1st Webinar Series on
Geotechnical Earthquake Engineering
(GEE)
Dr. El Naggar is a Distinguished University Professor of Western University, Canada. He is Editor-In-Chief of Soil Dynamics and Earthquake Engineering and past Associate Editor of the Canadian Geotechnical Journal. He published more than 500 technical papers/book chapters on foundations, soil-structure interaction and geotechnical earthquake engineering; and consulted on major projects worldwide. Dr. El Nagar attracted more than $20M of research funding and graduated more than 100 PhD and Master students. He received numerous awards including: Geosynthetics, Stermac, Meyerhof, Canadian Geotechnical Colloquium Speaker, Western University Distinguished Professorship, Faculty Scholar Award, Outstanding Teaching, and Research Excellence Awards as well as the 2015 Ontario Professional Engineers Medal for Engineering Research & Development. He is an elected Fellow of Canadian Academy of Engineers, Engineering Institute of Canada and the American Society for Civil Engineers
Seismic performance of bridge and marine structures supported by extended pile-shafts principally depends on the curvature demand in critical regions of the pile below ground level. The equivalent fixed-based cantilever model is commonly used to assess the local curvature ductility demand of a yielding pile-shaft at any inelastic displacement level. In this approach, adequate prior knowledge of several parameters including depth of fixity, plastic-hinge depth and equivalent plastic-hinge length is essential for proper estimation of ductility capacity. The present study aims to propose analytical formulations by using concepts of strain wedge method based on nonlinear behavior of soil-pile system to assess the key parameters of the equivalent cantilever model. In addition, a set of dimensionless design charts is produced based on an analytical approach covering a range of practical values of soil and pile properties. The ability of the developed model in assessing the curvature ductility demand of the bridge system is validated against several published full-scale tests on RC shafts in clay and sand. Finally, a general cyclic BNWF model is developed to account for the important features of soil-pile interaction problem including lateral load characteristics, soil cave-in, soil-pile side shear, gap formation, and strength and stiffness hardening/degradation.
GEORGE GAZETAS has served for 33 years as Professor of Geotechnical Engineering at the National Technical University of Athens, following an academic career in the US, where he taught at SUNY-Buffalo, Rensselaer (RPI), and Case Western Reserve University. His main research interests have focused on the dynamic response of footings, piles, caissons; the seismic response of earth dams and quay-walls; and soil–structure interaction. Much of his research has been inspired by observations after destructive earthquakes, being actively involved in reconnaissance expeditions of the earthquakes in Northridge (1994), Kobe (1995), Kocaeli (1999), Christchurch (2011), and Cephalonia (2014) among others. He established an annual 9-day educational trip to Kobe with his soil dynamics class, in the aftermath of that destructive earthquake. He has received awards for his research and teaching, including the first Shamsher Prakash Foundation Prize, the Walter Huber Civil Engineering Research Prize and James Croes Medal from ASCE, the Alfred Noble Prize from the Engineering Societies of America, the Prakash-ISET Award from the Indian Society for Earthquake Technology, and the Excellence in University Teaching Award from the Institute of Research &Technology in Greece. He has been the Coulomb (2009), Ishihara (2013), Maugeri (2019) and Kenneth Lee (2019) Lecturer. He was honored in 2019 as the 59th Rankine Lecturer by the ICE in London, and recently as Geo-Legend by the Geotechnical Institute of ASCE.
