- Prof. P. Anbazhagan, M.E, Ph.D, FICDM, ERF (AUS), AMEERI, LMIGS
Associate Professor,
Department of Civil Engineering,
Indian Institute of Science, Bangalore
Bangalore India 560 012.
Phone 080-22932467
Cell 09448100410
Alternate Email: anbazhagan@iisc.ac.in
anbazhagan2005@gmail.com
web page:http://civil.iisc.ac.in/%7Eanbazhagan/ - +919448100410
P Anbazhagan
Indian Institute of Science, Department of Civil Engineering, Faculty Member
- Dr. Anbazhagan Panjamani graduated in Civil Engineering (B.E.) from College of Engineering, Anna University, Guindy, ... moreDr. Anbazhagan Panjamani graduated in Civil Engineering (B.E.) from College of Engineering, Anna University, Guindy, Chennai, 2002, and received his Masters in Soil Mechanics and Foundation Engineering from the same institute in 2004. In 2007, he obtained his Doctorate in Geotechnical Engineering at Indian Institute of Science (IISc), Bangalore, India. Presently, he is serving as an Assistant Prof in Civil Engineering at Indian Institute of Science, Bangalore. His main interests are in earthquake Geotechnical engineering, applied geophysics and railway Geotechnical engineering. His research focuses on applied Geophysics for earthquake Geotechnical engineering problems and transport Geotechnical engineering problems. His research work on microzonation of Bangalore city was selected for Research highlights presentation on the IISc Main Web page - 2006. He received the prestigious Endeavor Fellowship Award from Australian Government in 2009 and worked on Railway Ballast in the University of Wollongong, NSW Australia. He received the IEI Young Engineers Award 2010-2011 from The Institution of Engineers (India) and the ISES Order of Merit 2015 Award for Outstanding Work in Earthquake Science, Young Scientist category, Indian Society of Earthquake Science. He is also serving as a visiting professor for the third time in King Saud University (KSU), Riyadh, Saudi Arabia. Dr. Anbazhagan has formulated a new teaching course "Engineering Seismology" for the first time in India. He has published about 66 Journal papers and 90 conference papers. He is a very active research personality and has received about 36.8 million (368 lakhs Indian Rupees) funding so far, and he is an active consultant in his area of research. He is also serving as an expert member on the committees for arriving nuclear power plant design parameters, Department of Atomic Energy. He is also involved in national mission on Dam Rehabilitation and Improvement Project (DRIP). Dr. Anbazhagan is serving as Editorial/Reviewer board member of the International Journal of Geotechnical Earthquake Engineering (IJGEE); International Journal of Civil Engineering (IJCE) and Journal of Civil Engineering (JCE). He serves as a reviewer for most of the leading journals in his area of research.edit
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The maximum possible earthquake magnitude ( ) calculation is indispensable in many seismic/engineering applications. It is obligatory for earthquake engineering community, disaster management agencies and the insurance industry. However,... more
The maximum possible earthquake magnitude ( ) calculation is indispensable in many seismic/engineering applications. It is obligatory for earthquake engineering community, disaster management agencies and the insurance industry. However, there is no universally accepted practice for estimating the value of (Kijko and Singh, 2011).The maximum magnitude is dened as the upper limit of earthquake magnitude for a given region and is synonymous with the magnitude of the largest credible. It assumes a sharp cutoff magnitude at , so that, by denition, no earthquakes are to be expected with magnitude exceeding . Presently, deterministic and probabilistic based approaches are being used for estimation. These approaches are based on the frequency magnitude distribution, seismicity data and maximum observed magnitude ( ) of seismic study area (SSA) which have lots of uncertainty. These approaches are suitable for the regions having long seismicity data and high seismicity rate. Furthermore, t...
The efficiency of track foundation material gradually decreases due to insufficient lateral confinement, ballast fouling, and loss of the shear strength of soil due to local liquefaction and clay pumping. This paper presents... more
The efficiency of track foundation material gradually decreases due to insufficient lateral confinement, ballast fouling, and loss of the shear strength of soil due to local liquefaction and clay pumping. This paper presents characterization of rail track subsurface to identify ...
