2. Thesis and Dissertations
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Item Behaviour of Adjacent Strip Footings on Unreinforced/Reinforced Granular Bed Overlying Clay with/without Void(National Institute of Technology Karnataka, Surathkal, 2021) S, Anaswara.; Shivashankar, R.In many situations, due to rapid urbanisation, such as lack of construction sites, structural and architectural restrictions, buildings are placed close to each other. In such cases, the stress isobars or the failure zones of closely spaced foundations may interfere with each other leading to the phenomenon called ‘Interference’. It has an impact on the stresses in the subsoil due to overlapping of stresses, bearing capacities, settlements and tilts of footings due to the superstructure loads. Recognising the effects of interference and designing the footings accordingly ensures the safety and good performance of the structures. The first part of this doctoral research work studies the interference effects of two/three-strip footings placed adjacent to each other on unreinforced/reinforced granular soils, including some experimental studies. Effects on stresses in foundation soil; bearing capacities, settlements and tilts of footings are being investigated. Parameters varied in this study are (i) Number of footings (In the case of two footings loaded simultaneously, both experimental and numerical studies are conducted. In the case of two footings loaded sequentially and three footings, numerical studies are done) (ii) Loading conditions (iii) Clear spacing between the footings and (iv) Number of reinforcement layers in foundation soil. With two footings, two loading conditions are considered. In the first loading condition, both the footings are loaded simultaneously up to failure. In the second loading condition, one of the footings representing an already existing foundation is loaded with half of the estimated failure load of single strip footing and adjacent footing loaded up to failure. It is observed that in the case of simultaneous loading, there is a certain critical spacing (S=2B) at which the footing/s carry the maximum load. At S/B=2, the interference effect improves the bearing capacity of the 50mm and 100mm footings by 37% and 74%, respectively. The effect of providing the reinforcements in layers in the foundation soil, beneath the footings, is seen in the increased bearing capacities, reduced settlements, and reduced tilts of the footings. Tilts are also found to be influenced by the loading conditions. On unreinforced soil, increasing the distance from 1B to 4B between the footings results in a nearly 12% reduction in tilt in interfered footing. At S/B=2, introducing three reinforcing layers beneath simultaneously loaded interfering footings results in a 2.6 per cent tilt viii reduction. In the case of sequential loading of old and new footing, providing reinforcement beneath the new footing and loading it to maximum, causes a somewhat larger tilt (6.32% increment) of already existing strip footings. As the second part of this doctoral research work, numerical studies are undertaken on the behaviour of two adjacent strip footings on unreinforced (GB) and reinforced granular bed (RGB) overlying clay with/without voids. The influence of different parameters such as granular bed thickness, length of reinforcement/s, number of layers of reinforcement, presence of void/s beneath the footing/s in the weak soil etc., on the behaviour of footings are carried out. With two adjacent strip footings on GB overlying weak soil, the bearing resistance of each footing is more (14% for B=1m and 36% for B=2m) than a single independent strip footing on GB overlying weak soil. The voids could be formed in weak soil due to various reasons, and the presence of voids will affect the performance of footings. Such voids tend to reduce the load-carrying capacity of the footing/s and alter the failure pattern of foundation soil. In the case of a single void under two footings, the maximum reduction in the bearing capacity of new footing (53% reduction for B=1m, H/B=1) is reported when the void is formed directly below the new footing. When a void is formed anywhere beneath the footing/s in the weak soil, either directly beneath or nearby close to the centre line of the footing/s, failure surfaces developed from the nearest footings tend to move towards the void and are found to be narrower than the no void case. However, providing a reinforced granular bed (RGB) over weak soil can be used as an effective method to maintain the good performance of footings, even when voids could be formed in future. The interference effect in top granular soil combined with the reinforcement effect is seen to effectively nullify the void effect. This research work attempted to provide an analytical model to estimate the ultimate bearing capacity of two and three adjacent strip footings resting on granular bed overlying weak soil, with a fair and acceptable degree of accuracy. The accuracy of the proposed model has verified with finite element simulations and the percentage error is about 13%.Item Evaluation of Pyrolyzed Areca Husk for the Removal of Ferrous Ions from Aqueous Solution(National Institute of Technology Karnataka, Surathkal, 2021) B, Sheeka Subramani.; Shrihari, S.; Manu, B.The hurdle of valorisation of Arecanut husk on one side and the pollution of aquatic bodies by heavy metals like Iron on the other end are contemplated together in this study. The areca husk is pyrolyzed at 450°C for two hours to obtain Biochar. Batch adsorption studies were employed to investigate the effect of adsorbent dosage (2-10 g/L), initial concentration of adsorbate (1-5 mg/L) and contact time (30 -360 min) at temperature of 28±2 °C & pH 4.0±0.2 for the removal of Iron from pyrolyzed areca husk. The adsorption capacity was found to increase with increase in initial Iron concentartion and contact time, but