2. Thesis and Dissertations
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Item Investigations on Accelerated Consolidation of Coir Reinforced Laterite, Lithomargic Clay and Blended Soils with Vertical Sand Drains for Pavement Foundations(National Institute of Technology Karnataka, Surathkal, 2013) Hegde, Ramakrishna; George, Varghese; Ravishankar, A.U.Pavement layers built over the sub-grades are designed to transmit loads to the soil layers below, keeping the deformations within limits even under adverse climatic and loading conditions. Sub-grades on embankments need to provide structural stability to support trafficloads. Soil obtained from borrow pits, transported, and laid on embankments for highway construction, have very low CBR values in the range of 1-2%. In the conventional practice of road construction, the consolidation of soil layers take 1-2 years to materialize after the soil is compacted. In this context, the use of natural fibers such as coir in providing vertical sand drains and in soil-reinforcement is expected to accelerate the process of consolidation by permitting pore-water pressures to be easily dissipated when subjected to overburden pressures, which will prevent further subsidence of lateritic sub-grades. The use of vertical drains, accelerate the radial drainage and enhance consolidation, by reducing the length of the drainage paths. However, it is found that more investigations need to be performed on the use of vertical drains for coir-fiber reinforced lateritic soils of the peninsular regions of India with special reference to the District of Dakshina Kannada. Research in this direction is expected to generate information on improving the efficiency of vertical drains, and will have a profound influence in the field of highway construction especially in tropical regions where coir is abundantly available. Laterite and Lithomargic (Shedi) soil samples used in this study were collected from a site close to National Institute of Technology Karnataka, located in the district of Dakshina Kannada, India. Tests for basic properties and CBR, were performed as per specifications of Bureau of Indian Standards (BIS). Investigations on consolidation were performed for samples of laterite soils, shedi soils and laterite blended with shedi (lithomargic) soils, using circular test moulds of ferrocement (of 70 cm. internal diameter, and 85 cm. internal height). Tests for consolidation were performed on the un-reinforced soil samples with and without the use of vertical sand drains. Similar tests were performed on randomly reinforced soil samples also, to assess the effect of the use of vertical drains. The randomly reinforced soil samples were prepared for optimal coir-fiber content by weight of soil, determined based on CBR studies. Each soil sample was first subjected to a preload of 50 kg (1.2x10-3 N/mm2) at the top of the cylindrical test mould, and the settlement was studied. When the settlement rate reduced to lesser than 0.02 mm per hour, the next increment of preload was applied. The procedure was repeated until the settlement readings were taken for a final preload of 500kg (11.6 x10-3 N/mm2). In the above studies, locally available river-sand passing through 4.75 mm IS sieve was used for fabricating the vertical drains. The aspect-ratio of coir fiber used was 1: 275. In this study, the use of sand randomly distributed with 1.0 % coir fiber was used. The coir reinforcement imparts lateral stability to the vertical drain, while enhancing the drainage properties. River sand of same characteristics was used in the preparation of the top and bottom layers of the cylindrical test mould to ensure uniform loading and drainage for the tests for settlement and consolidation. While analyzing the results for 100%L+0%S, it was seen that the soil attained stability at around the 121st minute after application of the pre-loads for UR (un-reinforced soil), UR-VD (un-reinforced soil with vertical drains), and RR-VD (randomly-reinforced soil with vertical drains). Using the 121st minute as the datum, it was observed that the effect ofproviding vertical drains alone was not significant when compared to the rate of settlement, for the entire range of pre-loads from 50 kg (1.2x10-3N/mm2) to 500kg (11.6x10-3N/mm2). Also, in the case of 100%L+0%S UR soils, it was observed that the maximum value of Cv of 2.0825 cm2/s was found to occur at a higher pressure range of 3.5 to 4.6 x10-3 N/mm2. In the case of UR-VD soil conditions, the maximum value of Cv of 2.2683 cm2/s was found to occur at a lower pressure range of 2.3 to 3.5 x10-3 N/mm2. Also, in the case of RR-VD soil conditions, the maximum value of Cv of 2.2882 cm2/s was found to occur at a lower pressure range of 2.3 to 3.5 x10-3 N/mm2. This indicates that the consolidation occurs at a faster rate at lower pressure ranges for reinforced soils. While analyzing the results for 0%L+100%S, it was seen that the soil attained stability at around the 225th minute after application of the pre-loads for UR, UR-VD, and RRVD soils. Using the 225th minute as the datum, it was observed that the effect of providing vertical drains was significant considering the rate of settlement for pre-loads ranging from 50kg (1.2x10-3N/mm2) to 250kg (5.8x10-3N/mm2). However, for higher pressures varying from 300kg (7x10-3 N/mm2) to 500kg (11.6x10-3N/mm2), further settlement was not found to be significant. For UR-VD soils, the