Department of Civil Engineering

Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

&nbsp;

IIT Palakkad

Droughts in the southeast USA have been linked to economic losses and intractable water conflicts. The region has witnessed several severe droughts events during the period from 1901 to 2005. In this study, spatiotemporal variability in meteorological drought characteristics in the southeast were analyzed using two different datasets by the means of standard precipitation index and standard precipitation evapotranspiration index for the period 1901–2005 for agricultural and non-agricultural seasons. The study periods were divided into three epochs 1901–1935, 1936–1970, and 1971–2005 and drought characteristics, in terms of severity, frequency, number, and trends were analyzed. Additionally, areal extent, drought severities and return periods associated with three severe drought years 1904, 1954, and 2000 were analyzed. Except for the state of Florida, results indicate decrease in drought severity during the recent epoch of 1970–2005 in the study domain. Trend analysis confirms that the study domain has become wetter over the last 105 years. Wetting trends were more prominent in the agricultural season. Additionally, droughts seem to have migrated from the western part of the study area encompassing the states of Alabama, Tennessee, Louisiana, and Mississippi to the Florida panhandle region during the recent epoch. Droughts exhibited higher spatiotemporal variability during the agricultural season compared to the non-agricultural seasons. Results also showed that early to mid-1950s experienced some of the most severe droughts in the study domain. Some of the drought events, such as the drought of 1954 and 2000, have been equivalent to a 100-year drought event in the southeast. The results from this study form the benchmark for studying the impacts of future climate change projections on meteorological droughts in the southeast. © 2016, Springer Science+Business Media Dordrecht.

World University root node

Natural Hazards

Spatiotemporal variability of meteorological droughts in southeastern USA

The lower Apalachicola–Chattahoochee–Flint River Basin in the Southeast United States represents a major agricultural area underlain by the highly productive karstic Upper Floridan aquifer (UFA). During El Niño Southern Oscillation-induced droughts, intense groundwater withdrawal for irrigation lowers streamflow in the Flint River due to its hydraulic connectivity with the UFA and threatens the habitat of the federally listed and endangered aquatic biota. This study assessed the compounding hydrologic effects of increased irrigation pumping during drought years (2010–2012) on stream–aquifer water exchange (stream–aquifer flux) between the Flint River and UFA using the United States Geological Survey modular finite element groundwater flow model. Principal component and K-means clustering analyses were used to identify critical stream reaches and tributaries that are adversely affected by irrigation pumping. Additionally, the effectiveness of possible water restriction scenarios on stream–aquifer flux was also analysed. Moreover, a cost–benefit analysis of acreage buyout procedure was conducted for various water restriction scenarios. Results indicate that increased groundwater withdrawal in Water Year 2011 decreased baseflow in the lower Apalachicola–Chattahoochee–Flint River Basin, particularly, in Spring Creek, where irrigation pumping during April, June, and July changed the creek condition from a gaining to losing stream. Results from sensitivity analysis and simulated water restrictions suggest that reducing pumping in selected sensitive areas is more effective in streamflow recovery (approximately 78%) than is reducing irrigation intensity by a prescribed percentage of current pumping rates, such as 15% or 30%, throughout the basin. Moreover, analysis of acreage buyout indicates that restrictions on irrigation withdrawal can have significant impacts on stream–aquifer flux in the Basin, especially in critical watersheds such as Spring and Ichawaynochaway Creeks. The proposed procedure for ranking of stream reaches (sensitivity analysis) in this study can be replicated in other study areas/models. This study provides useful information to policymakers for devising alternate irrigation water withdrawal policies during droughts for maintaining flow levels in the study area. Copyright © 2017 John Wiley &amp; Sons, Ltd.

Hydrological Processes

Evaluation of water-use policies for baseflow recovery during droughts in an agricultural intensive karst watershed: Case study of the lower Apalachicola–Chattahoochee–Flint River Basin, southeastern United States

14th Annual Meeting Asia Oceania Geosciences Society

Landuse/Land cover change detection and Modelling in Bharathapuzha River Basin

Alkali contamination of soils results in repeated structural failure when exposed. Though the effects of alkali on different soils have been investigated in recent years, a systematic research approach aimed at establishing swell behavior in non-swelling kaolinitic clays when exposed continuously with varying concentrations of alkali solution as pore fluid and its micro-level investigation is not well documented. Series of one-dimensional free swell tests and micro-level studies (XRD, SEM) have been carried out to investigate the alkali induced swell in non-swelling kaolinitic clays. Naturally available red earth and two commercial clays, namely ball clay and china clay, which predominantly contains kaolinite mineral are selected for the study. The swell test results showed that all three clays exhibited high swelling with alkali solutions (0.1 N, 1 N, 4 N, 8 N) when compared with water. The magnitude of swell observed in clays interacted with alkali solution ranged from a minimum of 8% to maximum of 56% depending upon the concentrations exposed. China clay showed a minimum swell of 8% with 8 N alkali solution to a maximum swell of 22% with 4 N alkali solution and red earth showed a minimum swell of 18% with 8 N alkali solution to a maximum of 27% with 0.1 N alkali solution. Whereas, ball clay showed a minimum swell of 12% with 0.1 N alkali solution and maximum swell of 56% with 8 N alkali solution. The resulted magnitude of alkali induced swell in clays is attributed to dispersion of clay particles and new mineral formations. To explore the formation of new minerals and morphological transformations a micro-level investigation is carried out on representative samples collected at the end of free swell tests. The formation of zeolite minerals viz. sodalite and cancrinite were evidenced from XRD results and rosette type structures were observed from SEM studies. © 2016 Elsevier B.V.