Current seismic geotechnical practice has embraced concepts inspired by pseudo-static thinking and force-based methodologies. The result is often over-designed foundations that, in addition to being uneconomical and difficult to implement, might unexpectedly lead to poor technical performance of foundation–structure systems. The lecture will address the benefits of drastically changing the established philosophy in seismic foundation design. Emphasis will be given to “foundation rocking and soil failure” of tall slender structures, the foundations of which are deliberately under-designed to ensure that, during strong shaking, substantially nonlinear and inelastic soil-foundation interaction takes place ― uplifting of footing from the supporting soil, along with mobilisation of bearing-capacity failure mechanisms in the soil. Thanks to the kinematic nature of seismic shaking, allowing such unconventional response limits the accelerations transmitted up into the super-structure, thereby reducing the inertia loading, and hence the overturning moments and shear forces onto the foundation. Owing to its cyclic nature, the inelastic response generates substantial damping, while exceedance of the ultimate capacity acts (only) momentarily and alternatingly. The two phenomena contribute towards decreased response intensity and acceptable levels of residual deformations (displacements and rotations). Deformations are further diminished by the beneficial contribution of gravity to re-centering of the foundation. It is shown that the resulting design leads to safer and more resilient performance than the conventional conservative design. To analyse the inelastic and nonlinear response of systems undergoing such unconventional modes of deformation, in addition to rigorous finite-element methods, a simplified equivalent-linear approach is highlighted in the presentation.
Prof. T. G. Sitharam Obtained his B E (Civil Engineering) from University of Mysore; Master’s from Indian Institute of Science, Bangalore in 1986 and Ph.D. from University of Waterloo, Ontario, Canada in 1991. He has served University of Texas at Austin, Austin, Texas, USA from 1991-94. Presently he is the Director of Indian Institute of Technology, Guwahati, Assam since July 2019. He also holds position of Director (additional charge) at Central Institute of Technology Kokrajhar, Assam. He is a Senior Professor, Department of Civil Engineering, Indian Institute of Science, Bangalore and he has served IISc for last 27 years. As the Director of IIT Guwahati, he was responsible for creating 5 new schools and five new academic centres at IITG during 2020-21 During his tenure, IITG has taken a position of Rank No 2 institute in citation per faculty in India (Rank 41 globally) in the recent QS world ranking 2022. IITG jumped 95 ranks from 2019 to 395th rank globally in 2022. In NIRF ranking, IITG ranked 8th rank in engineering in 2021 and earlier positioned at 7th rank in 2020. Prof. Sitharam has created a new Industry Interaction and special Initiative (II&SI) group at IITG and has attracted 22 number of companies at Research park and incubated large number of start-ups in Technology Incubation Centre of IITG. In 2020 -2021, IITG has transferred about 20 Technologies to industries during this pandemic. Presently he is Executive Council member of AICTE and Chairman, Eastern Zonal committee of AICTE. Prof. Sitharam is the member of Science and Engineering Research Board (SERB), Established through an Act of Parliament: SERB Act 2008, Department of Science & Technology, Government of India. He was the former Chairman, Research Council, CSIR-Central Building Research Institute (CBRI), Roorkee. Presently, he is the President of Indian Society for earthquake Technology and International Association for Coastal Reservoir Research (IACRR). He has published 500 technical papers, 20 books, with Google scholar H-index of 50 and I-10 index 146 with more than 8100 citations. He was listed in the world's top 2% of scientists for the most-cited research scientists in various disciplines by Stanford University in 2020 and again 2021. He has guided 40 Ph.D. students; 35 Masters Students, 25 postdoctoral students and several thousand industry professionals and teachers through continuing education workshops. He has filed for 5 patents, executed more than 120 consulting projects and 2 start-up companies to his credit. He is the Fellow of American Society of Civil Engineers (ASCE), Fellow of Institution of Civil Engineers (United Kingdom), Diplomat of Geotechnical Engineering (D.GE.) from Academy of Geo-Professionals, ASCE; Fellow of IGS, ISET, ISES and many other Societies in India and abroad. He is also a certified professional engineer and chartered engineer from IE.