relative increase in the settlement when compared to that of UR soils, ranged between 40.61% and 294.55%, with an average increase of 176.6% for the preload ranging between 50kg (1.2x10-3 N/mm2) and 250kg (5.8 x10-3 N/mm2). This is very significant from the practical point of view. But for pre-loads higher than 250kg, the effect of providing vertical sand drains alone (as in UR-VD soils) was not significant as it was found to vary between 4.01% and 13.06% only, with an average increase of 7.67%. Also the case of 0%L+100%S RR-VD soils, there was an additional increase of 32.6% in the settlement when compared to that of UR-VD soils for pre-load ranging from 50kg (1.2x10-3N/mm2) to 250kg (5.8x10-3N/mm2). For higher pre-loads, an increase of 10.76% was observed. Thus, it can be concluded that for 0%L+100%S RR-VD soils, there is a significant increase in settlement due to random reinforcement with coir fibres when coupled with the use of vertical drains. In the case of 0%L+100%S UR soils, it was observed that the maximum value of Cv of 1.0821 cm2/s was found to occur at a higher pressure range of 3.5 to 4.6 x10-3 N/mm2. In the case of UR-VD soil conditions, the maximum value of Cv of 1.3661 cm2/s was found to occur at a lower pressure range of 2.3 to 3.5 x10-3 N/mm2. Also, in the case of RR-VD soil conditions, the maximum value of Cv of 1.8277 cm2/s was found to occur at a lower pressure range of 2.3 to 3.5 x10-3 N/mm2. This indicates that the consolidation occurs at a faster rate at lower pressure ranges for reinforced soils. Similar studies were made on 75%L+25%S soils, 50%L+50%S and 25%L+75%S soils. In the above study, it was observed that in the case of lithomargic soils there was a significant increase in settlement at lower preload pressures. Reinforced soils of this category also displayed very high settlements, indicating that softer soils can be effectively consolidated using vertical drains and random reinforcements using natural fibers. In the case of pure lateritic soils, the use of vertical drains alone was not found to be effective. However, for other lateritic blends, the use of vertical drains significantly contributed to the settlement.Item Geohydrological Studies of Mulki River Basin Karnataka, India(National Institute of Technology Karnataka, Surathkal, 2013) K., Radhakrishnan; Lokesh, K. N.Water being the vital natural resource of concern, the sustainable development of the same is of much importance at present. A river basin or a watershed is a clearly defined basic unit to understand the water resources considering groundwater and surface water as a single resource for integrated development in a given terrain. The complex relationship that exists among soils, geology, land forms, rainfall, vegetation, land use practices and the condition of water resources is better understood and managed in a river basin or watershed. Characterizing and deriving the sustainable developmental plan for watershed, demands accurate information pertaining to its land use, soil, geology, geomorphology, meteorology, hydrogeology, quality of water, etc., in spatial domain. The erstwhile Dakshina Kannada district being blessed with many watersheds and heavy rainfall needs special attention in this regard thanks to its fast development in the coastal part of India. Mulki, a typical midland draining river basin in this coastal part of Karnataka in India has been studied and analyzed in order to understand the various aspects of its groundwater resources for the sustainable development and management. To attain this, an integration of various field and laboratory data of current and historical interest have been carried out in a spatial domain with different thematic maps derived from Survey of India (SOI) Toposheets and imageries of Indian Remote Sensing (IRS) Satellites. They have been visually and digitally processed and analyzed using geoinformatic technologies and statistical analysis. The geomorphologic studies and morphometric analysis revealed that the Mulki river having a drainage area of about 350 sq. km. is a 6th order, very coarse textured, rectilinear, dendritic, midland draining basin of matured topography with high discharge capacity and meager groundwater potential. Mulki River Basin has elbow bends in its midland area other than an offset of the NE-SW trending land mark structural ridge and WNW-ESE trending lineaments indicating structural deformation into its major course. Morphometric analysis and geomorphologic evidences such as pediplain, structural ridge, lateritic plateaus (mesas) of varying geological origin and time, waterfall, high sinuosity, cross bedding, meandering course and elbow bends inAbstract x Geohydrological Studies of Mulki River Basin, Karnataka, India. Ph.D. Thesis-2013 Department of Civil Engineering, National Institute of Technology Karnataka, Surathkal the middle stretches, river terraces, water pooling, etc., suggest neotectonic activity in this area which may be responsible for the groundwater storage and movement. The geology of the study area depicts rocks of Archaean to the Recent age, exposing fifteen lithological units representing Sargur group and Peninsular Gneissic complex of Archaean age, South Kanara Granite batholith, younger intrusive basic dykes and acid veins of Palaeoproterozoic age, laterites of Cenozoic age and coastal sands of Quaternary period and the Recent sediments of the alluvial deposits. But predominantly