decreases with the adsorbent dosage. Langmuir, Freundlich, Temkin and Dubinin-Radushkevich Isotherms was used to analyse the equilibrium data. Langmuir and Dubinin-Radushkevich model best described the uptake of Iron ions implying a monolayer adsorption with physisorption. Pseudo second order exhibited the best fit for the effectiveness of Iron adsorbtion indicating the maximum limit of chemisorption. Thermodynamic studies indicated that the adsorption was spontaneous and exothermic in nature. The mechanisms responsible for adsorption of Iron on pyrolysed areca husk was conducted by SEM-EDAX, XRD and FTIR indicating oxidation and precipitaion of Iron into complex compounds of jarosite and ferrous hydroxy sulphates. The results of the column studies suggest that the adsorption process is cost effective and can be scaled up to for continuous treatment of water. It was found that treatment efficiency improved with reduced flow rate and an increase in the height of adsorbent bed of the column. Maximum biosorption capacity of ferrous ions was observed as 0.487mg/g at bed depth of 3 cm; flow rate of 2 mL/min and initial concentration of 2 mg/L. PCA was also employed to predict the performance of the fixed bed column. It also indicated the same as the dynamic models. In conclusion, pyrolyzed areca husk can be technically & economically feasible alternative adsorbent material.Item An Experimental Investigation on Removal and Recovery of Phosphorus Using Sludge Conditioned with Skeleton Material(National Institute of Technology Karnataka, Surathkal, 2021) R, Rashmi H.; Devatha, C P.The production of excess sludge in wastewater treatment processes has been a serious issue for the operation of wastewater treatment plants (WWTPs) on both economic and environmental perspective. The disposal of sludge is a challenging task as it increases the handling and transportation cost. Therefore, sludge dewatering is the prominent to overcome the mentioned limitation. Dewatering using low-cost skeleton materials is a promising technique due to its efficiency, economic and environmental point of view. Further, it is a resource of nutrients like phosphorus and nitrates in not only in sludge but as well as in wastewater. However, phosphorus in the waste water leads to eutrophication of water bodies and result in algal blooms. As effluent discharge limits become more stringent, there is continued interest in removing phosphorus from wastewater. To prevent the receiving waters from eutrophication, the Enhanced Biological Phosphorus Removal (EBPR) process is a cost-effective and environmentally-friendly process for phosphorus removal in wastewater treatment systems. Phosphorus recovery from wastewater can help alleviate reliance on imported phosphate and reduce vulnerability to fluctuating prices. Hence in the present study, objectives have been framed in three phases. First phase deals with dewatering of sludge using the skeleton materials and its characterization. Second phase investigated on phosphorus removal using dewatered sludge by EBPR process and Finally recovery was carried out by crystallization. Reducing the moisture content in secondary sludge is a key factor in reducing the capital costs, operational costs, and transportation costs in wastewater management. In the present study, an attempt has been made to utilize granulated blast furnace slag and modified coconut shell biochar for sludge dewatering. In first phase, experimental work includes the initial characterization of the sludge and granulated blast furnace slag and evaluation of the dewatering ability of the treated sludge (capillary suction time, moisture content, turbidity, zeta potential, and heavy metal and biopolymer contents). Optimization using the Box-Behnken design was carried out with various operational parameters, and the best performance was found to be at a pH of 10, a dose of 0.34 g/g dry solids, and a contact time of 14 min. Characterization study was carried out by scanning electron microscopy in conjunction with energy dispersive X-ray spectroscopy, X-ray diffractometry, and Fourier transform infrared spectroscopy to confirm the structural features (dense), elemental composition, and the presence of different functional groups. Coconut shell is a bio waste and its availability is high as a waste in the coastal region of Karnataka, India. It is modified with ferric chloride to enhance the sludge dewaterability and it is evaluated experimentally (Capillary suction time, moisture content, settleability, zeta potential, heavy metals, and phosphate). Further, scanning electron microscopy, Fourier transformation infrared spectroscopy, and X-ray diffraction characterization were carried out to identify the structure change. A significant reduction in capillary suction time(56sec) and the moisture content (96.5%) of the dewatered sludge cake was obtained. Sludge dewatering using coconut shell biochar modified with ferric chloride was optimized by a Box Behnken method with three main factors including dosage, rapid mixing time, and slow mixing time. Optimum capillary suction time (55.8 sec) was achieved at coconut shell biochar modified with ferric chloride dosage (41% dry solids), rapid mixing time (10min), and slow mixing time (19min). The significant structural change in sludge particles was confirmed through characterization studies. During the dewatering process, the removal of heavy metal (cadmium, chromium, lead, and nickel) and phosphate (50.6%) was evident.anaerobicFor the second phase, an attempt was made to propose by EBPR induced with crystallization for the removal and recovery of phosphorus using dewatered sludge. An experimental investigation was carried out with the setup (anaerobi (anaerobi (anaerobi(anaerobi c-aerobic process) and was stably operated for 125 days. A sequential batch reactor of 4 liters was set up for the alternative anaerobic - anaerobic operation fitted with