Applied Clay Science

Swelling behavior of kaolinitic clays contaminated with alkali solutions: A micro-level study

Previous studies have demonstrated that a sudden change in stiffness at the base of a building (e.g., due to nonlinear deformation in the base isolator including sudden sliding) during seismic excitations may result in an increase in the floor-level acceleration responses when compared with the results of the same building but modeled as a linear structure (i.e., without allowing any stiffness change). It has also been demonstrated that this phenomenon occurs due to high-frequency modes getting excited during the nonlinear phase of the motion as a result of energy transfer from the adequately excited fundamental mode. In this part, a systematic analytical study is carried out to understand this energy-transfer phenomenon by formulating the equations of motions for different stages of hysteresis. For simplicity, an initial velocity profile proportional to the fundamental mode of a multi-degree-of-freedom (MDOF) system is considered and the free-vibration response of the system is studied. A numerical investigation is then carried out in which the influence of different parameters on the energy transfer to higher modes of a system is studied. Further, using the results of the perturbation approach, simplified approximate expressions are also obtained to understand the contribution of different terms. It has been shown that the second mode receives the maximum amount of energy from the fundamental mode and the transfer of energy reduces with the increase in mode number. Further, it has been observed that the transfer of energy to the second mode increases for (1) higher initial energy content of the fundamental mode, (2) less spacing between the second and fundamental modes, and (3) lower postyield stiffness of the bilinear spring. To validate the energy-transfer phenomenon experimentally, shake table experiments with a scaled model were conducted alternatively with two different base conditions: (1) fixed base, and (2) structure isolated by sliding isolators. To better understand the energy-transfer phenomenon, a secondary component was also attached to the second floor of the structure with its frequency tuned to the second mode of the structure. A low-amplitude sinusoidal base excitation followed by a sudden jerk was considered. From the recorded floor accelerations and component acceleration responses, it is concluded that energy transfer from the adequately excited fundamental mode to higher modes occurs due to a sudden change in stiffness of the structure as a result of sudden sliding. © 2017 American Society of Civil Engineers.

Journal of Engineering Mechanics

Energy transfer to high-frequency modes of a building due to sudden change in stiffness at its base

In optimal control design, two of the most popular strategies used are linear quadratic regulator (LQR) control and the H2 norm optimization. This paper obtains a mathematical equivalence between the performance index of an LQR control algorithm and the H2 norm of a linear system. For a single-input excitation such as an earthquake, the optimal gain for an LQR control algorithm is the same as that of an H2 norm minimization of the system. This observation leads to the inference that for a linear system, quadratic optimal gain for a free vibration of the system can also be used as an optimal gain for the forced vibration of the system. However, the same results are not true for multi-input excitations, such as wind or blast loads. In these cases, optimal gains must be obtained separately for the two algorithms. © 2016 American Society of Civil Engineers.

Equivalence of Optimal Gain between H2 Norm Minimization and LQR Control of a Linear System

IRF Middle East \& North Africa Regional Congress \& Exhibition, Dubai, UAE

CRACKING PERFORMANCE INVESTIGATION OF ASPHALT-RUBBER GAP- GRADED MIXTURES : EMPHASIS ON AGGREGATE GRADATION

The influence of discrete and randomly distributed fibers (DRDF) on the improvement of the resistance to cracking of clay-based landfill covers was studied by conducting a series of centrifuge model tests. A motor-based differential settlement simulator (MDSS) was used to induce differential settlements to the soil layers during centrifuge tests performed at 40g using the 4.5 m radius beam centrifuge at Indian Institute of Technology Bombay. A digital image cross-correlation (DIC) technique was used to capture deformations of the model barriers and to obtain strain field distributions. Thickness of the unreinforced barriers (URSB) and fiber-reinforced barriers (FRSB) were varied as 15 mm (similar to 0.6 m in the field) and 25 mm (1.0 m). Fiber lengths were varied as 30, 60, and 90 mm. The strain at water breakthrough of 15 mm (0.6 m) and 25 mm (1 m) FRSB were respectively 1.9 and 2.2 times higher compared to identical URSBs. A relatively crack-free surface was observed for FRSB with longer fibers even after subjected to differential settlement of 1 m. © 2016 American Society of Civil Engineers.

Journal of Geotechnical and Geoenvironmental Engineering

Centrifuge modeling and digital image cross-correlation analysis of geofiber-reinforced clay-based landfill covers

Indian Concrete Journal

Need of an efficient particle size analysis and its influence on properties of concrete

A field evaluation of an underwater tunnel was conducted using a variety of nondestructive testing (NDT) methods, including visual inspection, air- and ground-coupled ground-penetrating radar (GPR), ultrasonic tomography (UST), and impact echo (IE). An air-coupled GPR antenna was used along with visual inspection to identify areas of interest in the Chesapeake Channel Tunnel near Norfolk, Virginia. After potential regions were identified, a robotic scanner with pneumatically driven suction feet was used to automatically scan the area using ground-coupled GPR, UST, and IE. Regions were also evaluated using manually applied UST. These methods combined with powerful software presented the element under inspection as a 3D volume for thorough inspection. This study shows that this particular combination of NDT techniques can efficiently and effectively identify and locate reinforcement, backwall depth, and potentially delaminated areas. By analyzing the phase shift of ultrasonic waves, it is also shown that UST techniques can be used to potentially determine the condition of the backwall and reinforcement bonding. © 2017 American Society of Civil Engineers.