the rocks like Granite/Granitic gneisses with occasional laterite capping and unconsolidated river and marine sediments, occupy the area. Basic intrusives like dolerite and gabbro, and acidic intrusives like pegmatite and quartz veins are found at many places shaping the hillocks, ridges and mounds in the terrain. Many sets of joints are parallel to the river course in the ENE-WSW directions other than NE-SW, N-S, E-W and NW-SE which influence or guide the groundwater potential of the area. The NNW-SSE trending dolerite dykes are numerous and relatively abundant in granite. Foliations and joints in rocks dip either north or northeast directions favouring groundwater storage and movement in the upstream directions. Geology of the area and lineament studies confirm the earlier report of three active faults in the area which are responsible for the offset of the river and recent neotectonic activity in this area. There are some lineaments in the basin extending up to the Western Ghats which will be highly potential for groundwater explorations. NE-SW trending structural ridge of intrusive rock (mainly gabbroic) forms a major lineament in the eastern part of the basin. There are about seven genetic types of soils spread over the basin, broadly divided into four types depending on geohydrological condition as alluvial soils, loamy soils, gravelly clayey skeletal soil and lateritic soils of different encrustations. The soils and geological structures such as lineaments and joints in the otherwise hard and impervious rocks have an influence on the geohydrological conditions of this study area. Water quality, being an important criteria for deciding the suitability for drinking and irrigation purposes, about 21 important physico-chemical water quality parameters (of groundwater and surface water) have been analyzed and seven irrigation water quality parameters have been computed for 154 randomly selected water samples collected during pre-monsoon seasons of 2008 and 2009; and 95 samples collected during postmonsoon period of 2009 to understand the utility values of the same and its spatial variation. Statistical analysis of the above parameters and a comparison with acceptable drinking water quality standards revealed that most of the water samples collected during pre- and post-monsoon periods found to have quality parameters well within permissible limits. However, the spatial variation maps of vulnerable parameters and vulnerability map of water quality has been prepared, and it has been found that certain parameters like Fe, Ca, Chloride, pH, TDS, Total Hardness and Turbidity were beyond permissible limit of potable water during pre-monsoon period especially near to the coast. Salt water intrusion has taken place up to about 7 km. from the coast along the river course. The majority of the post-monsoon water samples are found to be acidic in nature influenced by the geology of the area. The drinking water qualities of surface water sources during pre-monsoon have been affected more compared to groundwater sources in the study area. There is a significant difference between the bore well water chemistry and open well water chemistry, as well as the pre-monsoon water quality and post-monsoon water quality. Bore well waters, except near the coast, are influenced by the silicate weathering of the igneous rocks, whereas the open well waters are influenced by the clay mineral reaction except those near the coast, influenced by the chloride dissolution from the salt water ingression in the study area. The total hydrochemistry in the study area is dominated by alkaline earth (64%) and strong acids (55%) with carbonate hardness (33%) (secondary alkalinity) and primary salinity (26%) influenced by the weathered granitic gneisses and leached laterite besides the influence of saline water. During pre-monsoon season Rock interaction Domain is having a dominating influence on the groundwater whereas in post-monsoon season Precipitation domain influences open well water. The difference in the hydrochemistry during pre-monsoon and postmonsoon periods indicates the influence of weathering, infiltration, mixing and leaching in the study area. A great variation is noticed in irrigation water suitability based on different characteristics and is found to be 95% (pre-monsoon) and 100% (post-monsoon) based on EC, 100% (pre-monsoon) and 98% (post-monsoon) based on SAR, 84% (pre-monsoon) and 33% (post-monsoon) based on % Na, and 60% (pre-monsoon) and 03% (post-monsoon) based on RSC. All groundwater samples fall under no problem category of sodium water type irrigation quality with low to medium salinity. Therefore, they can be used for irrigation on all types of soil with little danger of exchangeable sodium. An analysis of the Water Quality Indices (WQI) and its mapping in spatial and temporal domain in the study area found to be a faster and better tool in assessing and rating the suitability of groundwater for drinking water based on quality weightage. The very high WQI at the coastal front near the mouth of the river and its extension along the river course upstream up to a certain distance during pre-monsoon indicates the influence of saline water and its migration along tidal water in this area. The temporal variation in distribution pattern and density of WQI points to the significant role of precipitation and infiltration playing in the determination of water quality. As a