rectangular peddle mechanical stirrer and a air diffuser. Effect of pH on EBPR was studies for one complete cycle in a batch mode. Metabolism of PAOs takes place in anaerobicanaerobic anaerobic-aerobic process and that is in anaerobic process PAOs releases phosphorus and at is in anaerobic process PAOs releases phosphorus and in aerobic process phosphorus uptake takes place. The phosphorus removal efficiency was achieved in this process as 84%.Item Geotechnical Studies on Marine Clay Stabilized Using Quarry Dust, Granulated Blast Furnace Slag and Cement and its Applications(National Institute of Technology Karnataka, Surathkal, 2021) K, Preetham H.; Nayak, Sitaram.Coastal region has vast existence of problematic clayey soil referred as marine clay. This problematic soil is characterized by its high consistency limits, high compressibility and low shear strength. In order to overcome these problems, an industrial by-product obtained from the rock crushers and iron industry i.e. Quarry dust (QD) and granulated blast furnace slag (GBFS) has been utilized to enhance the strength and index properties of marine clay. Marine clay was replaced by these granular by-products in various proportions and evaluated for its geotechnical performance. From the experimental data, it was observed that marine clay when replaced with 35% QD and 40% GBFS produced good improvement in UCC strength and shear strength and this proportion is termed as optimum combination. The research includes an experimental investigation on cement addition to optimum QD-marine clay and Optimum GBFS-marine clay combinations on their shear strength parameters. The improvement in strength was justified by conducting microstructural analysis using SEM and XRD. The experimental results are used in numerical analysis i.e., in PLAXIS 2D for load-settlement analysis of a strip footing. In addition, the study also extends in evaluating the effectiveness of QD and GBFS along with cement in the production of compressed stabilized earth blocks (CSEB). From the current study, it is concluded that marine clay stabilized using QD and GBFS with/without cement can be effectively used in geotechnical applications, thereby increasing the rate of effective disposal of GBFS. Also, Study infers GBFS s more effective in stabilizing marine clay compared to quarry dust.Item Structural Reliability Analysis with Imprecise Uncertainties(National Institute of Technology Karnataka, Surathkal, 2021) K, Spoorthi S.; Balu, A S.Analysis and design involves consideration of many factors which are inherently uncertain. Reliability analysis requires information about the uncertainties in the system, and structural reliability is the probability of a structure performing its purpose adequately for the period of time intended under the operating conditions encountered. Many approaches developed for dealing with the uncertainties demand a mathematical representation of uncertainties on the basis of available information. Probability theory is the most customary technique to describe the uncertainties as random variables characterised by the probability density functions (PDF). However, if the data is inaccurate, ambiguous and incomplete, it is inept to form the PDF, and hence the conventional probabilistic approach becomes inadequate. Therefore, the imprecise parameters should be treated appropriately for improving the reliability of the system. If the information about the uncertainty is insufficient and non-stochastic in nature, the approaches based on interval analysis or fuzzy set theory can be adopted in uncertainty quantification. Hybrid approaches are also available to handle the situations where both the nature of uncertainties namely aleatory and epistemic are uniquely present in the system. In reality, when the aleatory uncertainty is characterised with imprecise parameters, none of the above approaches yields a reliable and optimum design. In such situations, the concepts of probability-box (p-box) can be adopted for characterising the uncertainties. Uncertainty analysis of multi-dimensional and highly nonlinear structures using simulation-based methods is cumbersome, and the hybridity demands the exploration of entire domain of bounds on imprecision. Response surface methods facilitate surrogate models to reduce the effort involved during the simulation. High dimensional model representation (HDMR) is a computationally efficient technique developed for the parameter interaction in physical problems. Therefore, in the present work, HDMR based uncertainty analysis is developed for estimating the structural reliability in the presence of various imprecise uncertainties. The methodology involves characterising the imprecise uncertainties as p-box variables, developing limit state functions using HDMR techniques, and estimating the reliability by interval Monte-Carlo simulations. Furthermore, as the prediction of structural behaviour might diverge due to the presence of various uncertainties, an attempt has been made by studying the systems with hybrid uncertainties from four different sources. The results of the numerical examples are compared with the traditional approaches to demonstrate the efficiency of the methodology.Item Studies on the Behaviour of Pervious Concrete Column Improved Ground Subjected to Static Shear and Seismic Load(National Institute of Technology Karnataka, Surathkal, 2021) V, Rashma R S.; Shivashankar, R.; Jayalekshmi, B R.Granular piles or stone columns are extensively used across the globe for improving soft soils, especially for supporting embankments on soft grounds, because of its ease of construction and inherent advantages. Various modified stone columns and their behaviour under vertical loading are extensively reported in literature. However, the behaviour of improved ground under lateral loading conditions are limited. Additionally, among all the reported externally/internally improved stone