Departmental Conferences

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Browsing Departmental Conferences by Conference "ERE 2009"

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    Calcite and dolomite mineralization in the area around Balangoda and critical analysis of mining methods and utilization of the deposits
    (2014-08-08) Jayatissa, MDCP; Urapola, MOA; Perera, PAAP; Chandrakumara, GAK; Weerawarnakula, S; Abeysinghe, AMKB
    Among the industrial minerals found in Sri Lanka Calcium and Magnesium Carbonate bearing minerals and rocks play a major role in local industry. Crystalline Dolomite and Calcite found in metamorphic terrains are used in ceramic industry, fertilizer industry and in local lime manufacturing plants. Major Calcite and Dolomite occurrences in the metamorphic Precambrian basement are found in Digana, Kekirawa, Polonnaruwa, Balangoda, Baddulla, and Okkampitiya. Studies carried out in the area around Balangoda showed the calcite and dolomite occurrences are located in the area of Illukpellessa, Rajawaka and Molamure. Legal and illegal small scale mining has been carried out in the area during last few decades. Studies also showed most of the mining is carried out haphazardly. No proper mining methods have been used for maximum utilization of the deposits. Furthermore, long term mining has not uplifted the socio-economic conditions of the people of the area and proper environmental protection methods have also not been used. Systematic mapping of the deposits, educating miners on proper mining methods, safety precautions and value of environment protection could lead for better utilization of the deposits. Proper financial guidance through possible co-operate system to obtain financial assistance for mining, transporting materials and finding systematic market for continuous material supply could also uplift the socio-economiccondition of the community.
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    Design and fabrication of cable bolt for excavation in a fractured rock
    (2014-08-08) Dhanawardana, YLC; Siriwardana, HDPM; Henderson, SH; Kumara, HMCP; Indika, KAS; Dharmaratne, PGR; Welideniya, HS; Rohitha, LPS
    In fractured rock masses, large excavations have an unsupported stand-up times Jess than the minimum time required to support the roof after the excavation. Therefore, the principal objective in the design of a support system is to help the rock mass to support itself. The use of rock bolts is a very flexible supporting method that can be combined with wire mesh, shotcrete and concrete lining. During past years a wide variety of dowels and bolt types were developed but most of them failed within a short period and the cost were high. Advantages of cable strand supports have been well documented and include flexibility, strength, and ease of installation. Main objective of this project is to design rock bolts using discarded wire ropes 01' cables at a low cost. A detailed designing methodology was carried out to fabricate this bolt. The bolt consists of nearly 1.6m long cable and 16 em of anchored part and cable tightening part. Outer diameter of bolt is 33 mm and inner diameter is 12 mm and used cable diameter is Smm. Field data illustrated the amount of load measurements that the bolt can carry is 5 kN, Suggestions were made to improve the design, which will enhance bolt performance. Field tests carried out at Bogala Lanka Graphite Ltd proved that cable bolts are effective in Sri Lankan conditions.