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Research Interests: Civil Engineering, Earthquake Engineering, Neural Network, Statistical Learning Theory, Cross Validation, and 10 moreSupport vector machine, Spatial Variability, Ordinary Kriging, Numerical Model, Levenberg Marquardt, Artificial Neural Network, Geological and Geotechnical Engineering, Backpropagation Algorithm, multi layer perceptron, and Loss function
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In the present study, acceleration design-response spectra (ADRS) for deep and shallow sites have been proposed for different seismic site classification as per NEHRP. Nonlinear site response analysis has been performed at different... more
In the present study, acceleration design-response spectra (ADRS) for deep and shallow sites have been proposed for different seismic site classification as per NEHRP. Nonlinear site response analysis has been performed at different subsurface profiles and surface spectra have been derived. The site factors in terms of short period or 0.2 s (Fa) and long period or 1.0 s (Fv) for both the regions has been estimated. Finally, using these site factors, ADRS for both the regions have been proposed. This is the first time such extensive study has been done for developing the ADRS for the deep and shallow sites of India or Asia for different seismic site class.
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The conventional Cornell’s source-based approach of probabilistic seismic-hazard assessment (PSHA) has been employed all around the world, whilst many studies often rely on the use of computer packages such as FRISK (McGuire FRISK—a... more
The conventional Cornell’s source-based approach of probabilistic seismic-hazard assessment (PSHA) has been employed all around the world, whilst many studies often rely on the use of computer packages such as FRISK (McGuire FRISK—a computer program for seismic risk analysis. Open-File Report 78-1007, United States Geological Survey, Department of Interior, Washington 1978) and SEISRISK III (Bender and Perkins SEISRISK III—a computer program for seismic hazard estimation, Bulletin 1772. United States Geological Survey, Department of Interior, Washington 1987). A “black-box” syndrome may be resulted if the user of the software does not have another simple and robust PSHA method that can be used to make comparisons. An alternative method for PSHA, namely direct amplitude-based (DAB) approach, has been developed as a heuristic and efficient method enabling users to undertake their own sanity checks on outputs from computer packages. This paper experiments the application of the DAB app...
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Research Interests: Civil Engineering, Earthquake Engineering, Neural Network, Statistical Learning Theory, Cross Validation, and 10 moreSupport vector machine, Spatial Variability, Ordinary Kriging, Numerical Model, Levenberg Marquardt, Artificial Neural Network, Geological and Geotechnical Engineering, Backpropagation Algorithm, multi layer perceptron, and Loss function
The Manuscript entitled “Probabilistic seismic hazard analysis using logic tree approachPatna District (India)” presents a comprehensive PSHA study for one specific region in north India. Authors employ different alternatives for main... more
The Manuscript entitled “Probabilistic seismic hazard analysis using logic tree approachPatna District (India)” presents a comprehensive PSHA study for one specific region in north India. Authors employ different alternatives for main PSHA-analyse components including, e.g., Mc , maximum magnitude, GMPE-set, zonation model, etc. to populate the epistemic logic tree. The study is confident, uses extensive local sources dataset and employs up-to-date PSHA analytical tools incorporated into the logic tree approach to treat the epistemic uncertainty.
The objective of this study is to investigate the shear strength characteristics, energy absorption capacity and brittleness index of sand-tire crumb mixtures using simple direct shear test and Unconsolidated Undrained (UU) triaxial test... more
The objective of this study is to investigate the shear strength characteristics, energy absorption capacity and brittleness index of sand-tire crumb mixtures using simple direct shear test and Unconsolidated Undrained (UU) triaxial test for the effective use of waste tire crumbs for seismic isolation of building. Tire crumbs were prepared with special machinery where scrap tires were crushed into pieces and powders after removal of steel belting. The processed tire crumbs obtained from local industry were sieved into four size groups, i.e. 8 mm 5.6 mm, 5.6 mm 4.75 mm, 4.75 mm 2 mm, and 2 mm 1 mm and relatively uniform sand has been selected to generate sand-tire crumb mixtures (STCM). Grouped tire crumbs are mixed with sand to generate STCM samples having 0%, 10%, 15%, 20%, 25%, and 30% tire crumbs by volume. Direct shear and UU triaxial compression tests have been carried out on STCM samples for different normal and confining pressure with constant density of 1.54 g/cc. Stressstra...