columns, very few modified stone columns like encased stone columns, deep cement columns and rigid columns are generally used in practice. Therefore, present study considers modified stone column as pervious concrete column which is reported as an alternative to conventional stone column owing to its comparable permeability characteristics with stone column in addition to its higher vertical load carrying capacity. The behaviour of pervious concrete column improved ground under static shear and seismic loading conditions are carried out and compared with the performance of conventional stone column improved ground. In the first part of the study, the behaviour of stone column and pervious concrete column under static shear loading conditions are investigated. The shearing resistances of pervious concrete column improved ground vis-à-vis ordinary stone column improved ground under static shear loading conditions are assessed. Numerical analyses were carried out by simulating direct shear test model and large shear test model, representing pervious concrete column improved ground using ABAQUS software. The single column modelled in the study represents the column placed beneath the toe of the embankment, where shear loading is predominant. Inclined direct shear tests are also analyzed by varying the slope (+/-) of potential failure surface with horizontal to represent the actual practical conditions. A total of 378 direct shear test models are analyzed to study the effect of normal pressure, effect of diameter, effect of reinforcement and effect of shear surface inclinations. The ultimate shear strength of pervious concrete column improved ground is found to be higher than ordinary stone column improved ground. It is found that the pervious concrete column improved ground under zero normal pressure has significant shear resistance than ordinary stone column improved ground and could be provided beneath the toe of the embankment for better shear performance. In order to study the performance of improved ground with floating and end-bearing pervious concrete columns, large shear test tank model with increased depth is analyzed. The shear response of improved ground is quantified, and the parameters considered are depth of pervious concrete column/pile, floating and end bearing piles, diameter, single pile and two pile group and distance from the edge of loading area in the model. It is observed that the pervious concrete column improved ground exhibits better shear performance than ordinary stone column improved ground. It is found that the pervious concrete column undergoes very small lateral deflections. It is also observed that more number of pervious concrete columns, and closer they are to the loaded area, better is the shear performance. The end bearing pervious concrete column improved ground is found to have significantly higher shear resistance than floating pervious concrete column improved ground. Therefore, it is suggested to provide full depth of pervious concrete column up to the bearing strata for achieving better shear performance. Pervious concrete columns show significantly lesser lateral displacements compared to ordinary stone columns. Peak lateral displacements in case of pervious concrete column are at the surface and the deflected profile of the column is very much like that of a rigid pile with a free or unrestrained head condition. Stone columns are highly recommended for mitigating liquefaction and the feasibility of pervious concrete column in preventing liquefaction is addressed in the second part of this study. Liquefaction induced lateral spreading causes catastrophic damages during and after earthquakes. Therefore, the effectiveness of pervious concrete column remediation in soil strata for mitigating liquefaction-induced lateral spreading is emphasized. The seismic performance of pervious concrete column improved ground is compared with conventional stone column improved ground. Three-dimensional finite element analysis using OpenSeesPL software is conducted to study the ground lateral deformation, excess pore water pressure generation and shear-strain behaviour of pervious concrete column improved ground on a mildly sloping soil strata of infinite extent under seismic loading. The parameters influencing the seismic performance of improved ground like area ratio, founding depth of columns, diameter of columns and hydraulic conductivity of columns are considered. The efficacy of pervious concrete column on three types of soil strata in mitigating liquefaction along with parameters influencing ground lateral deformation such as thickness of sandwiched liquefiable soil layer, permeability of surrounding soil, ground surface inclination, peak ground acceleration and surcharge load are reported. The influence of earthquake characteristics such as frequency content, significant duration, time of peak ground acceleration and arias intensity on lateral displacement, excess pore pressure dissipation and shear stress-strain behaviour of modelled ground are also studied. Total stress analysis is also conducted and compared with effective stress analysis on maximum response profile along the depth of improved ground with column inclusions when subjected to earthquake loading conditions. The stone column gets distorted during seismic loading due to shearing and causes dilation. The distorted gravel structure of stone column increases the length of the drainage path and retards the dissipation of excess pore water generated due to shaking. Whereas the pervious concrete column structure is not distorted due to seismic shaking and the pervious concrete column inclusion reduces drainage path for excess pore water to dissipate quickly. Therefore, the seismic shear strains developed in the surrounding soil is drastically reduced. The limited excess pore pressure generation and relatively higher effective confinement reduces the lateral