An exponential rise in population along with uncontrolled and unplanned urbanisation exposed to earthquakes reeks a plenitude of hazard in terms of life and property. The majority of the damage due to earthquakes is caused by poorly designed and built structures that have not considered appropriate seismic forces on the structure due to potential earthquakes in the region. Effects, mechanics, and impact of an earthquake in terms of ground shaking, site effects, liquefaction, and landslides had been broadly covered in the past, and recent developments have catered profound understanding of earthquakes. Consideration of uncertainties in properties of the ground and also other uncertainties in earthquake occurrence is critically important throughout the assessment process. Our recent studies on ground motion attenuation characteristics, comprehensive seismic hazard analyses, site effects, liquefaction behaviour, seismic microzonation, ground motion analyses, joint time-frequency analysis based ground motion synthesis, etc., have largely contributed to geotechnical earthquake engineering. Our detailed experimental and numerical works on liquefaction have improved the understanding of the liquefaction of sands. Installation of ground motion sensors and monitoring of earthquakes have further supplemented geotechnical earthquake engineering research in the country. Recent surveys on earthquake preparedness and readiness indices have pointed out the urgent need for general awareness, and an action plan toward mitigating and managing the hazard due to earthquakes. In this talk, I will discuss my student's contribution to the field of Geotechnical Earthquake Engineering, which will lead to a disaster-resilient society.
Kyle Rollins received his BS degree from Brigham Young University (BYU) and his Ph.D. from the University of California at Berkeley. After working as a geotechnical consultant, he joined the Civil Engineering faculty at BYU in 1987 following his father who was previously a geotechnical professor. His research has involved geotechnical earthquake engineering, gravel liquefaction, lateral pile group interaction, bridge abutment behavior, collapsible soils, and soil improvement techniques. He has supervised more than 130 graduate students and published over 220 papers. ASCE has recognized his work with the Huber research award, the Wellington prize, and the Wallace Hayward Baker award. He was the Cross-Canada Geotechnical lecturer for the Canadian Geotechnical Society. He received the Osterberg Award for innovation in foundation engineering from the Deep Foundations Institute.
To improve our understanding of downdrag on deep foundations in liquefied soil, Prof. Rollins has conducted a series of full-scale tests using blast induced liquefaction. Full-scale tests have involved 30 cm driven steel pipe piles in Vancouver, Canada; 60 cm Augercast piles in New Zealand; a 25 cm micropile in Italy, three 45 cm driven piles in the US, and a group of piles in Italy. Liquefaction induced settlements ranged from 5 to 27 cm. In contrast to some theories, measured negative skin friction in the liquefied sand was not zero. As the liquefied sand reconsolidated, the sand exerted negative friction on the piles that was about 50% of the positive skin friction before liquefaction. In contrast, within non-liquefied layers, significant negative skin friction developed that was approximately equal to the positive skin friction prior to liquefaction. Pile settlement was reasonably well predicted using the neutral plane approach. The toe resistance vs. displacement curve played a key role in determining the pile settlement which was often much less than the soil settlement. Piles within the groups experienced reduced downdrag forces. Static pile load tests conducted before and two months after liquefaction showed that side friction in liquefied layers requires significant time to regain its strength. Prof. Rollins will show videos of blast-induced liquefaction, sand boil formation, and pile performance.
