CERIS - 2012

Permanent URI for this collectionhttp://192.248.9.226/handle/123/18177

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Browsing CERIS - 2012 by Author "De Silva, LIN"

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    Evaluation of soil liquefaction in Sri Lanka - a dynamic approach using geotechnical investigation data
    (Department of Civil Engineering, University of Moratuwa, Sri Lanka., 2012-12) Kumarasiri, C; de Silva, N; Abayakoon, S; Nawagamuwa, U; De Silva, LIN
    Soil Liquefaction is a process, where granular soils below the ground water table temporary lose its strength and behaved as a viscous fluid rather than a solid. The porewater pressure is suddenly increased during an earthquake due to the cyclic loading. The increased porewater pressure is forced the soil particles to suspend in water. As a result, the buildings, utility services, natural substances and other structures are collapsed causing severe damage to the people and the nature. In Sri Lanka, it is rare to find the historical data of liquefaction or related incidents. Recent studies demonstrated that there is a potential for liquefaction in some places of the island. It could be evaluated by using the basic geotechnical investigation data, according to the simplified procedure proposed by Seed and Idriss (1971). This paper is intended to evaluate the liquefaction potential in Sri Lanka by identifying the liquefiable layer thickness, using an extensive geotechnical investigation data base. As per the analysis 384 locations were identified as susceptible for liquefaction with various layer thicknesses out of 3282 locations analysed. Further, the analysis has extended for varied ground water table.
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    Indoor air quality (IAQ) inside a hospital theatre
    (Department of Civil Engineering, University of Moratuwa, 2012-12) Gunaratne, S; Gunatilake, D; Madushanka, R; Perera, TM; Jayasinghe, C; Perera, A; Rajapaksa, S; Nawagamuwa, U; De Silva, LIN
    In this research study, the effect Abstract: of the activities associated with a hospital theatre, on its IAQ has been studied since the theatre staff experience some discomfort while being inside the theatre. In order to evaluate this, variation of Carbon Dioxide (CO:), Carbon Monoxide (CO), Total Volatile Organic Compounds (TVOC) and Particulate Matter less than 2.5 microns (PM25) concentrations inside the theatre were measured and analyzed. Significant variations were observed in the concentrations of CO:, TVOC and CO inside the operation theatre. CO2 concentration inside the room increased at the beginning and end of the surgeries due to high occupant density and also during Laparoscopic surgeries. TVOC concentration was affected by the usage of different chemicals during the surgery. Major effect to the CO concentration was by Diathermy.
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    Study of ground vibration due to rock blasting of metal quarry: a case study
    (Department of Civil Engineering, University of Moratuwa, 2012-12) Madanayaka, TA; de Silva, LIN; Dharmarathne, PGR; Nawagamuwa, U; De Silva, LIN
    This study was carried out to compare vertical and horizontal bench blast(s) at a granitic gneiss rock quarry located in Colombo, Sri Lanka and predict the resulting peak particle velocities of ground vibration levels. To achieve these objectives, particle velocities and frequencies of 38 and 35 blasts respectively were measured in three perpendicular directions for horizontal and vertical bench blasts respectively with the use of Instantel Blastmate II seismographs. In the blasts, Ammonium Nitrate (ANFO)(blasting agent) primed by a Gelatine Dynamite primer were electrically initiated. Scaled distance parameters (Maximum charge weight per delay and distance between blasting points to monitoring location) were also recorded. The extensively used equation for seismic low of propagation proposed by Devine (1962) and Devine and Duvall (1963) was used for the prediction of peak particle velocities. Points were plotted with Peak Particle Velocity (PPV) in Y- axis against Scaled Distance (D/Q03) in X- axis. Regression analysis was performed to define the line of best fit. At the end of statistical analysis, an empirical relationship with good correlation was established for prediction of peak particle velocity. Frequency analysis was also done for dominant frequency and Zero crossing frequency to identify the effect of frequency of ground vibration to structural damages and defining the most suitable type of frequency analysis to define the single frequency value for ground vibration. The established relationship, frequency analysis and result obtained are presented.