displacement of pervious concrete column improved ground significantly. It is found from various response parameters that the pervious concrete column improved ground has better seismic performance than conventional stone column improved ground. The lateral deformation profile of pervious concrete column is found to be similar to that of concrete pile, allowing excess pore water pressure to dissipate through the pores of pervious concrete column. Liquefaction-induced lateral deformation is found to be lesser in pervious concrete column improved ground in comparison with stone column improved ground. The lateral deformation of pervious concrete column remediated ground is found to be independent of surrounding soil permeability. The pervious concrete column inclusion is found to be a better alternative to stone column in mitigating liquefaction in susceptible soils like loose sand, medium-dense sand, sandwiched sand deposits and silt strata. It is also found that the pervious concrete column remediation is a better alternative than stone column in seismically active regions even with peak ground acceleration of 0.6g. It is found that the generation of excess pore pressure reaches near zero values when the permeability of pervious concrete column is greater than 0.3 m/s irrespective of the characteristics of the earthquake events. From total stress analysis and effective stress analysis, it is observed that for column improved ground, in addition to pore pressure build-up, the maximum response profile is highly influenced by significant duration and frequency of seismic excitation. It is also concluded that pervious concrete columns could be used as an alternative to conventional stone columns to mitigate liquefaction to a larger extent.Item Assessment of Impact of Roadside Frictions on Passenger Car Unit Values and Capacity of Urban Roads in Disordered Traffic Using Microscopic Simulation Model(National Institute of Technology Karnataka, Surathkal, 2021) Raj, Pooja; Ravi Shankar, A. U.; Gowri, A.Representation of traffic in terms of its car equivalences (Passenger Car Unit) is more appropriate to estimate capacity in disordered traffic due to the presence of several vehicle types with varying static and dynamic characteristics following poor lane discipline. Many attempts have been made to overcome the complexities involved in accurate estimation of Passenger Car Unit (PCU) in disordered traffic. The widely used method for PCU estimation considers the relative speed and projected area (length × width) of vehicles. However, as a vehicle will be influenced by a larger area than its projected area, which is proportionate to the surrounding vehicle types (effective area of a vehicle); this study aims to deal with the influence of surrounding vehicles while estimating its PCU value under disordered traffic condition. PCU values are influenced by various factors such as traffic conditions, geometric conditions, road side frictions, etc. Among these factors, roadside frictions (e.g., curbside bus stops, undesignated pedestrian crossings, roadside parking) cause significant deterioration in the quality of urban traffic flow and thus, considerably influence road capacity which in turn affects the PCU values. Many research works have been carried out to investigate the impacts of some of the influencing factors (e.g., vehicular composition, traffic volume, road width) on traffic characteristics as well as PCU values. However, the sensitivity of PCU values and capacity due to the presence of roadside frictions are not adequately studied. Furthermore, PCU values and capacity for urban roads recommended by the existing manuals (e.g., IRC 106 1990) are applicable only for the ideal/base sections i.e., the section devoid of any side frictions. The recently published highway capacity manual (Indo-HCM 2017) suggests adjustment factors for capacity estimation of roads with the presence of a few side frictions (e.g., parking, access points, bus stops), however, the adjustment factors for estimating PCU values are not suggested. To address these gaps, this research study aims to estimate PCU values for vehicles under the influence of curbside bus stop and undesignated pedestrian crossings which are the most common roadside frictions being observed in developing countries. As the change in PCU values will have an influence on capacity as well, it is essential to study the impact of curbside bus stop and undesignated pedestrian crossings on capacity. Lack of space for providing ii exclusive bus bays and higher demand for public transport buses in urban roads justify the need for investigating the influence of curbside bus stop. The non-compliant behaviour of pedestrians at undesignated pedestrian crossings creates complex vehicle-pedestrian interactions which affect the capacity of roads and thus, this justifies the need for studying the influence of pedestrians. Furthermore, the influence of side frictions on PCU values and capacity are not considered in the existing studies which used simulation tools. Hence, this study mainly aims at development of a simulation model to examine the influence of these side frictions on PCU values as well as capacity. Methodology of this study involves development and validation of a microscopic simulation model for ideal section (base model) using the data collected from Bangalore city, India. To study the impact of side frictions on PCU values and capacity, two different urban divided arterials are selected; one with the presence of curbside bus stop and an ideal section near it (Ideal_bus), and another with undesignated pedestrian crossings and an ideal section near it (Ideal_ped). Logics involved in base model development are formulated and implemented in MATLAB using object-oriented programming concepts. To estimate the PCU values for different vehicles, a new methodology considering the influence of surrounding vehicles is proposed and