http://ir.lib.ruh.ac.lk/handle/iruor/20784 Sun, 26 Apr 2026 15:44:55 GMT 2026-04-26T15:44:55Z http://ir.lib.ruh.ac.lk/handle/iruor/20789 Use of contingency to control the cost overrun in Sri Lankan high-rise building projects. Weerasinghe, W.M.H.N.; Jayasuriya, D.M.S. Cost overruns are commonly encountered in construction projects worldwide, and they are especially recognized in Sri Lankan high-rise building projects. The study focuses on effectively allocating contingencies amidst the uncertainties encountered in these efforts. Contingency allocation in Sri Lanka appears to be theoretically well-founded but is limited in practical implementation. This research aims to address this issue by accurately allocating contingencies in these projects, taking into account the uncertainties they face. Although contingency allocation has a solid theoretical foundation, its practical application seems to be limited, particularly in Sri Lanka. A mixed-method research approach was adopted. The results of the study highlight the primary reasons for cost overruns in high-rise building projects, including fluctuations in material costs, poor project management and planning, and construction delays. The previous study also reveals that despite the availability of other methods, percentage allocation remains the most commonly used technique for determining contingency in the industry .The study identified a lack of understanding and regulatory support for modern contingency methods, recommending accurate cost estimation and effective measures to control cost overruns in high-rise construction projects. Addressing these challenges suggests seminars, workshops, and industry-specific modules at universities in Sri Lanka. Tue, 01 Apr 2025 00:00:00 GMT http://ir.lib.ruh.ac.lk/handle/iruor/20789 2025-04-01T00:00:00Z http://ir.lib.ruh.ac.lk/handle/iruor/20788 Laboratory Analysis of Identifying Influence of Vegetation, Bed Type, River Regulation on Microplastic Transportation in Open Channels. Wijeratna, D.D.D.S.; Fazi, A. Zakib; Gomes, Pattiyage I.A. The intricate dynamics of microplastic transport in open channels involve factors such as water flow velocity, turbulence, water depth, sediment characteristics, particle size, and channel morphology. In this context, a laboratory study was conducted to explore the influence of different factors on microplastic transport, including vegetation patterns, discharge rates, microplastic types, bed type, and the impact of dam structures. The experiment was done using three different microplastics ranging their densities from 910 to 1350 kgm-3. Hydrilla was used as vegetation in three different patterns along the open channel bed to find the influence of vegetation density and pattern. The effect of different bed types and two dam structures were used representing river regulation to monitor microplastic transportation. Overall microplastic transportation was directly correlated with discharge under all conditions except for denser microplastics in gravel bed condition. There was a significant influence of vegetation pattern rather than the vegetation density in retaining microplastics. The study showed that dam structures allowing seepage flow was more effective in retaining microplastic rather than dams allowing overflow. This study paves the way to understand the inter relationships between different hydrological and morphological factors affecting microplastic transportation in open channels. Tue, 01 Apr 2025 00:00:00 GMT http://ir.lib.ruh.ac.lk/handle/iruor/20788 2025-04-01T00:00:00Z http://ir.lib.ruh.ac.lk/handle/iruor/20787 Analyzing slope rectification strategies using the shear strength reduction method. Ranasinghe, R.T.; Sampath, K.H.S.M. This study focuses on enhancing the understanding of the effectiveness of sub-horizontal drainage as a slope rectification method and assessing the effectiveness of the shear strength reduction method in practical applications. It compares the results with the limit equilibrium method. Based on the analysis result on the homogeneous slope, sub-horizontal drains are most effective when positioned at the toe of a slope. Furthermore, the research finds that extending drains beyond a 15 m length in the homogeneous slope gradually reduces the rate of increase in the safety factor. Theoretical suggestions indicate that sub-horizontal drains are most efficient when installed at a 0-degree angle. Modeling sub-horizontal drains using these maximum effective drain parameters can increase the factor of safety to 1.394 in the limit equilibrium method and 1.325 in the shear strength reduction method, respectively. The analysis of drain performance has revealed that sub-horizontal drains can effectively improve the stability of the slope during rainfall. The analysis results for the case study on Pinnawala slope indicate a factor of safety of 1.058 and a shear strength reduction factor of 1.04 before installing the sub-horizontal drain. After improving the sub-horizontal drain, the factor of safety increases to 1.202 and the strength reduction factor to 1.2, respectively. Tue, 01 Apr 2025 00:00:00 GMT http://ir.lib.ruh.ac.lk/handle/iruor/20787 2025-04-01T00:00:00Z http://ir.lib.ruh.ac.lk/handle/iruor/20786 Stabilization of Subgrade Using Geosynthetics. Kumara, U.D.M.; Priyankara, N.H. Dealing with weak subgrades in road construction emerges innovative engineering resolutions to challenge their adverse effects on construction durability, safety, and cost-efficiency. Weak subgrades contribute to pavement settlements, resulting in frequent and costly maintenance, reduced load-bearing capacity, and safety risks. Conventional treatment methods cause various challenges such as cost, time, and environmental concerns. This research aims to investigate the effect of geosynthetics in improving weak subgrade performance, considering geosynthetic type and location within flexible pavement structures. In accordance with Sri Lanka’s CIDA guidelines, which regulate a minimum subgrade 4-day-soaked California Bearing Ratio (CBR) value of 5%, this study attempts to develop a predictive model capable of estimating the 4-day soaked CBR value of subgrade soil while taking changes in moisture content into consideration. The research findings exhibit the efficiency of applying geosynthetic layers at the subgrade-subbase interface in dramatic augmenting the ultimate load-bearing capacity of weak subgrades, especially those with 4-day soaked CBR values below 5%. Geosynthetics appear as a promising, cost-efficient, and environmentally sustainable solution to mitigate the challenges associated with weak subgrade soils in road construction, offering the potential for enhanced construction durability, safety, and cost optimization. Tue, 01 Apr 2025 00:00:00 GMT http://ir.lib.ruh.ac.lk/handle/iruor/20786 2025-04-01T00:00:00Z