Prof. Deepankar Choudhury is the Prof. T. Kant Chair Professor and Head of Civil Engineering department of IIT Bombay, Mumbai, India. Throughout 1st class 1st GOLD Medalist in academics, Prof. Choudhury did his PhD from IISc Bangalore, India in 2002 and received Prof. G. A. Leonard’s Best PhD Thesis award from IGS, New Delhi. In addition to IIT Bombay, he worked as a faculty member at IIT Kanpur, new IITs at Gandhinagar and Dharwad (on deputation from IIT Bombay as mentor), as Adjunct Professor of AcSIR with CSIR-CBRI Roorkee, as Visiting Professor/Fellow/Scientist at NUS Singapore, UoW Australia, UC Berkeley USA, Kagoshima University Japan, TU Darmstadt Germany, INU South Korea. Prof. Choudhury’s major research areas are Geotechnical Earthquake Engineering, Foundation Engineering, Soil-Structure Interaction, Computational Geomechanics. His over 300 technical peer reviewed publications including over 180 journal papers with several citations show the global acceptability of his research works. Prof. Choudhury already supervised 30 PhD theses, among those 6 had received Best PhD thesis awards from IIT Bombay / IGS New Delhi / INAE etc. Prof. Choudhury is an elected Fellow (FNASc) of the National Academy of Sciences, Prayagraj (Allahabad), India. A BOYSCAST Fellow of India, Prof. Choudhury internationally is Alexander von Humboldt Fellow of Germany, JSPS Fellow of Japan, TWAS-VS Fellow of The World Academy of Sciences, Italy, and Fellow of American Society of Civil Engineers (ASCE), USA, in addition to National Fellow of Institution of Engineers India (FIE), Indian Geotechnical Society (FIGS), Indian Society of Earthquake Technology (FISET). Prof. Choudhury, a recipient of Prof. C. S. Desai Medal of IACMAG, USA in 2017. He received several Young Scientist/Engineer Awards from various academies/societies of India like INSA, NASI, ISCA, INAE, IEI, DST, DAE, ISTE and from abroad like APACM, SP Research Foundation. Prof. Choudhury’s name has been listed among the top 2% scientists of the world as per the data published by Stanford University, USA. Prof. Choudhury’s Video lectures in YouTube through NPTEL distance education program of Govt. of India on topics ‘Soil Dynamics’ and ‘Geotechnical Earthquake Engineering’ are highly popular. He received Best Teacher Award and Best Researcher Awards of IIT Bombay. He is an Associate Editor of ASCE-International Journal of Geomechanics, Indian Geotechnical Journal (Springer), Journal of Civil Engineering of IEI (Springer). He served as Editorial Board Member for journals like, Soils and Foundations (Elsevier), Canadian Geotechnical Journal, Geotechnical and Geological Engineering (Springer). He worked as Secretary of TC 207 (Soil-Structure Interactions and Retaining Walls) of ISSMGE and former Secretary of TC 212 (Deep Foundations) of ISSMGE, in addition to present and former member of TC 203 and Editorial Board of ISSMGE Bulletin. Prof. Choudhury provides technical expert advises for various industry projects as a consultant.
This GEE webinar will discuss the challenges encountered in providing the design solutions to some of the complex geotechnical structures subjected to static and dynamic loading conditions. The first study is pertaining to the analysis of the foundation system of a new Nuclear Power Plant, which is going to build on the alluvial soil for the first time in India as compared to other NPPs founded on rock. To ensure the seismic safety of the foundation of NPP structures, site-specific seismic hazard assessment was carried out by incorporating local soil conditions, and rigorous dynamic soil-structure interaction (SSI) was used to provide design solution for foundations. For this proposed NPP site, combined pile raft foundation (CPRF) is getting implemented considering the settlement criteria based on functionality of the NPP. Another study is pertaining to the buried pipelines which are widely used for transporting various substances such as natural gas, oil, water, etc. From a geotechnical perspective, the most common reason for the failure of buried pipelines is due to the permanent ground deformation (PGD) resulting from earthquake-induced hazards like landslides, fault movement, etc. This webinar will also discuss the impact of such PGD on buried pipelines. Also, a case study of challenges and solutions given for the seismic design of the foundation system for India’s longest (21.8 km) sea bridge (MTHL) in Mumbai will be discussed. Another foundation solution provided for a seismically active region near India-Nepal border for the construction of India’s largest petroleum terminal will be presented.
