Browsing by Author "Peiris, TA"

Now showing 1 - 9 of 9

item: Article-Abstract
A system for land development approval management using geographic information systems : A case study of Thimbirigasyaya Ward, Colombo
Leelananda, HH; Wijesekera, NTS; Peiris, TA
In a developing Country like Sri Lanka, it is very important to plan and manage its land development programmes to attract investments to develop land resources. In this context special emphasis should be given to urban areas. The prevailing systems of issuing preliminary land development clearance by the Urban Development Authority (UDA) which is based on a manual filing system consumes significant time and is unable to provide alternative solutions to prospective developers. Most of the countries use Geographic Information Systems (GIS) for similar land management work. A study was carried out, selecting Thimbirigasyaya ward of Colombo Municipal Council (CMC) to develop a GIS based land data management system in order to carry out the management of the land clearances in an efficient manner. Land parcel information obtained from CMC and UDA were scanned, spatial data were georeferenced and a mosaic was constructed. Input data were subjected to accuracy checks and were verified. Accuracies of data duplication, length, extent etc., were found satisfactory and adequate for UDA land clearance work. The database also incorporates the UDA conditions stipulated for location, zone and regulations enabling the checking of applications. The developed land information system was designed to include all functional aspects in the previous systems and additional capability to provide alternative solutions. The system developed using GIS was verified for computational accuracy using manual calculations. Adequacy checks were done with respect to the approved regulations. The developed Land Management Information system reduces the application processing time from 40 days to 5 days enabling quick decision-making. Present day IT tools such as Geographic Information Systems enable easy management of land parcels and possesses capability to overlay and analyze special data with minimum time. The present study highlights the data and accuracy requirements of the methodology to develop spatial databases for land development management. It also provides alternative solutions and can be used for land management policy analysis
item: Thesis-Abstract
Application of geographic information system for land clearances in the city of Colombo Sri Lanka
(11/30/2011) Leelananda, HH; Wijesekera, NTS; Peiris, TA
The study aims to improve land clearance processes in Urban Development Authority (UDA) with the support of Geographic Information Systems. The objective is realized through the conduct of geographical analysis, query, and modeling. The study takes Thimbirigasyaya Ward in the City of Colombo as a case for developing the land clearance system. UDA is the main Government Agency dealing with physical planning in Sri Lanka. The primary activity of the UDA is the preparation, implementation, and maintaining of National Physical Plans, Regional Structure Plans, and Local Development Plan within its declared areas. A study is done to understand the context of land clearance processes in UDA and to develop a digital system for land clearances. The study takes a critical look at how UDA practices land clearances and monitoring, and applies information technology tools to support such functions. It reviews UDA regulations and identifies issues in land clearances and database management. The method that has been exercised in developing a Land Information System (LIS) is basically in three forms. They are (1) Identifications of shortcomings in the present system. (2) Identifications of targets. (3) Finding ways in reaching the targets. Collection of data is first subjected to detailed study in order to find its accuracy and a database has been to developed using data layers and attributes by converting analog maps and statistical data into digital form. Then land information were tested and verified for its accuracy. Selection of the study area was done through a suitability analysis and availability of updated data. A model was then developed using GIS tools, its data accuracy was checked and found that the results had been in proper order. The developed LIS was compared with the existing processing system and was proved effective. The accuracy of the data is very important in the process of developing a good LIS. In this study checks were carried out to ensure data accuracy. Numerical checks including stepwise calculations and field measurements were done to verify the model. The system developed using GIS has a significant advantage over the existing system. Clear improvements were visible in the area of labour and time saving and also in the provision of alternative solutions. System output identified the present distribution and use of land parcels. This gives rise to the need of establishing norms for rational decision making. UDA is basically benefited by this system on followings. (1) Serve as platform to integrate data and facilitate data exchange, (2) provide immediate access to data, (3) spatial analysis for selection of alternative sites, and (4) easy decision-making.