incorporated in the validated model. The base validated model is then modified to simulate the traffic manoeuvers on urban roads in the presence of curbside bus stop (bus stop model). To study the vehicle-pedestrian interactions in disordered traffic, the base model is modified in such a way that the movement logics of vehicles and pedestrians consider vehicle-pedestrian interactions (vehicle-pedestrian interaction model). The relative influences of various parameters such as traffic volume, vehicular composition, bus proportion (applicable only for bus stop section), proportion of stopping buses (applicable only for bus stop section), and pedestrian volume (applicable only for pedestrian section) in the presence of side frictions are investigated by carrying out sensitivity analysis. With simulated results from sensitivity analysis, regression models are developed to predict PCU values for different types of vehicles and capacity of road sections, with and without curbside bus stop, and with and without undesignated pedestrian crossings. iii The simulated results of sensitivity analysis indicate the significant differences in PCU values due to the presence of curbside bus stops when vehicular composition, bus proportion, proportion of stopping buses, and traffic volume are varied. For observed vehicular composition and traffic volume, simulated PCU values for bus showed a drastic increment of 28% in bus stop section when compared to that of ideal section. As curbside bus stops create temporal pseudo bottlenecks, capacity of bus stop section significantly gets reduced by 18% from that of ideal section for observed vehicular composition. Due to the impact of undesignated pedestrian crossings, the capacity reduction in pedestrian section when compared to that of ideal section is found to be 19.1% for observed vehicular composition and pedestrian volume. PCU values for vehicles are also found to have significant variations with change in vehicular composition, traffic volume and pedestrian volume. The study findings and results can be used by traffic engineers and planners to predict realistic PCU and capacity values for planning and designing of new facilities with side frictions instead of directly adopting the values available in the existing manuals. The study results find interesting implications in updating standards related to PCU and capacity estimation considering the influence of curbside bus stops and undesignated pedestrian crossings. In future, this research can be extended to study the impact of curbside bus stops, undesignated pedestrian crossings and other roadside frictions (e.g., parking, encroachments) on PCU values and capacity of different facility types (e.g., urban undivided roads, rural roads, intersections) by modifying the logics in the simulation model. The bus stop model can be further modified to simulate the traffic manoeuvers in sections with bus bays and exclusive bus lanes. The model describing the vehicle-pedestrian interactions can be modified to determine surrogate safety measures (e.g., time-to-collision between vehicles and pedestrians) that reflect the safety of urban roads (where the presence of pedestrians is significant).Item Time-Dependent Failure Possibility Analysis of Reinforced Concrete Structures(National Institute of Technology Karnataka, Surathkal, 2021) Woju, Utino Worabo.; Balu, A S.Structural performance depends on the design, construction, environment, utilization, and reliability aspects. From these, other factors can be controlled by adopting proper design and construction techniques, but the environmental factors are difficult to control. Hence, the environmental factors in the analysis and design are mostly not considered sufficient in practice; however, they have significant effects on the performance of the structures in the design life. It is in this light that this study aimed at performing the time-dependent safety and serviceability performance analysis of reinforced concrete structures majorly considering environmental factors such as creep, shrinkage, and corrosion that possess uncertainty. To achieve the desired objective, a simply supported reinforced concrete beam was designed and detailed to Eurocode (EC2). Different design parameters such as corrosion parameters, creep and shrinkage, the time-dependent properties of the material have been identified and modeled through a thorough literature review. The empirical equations provided in design codes were modified to consider the time-variant parameters in time-dependent performance analysis. In the presence of uncertainty of parameters, it is impossible to obtain the absolute reliability of the structure. The sources of uncertainties in reinforced concrete are the randomness of variables, mathematical models, physical models, environmental factors, and gross error. Uncertainties broadly classified as aleatory and epistemic uncertainties. This research mainly addressed the epistemic uncertainty of reinforced concrete structure to handle the imprecise data using fuzzy concepts. The fuzziness of variables identified and their membership functions were generated by MATLAB R2018a using the heuristic method. In addition to the identification of fuzziness of variables, the study further extended to design optimization and performance level evaluation of reinforced concrete structure using fuzzy relation and fuzzy composition to explore the application of fuzzy concepts. In the design of reinforced concrete structure using fuzzy relation and composition methods, the design is taken as optimum when the performance degree of membership tends to unity. Failure possibility is a measure of safety when a structure encounters with fuzzy uncertainties. If uncertainties are time-dependent, the possibility of performance under zero results in time-dependent failure possibility, and it becomes more pronounced during improper consideration of environmental