part of systematic identification, quantification and management of regional hydrologic regime, geophysical investigations especially Vertical Electrical Soundings (VES) have been carried out at about 129 selected stations representing different terrains in the basin to understand the subsurface lithology, groundwater quality and aquifer characteristics at different depths. The data has been interpreted using resistivity cross sections and correlated with a few available drilled data/geology of the area in order to understand the aquifer characteristics and resource potential. Saline water ingression studies also have been carried out using these data along the coastal stretch. From the hydrometeorological analysis, the study area is found to be falling under tropical humid climatic zone where hot humid climate prevails throughout the year. The rainfall of the study area falling in the wet climatic zone is uneven and shows an overall decreasing trend for the last four decades. From the last four decade’s rainfall data analysis, the average annual rainfall is found to be about 4264.09 mm falling in the wet climatic zone giving rise to an average volume of about 1496.70x106 m3 storm water per annum in the basin. The rainfall spread for about five to six months in the study area shows spatial and temporal variation in its distribution with a minimum of 66 days at Mulki during 1973 to 161days at Karkala during 1978. The average daily rainfall also found to be varied from 12.3mm during 1973 to 53.2mm during 1997. A balance in distribution of rainfall found to be characteristic of this area where deficient years or dry years almost equaled the wet years in all three point stations during the 30 years observations period. Temporal and spatial variations in rainfall have been noticed in the study area, where 87% of rainfall is contributed from southwest monsoon spread over a period of four months and the decrease in trend is from Karkala to Mulki in a northeast to southwest direction. However, the moving average curve of rainfall denotes a nine year trend of continuous variation in its pattern and periodicity. The frequency probability analysis of magnitude and return period of rainfall in the basin demonstrate that rainfall above 3176.9mm have a chance of returning every year with 67% to 98% dependence. The computed water budget of the area shows an actual evapotranspiration of 30% of rainfall against the maximum potential evapotranspiration of 46.6% and a runoff about 771.16 x 106 cubic meters per annum from the study area. Groundwater assessment and management studies revealed that there is a surplus availability of storm water and groundwater balance in the 43 villages of the 17 Panchayats falling in the Mulki River basin, but not managed properly underutilizing its huge potential. Estimation of groundwater recharge and potential has been carried out using water table fluctuation data obtained from three observation wells other than 36 observation wells periodically monitored for a period of one year. The average annual decline in the water table of the study area is found to be about 6.85m during last one decade giving rise to a draft of 2,404.35x106 cubic meters per annum. Approximate water demand and utilization has been estimated based on Village Panchayat resource data. Even with a net annual recharge of 24,302 ha.m. of groundwater available for development in the study area, the annual net draft for utilisation from the aquifer is estimated to be 993.93 ha.m. only and a balance potential of 23,308 ha.m. is available for future utilization, but unevenly distributed in the area and lost as groundwater flow. Cultivated area of about 27% in the basin has been found in clustered strips irrigated by a good practice of rain fed traditional structures like tanks, ponds, etc. About 73 such structures ideally located with a concentration of one in 4.8 sq. km. spread over an area of 13.5 hectares with a maximum storage capacity of 0.23 MCM have been identified, delineated and mapped from the study area. Rehabilitating old Rainwater Harvesting Structures (RWHS) and increasing the density of tanks at the rate of at least one in one sq km. area can use more than 50 per cent of the runoff water considering the future needs of development. Case studies carried out to understand the viability of these resources proved these to be very effective. About 56 microwatersheds, significant in the sustainable development, spread over an area of about 46.14 sq. kms. comprising 13% of the Mulki River basin have been identified and delineated. Development of microwatersheds along with rehabilitation of abandoned and silted traditional rainwater harvesting structures found to be an efficient management practise to improve the water resource of this area for drinking and irrigational purposes. Geoinfomatic application found to be a very useful tool in the preparation of various thematic maps and integration of data for efficient planning and management of the water resources in the study area for sustainable development.Item Seismic Response Of Substation Equipment with Porcelain Components Seismic Response of Substation Equipment with Porcelain Components(National Institute of Technology Karnataka, Surathkal, 2013) Srujana, N.; Ramesh Babu, R.; Venkataramana, KattaThe performance of equipment and structures during earthquake depends on their configuration, strength of construction, ductility