Jonathan Bray, Ph.D., P.E., NAE is the Faculty Chair in Earthquake Engineering Excellence at the University of California, Berkeley. Dr. Bray is a registered professional civil engineer and has served as a consultant on important engineering projects and peer review panels. He has authored more than 400 research publications on topics that include liquefaction and its effects on structures, seismic performance of earth structures, earthquake ground motions, and earthquake fault rupture propagation. He created and led the Geotechnical Extreme Events Reconnaissance (GEER) Association. Dr. Bray is a member of the US National Academy of Engineering and has received several honors, including the H. Bolton Seed Medal, Terzaghi Award, Ishihara Lecture, Peck Award, Joyner Lecture, Middlebrooks Award, Huber Research Prize, Packard Foundation Fellowship, and NSF Presidential Young Investigator Award.
Pseudostatic slope stability procedures are commonly used in engineering practice. However, the selection of the seismic coefficient employed in the analysis is often based on precedence without due consideration of the amount of seismic displacement that constitutes satisfactory performance for each particular project and without incorporating the vastly different seismic exposure for sites around the world. In this talk, a rational basis for selecting the seismic coefficient is presented. The proposed procedure requires that the engineer establishes the project-specific allowable level of seismic displacement. The seismic response characteristics of the slope are represented by the fundamental period of the potential sliding mass, and the site-dependent seismic demand is characterized by the 5% damped elastic design spectral acceleration at the degraded period of the potential sliding mass. The level of uncertainty in the estimates of the seismic demand and displacement can be handled through the use of different percentile estimates of these values. With the proposed methodology, the engineer can properly incorporate the amount of seismic displacement judged to be allowable and the seismic hazard at the site in the selection of the seismic coefficient.
Ioannis Anastasopoulos has been Full Professor and Chair of Geotechnical Engineering at ETH Zurich since 2016. He specializes in geotechnical earthquake engineering and soil–structure interaction, combining numerical with experimental methods. His academic degrees include a PhD from the National Technical University of Athens (NTUA), an MSc from Purdue University, and a Civil Engineering Diploma from NTUA. His research interests include resilient seismic design and preparedness, innovative seismic hazard mitigation techniques, sustainable retrofit of bridge foundations, improved methods for sustainable geotechnical construction, faulting and its effects on infrastructure, site effects and slope stabilization, foundations for renewable energy, tsunamis and their effects on coastal infrastructure, scouring of bridge foundations, soil liquefaction and structure–soil–structure interaction. He is the inaugural recipient of the Young Researcher Award of the ISSMGE in Geotechnical Earthquake Engineering, and the winner of the 2012 Shamsher Prakash Research Award. He has been involved as a consultant in a variety of projects of significance in Europe, but also in the US and the Middle East. His consulting work ranges from the design of pile-rafts of tall buildings/towers, special seismic design for new and retrofit of existing bridges, retaining walls, metro stations and tunnels, to harbour quay walls, and special design against faulting–induced deformation. He is National Delegate-Expert for Switzerland for the 2nd generation of Eurocode 7 and member of the SIA 267 Commission on Geotechnical Design. Moreover, he is actively engaged in the organization of international conferences (e.g., ICONHIC), specialized workshops and training courses, fostering knowledge transfer and fruitful interactions between the academia and the industry. He currently serves as Associate Editor of Soil Dynamics and Earthquake Engineering, Journal of Earthquake Engineering, and Frontiers in Built Environment, and has served as EBM of Géotechnique and of the ICE Geotechnical Engineering Journal. As of 2021, he is a member of the Board of Directors of the International Association for Earthquake Engineering (IAEE).