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The high level of seismicity associated with the Himalayan tectonic province results in the site amplification of the deep Indo-Gangetic Basin (IGB) alluvial deposits. IGB had experienced catastrophic earthquake damages due to the... more
The high level of seismicity associated with the Himalayan tectonic province results in the site amplification of the deep Indo-Gangetic Basin (IGB) alluvial deposits. IGB had experienced catastrophic earthquake damages due to the presence of thick soil depth of 0.05 km to about 4 km. However, very few studies have been carried out to characterize the IGB soil up to shallow depth and limited attempts have been made to measure the dynamic properties of the deep soil column. Hence, in this study, shear velocity profile ( ) up to 200 m depth is measured using combined active and passive multichannel analysis of surface wave (MASW) survey in 75 selected locations in IGB. Further, these sites are classified and characterized based on time-averaged in the upper 30 m depth as per NEHRP seismic site classification. The measured profiles are further used to estimate the site-specific response parameters at different locations by carrying out non-linear site response analysis. Input ground mo...
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The primary objective of the study is to estimate the energy absorption (EA) capacity, brittleness index (ductility) and stiffness characteristics of Sand-Tire Crumb Mixtures (STCM) using direct shear test and Unconsolidated Undrained... more
The primary objective of the study is to estimate the energy absorption (EA) capacity, brittleness index (ductility) and stiffness characteristics of Sand-Tire Crumb Mixtures (STCM) using direct shear test and Unconsolidated Undrained (UU) triaxial test for the effective reuse of waste tire crumbs as isolation materials. The properties considered include, strength and deformation characteristics of a STCM. A relatively uniform sand and readily available tire crumb grouped into four size has been selected to generate STCM. Experimental studies have been carried out on STCM with constant density of 1.54 g/cc. Stress-strain curve obtained from UU test has been used to estimate EA. The experimental results show that peak strength, EA and stiffness increases with increasing percentage of tire crumbs up to 25% and starts decreasing thereafter. Among the tested tire crumb sizes, crumb size IV provide the maximum EA without compromising on strength compared to other tire crumb sizes.
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This study presents site classification using 30 m average concept and newly proposed soil average by considering 30 sets of boreholes and shear wave velocity data. Shear wave velocity (V) is measured by carrying out multichannel analysis... more
This study presents site classification using 30 m average concept and newly proposed soil average by considering 30 sets of boreholes and shear wave velocity data. Shear wave velocity (V) is measured by carrying out multichannel analysis of surface wave (MASW) survey close to ...
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Ground penetrating radar (GPR) is a non-invasive geophysical technique which is capable of providing continuous high-resolution imaging of the subsurface. GPR is widely used in geotechnical engineering and most of the interpretations are... more
Ground penetrating radar (GPR) is a non-invasive geophysical technique which is capable of providing continuous high-resolution imaging of the subsurface. GPR is widely used in geotechnical engineering and most of the interpretations are visual based and qualitative. The objective of this study is to produce an effective algorithm to interpret a GPR wave form, so that it can be used to quantify the changes occurring in the subsurface more precisely. In this study, a GPR survey has been carried out at 10 selected locations in Coimbatore, India using low frequency (25MHz) ground coupled rough terrain antenna. Subsurface information was interpreted through a visual method by looking at the wave pattern changes. Time domain wave forms were converted as frequency domain; Fast Fourier Transform (FFT) spectrum were developed. The peak frequency (݂ ሻ from FFT has nearly the same range of values for all the traces within that layer. In the absence of borehole data, soil layer interfaces ar...
Study of seismic hazard and site response are essential and has become mandatory for the design of important structures. Subsurface investigation is an important step, from where input parameters for site response studies like shear wave... more
Study of seismic hazard and site response are essential and has become mandatory for the design of important structures. Subsurface investigation is an important step, from where input parameters for site response studies like shear wave velocity (Vs), density, thickness and damping characteristics etc are obtained. Most of the site response studies at shallow bedrock site are usually carried out by using Standard penetration test (SPT) N values and Vs from Multichannel Analysis of Surface Waves (MASW) with assumption that soil layers are horizontal, uniform and homogeneous. These assumptions are not completely true in shallow bedrock region due to heterogeneous soil deposits. The objective of this study is to generate subsurface profiles at shallow bedrock region using integrated site investigation testing. In this study drilling of borehole with SPT N value measurement, seismic testing of MASW and Electrical Resistivity Tomography (ERT) has been carried out at selected locations i...