and their dynamic properties. Lightly damped structures having one or more natural modes of oscillation within the frequency band of ground excitation may experience considerable amplification of forces, component stresses and deflections. Substation equipment comes under this category. The satisfactory operation of substation during and after an earthquake depends on the survival, without malfunction, of many diverse type of equipment. Individual equipment needs to be properly engineered. In addition, their anchorages and interconnections need to be well designed.Porcelain components are identified as most vulnerable parts against earthquake vibrations than any other components of the substation. In this research, substation equipment are divided into three categories based on the length of porcelain cylinders/components and bushings. i.e., short, medium and long porcelain insulator components. Electrical equipment are mounted on support structure or on Transformer tanks. Support structure and Transformer tank amplify the ground acceleration at the base of porcelain components.Dynamic characteristics of substation equipment are calculated by carrying out shake table experiments and finite element analysis. Assumptions are introducedin finite element modeling of equipment with respect to internal components like coil windings, metering equipment, insulating oil etc., are appropriately lumped at respective nodes to reduce the complexity involved in modelling non structural components. Basic validation of finite element models of substation components have been done with shake table experiments. Results of shake table experiments and finite element analyses are compared well with the less difference. The research concentrated towards identifyingexact earthquake ground motion amplification at the base of the porcelain components. At the same time discussions are presented on ground motion amplification of equipment with respect to recommendations available in International standards like IEEE-693-2005.Item Fenton and Photo-Fenton Oxidation of Selected Pharmaceutical Compounds in Water(National Institute of Technology Karnataka, Surathkal, 2013) Mahamood; Manu, B.In the present study, the degradation of three selected pharmaceuticals viz. paracetamol (PCM), amoxicillin (AMX) and diclofenac (DCF) is carried out using Fenton and UVC assisted photo-Fenton oxidation processes in batch mode at ambient temperature (27 ± 3o C). In addition to Fe2+, iron extracted from laterite soil (Fe (LS)) is also studied as an alternate catalyst in Fenton reagent. The experimental conditions like pH, [H2O2]0, [Fe2+]0, [Fe (LS)]0, are optimized by Fenton process for the initial concentration of 0.066 mM for PCM, 0.027 mM for AMX and 0.031 mM for DCF. For the optimization of the initial experimental conditions, drug degradation and chemical oxygen demand (COD) removal are measured as the objective parameters. The optimum pH for the degradation of PCM and AMX is 3.0 but for DCF and mixture of the drugs it is 3.5. The H2O2 is varied in the range 0 to 2.94 mM, Fe2+ is varied from 0 to 0.036 mM and Fe (LS) is varied from 0.004 to 0.036 mM for their optimization in Fenton oxidation. The optimum molar ratio of [H2O2]0 : [Fe2+]0 is observed to be 98.55 : 1 for PCM, 98.55 : 1 for AMX and 57.49 : 1 for DCF. However, the [H2O2]0 : [Fe (LS)]0 molar ratios are observed as 65.70 : 1 for PCM, 76.65 : 1 for AMX and 76.65 : 1 for DCF. Then, the Fenton and photo-Fenton oxidations are carried out at the optimal conditions for the initial drug concentration in the range of 0.066 – 0.331 mM for PCM, 0.027 – 0.137 mM for AMX and 0.031 – 0.157 mM for DCF. The degradation of PCM and AMX is 100 % but the degradation of the DCF is only 79.29 % with Fe2+ and 74.29 % with Fe (LS) in Fenton oxidation for 240 min of reaction time. However, in 120 minutes UV irradiation time, the photo – Fenton oxidation has demonstrated 100 % degradation of PCM and AMX for both the catalysts but DCF degradation is 98.57 % (with Fe2+) and 85.71 % (with Fe (LS)). It is also observed that the degradation and mineralization is more with Fe2+ than Fe (LS) for both PCM and DCF; but it is more with Fe (LS) than Fe2+ for AMX. In Fenton oxidation of mixture of drugs using Fe2+, the percent drug degradation is 68.55 (PCM), 70.77 (AMX), 62.56 (DCF) and percent COD removal is 64.80 in 240 min. Similarly, when Fe (LS) is used in Fenton oxidation, the percent drug degradation is 57.22 (PCM), 76.71 (AMX), 55.75 (DCF) and percent COD removal is 60.00 in 240 min. However, in photo-Fenton oxidation of mixture of drugs using Fe2+, the percent drug degradation is 70.01 (PCM), 75.70 (AMX), 64.79 (DCF) and percent COD removal is 74.40 in 120 min. On the other hand, using Fe (LS), the percent drug degradation is 59.98 (PCM), 77.87 (AMX), 59.29 (DCF) and percent COD removal is 58.40 in 120 min. The value of the pseudo secondorder rate constants for DCF > PCM > AMX when they are treated individually. The complete degradation of model drugs is observed with Fe2+ as well as Fe (LS) as catalysts in both the AOPs. Therefore, Fe (LS) may be effectively used as an alternate catalyst in Fenton’s reagent to degrade the selected drugs in water. The operating cost for the treatment of drugs in mixture is less by about 49 % with Fe2+ and 40 % with Fe (LS) in Fenton process and about 59 % with Fe2+ and 57 % with Fe (LS) in photo-Fenton process when compared to