factors. Therefore, in this study, time-dependent parameters are taken into account for exploring the effects of environmental factors in reinforced concrete structures. Possible failure modes were identified and estimated using modified time-variant empirical equations to consider the propagation of input variables that are characterized by membership functions to output responses. Then, the time-dependent failure possibility is evaluated by the numerical optimization procedure. Real-time data has been collected from the city of Addis Ababa, Ethiopia for the case study to substantiate the methodology presented in this study. From the detailed modeling and analysis, considering the moderate corrosion rate with corresponding ambient temperature and relative humidity of the considered site, the structure safely performs for less than half of its design life.Item Influence of Aging Condition on Performance of Fine Aggregate Asphaltic Matrix(National Institute of Technology Karnataka, Surathkal, 2021) Akhandappagol, Ningappa.; N, Suresha S.The major distresses in the flexible pavement are fatigue cracking, rutting, and moisture induced damage. There is lack of consideration of ideal test methods to evaluate the distresses present in the asphaltic pavement. By knowing the majority of the distresses appear within the mortar or Fine Aggregate Matrix (FAM) of the asphalt mixture, researchers have started to use this FAM phase in place of full asphalt mixtures to characterise the performance properties. Additionally, one can also attain higher precision in test results from Dynamic Shear Rheometer (DSR) by maintaining the uniformity in the prepared FAM specimens. The thesis report presents the research study performed on FAM mixtures focusing on its test methodology, rheological investigation results, and conclusions of the study. The main objectives of the present research is (i) to investigate the effect of different long-term oven aging (LTOA) levels on performance properties of FAM mixtures to mitigate the fatigue cracking in asphalt pavement, (ii) to assess and analyse the effect of binder types, different loads, and temperatures on creep and recovery performance of the FAM mixtures, (iii) to assess and analyse the impact of moisture on creep recovery response of FAM mixtures. To achieve this objective, a detailed test plan was prepared based on exhaustive review of research findings related to FAM mixtures and the latest practices for FAM characterisation were adopted by various agencies across the world. Major differences were observed in these practices, particularly with respect to the different aging methods, gradations used/considerations, specimen preparation method, and considerations of air voids, binder content, binder grade, and binder types. In light of the above, the rheological investigation was carried out on FAM mixtures in three stages, i) Cracking susceptibility of FAM mixtures prepared with three different asphalt binders VG-30, VG-40, and PMB(S) is evaluated through the experimental testing and numerical modeling on FAM mixtures produced at design (laboratory) stage. Various criteria and approaches for the prediction of cracking in FAM mixtures are assessed and their correlation is discussed. Different levels of aging in laboratory are simulated, and the effects of long term oven aging (LTOA) on linear viscoelastic parameters, and fatigue characteristics of FAM mixtures are explored. ii) Creep recovery behavior of FAM mixtures were evaluated by vii determining the percent recovery (%R) and non-recoverable creep compliance (Jnr) parameters from the Multiple Stress Creep Recovery (MSCR) test at different stress levels and temperatures. Additionally, strain response from the Burgers four element model was also modelled and compared with the observed experimental results, iii) Resistance to moisture-induced damage of FAM mixtures was evaluated by determining the ratios of %R and Jnr in dry and wet conditions from the Static Creep Recovery (SCR) test at 40°C for different stress levels. Results of the study indicated that irrespective of the aging level applied to the FAM specimens, there is a small difference in the LVE limit was found for all FAM mixtures. Viscoelastic properties (|G*| and δ) for FAM specimen aged for 24 hrs at 135°C, and 12 days at 95°C aged FAM specimens showed similar results from the master curve plots. The fatigue life of FAM mixtures decreased as the aging level increases as expected. Despite of the similar viscoelastic properties, the trend observed between FAM mixtures aged 12 days at 95°C and 24 hrs at 135°C were not found to have similar fatigue life. Among FAM mixtures considered, the F2 mixture prepared with asphalt binder (VG-40) showed good resistance against permanent deformation for all the considered temperatures and corresponding stress levels. An important finding of this study also reported that Burgers model can be successfully applied for creep-recovery response of FAM mixtures under different temperatures and stress levels considered in this research. Further, the F3 mixture shows the highest %Rratio and lowest Jnr_ratio values compared to the other two FAM mixtures, indicating a lower sensitivity to moisture damage which could be possibly due to the use of polymer modifier in F3 mixture. Overall, based on the findings observed from the above rheological investigations, the FAM phase of full asphalt mixtures can be successfully used to characterise the effect of long-term aging on viscoelastic and fatigue properties of FAM mixtures. Similarly, FAM phase can also be used successfully to describe the permanent deformation, and moisture induced damage characteristics of FAM mixtures.Item Development of Simulation Model for Leachate Migration near Vamanjoor Landfill and Treatment of Leachate by Nanoparticles(National Institute of Technology Karnataka, Surathkal, 2021) Anand, Divya.; Shrihari, S.; H, Ramesh.The