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Earthquake activities in the many parts of world had shown the importance of local soil condition in the propagated wave motion. In this paper an attempt has been made to estimate site effects of deep soil column in Lucknow, Indo-Gangetic... more
Earthquake activities in the many parts of world had shown the importance of local soil condition in the propagated wave motion. In this paper an attempt has been made to estimate site effects of deep soil column in Lucknow, Indo-Gangetic basin for scenario earthquakes at Himalayan plate boundary. Based on previous study, the synthetic ground motion has been generated using Stochastic Finite Fault model (FINSIM) for two scenario earthquakes at seismic gaps. One seismic gap called as western location/seismic gap is located about 307.88km from site and gives the peak ground acceleration of 0.11g at site. Another one is the Central seismic gap/location is located in central seismic gap at 229.77km from the site and gives the Peak Ground Acceleration (PGA) of 0.218g. The local soil layer details with standard penetration test N value have been collected for the main location in Lucknow from literates. The general soil found for this site is silty sand and silty clays having SPT N value ...
The Ground Penetrating Radar (GPR) is a very useful and most widely used tool for the forensic investigation as it supports all the necessary information to forensic study. In this paper the GPR was used to investigate failed soil fill... more
The Ground Penetrating Radar (GPR) is a very useful and most widely used tool for the forensic investigation as it supports all the necessary information to forensic study. In this paper the GPR was used to investigate failed soil fill due to poor compaction and failed nailed wall due to seepage saturation. In order to understand GPR wave character and dielectric constant in different degree of saturation and compaction, a model sections has been constructed and GPR study has been carried out. It was found that the GPR wave amplitude decreases with increase in moisture content and bulk density. A detailed GPR study was carried out in the failed floor slab over filled soil in the 90% completed industrial building. The study shows that heterogeneous compaction resulted in high saturation during heavy rain and caused larger settlements. The seepage water saturation caused failure of nailed wall for open excavation of 15 m in an under construction site. GPR survey has been carried out t...
Seismic codes are important guidelines for urban planning and infrastructure development. Seismic codes are mainly used for earthquake resistant design of new structures and retrofitting existing structures. The geotechnical aspects play... more
Seismic codes are important guidelines for urban planning and infrastructure development. Seismic codes are mainly used for earthquake resistant design of new structures and retrofitting existing structures. The geotechnical aspects play a crucial role in the development of response spectra for a site/region which is the basis for any earthquake resistant designs. In this study an attempt has been made to study the geotechnical provisions in the Indian earthquake code of “Criteria for earthquake resistant design of structures” 17 . The first version of this code was released by the Bureau of Indian Standards in the year 1962 and followed by many revisions soon after major earthquakes in the country. The modification in the zonation map of India with occurrence of significant earthquakes shows that the assessment of hazard on a regional scale is not consistent with local variation. India has diverse geology and geotechnical material (soil and rock) properties with typical borelogs fr...
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Research Interests: Geophysics and Seismology
Even though the size of the earthquake is moderate, presence of soft soil near the surface can cause devastating damage due to local site and induced effects like liquefaction. Evidence of liquefaction due to past Indian earthquakes was... more
Even though the size of the earthquake is moderate, presence of soft soil near the surface can cause devastating damage due to local site and induced effects like liquefaction. Evidence of liquefaction due to past Indian earthquakes was highlighted in many Paleo-seismic studies, particularly in the Himalayan region. The objective of this paper is subsurface characterization of part Indo-Gangetic Basin (IGB) and estimation of liquefaction hazards for the possible surface ground motions based on the region seismic study. Drilling of boreholes and measurement of standard penetration N values are carried out at selected locations for subsurface characterization. Possibility of liquefaction for soil deposits are assessed by comparing the grain size distribution curves obtained from laboratory tests with the range of grain size distribution curves of potentially liquefiable soils. The minimum factor of safety values has been identified for each location and presented in the form of maps s...
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Standard Penetration Test (SPT) N values and the energy correction factor play a crucial role in the soil liquefaction assessment. In the Liquefaction potential assessment, the cyclic resistance ratio is estimated considering soil... more
Standard Penetration Test (SPT) N values and the energy correction factor play a crucial role in the soil liquefaction assessment. In the Liquefaction potential assessment, the cyclic resistance ratio is estimated considering soil strength measured through SPT N values. Due to various mechanical energy losses, energy measured just below anvil and above the sampler doesn't equal the theoretical energy, hence corrected SPT N values are used in the most of the codes. However Indian Standard Code does not specify any correction for hammer energy, various studies have shown that there is a need to upgrade the present version of IS 1893. In this study, an attempt has been made to measure, hammer energy first time in India uses indigenously developed SPT-Hammer Energy Measuring Apparatus (HEMA) by the Department of Civil Engineering, IISc, Bangalore at below the anvil and above the sampler tube. Then variations of energy values are used to understand the effect on the estimation of liquefaction potential in Indian cities.