the costs for the treatment of the drugs individually. Furthermore, Fenton and photo-Fenton oxidation using Fe (LS) as catalyst appears to be a very promising technology for the oxidation of PCM, AMX and DCF in aqueous solutions.Item Studies on Land Use/Land Cover Changes and Water Quality Due to Urbanization Along the Coastal Areas of Dakshina Kannada District, Karnataka, India(National Institute of Technology Karnataka, Surathkal, 2013) Rajagopal, B.; Dwarakish, G. S.; Shrihari, S.Increasing population and urbanization result in land use and land cover changes from local to global scales. The coastal area of Dakshina Kannada district of Karnataka, India has witnessed a phenomenal development in the last couple of decades and it is expected that this trend will continue at a much faster rate due to the setting up of Special Economic Zones (SEZs) and their expansions in Mangalore. Therefore an attempt was made in this research to study the land use/land cover changes that have taken place for 25 years from 1983-2008 and to assess the urbanization impacts on water quality. The study area lies between 12°45’ N to 13°7’30” N latitude and 74°45’ E to 75° E longitude having an area of about 777 square kilometres. Six Indian Remote Sensing (IRS) satellite images were used in the study. Supervised classification with maximum likelihood algorithm was adopted in the study and the accuracy assessment was done. The results indicate that the urban/built-up area has increased by 270% and the population has increased by 215% during the study period. A total of 1500 water samples pertaining to sea, rivers and groundwater were collected during November 2006 and October 2007 and analyzed for twenty five physical, chemical and bacteriological characteristics. The over all quality of groundwater in Mangalore city was seem to be deteriorating. The pH value showed a decreasing trend, while the concentration of Nitrates showed increasing trend, though at present it is well within the standards. The global water quality indices determined for River Nethravati varied from ‘Fair’ to ‘Good’ and the indices for River Gurpur can be categorized as ‘Fair’. Urban growth prediction helps the urban planners and policy makers in providing better infrastructure services to a huge number of new urban residents. In the study area, the urban/built-up area is predicted to increase to 381 sq. km and the population is expected to reach 2.6 millions by the year 2028. The population in the study area has already reached saturation levels; therefore any further increase in population will result in environmental degradation. This indicates that the available resources are not sustainable and the carrying capacity of the region is untenable.Item Studies on Potential Usage of Fly Ash in Steel Fiber Reinforced Concrete for Rigid Pavements(National Institute of Technology Karnataka, Surathkal, 2013) A., Chandrashekhar; Chandrashekhar, A.UThe ever-growing needs of transportation systems have always necessitated continuous research to make pavements functional, stable, safe, serviceable and durable. With demands exponentially increasing and available resources decreasing, search for materials, construction techniques and performance appraisal is more than ever. Any material when rejected as worthless after its utility period was over is termed as waste material. The tendency of throwing such material not only led to resource crunch and also their collection, conveyance, processing and disposal posed severe problems. Serious attempts began to seek no waste, low waste and waste utilization. Recovery, recycle and reuse of wastes, product, plant and process modifications are being tried. Highway construction industry also has embraced these methods where in waste is being utilized as ingredients in paving material. Industrial wastes like coal ash, blast furnace slag, bottom ash, rubber tires have significant potential to replace conventional materials for various applications in highway construction. Steel fiber reinforced concrete has been investigated and successfully employed in various applications in Civil Engineering projects. The present work is an experimental and analytical investigation to study the usage potential of steel fiber reinforced fly ash concrete(SFRC) with special emphasis to serviceability and durability. Issues like material characterization, cause effect relationship between fatigue failure and load stress level, and temperature gradients effects have been addressed. Concrete grades M40 and M30 have been considered for the investigation as these are widely used. The mixes have been designed as per relevant Codes of Practice. Cubes for compression tests, prisms for modulus of rupture and flexural fatigue tests have been cast, cured and tested. To study the effect of temperature profile on performance and to know the load deformation characteristics of the proposed material, 900 mm x 900mm x 150mm slabs have been used. The use of fly ash in plain concrete as cement replacement tends to reduce all the strengths at the age of 28 days. Along with steel fibers (Vf= 1%), fly ash concrete (with 40% cement replacement) overcomes this deficiency and the enhancement ofstrength of 10% was observed. The steel fiber fly ash concretes have shown better fatigue performance comparative to the reference concrete. A new fatigue equation for projection of design fatigue life has been proposed. The thermal