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    Determination of uniaxial compressive strength using point load index of high grade metamorphic rocks from western Sri Lanka
    (2014-08-08)
    This research is focused on finding the correlation of unconfined compressive strength (UCS) with Point load Index (PU) of gneissic rocks, and to propose proper correlating value, based on a study carried out for Sri Lankan Gneissic rocks. There has been an increasing use of the PU as a measure of :rock strength since its introduction in 1972. The small size and the simplicity of the point load tester have led to its use on site in many projects. The rock samples were obtained from three rock quarries in the Western Province. Using the results of laboratory testing of gneissic rocks under point loading as well as in Uniaxial Compression, and statistical analysis, different conversion factors relating UCS and PU are determined for each quarry. The sample preparation and testing arc conducted according to the ASTM code. Exactly 206 individual test results, from 3:1 distinct rock units were used. The conversion factor between UCS and PLI of the study is found to be between 9 and 14. The results of the study are useful to find the strength of rocks conveniently through point load testing
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    Development of a flood hazard zonation map fur "Kalu Ganga" basin by GIS modelling
    (2014-07-01) Welivitiya, WDDP; Jayasingha, JMHCB; Musheen, MK; Saputhanthri, SV; Samaranayake, TDNT; Seneviratne, A; Dissanayake, DMDOK
    "Kalu ganga" (river) is one of the major rivers in Sri Lanka situated in south-western part of the country. Kalu ganga basin area is a highly populated area comprising urban centres and agricultural fields. River floods frequently occur in this area resulting severe damage and destructions. Local planers, decision makers and disaster relief organizations lacks accurate information on the spatial distribution of flooding and the land-use types. Only minimal efforts and resources have been allocated to deal with this problem. The objective of this research is to develop flood hazard zone maps for the Kalu ganga basin area in a Geographic Information Systems (GIS) environment. The applied methodology is comprised of 5 phases. They are preparation phase, fieldwork and data acquisition phase, modelling and flood hazard map generation phase, validation phase and reporting phase. According to the generated flood hazard map, Kuruvita, Elapitiya and Rathnapura divisional secretariats have the highest risk of flooding. Most divisional secretariats in the western province exhibit low or moderate risks of flooding. According to the analysis of flood hazard map with land-use classes, 2307hectares of residential areas and 5568 hectares of agricultural fields were found to be at high risk of flooding.
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    Development of oceanographic information dissemination system; an application of web GIS
    (2014-07-01) Senevirathne, AMNKBl; Pathirage, PU; Wijerathne, HKP; Kuhatheepan, S; Kuperajah, NI; Rajapaksha, JK; Abeysinghe, AMKB
    It is an essential requirement to promote offshore fishing activities systematically to protect the coastal fishery resources, which are in optimal level of exploitation. One of the alternatives available is to divert coastal fishing effort to offshore by providing information on offshore fishing grounds and favourable environmental parameters. Objective of this present study is to implement web GIS (Geographic Information System) as a supporting tool to transfer the satellite derived favourable environmental parameters for fish aggregations to the end user. In this study, satellite data were processed using remote sensing and GIS software and the web GIS application was developed using open source Map Server, PostgreSQL, PostGlS and Mapbender software. Four models were developed to process the raw data and processed data are uploaded weekly to the World Wide Web to enhance fishing activities. Potential fishing grounds, sea surface temperature (SST), chlorophyll (<""1-:(Lse),a surface height (SSH), ocean currents, bathymetry, exclusive economic zone and fishery harbour locations are displayed in the web GIS interface. Viewing, zooming, panning, distance measuring, displaying coordinates and attributes and load WMS(Web Map Service) functions are enabled to provide a dynamic framework to the user,
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    Editing a digital elevation model to achieve, a correct stream network: an application to , " Kalu-ganga river in, Sri Lanka
    (2014-07-01) Nandalal, HK; Ratnayake, UR
    Modelling a watershed accurately is an important step in water resources management. Geographic Information Systems (GIS) together with mathematical models have made modelling watersheds an easy task. Digital Elevation Model (OEM) is a primary data set necessary to model a watershed. OEMs are developed using many methods and OEMs developed from remotely sensed data are the cheapest. Some of them are freely available on-line. In modelling watersheds, it is a common practice to delineate the stream network from a OEM.Matching of the delineated stream network with the natural stream network will depend on the accuracy of the OEM. Some hydrologic models contain built-in functions to edit . OEMs to overcome this problem. Hydrologic model, HEC GeoHMS, contains such a function to edit OEMas-required by the user. To edit the OEM it is necessary to have the exact stream network to compare with the delineated network. In this work, Kaluganga River stream network was delineated using a OEM available freely on-line and it was compared with the natural stream network of Kalu-ganga River digitized from 1:50,000maps produced by the Department of Survey. Then the OEM was edited using the HEC GeoHMS model to achieve the desired stream network.