item: Conference-Extended-Abstract
Consolidation testing of peaty clay
(2003) Kugan, R; Puswewala, UGA; Kulathilaka, SAS; Peiris, TA
The first rational theory to explain the settlements occurring in saturated clays was the 1- D theory of consolidation proposed by Terzaghi (1925). One of the main advantages of the theoretical modelling of consolidation is that it becomes possible to carryout laboratory tests on thin samples of clay. a few centimetres thick (with one increment of load normally maintained for 24 hours). and then from the laboratory results predict the settlements in the field where the clay layer may be several meters thick and where the settlements may take place over a long period of time.
item: Conference-Extended-Abstract
Deformation analysis in model soil slope studies
(2003) Rathnasiri, RM; Peiris, TA; Puswewala, UGA
In model soil slope studies as related to Geotechnical Engineering. the engineers arc interested in the failure surface and the maximum shear strength developed there upon failure. Monitoring the displacements and strains developed in the soil body during deformation. as a result of either surcharge loading or changes in the pore water pressure. holds a significant importance in Geotechnical Engineering. for example in investigations related to foundation engineering.
item: Conference-Full-text
Methodology to demonstrate pile capacity In relaxing ground
(2013-11-15) Peiris, TA; Morris, B; Kelly, R; Chan, K
Driven pre-stressed concrete piles have been used as a foundation system to support abutments and piers of a bridge constructed near Ballina in New South Wales, Australia. In order to achieve the required geotechnical capacity, the piles were required to be driven through soft clay and sand to moderately weathered rock. Pile Driving Analyser (PDA) testing together with CAPWAP analysis was performed to assess the integrity and geotechnical capacity of the driven piles. Pile damage was observed during driving. To prevent damage a rock shoe was retrofitted to the piles prior to installation. Reductions in pile capacity (or relaxation) were observed between end of drive (EOD) and later restrike testing (RST). A substantial amount of additional pile testing was performed at different times after driving to assess the changes in pile capacity over time. Most piles were re-driven to achieve higher capacity. Pile capacity could not be achieved in one pier and additional piles were installed to reduce the required pile test load
item: Article-Abstract
Potential of urban land management using geographic information systems: A study of Thimbirigasyaya ward Colombo
Leelananda, HH; Wijesekera, NTS; Peiris, TA
With the population growth and associated high levels of urbanization, sustainable urban development has become a critical issue in Sri Lanka. A land information management tool was developed for the Thimbirigasyaya ward of the Colombo Municipal Council (CMC) Sri Lanka using a Geographic Information System incorporating multi layer analysis. The layers incorporated contained the spatial distribution of land parcels, buildings along with zoning details established by the Urban Development Authority. This paper presents the potential of the GIS based system for rational land parcel management by considering various scenario with respect to the presently available zoning, zoning regulations combining with land parcel and building information. Potential use of GIS for Land Management in the Colombo city including real estate development and also drainage improvement is discussed. Proposals are made for the decision makers to take into consideration when executing responsible action. In the analysis it was identified that the Primary Residential Zone meant for high rises is mostly of low rises and there is a significant potential for development. Overlay operations enable a manager to identify amalgamation options to suit the land development policy of the UDA. The tool also demonstrates the identification of old buildings that may be worthy of demolition to make room for planned development. The tool also enabled the identification of main user types within identified zones so that a decision maker could propose better economic use of land through means of relocation. This casestudy presents not only the importance of land clearance management but also the vast potential for policy making and rational management.