absorption characteristics were found to be unchanged by addition of fly ash to the conventional concrete. Investigations on influence of nonlinear temperature profiles on performance have shown that the resulting temperature stress is 10-30% higher than that obtained using the conventional linear temperature gradient assumption and its incorporation in pavement design has been highlighted.Item Design Consistency Evaluation of Rural Highways(National Institute of Technology Karnataka, Surathkal, 2013) N.J, Sowmya; Ravishankar, A.U.Rapid growth of population and increasing economic activities are the twin factors that contribute to the tremendous increase in the vehicle population which, in turn, contributes to the growing number of road accidents. Road accidents are complex events involving a variety of factors, including highway geometry, driver behaviour, weather conditions, and speed limits. Several studies have been conducted to determine the relationship between factors associated with accidents and their effect on safety. Improving highway design consistency is considered to be an important strategy for improving traffic safety. Geometric design consistency evaluation is a widely used method of determining sections of highways which require alignment improvement. Identifying and treating any inconsistency on a highway can significantly improve its safety performance. A critical factor in highway design is maintaining a good consistency with a road geometry that meets the driver’s expectations. Considerable research has been undertaken to explain this concept, including identifying potential consistency measures and developing models to estimate them. However, considerable amount of work has not been carried out to evaluate the geometric consistency in India. Rural roads constitute about 80 per cent of Indian road network. Therefore, rural road safety accounts for a considerable share of the total road safety problem. In Dakshina Kannada District, and even in Karnataka state, intermediate lane highways make more than 50 per cent of the principal road network. The majority of these intermediate lane rural highways are historical routes and many of them do not follow a specific design code. Therefore, road safety of intermediate lane roads is a very important issue in the development of the country. This study aims to enhance the safety of these existing highways based on an understanding of actual driving behaviour by means of field data measurements, and to verify their conformance to a consistency evaluation model. Both horizontal and vertical alignments are the main focus of this study. The horizontal alignment of a road consists of a straight tangent followed by horizontal curve, whereas the vertical alignment of the road consists of a level section followedvii by a vertical curve. This study deals with developing appropriate design consistency evaluation criteria of horizontal and vertical curves using geometric, speed, and accident data of eight intermediate lane rural highways. Geometric details of a road were collected from the field and CAD (Computer Aided Design) drawings were prepared using the details of surveying. A spot speed survey was conducted for passenger cars on the approach tangent and at the beginning, middle, and end points of horizontal curves and on the approach tangent, limiting point and summit point of vertical curves. The accident details were collected for six years (from 2005 to 2010) from different police stations. The operating speed prediction models were developed for both horizontal and vertical curves. The speed change experienced by the same driver from tangent to curve i.e. speed differential was also studied for horizontal curves, and the models were developed to predict this change. Consistency evaluation criteria for horizontal curves and vertical curves were also developed to enhance the safety of the alignment. Alignment indices, are the another set of quantitative measures, were used to identify the inconsistencies that exist on intermediate lane rural highways. Finally, an attempt was made to develop the relationship between safety and alignment indices.Item Seismic Response of Laterite Masonry Structures(2013) Unnikrishnan, Sujatha; Narasimhan, Mattur C; Venkataramana, KattaLaterite is the most favored masonry material in south-west coastal areas of India due to its availability in abundance. However, not much research has been carried out so far on the structural performance of laterite masonry. The studies addressing the seismic performance of laterite masonry buildings are almost nil and hence there is a need for research in this area. The strength and elastic properties of laterite masonry are influenced by the individual properties of laterite blocks and mortar used and the nature of bond between them. Experimental investigations were carried out on the strength characteristics of laterite blocks, cement mortar specimens and stack-bonded laterite masonry prisms under uniaxial compression. From these studies laterite masonry may be classified as weak-soft unit and strong-stiff mortar masonry. Stack bonded laterite masonry prism was modeled using commercially available finite element software and analyzed to understand the stress distribution pattern. Parametric studies were also conducted. In south-west coastal areas of India masonry structures are normally box-type structures with either a light roof or