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- 저자 : Usama Khalid (검색결과 2 건)
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Khalid Farooq,Zia ur Rehman,Muqadas Shahzadi,Hassan Mujtaba,Usama Khalid 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.1
In this paper, Desirability Optimization Methodology (DOM) is employed to achieve optimum sand bentonite mixture (SBM) based on multiple antagonist macro-geotechnical responses of the compacted SBM prepared using poorly graded sand with the mean grain size around 0.2 mm and bentonite with plasticity index around 157% for the stable engineered barriers (EBs). For this purpose, varying mix designs of SBM compacted at compaction energy of 2,700 kN-m/m3 are initially tested to determine their mechanical properties, volumetric-change behavior, and hydraulic conductivity. The unconfined compressive strength, cohesion, angle of internal fiction, swell pressure, compression index, and hydraulic conductivity are taken as the geotechnical design parameters for the SBM. Mathematical models are developed and statistically validated for these design parameters using sand content (SC) and bentonite content (BC) as the predictors. In addition, models are also developed to predict compression curves for compacted SBMs. Moreover, microstructural evaluation is conducted through scanning electron microscope (SEM) analysis to determine the SBM having a desirable microstructure for stable EB. It is observed that a major shift in the microstructure from medium pores to micro-pores occurs for the BC between 20% and 30%. Afterward, optimization of SBM is carried out by integrating developed models for the geotechnical design parameters in a desirability function (D) algorithm, which is subsequently simulated by setting maximization of strength and minimization of swell pressure, compressibility and hydraulic conductivity of compacted SBM as the goals. A reasonably high D-value is achieved for the SBMs having SC:BC in a range of 74:26 to 78:22 with the highest at 75.63:24.37 against the set goals. This study manifests an effective and pragmatic strategy for designing the SBM for a stable EB considering its antagonist hydraulic, volumetric change, and mechanical responses.
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Sustainable Utilization of Powdered Glass to Improve the Mechanical Behavior of Fat Clay
Hassan Mujtaba,Usama Khalid,Khalid Farooq,Mehboob Elahi,Ziaur Rehman,Hussain Mustafa Shahzad 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.12
Civil engineering infrastructure like roads, bridges, railway tracks, and building structures constructed on fat clay becomes suspicious due to adverse change in the behavior of such soil on interaction with water. To solve such problems especially in underdeveloped countries, application of industrial waste like glass is associated with technical, financial, and environmentalbenefits. Emphasis of current study is to determine the consequences of powdered glass (GC) on mechanical behavior of fat clay. A fat clayey sample was collected from location of Nandipur, and glass was taken from local glass market in powdered form. Samples were remolded at optimum moisture content and maximum dry unit weight by mixing GC up to 14%. Soil classification tests, modified compaction tests, unconfined compression tests, one-dimensional consolidation tests, California bearing ratio (CBR) tests, and scanning electron microscope were performed. With increasing GC, the consistency limits, compression characteristics, swell characteristics, and optimum moisture content decreased while maximum dry unit weight, yield stress, CBR, and unconfined compression strength increased. Influence of GC is also observed on microstructure of treated clay. After 12% GC, aforementioned geotechnical characteristics behave inversely for selected clay. The optimum GC-value for the tested clay is about 12%, however, this value may vary from clay to clay.
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