The vast majority of existing bridges were built before the 90’s, without any or just basic seismic design. Pile group strengthening can be a challenging, costly, and time-consuming operation, calling for optimised solutions. The lecture will look into the behaviour of pile groups under combined Vertical, Horizontal and Moment (VHM) loading, combining 3D Finite Element (FE) and centrifuge modelling. Initially, a proof-of-concept study is conducted, inspired by the recent widening of a Swiss bridge. According to conventional design, the existing pile group needs retrofit to accommodate the increased seismic loads due to widening. An unconventional “do-nothing” approach is explored (maintaining the existing foundation), exploiting nonlinear soil response. Such an approach requires improved design methods and better definition of the ultimate capacity of pile groups under combined loading. In this context, after developing a database of Swiss bridges and identifying pile group typologies encountered in practice, a fundamental yet representative 2 x 1 bored pile group is tested at the ETH Zurich (ETHZ) Geotechnical Centrifuge Centre (GCC). Four experimental setups are developed and verified for vertical, pushover, combined, and vibration testing. After determining the bearing capacity under vertical loading, pushover loading is employed to measure the moment capacity 〖(𝑀〗_𝑢𝑙𝑡) of a lightly- and a heavily-loaded (widening) pile group. In contrast to intuitive expectations, the heavily-loaded system mobilises larger 𝑀_𝑢𝑙𝑡. Combined loading is performed to derive experimental failure envelopes, confirming their tendency to expand with increasing vertical load. The centrifugulte results are used for FE model validation. The numerical technique is upgraded to account for nonlinear soil–pile interaction, using hypoplasticity for sand and appropriate modelling of interfaces and pile response. The transition to prototype scale accounts for scale effects, and employs the Concrete Damaged Plasticity (CDP) model for proper simulation of the reinforced concrete (RC) piles. The latter is a key advancement, accounting for the axial load dependency of bending moment capacity. The problem is studied parametrically, deriving failure envelopes in function of vertical loading, confirming the increases of pile group capacity with increasing vertical load. Finally, the Limit Equilibrium method is used to derive closed-form analytical failure envelopes, providing a useful design tool for engineering practice. The latter are verified against the FE analysis results.
Sebastiano Foti is a Professor in Geotechnical Engineering and Vice-Rector for Education at Politecnico di Torino, where he also received his PhD degree. He has been chair for the Civil Engineering program from 2015 to 2018. He is a member of the Technical Committees TC 203: Earthquakes and a past core member of TC 102: In situ tests of ISSMGE. He has been a member of the Project Team for drafting the new version of Eurocode 7 - Geotechnical design - Part 2: Ground investigation and testing. His research activity is mainly devoted to geophysical methods for geotechnical characterization, with particular reference to surface wave testing, seismic waves in porous media and the use of geophysical techniques in the lab. His other research interests include seismic site response, soil-structure interaction, structural dynamic tests for the assessment of existing foundation systems. He has published over 200 papers in scientific journals and technical conferences, three books and six book chapters. He served in the editorial board of Soils and Foundations from 2015 to 2017. He was awarded the Geotechnical Research Medal (Bishop Medal) 2003 by the Institution of Civil Engineers (UK) for the best paper on geotechnical engineering, an Honorable Mention in the Best Paper category in the Geophysics journal in 2011 by the Society of Exploration Geophysics (USA) and the Outstanding Paper Award from Earthquake Spectra 2018 by the Earthquake Engineering Research Institute (USA).
Ground response analyses (GRAs) represent a key element for the non-ergodic (site-specific) evaluation of the seismic hazard. Definition of input parameters for the numerical models requires an accurate and comprehensive site characterization. In the recent past, several collaborative benchmark exercises have shown the existence of a certain level of “uncompressible uncertainty” in laboratory and in situ tests that need to be considered. Within this context, geostatistical models are helpful in quantifying the influence of such uncertainties. Specifically, as the stratigraphic amplification is strongly sensitive to the shear wave velocity profile, the first part of the webinar will be devoted to present a recent geostatistical model focusing on this parameter. This model provides an efficient and effective tool for the generation of stochastic, but realistic soil profiles. Two applications of the proposed geostatistical model will be then presented. Firstly, an example of site-specific analysis to evaluate the impact of uncertainties in the geotechnical site characterization on the computed seismic hazard, taken from the experience of the microzonation project in central Italy in the aftermaths of the 2016 seismic sequence. The last section of the webinar will introduce a stochastic database of ground response analyses and its applications: the verification of the new classification scheme proposed in the draft of the second generation of the structural Eurocodes (specifically in Eurocode 8 – part 1); and a systematic comparative analysis between non-linear and equivalent linear approaches.