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    Effects of joint orientation in tunneling
    (2014-08-08) Selvasekaran, R; Appuhami, KAIS; Kumarasiri, SAI; Fernandopulle, SN; Lakmal, HMAG; Dharmaratne, PGR
    This research is focused on the effects of joint orientation with respect to the direction of tunnel axis. It is expected that the stability of surrounding rock is affected by the strike and dip of the joints and the direction of the tunnel axis, whether it is with the dip or against dip etc. similarly the spacing of joints will also affect the stability. The orientation of joints in different directions can form blocks liable to fall. The objective of this research project is to determine the degree of influence of joints' strike and dip orientation in tunneling. Field works related to this project was carried out at the Bogala Graphite Lanka Ltd. Tunnel mapping and other observations related to the project were made at 489.6m level in Bogata mine. Models were made with joint spacing of 15mm with two joint sets (joint sets parallel to tunnel axis and joint sets perpendicular to tunnel axis). Tunnels were created with 90mm diameter with dip angles of joints are 00,300,600,and 900. The tunnels models are loaded using UCS machine and observed the behavior of rock mass around the tunnels during loading. From the results the most preferable dip angle for the joint strike perpendicular to the tunnel axis would be the 900 and for the joint strike parallel to the tunnel axis would be 00.
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    Hydrological analysis of Sooriyawewa area using remote sensing and GIS techniques
    (2014-08-06) Senanayake, IP; Dissanayake, DMDOK; Puswewala, UGA
    Sri Lanka is traditionally divided into three main zones namely Wet Zone, Intermediate Zone and Dry Zone according to the average annual rainfall. The dry zone of Sri Lanka is very often faced with severe drought conditions and the situation is becoming worse as time moves on. On the basis of surface water availability, Hambantota area, which falls with in the dry zone, appears to be a heavily affected area. Proper water management systems as well as preservation of existing surface and ground water resources and recycling are essential measures to overcome this problem. Hydrological analysis of the area is needed for a proper water management system. Integration of Remote Sensing and Geographical Information System (GIS) techniques provides a reliable, accurate and updated database on land and water resources, which is a pre-requisite for a proper water management system. Sooriyawewa was selected as the project area considering the average rainfall variations in Hambantota District. The spatial data based hydrological conditions such as, flow direction, catchments, drainage lines, drainage points, etc. were interpreted in the area. The hydrological condition in Sooriyawewa area is adequately delineated using these techniques, as pre-requisite to a proper water management system.
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    Impacts of salt water intrusion on construction aggregates of 'Kalu Ganga' estuary
    (2014-08-08) Silva, KBA; Kumara, IGIK; Rathnayake, NP
    'Kalu Ganga' is one of the main suppliers of river sand (113,360 cubes per year) in the country. Due to the continuation of sand mining, salt water intrusion has been increased over the years. The focus of the current research is to understand impacts of salt water intrusion on river sand and to understand whether the absolute chloride content of mined sand is within permissible level (0.075% Cl-) for the construction purposes. Two surveys were conducted along 'Kalu Ganga' estuary (10 km from river mouth) in predetermined intervals to measure depth, conductivity profiles and to collect sediments samples. Survey dates (16/12/2008 and 12/03/2009) were selected considering the maximum difference of tide and rain fall. The sand samples were ana lysed for Ct- content. Results showed significant salt water intrusion even during dry season ("'2300 IlS/ cm). All measured conductivity values were similar to the conductivity levels observed at the sea mouth. But du:ring dry season the CI- content of sediments is relatively high at river mouth. However, during rainy season, measured salt water intrusion levels were dropped down remarkably ("'200 IlS/ cm) and even at the sea mouth, sediment samples showed significant low values of absolute Cl- content (0.0176%). Therefore, it is recommended to extract sand from O.5km from the sea mouth only during rainy season. This will also control the flooding in Kaluthara area. However, further studies are necessary for understanding other environmental effects of river sand mining near the sea mouth.