a rigid roof. Efficiency of different types of seismic strengthening measures like lintel band, roof band etc. were studied on both these types of structures. A method of reinforcing laterite masonry with vertical reinforcement called ‘containment reinforcement’ has also been tried. Different configurations of box-type laterite masonry structures with these strengthening measures were modeled. Free vibration studies were conducted to find the natural frequencies and mode shapes of boxtype laterite masonry structures without and with roof. Response of single storeyed boxtype laterite masonry structures, to El-Centro acceleration input was obtained using timehistory analysis. The effect of strengthening factors like lintel band, roof band and containment reinforcement on the natural frequencies, mode shapes and time-history responses were analyzed. Responses of some of these structures to Kobe and Koyna accelerations were also studiedItem Effect of Reinforcement Corrosion on the Bond Strength of RC Members(National Institute of Technology Karnataka, Surathkal, 2014) Shetty, Akshatha; Venkataramana, Katta; Narayan, K. S. BabuCorrosion of reinforcing steel is the most detrimental effect endangering the structural performance. Present investigation has been taken up to study the detrimental effect of corrosion on bond behaviour. Anchorage bond strength and Flexural bond strength characteristics are studied in this research. Two types of cements namely Ordinary Portland Cement (OPC) and Portland Pozzolona Cement (PPC) have been used. Bond strength study has been carried out for controlled beam specimen and for specimens subjected to different levels of corrosion. Loss in mass of reinforcement bar has been taken as the basis to fix corrosion levels. Accelerated corrosion technique has been adopted to control corrosion rate by regulating current over predetermined durations. For the study of anchorage bond strength, cylindrical specimens have been adopted. Concrete grade of M20 and Fe-415 grade of 16mm diameter bar have been used. From the study it has been observed that for corrosion levels upto 2.5%, bond strength is unaffected. But for corrosion levels beyond 2.5%, there is considerable decrease in bond strength. For understanding the performance of flexural bond strength, National Bureau of Standard (NBS) beams have been investigated. Concrete grade M30 and steel Fe-415 have been used. From the experimental investigation it has been observed that load carrying capacity drops by about 1.6%, for every percentage increase in corrosion level. Bond strength degradation of 2.6% at slip initiation and 2.1% at end of slip have been observed for every percentage increase in corrosion level for OPC concrete beam specimens. For PPC concrete, bond strength degradation of 2% at slip initiation and 2.1% at end of slip have been observed. In numerical study, finite element method was used. ANSYS commercial software is used for the study. From the numerical modelling it has been observed that load carrying capacity drops by about 1.8%, for every percentage increase in corrosionlevel. The bond strength degradation values are 3% and 2.4% at initiation of slip and end of slip respectively per percentage increase in corrosion level. Lastly, an attempt has been made to apply the proposed prediction equations to estimate corrosion in real life structures.Item Water Quality Assessment in Distribution System Using Artificial Intelligence(National Institute of Technology Karnataka, Surathkal, 2014) Krishnaji, Patki Vinayak; Shrihari, S.; Manu, B.In this study various artificial intelligence techniques have been compared for assessment and prediction of water quality in various zones of municipal distribution system using six physico-chemical characteristics viz. pH, alkalinity, hardness, dissolved oxygen (DO), total solids (TS) and most probable number (MPN). Fuzzy expert system, artificial neural network (ANN) and adaptive neuro fuzzy inference system (ANFIS) were used for the comparative study. The proposed expert system includes a fuzzy model consisting of IF-THEN rules to determine WQI based on water quality characteristics. The fuzzy models are developed using triangular and trapezoidal membership functions with centroid, bisector and mean of maxima (MOM) methods for defuzzification. In ANN method the cascade feed forward back propagation (CFBP) and feed forward back propagation (FFBP) algorithms were compared for prediction of water quality in the municipal distribution system. The comparative study was carried out by varying the number of neuron (1-10) in the hidden layer, by changing length of training dataset and by changing transfer function. ANFIS models are developed by using triangular, trapezoidal, bell and Gaussian membership function. Further, these artificial intelligence techniques are compared with multiple linear regression technique, which is the commonly used statistical technique for modelling water quality variables. The study revealed that artificial neural network (ANN) outperforms other modelling techniques and is a robust tool for understanding the poorly defined relations between water quality variables and water quality index (WQI) in municipal distribution system. This tool could be of great help to the distribution system operator and manager to find change in WQI with changes in water quality varibles.
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