Anuradhapura district is considerably populated and the safety and the available quantity of water is crucial for the people. Water samples were collected from selected locations during South- West monsoon period, Second Inter monsoon period and North-East monsoon period from September 2016 to March 2017. The samples were analysed for pH, turbidity, conductivity, fluoride, chloride, magnesium and calcium as basic drinking water quality parameters. Only the shallow regolith aquifers are considered for the study. The groundwater quality variation of the area shows a considerable variation from dry season to rainy season in general water quality of the area, and is in acceptable limit for most of the basic parameters. With the seasonal changes Fluoride and Chloride content is higher than permissible limits in some areas.
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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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Demand estimating model to forecast the building material requirements for the construction and allied industries in Sri Lanka
Maduranga, WWDD; Nithushan, N; Jayasinghe, JKSN; Dissanayake, DMDOK; ; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y
Over the past few years, there has been a high level of interest in modelling demand estimation for the construction and allied industries in Sri Lanka. Demand estimation is a process that involves coming up with an estimate of the level of demand for a product or service and, typically confined to a particular period of time, a month, quarter or year. Demand estimation methods can be categorized into two main categories according to the technique applied to analyse data. Different approaches are survey methods and statistical methods. For a good quantitative analysis, statistical methods are more preferable. Regression analysis method which comes under econometric statistical method is more preferable to develop demand estimation models since it has high accuracy level. In the regression analysis, there are two methods to develop the model. These are Single Regression Analysis and Multiple Regression Analysis. The few steps to develop the estimation models are statement of a theory or hypothesis, model specification, data collection, estimation of parameters, checking goodness of it, hypothesis testing and forecasting. In this project, there are two models for sand and ABC materials each and the first model is for dust and ¾ particle size. Developed model for chip particles was rejected due to inaccuracy of the unavailability of required data. In validation, sand and ¾ particle size have shown very high accuracy when as dust and ABC has shown quite lower accuracy.
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Development of a methodology to map railway lines and surrounding land use using UAVs
Manatunga, UI; Munasinghe, N; Premasiri, HMR; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y
High accurate railway maps and terrain information (Digital Elevation Models) is a major concern for future railway constructions and railway lines development.The mapping of railway line using ground based surveying techniques istime consuming and problematic.Unmanned Aerial Vehicles (UAV) technology has revolutionized the aerial photogrammetric mapping due to its low cost and high spatial resolution. It enables mapping the land use with greater accuracy in both 2D and 3D. The “DJI Phantom 4“ drone was selected as the UAV platform to acquire image data. In this study, we have developed a fully automated and highly accurate engineering approach for detecting land use and railway line, which is based on textural information from orthophoto and elevation information (Digital Surface Models)obtained from the drone.The Pix4D software was used to develop the orthophoto and a Digital Surface Model (DSM) and the DSM was validated by using the ground control points.The rule sets knowledge-based classification method in object oriented classification was used to classify the land use and railway with the use of “eCognition“ software. Finally, the results were compared with digitize land use layer to validate the results, and obtained overall accuracy of 90.15%.
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Key factors of metastable phase formation for strength development in steel slag and dredged soil mixtures
Toda, K; Otake, T; Sato, T; Sato, H; Weerakoon, N; Nishimura, S; ; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y.;
The usage of by-products from industrial activities, as construction resources is awaited in Japan to decrease the environmental impacts. Steel slag from ironworks and dredged soil extracted beneath the ports are examples for such resources. Recently, it is discovered that mixtures of steel slag with dredged soil are hardened. This discovery may expand their application into building materials for undersea construction which may solve the problem. Nonetheless, different combinations of a type of steel slag and dredged soil from various areas show gaps in strength development. The relationship between mixing condition and strength development is not clarified, making the mixture difficult to be utilized for the above application. Understanding of the hardening mechanism of the steel slag-dredged soil mixture would enable the prediction of the strength with a particular combination of steel slag and dredged soil. To achieve it, clarifying the secondary mineral formation that contributes to hardening is essential. Previous studies suggested that the strength development was related to the pozzolanic reaction, which results in cementation by the formation of calcium silicate hydrates (C-S-H). Key factors in the pozzolanic reaction are the increase in pH of the pore water and the supply of calcium and silica ions to pore water. While calcium supply is determined to be Ca(OH)2 in steel slag which also increases pH by its hydration, silica supply is only suggested to be originated in dredged soils. The objective of this study is set to understand the effects of silica-bearing phases in dredged soil on the strength development of steel slag-dredged soil mixture. In this study, dredged soils from various sampling locations (A, B, C and D) and steel slag from ironworks-1 were mixed for the investigation. The unconfined compressive strength showed mixtures with soil-A exhibits the highest strength, followed by those with B, C and D. Firstly, the silica ion which is most likely to be supplied from dredged soils was investigated. The biogenic silica content and inorganic amorphous silica such as volcanic glass content were quantified. XRD analysis showed no significant difference between the mineralogical compositions of all the dredged soils including clay minerals. Then, the effect of humic acid which may limit the supply of soluble calcium is quantified and its functional groups are analysed to see the effect on strength development of the mixtures. Through geochemical modeling for estimation of C-S-H formed from above silica supply, we suggest that the silica supply from each silica-bearing phase of dredged soils may be the driving force for the pozzolanic reaction for the strength development.

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