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    Operational hydrodynamic numerical model covering Sri Lanka waters
    (2014-08-08) Girihagama, RWRHMRLNK; Dissanayake, DMSS; Wijerathne, EMS; Rathnayake, NP
    As a part of ongoing project on development of operational hydrodynamic model covering Sri Lanka Waters and Northern Indian Ocean (67.5- 99.5 E and 1.5 S to 24.5 N), we employed a Princeton Ocean Model, NOAA (POM 08) to simulate wind driven circulation, sea surface topography, sea level setup, upwelling and possible storm surge conditions. The JEBCO0.5 min bathymetry was interpolated to generate high resolution horizontal and vertical grid domain. For the model initial salinity and temperature data were extracted from World Ocean Atlas 2005 (WOA '05). Seasonal wind driven circulation simulations were carried out by forcing monthly mean NCEP climatologically winds. Experimental model runs were carried out with different wind speeds and directions to examine the possible storm surge conditions. The model runs with SW winds reveals significant sea level setup on the Bangladesh coast. The model results of SSH are compared with observational data from the TOPEX altimeter. The model successfully captures many of the important circulation features observed in the region. This includes the reversing wind driven circulation, upwelling off south of Sri Lanka during SW monsoon, strong currents south of Sri Lanka. The long term goal of this project is the establishment of an operational hydrodynamic model to forecast physical process including storm surge conditions covering Sri Lanka Waters and Northern Indian Ocean.
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    Selection of an effective substrate to treat gray water in horizontal flow constructed wetlands
    (2014-08-06) Thirukumaran, AK; Ehamparam, S; Darmini, S; Karunarathne, S
    A study was carried out to compare the performances of different substrates used in a laboratory scale subsurface flow constructed wetland systems to treat gray water released from the university staff canteen. Three wooden boxes with the dimensions of 60cm x 25cm x 25cm were fabricated and 15mm rock aggregates, pebbles (15mm) and broken tiles (25mm) were used as substrates (which were selected considering the availability) in each of the boxes. Each horizontal subsurface flow bed was fed in a batch process with gray water with a flow rate of 20 litres per day. The retention time for each batch was maintained as 6 days. BOD, COO, pH, conductivity, N03-, P043-, turbidity and temperature in the influent and the effluent were monitored for every batch of waste water passed through the systems and their removal efficiencies were determined. The highest removal efficiencies of COD and, BOD,and P043- were 80%-90%and 60%- 80%, respectively were recorded from broken tiles, while highest removal efficiency of N03-, of 60%- 90%, was recorded from aggregates. Removal of turbidity in all three tanks was similar being between 60%- 90%. Hence, crushed aggregates and broken tiles are found to be the best substrates, considering the removal efficiencies to treat gray water.
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    Ventilation of underground workings and improvement of comfort levels
    (2014-08-08) Hewage, SC; Rajapakse, RAAC; Rathnayake, RMD; Prasanna, EAP; Dissanayake, DMAK; Dharmaratne, PGR; Welideniya, HS; Rohitha, LPS
    Ventilation of underground mines is required to dilute and remove hazardous gases, control heat and provide oxygen for workers and machinery. Kahatagaha- Kolongaha mines, Dodamgaslanda was selected for the present study as it was restarted recently and therefore very little research has been done on air quantity and quality of the mine. The objectives of this research are to make a proposal to rectify the existing ventilation system and to upgrade the existing airflow system with modifications to the present system. A detailed ventilation survey was carried out by measuring the variations of airflow, pressure drop and humidity differences along four levels of the mine (i.e. 565ft, 805ft, and 965ft and 1132ft levels) and compared with the corresponding standard values which describe the permissible conditions to be met for working underground. The distributions of airflows, pressures and humidity in each level could be detailed on graphs and the areas where the additional air supplies were identified. It was proposed to install a dehumidifier to reduce the humidity level inside the mine. Suggestions were made to improve the present ventilation system by locating two booster fans in level 565 ft and 805 ft, which will enhance mine air quality increasing health and safety aspects of underground environment.