Scott J. Brandenberg is a Professor in the Civil and Environmental Engineering Department at the University of California, Los Angeles. His research expertise lies primarily in geotechnical earthquake engineering, with focus on multi-hazard reliability of levee systems, the response of deep foundations to liquefaction-induced lateral spreading, seismic earth pressures acting on earth retention systems, and cyberinfrastructure projects, including development of community databases for liquefaction assessment. He has authored over 100 technical papers, and received the 2015 Walter L. Huber Award, 2013 Shamsher Prakash Research Award, and 2010 Arthur Casagrande Professional Development Award. He earned his PhD and MS in 2005 and 2002, respectively, from the University of California, Davis, and his BS in 2000 from Cal Poly, San Luis Obispo. He served as the Associate Dean for Diversity and Inclusion in the UCLA Samueli School of Engineering from 2017 through 2020.
Sacramento / San Joaquin Delta is a 3400 km2 estuary located at the confluence of the Sacramento and San Joaquin rivers in northern California. The Delta is the hub of California's water distribution system, serving over 22 million agricultural and urban users in the San Joaquin Valley and southern California. Delta levees circumscribe "islands" that are commonly 3 to 5 m below sea level due to oxidation and wind erosion of the organic peat soils that are prevalent in the Delta. A major concern is that an earthquake in this region of moderate seismicity could simultaneously fail multiple levees, drawing saline water from the west into the flooding islands, thereby halting water delivery. This presentation will discuss the history of the Delta, field and centrifuge testing of a levees resting atop peat soil, fundamentals of peat behavior, fragility analysis of levee systems in Japan shaken by recent strong earthquakes, and a system reliability procedure suitable for application to spatially distributed infrastructure systems like levees.
Ikuo Towhata is Professor Emeritus in the University of Tokyo, Japan. Also, worked at the University of British Columbia, Vancouver, the Asian Institute of Technology in Bangkok, and the Public Works Research Institute together with Univ. Tokyo. Presently he serves as Chair, Professional Image Committee of ISSMGE. Earlier he served as a Professor in the University of Tokyo from 1994 – 2015. He also served as a Distinguished visiting professor at IIT Bombay: July – December 2016 and the Life Fellow of the Indian Geotechnical Society. He received several prestigious awards namely 1998-1999 Shamsher Prakash Research Award, USA, of Soil Dynamics, 2005 Heritage Lecturer, International Conference on Soil Mechanics and Geotechnical Engineering, 2018 Shamsher Prakash ISET Award 2018 for Significant Contribution in Geotechnical Earthquake Engineering, the Indian Society of Earthquake Technology, December 2018, 2019 Ishihara Lecturer, TC203 on earthquake, International Society for Soil Mechanics and Geotechnical Engineering, 7th Int. Conf. Earthquake Geotechnical Engineering, Rome, Japanese Geotechnical Society awards: best paper award twice, research contribution award, and technical development awards, Japan Society of Civil Engineers: Book publication award: Geotechnical Earthquake Engineering (2008) publ. from Springer. He served as Vice President for Asia, International Society for Soil Mechanics and Geotechnical Engineering for the term 2013 to 2017 and President of the Japanese Geotechnical Society from 2014 to 2016. He published 500 research articles in international journals and conference proceedings.