Utilizing rubber tyres in vibration mitigation can be a viable approach of resolving the chronic problems associated with disposal of waste tyres. However, the dynamic properties of sand-tyre crumb mixtures (STCM) are essential for the... more
Utilizing rubber tyres in vibration mitigation can be a viable approach of resolving the chronic problems associated with disposal of waste tyres. However, the dynamic properties of sand-tyre crumb mixtures (STCM) are essential for the design of a vibration isolation system. In this study, the dynamic properties of STCM in terms of shear modulus and damping ratio are presented against the shear strain. The modulus and damping ratio of STCM for small to large shear strain were measured using Torsional resonant column tests and cyclic triaxial tests, for two composition of tyre crumbs (50% and 75%) and three different confining pressure (50, 100, and 200 kPa). The results showed that, shear modulus and the damping ratio of the mixtures are strongly influenced by the percentage of rubber inclusion. Shear modulus decreased with an increase in tyre crumb inclusion for all the confining pressure, whereas the damping ratio increases with the increase in rubber content in STCM. For any percentage of tyre crumbs inclusion, the shear modulus increases and damping ratio decrease with increasing confining pressure. These results are useful to understand the dynamic response of STCM and further used in model studies to design a low cost isolation system.
This paper presents forensic investigations of earthquake induced failures during Sikkim 2011 Earthquake, India. Detailed field geotechnical observations and geophysical investigations have been carried out at selected locations affected... more
This paper presents forensic investigations of earthquake induced failures during Sikkim 2011 Earthquake, India. Detailed field geotechnical observations and geophysical investigations have been carried out at selected locations affected by 2011 Sikkim earthquake. Field observation, drilling of boreholes with sample collection (DBS), surface wave testing by Multichannel Analysis of Surface Wave (MASW) method and Ground Penetrating Radar (GPR) survey have been carried out at sites having slope failures, settlement and structural failures. Three different failure cases: distressed pavement over a natural slope, a school building, and secretariat building failures are discussed with reference to the field tests carried out. GPR radargram showed the cracked portion of pavement and the depth of the cracks. DBS and MASW at school building show the presence of loose cohesionless soil layer below the top dense layer, which might have undergone cyclic mobility and hence resulted in a settlement and cracks in the floor slab. GPR investigation at Sikkim secretariat building showed that the building is constructed on a sloped ground, where one side is filled with soil (damaged side) and the other side is directly resting on the rock. The study highlights the possible reasons for local seismic wave amplification and the associated damage with the help of field investigation carried out.
Study of seismic hazard and site response are essential and has become mandatory for the design of important structures. Subsurface investigation is an important step, from where input parameters for site response studies like shear wave... more
Study of seismic hazard and site response are essential and has become mandatory for the design of important structures. Subsurface investigation is an important step, from where input parameters for site response studies like shear wave velocity (Vs), density, thickness and damping characteristics etc are obtained. Most of the site response studies at shallow bedrock site are usually carried out by using Standard penetration test (SPT) N values and Vs from Multichannel Analysis of Surface Waves (MASW) with assumption that soil layers are horizontal, uniform and homogeneous. These assumptions are not completely true in shallow bedrock region due to heterogeneous soil deposits. The objective of this study is to generate subsurface profiles at shallow bedrock region using integrated site investigation testing. In this study drilling of borehole with SPT N value measurement, seismic testing of MASW and Electrical Resistivity Tomography (ERT) has been carried out at selected locations in Hampi, Karnataka, India. SPT gives soil type and density, MASW gives shear wave velocity and resistivity testing gives layer thickness. Integrated subsurface profiles are generated and are used to understand variation of subsurface layers in shallow bedrock sites and validate 1-D site response study assumptions. These subsurface profiles may be further used to understand difference of 1-D and 2-D site response.