item: Conference-Full-text
Prediction settlements of foundations on soft soils - a case study
(1999) Thilakasiri, HS; Peiris, TA; Tennakoon, BL
Excessive settlement of engineering structures and subsequent correction procedure have become a major concern for both the public and the engineering community. The severity of the above problem has increased due to the use of more filled marshy lands for construction. If one studies the problem of excessive settlement of most domestic structures constructed on fills, it could be clearly attributed to the violation of fundamental engineering principles. Lack of engineering knowledge and judgement or sheer negligence of basic engineering principles could be main reasons. If a structure is to be constructed on soft grounds it is clear that the ground should be improved before the construction or the construction procedure should be phased out in such a way that the final settlement, more importantly differential settlement, is within allowable limits for that particular structure. Pre-loading (with or without sand drains), replacement of the soft soil with good material, dynamic replacement and electro-osmosis are some of the methods used for improvement of clayey or peaty deposits. Of the above methods, pre-loading is widely used due to its economy and simplicity. Important considerations in pre-loading are: duration of pre-loading; height of pre-load heap (surcharge load) and the monitoring of settlement experienced. In this paper a case study of construction of a building in marshy lands violating some basic engineering principles is presented. Use of some basic soil properties together with in-situ testing (e.g. Standard Cone Penetration Test) to predict the ultimate settlement under the pre-loading is illustrated. Furthermore, the rate of settlement, an essential component of the pre-loading design, is obtained by curve fitting the settlement data while the pre-loading is in progress. This method of using basic soil properties together with in-situ tests to predict ultimate settlement and curve fitting data to predict the rate of settlement does not require the almost impossible process of obtaining undisturbed soft soil samples for laboratory testing.
item: Thesis-Abstract
Simulation of deep excavation using finite element method
Jayakody, NJ; Peiris, TA
Finite Element calculations are frequently used in the design of deep excavations because prediction of ground movements and wall deformation is not possible with classical limit equilibrium fixed earth support and free earth support methods. To solve such geotechnical boundary value problems successfully, appropriate constitutive laws should be used for the description of mechanical behaviour of the soils. Two possible behaviour of soils can be categorized as those with a constitutive law based on plasticity and those based on elasticity. A key distinction between the plasticity and the elasticity group is that in the latter, strains are recoverable upon decrease in stresses, where as in elastoplastic models strain are only partly recoverable. A crucial point in making the choice of a suitable soil constitutive model is the ease with which values can be assigned to the model constants. The level of investigations carried out and the type of data available is another factor. Considering the above points mentioned, the study summarizes the application of a simple linear elastic model and a non linear elastic [Hyperbolic] model for modeling the 15m deep base excavation supported by an anchored secant bored pile wall. Finite element software SIGMAW is applied for a 2-D plain strain type analysis. The mechanical behaviour of the soil is modeled with linear and non linear elastic constitutive model using reasonable soil parameters, derived through limited tests. The actual excavation was carried out in 4 steps. Pre-stressed anchors were used as additional supports, just before each excavation step. The wall deformations were obtained through inclinometers installed at several locations. The FEM simulation was carried out in this research and the computed and observed deformation patterns were compared.
item: Conference-Full-text
Simulation of deep excavations using finite element method
(2001) Jayakody, NJ; Peiris, TA
Finite Element calculations arc frequently utilized for the design of deep excavations because a prediction of ground movements and wail deformation is not possible with classical limit equilibrium methods. To solve such Geotechnical boundary value problems, appropriate constitutive laws are necessary for the description of mechanical behaviours of soils. The possible combinations of these behaviours are divided into two groups; those with a constitutive law based on plasticity and those without. The latter group contains linear elasticity and variable elasticity. A key distinction between the plasticity and the elasticity group is that in latter, strains are recoverable upon decreases in stresses, where as elastoplastic models strains are only partly recoverable. A crucial point in determining the choice of a suitable soil constitutive model is the ease with, which values can be assigned to the constants defining it. With considering those pointed above, this paper summarizes the application of simplest linear elasticity analysis for convenience for modeling 15m deep base excavation supported with bored pile wall. Finite element software GEO SLOPE/SIGMAW DEFINE is applied for 2-D plain strain analysis. The mechanical behaviour of the soil is modeled with linear elastic constitutive model using reasonable soil parameters. Excavation was carried out in 4 steps, pre-stressed anchors were used as additional supports, just before each excavation step. The FEM simulation was carried out to compare the computed and observed pattern.