impact of leachate from landfill on groundwater has paid a lot of global attention because of its devastating environmental significance. The outputs from landfill induce heavy impacts or risks to the environment forcing the concerned authorities to impose more strict constraints and hence leachate is to be treated before it migrates to the neighboring environment. The Mangaluru City Corporation is collecting the waste on a daily basis and dumping it into a landfill at Vamanjoor located nearly 8.5 km from city centre. The landfill has got a bottom liner, but the drainage to collect leachate is not fully functional. Hence all the untreated leachate formed at the bottom, finds its trails into the neighbouring environment polluting the underlying aquifer. The water sample from observation wells were analysed and results shows that the wells located in 1 km around the landfill are contaminated with the landfill as point source from where contaminants are continuously injected. The leachate collected from landfill was analyzed in the laboratory for various physico-chemical parameters and were compared to the Standards of disposal for Indian standards for surface water IS 2296-1982. It showed that most of the parameters exceeded specified standard for the disposal of waste. Since the composition of the on-site leachate changes every day, in order to maintain repeatable composition, synthetic leachate was prepared in the laboratory. The nano iron was synthesized in the laboratory and characterized using Scanning Electron Microscope. The removal efficiency of chemical oxygen demand (COD) from synthetic leachate using nano iron was studied. For analyzing significant factors which favors the reaction such as pH, initial concentration, optimum concentration of adsorbent to be added, batch experiments were conducted using nano iron with and without starch coating. Batch experiments proved that pH of solution was an important parameter while kinetics coefficients were directly related to pH with correlation coefficients R2> 0.90. The nano iron dosage of 2 mg/l enhances removal efficiency of COD beyond that dosage the effluent will have traces of iron beyond the limit which is undesirable. Based on the removal efficiency which is around 60%, optimum conditions were adopted for continuous fixed-bed study. In a perspex column the nano iron coated with starch is sandwiched between ii untreated natural lateritic soil and the synthetic leachate was allowed to pass through it. The removal efficiency was obtained by comparing COD of influent and COD of effluent. A comparison of batch and column reactor has been done where continuous fixed-bed column was found to be more effective in removal of COD with removal efficiency of 68% in the remediation of leachate which may be due to the adsorption by laterite soil. Evaluation of Freundlich, Langmuir and D–R isotherm models were done. The kinetics of the experiments shows that it follows pseudo first order reaction kinetics. Because of its high removal efficiency, nano iron coated with starch has been taken as an effective remedial agent in treatment of leachate. As it showed better removal efficiency during continuous fixed-bed column studies, it can be used as adsorbent in permeable reactive barriers. Permanent reactive barriers are specially designed reactive zone which extends beneath water table which intercepts and degrade the contaminants in groundwater. The current study focuses on determination of extent of groundwater contamination on a typical tropical coastal aquifer due to a landfill located at Vamanjoor in Dakshina Kannada district, India. MODFLOW which is a standard and popular flow model was used to simulate groundwater flow and MT3DMS was used for simulating contaminant transport because of its ability to model various complexes such as advection, dispersion and chemical reaction involved in the solute transport. The aquifer considered is a shallow, unconfined one with laterite soil which gets good rains during monsoon and will be dry during rest of the year. The adsorption by laterite soil has been considered. The specific yield and transmissivity were estimated to be 7.85% and 213 m2/day respectively. After calibrating successfully with Nash–Sutcliffe efficiency 0.8, horizontal hydraulic conductivity was set as 7m/day. Validation of model was then done with the field data and is applied for forecasting the spread of contaminant for anticipated future scenarios. The results show that in spite of retardation offered by lateritic soil, contaminant trail is expanding with a velocity of 0.15 m/day in downstream direction. The solute transport model MT3DMS was successfully applied to simulate the contaminant transport of the study area. Since MT3DMS model involves the model structure involved in MODFLOW, the model domain was not altered. The model was iii calibrated and validated with reasonable precision (correlation coefficient R2> 0.7) which shows that the model performance is good. The simulated results show that the contaminant has spread for a distance of 1 km radius around the landfill which is in accordance with the actual value of the water quality analysis of observation wells. The model after calibration and validation is applied for the evaluation of general regional impact on the groundwater system for future scenarios. The study revealed that the contamination has spread for a distance of nearly 1 km from the landfill and plume is expanding at a rate of 0.15 m /day. By 15 years the plume will reach a distance of 1.8 km from the landfill. If permanent reactive barrier is installed the expansion of plume can prevented and the pollutant at the observation well located at 1 km from landfill can be reduced less than 400 mg /l. Hence installation of permeable reactive barrier with nano iron can be taken as a remedial alternative in order to control groundwater pollution due to landfill leachate.