The objective of this paper is to estimate the maximum magnitude () which is defined as the upper limit of earthquake magnitude for a given region by a new approach considering regional rupture characteristics. The proposed method has... more
The objective of this paper is to estimate the maximum magnitude () which is defined as the upper limit of earthquake magnitude for a given region by a new approach considering regional rupture characteristics. The proposed method has been explained in details and examined for an active seismic region. Seismic study area (SSA) has been generated by dividing into radii of 200 km and 500 km, based on the seismicity and seismotectonics. The regional rupture character has been established by considering Percentage Fault Rupture (PFR), which is the ratio of subsurface rupture length (RLD) to Total Fault Length (TFL) expressed in percentage. PFR is used for determining RLD, which is further used for estimating the maximum magnitude for each source. Maximum magnitude for SSA of Kanpur region has been estimated and compared with the values from existing methods. It is observed from the study that the existing deterministic and probabilistic estimation methods are sensitive to SSA radius, magnitude of completeness (, and parameters and values. However from the proposed method is a function of the rupture character and is irrespective of the SSA and , and parameters and values. KEYWORDS Maximum earthquake magnitude (), regional Rupture Characteristics, and G-R parameters, magnitude of completeness, maximum observed magnitude (). You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com)
This study investigates the mechanical behavior of geosynthetic-reinforced composite materials, Sand-Tyre Crumb Mixtures (STCM) by conducting Unconsolidated Undrained (UU) triaxial tests. The main objective of this study is to evaluate... more
This study investigates the mechanical behavior of geosynthetic-reinforced composite materials, Sand-Tyre Crumb Mixtures (STCM) by conducting Unconsolidated Undrained (UU) triaxial tests. The main objective of this study is to evaluate the stress-strain characteristics of STCM in geosynthetic-reinforced works. The mechanical behavior of geosynthetic-reinforced STCM has been investigated by varying proportions of tyre crumbs (50% and 75% tyre crumbs by volume), type of geosynthetic (geotextile, geogrid and geonets), number of geosynthetic layers (1 to 4 layers) and confining pressure. A series of UU triaxial tests has been carried out to select the optimum size of tyre crumb. Tyre crumb that provides comparatively higher stiffness is considered as the optimal size and has been used in the investigation on geosynthetic-reinforced STCM. The results demonstrate that STCM reinforced by geotextile has enhanced peak strength, axial strain at failure, energy absorption and ductility capacity. Also, it has been found that the type of geosynthetic significantly influences the shear strength of STCM.
Liquefaction hazard is one of the major concerns for earthquake geotechnical engineering. In this paper an attempt has been made to assess liquefaction potential of Chennai city using SPT N values. Chennai is located between 12.75° to... more
Liquefaction hazard is one of the major concerns for earthquake geotechnical engineering. In this paper an attempt has been made to assess liquefaction potential of Chennai city using SPT N values. Chennai is located between 12.75° to 13.25° N and 80.0° to 80.5° E on the southeast coast of India and in the northeast corner of Tamil Nadu. To understand the liquefaction possibility of Chennai city, about 650 Borelogs have been collected from different geotechnical agencies and used for the analysis. These boreholes were drilled for different projects in Chennai, most of them were drilled up to hard stratum and a minimum depth of 10m. SPT borehole data contains information about depth of water table, the classification of soil and the field observed 'N' values, index properties, rock depth. These borehole information are used to prepare N corrected table by applying the universally followed correction factors for liquefaction study. These corrected N values are further used to estimate the factor of safety against liquefaction of soil layer. Based on the factor of safety, the regional liquefaction hazard maps have been developed for depths of 1.5m, 3.0m, 6.0m and 10.0m. To represent the worst scenario, least factor of safety has been identified for each borehole location and mapped. Further the estimated factor of safety against liquefaction is used to estimate liquefaction potential index by considering depth of layer. These results are analyzed and compared in this paper.
Ground penetrating radar (GPR) is a widely used non destructive testing method for the identification of subsurface features in transportation geotechnical engineering. GPR is a geophysical technique to detect and identify structures,... more
Ground penetrating radar (GPR) is a widely used non destructive testing method for the identification of subsurface features in transportation geotechnical engineering. GPR is a geophysical technique to detect and identify structures, either natural or man-made, below the ground surface with the help of electromagnetic radiations. In this study an attempt has been made to extent possibility of using GPR for pavement structural evaluation. The structural assessment of existing road pavements are carried out using GPR antennas of 1.6 GHz and 500 MHz. A model test section was constructed using different layers of Sand, Red soil, Concrete block and steel pipes to estimate the difference in dielectric properties. Field GPR survey has been carried out at selected eight locations in Bangalore. GPR data has been collected and thickness is evaluated, in the same location boreholes were drilled core samples are collected. Thickness of core samples are measured in the lab and compared with GPR results. The obtained results from both borehole data and GPR data shows almost similar.
In the past few decades, rapid urbanization can be seen all over the world, while most of this has occurred in developing countries, owing to the breakdown of the rural economy and the consequential migration of rural population to urban... more
In the past few decades, rapid urbanization can be seen all over the world, while most of this has occurred in developing countries, owing to the breakdown of the rural economy and the consequential migration of rural population to urban areas. It is foreseen that severe devastation and high death tolls could be resulted if a major earthquake occurs in one of these urban cities, where fragile buildings and infrastructures prevail. On the other hand, scrap tire disposal has been a significant environmental problem in many urban cities due to the huge increase in the number of vehicles. It has been a hot topic among engineering community to find new beneficial ways to recycle and reuse the huge stockpile. This paper proposes a new method of utilizing scrap tires for earthquake protection. The method involves mixing scrap tires with soil sediments and placing the mixtures around foundations of building structures for seismic isolation. The validity of the proposed method has been shown by a series of numerical simulations.
The efficiency of track foundation material gradually decreases due to insufficient lateral confinement, ballast fouling, and loss of the shear strength of soil due to local liquefaction and clay pumping. This paper presents... more
The efficiency of track foundation material gradually decreases due to insufficient lateral confinement, ballast fouling, and loss of the shear strength of soil due to local liquefaction and clay pumping. This paper presents characterization of rail track subsurface to identify ballast fouling and subsurface layers (capping layer, sub grade) strength using seismic refraction survey. Seismic refraction survey of multichannel analysis of surface wave analysis (MASW) has been carried out in model track and field track. Shear wave velocity obtained from MASW was used to identify the fouling character of track ballast, there by to evaluate track conditions. The shear velocity of fouled ballast increases with fouling percentage and reaches a maximum value then decreases. This character is used to define optimum and critical fouling points of fouled ballast. This article also highlights ballast gradation followed in India and comparison of Indian ballast gradation with international gradation standards. The ballast gradation followed by Indian railways is poorly graded and more favorable for drainage.
Determining flexible and rigid pavement layer thickness and stiffness are important for pavement evaluation and provides data for pavement management systems (PMS). Many conventional methods practiced are time consuming and random... more
Determining flexible and rigid pavement layer thickness and stiffness are important for pavement evaluation and provides data for pavement management systems (PMS). Many conventional methods practiced are time consuming and random testing. In this study an attempt has been made to assess thickness and structural characters of the existing road pavements using GPR antenna of 1.6 GHz and MASW of 24 channel geode seismograph with 4.5Hz geophones. Eight testing locations have been carefully selected in Bangalore by considering surface quality and type of roads. GPR and MASW survey has been carried out simultaneous in these locations. GPR gives electromagnetic wave velocity of subsurface layers, which are used to estimate pavement layer thickness. MASW gives shear wave velocity, which are used to estimate low strain dynamic properties of pavement layers. These results are compared with boreholes samples collected in the same locations. Initial comparison shows that these non destructive tests are effective in assessing thickness and quality (stiffness) with accuracy of more than 93% within short time.
Devastating earthquakes have caused large causalities in the early 20 th century in Himalayan region. Owing to the increase in population and with the increase in the infrastructure, compared to the past the damages will be catastrophic... more
Devastating earthquakes have caused large causalities in the early 20 th century in Himalayan region. Owing to the increase in population and with the increase in the infrastructure, compared to the past the damages will be catastrophic is case of any future event. Many researchers have highlighted the possible existence of seismic gap along the Himalayan region both in terms of time and location. Understanding of site effects and amplification become mandatory in this region. Site amplification depends on the dynamic properties of soil, thickness above rock/ hard layer and input ground motion. Limited attempt has been made in India to measure and understand site effects in deep basic due to paucity of recorded ground motion data at rock and ground. Hence in this paper an attempt has been made to estimate amplification from past event isoseismal map and compared with the surface PGA (Peak Ground Acceleration) obtained from site response analysis for selected sites.