Discussion on coseismic landslides has been so far based on the relationship between the load and the resistance as conventional soil mechanics supposed. In contrast, this presentation attempts to shed more light on the water effects on slope instability from different directions. First, the recent experiences are introduced in which ground water triggered or aggravated the extent of landslide; both coseismic and nonseismic examples are taken. Second, the deterioration or decay of geomaterials undergoing water action is introduced, thereby showing that the material properties of concerned slopes are damaged with time. Third, the risk of melting glacier in the course of climate warming is touched upon. Note that snow avalanche was triggered by the Gorkha earthquake in Nepal with devastating effects on the local community. Moreover, there was a chain of hazard in the recent time in which glacier melting triggered a huge landslide, the landslide mass formed a natural dam, the natural dam breached and initiated a debris flow, and the debris flow traveled hundreds of km downstream and caused flood disaster. This suggests a risk of compound disaster. It is a pity that the present state of engineering cannot handle the difficult situation except demonstrating people hazard maps, recommending them not to live in potentially hazardous areas. However, the hazard maps have problems as well such as overestimation and underestimation of the risk of natural disasters.
Misko Cubrinovski is Professor of Geotechnical and Earthquake Engineering in the Department of Civil and Natural Resources Engineering, University of Canterbury, Christchurch, New Zealand. He holds a BSc degree in Civil Engineering, MSc degree in Earthquake Engineering, and a PhD degree in Geotechnical Engineering (from the University of Tokyo, 1993). His career involves 38 years of work in the academia and the profession including seven years in Macedonia, 15 years in Japan, and 16 years in New Zealand. His research interests and expertise are in geotechnical earthquake engineering and in particular problems associated with soil liquefaction, seismic response of earth structures and soil-structure interaction. Cubrinovski has authored or co-authored over 350 technical publications, and has worked as a geotechnical specialist and advisor on over 50 significant engineering projects. His honours include the Ralph B. Peck Award (ASCE), Norman Medal (ASCE), Geomechanics Lecture Award (NZGS), Outstanding Paper Award (ASCE), Outstanding Paper Award (EERI), Director’s Award of Taisei Corporation (Tokyo, Japan), Ivan Skinner Award (NZSEE) and ANZ Joint Societies Award. Cubrinovski is a Faculty Member of the international postgraduate programme in Earthquake Engineering at the Rose School, Pavia, Italy, and Fellow of the University of Tokyo. He is the current chair of the Technical Committee on Earthquake Geotechnical Engineering and Associated Problems (TC203) of ISSMGE.
Soil liquefaction during earthquakes often causes extensive damage to land and structures, with consequent severe socio-economic disruptions that have long-term impacts on communities. This was demonstrated in recent New Zealand earthquakes in which liquefaction of reclaimed land affected critical infrastructure in Wellington, the capitol of New Zealand, and widespread urban liquefaction affected nearly half of the residential area of Christchurch, the second largest city of New Zealand. While clearly highly relevant for geotechnical and earthquake engineers, evaluation of liquefaction problems is challenging and requires in-depth considerations of soil characteristics and behaviour during earthquakes. In this talk, two fundamental aspects of soil behaviour will be explored, one related to micro-scale (particle level) and the other related to macro-scale (deposit level). In the first part, the important influence of grain-size composition on the packing of soils, penetration resistance, relative density of soils and eventual liquefaction resistance are discussed on the example of reclamations composed of gravel-sand-silt mixtures with a predominant gravel content by weight. Challenges in the liquefaction assessment are discussed in the context of non-standard soils that are problematic in simplified liquefaction assessment (i.e. soils that are not well represented in the empirical database). In the second part of the presentation, the dynamic response of soil deposits composed of liquefiable soils are explored using advanced dynamic analyses (seismic effective stress analyses). They illustrate important effects of cross-layer interactions within the deposit and governing role of system response effects in liquefying deposits. Two types of interaction mechanisms are identified: mechanisms that intensify liquefaction severity and mechanisms that mitigate liquefaction manifestation at the ground surface. It is shown that these contrasting mechanisms may lead to dramatically different outcomes (i.e. severe liquefaction manifestation versus no liquefaction manifestation) despite the nominally similar liquefaction potential of the deposits based on simplified liquefaction evaluation methods. Both issues are discussed using well-documented case histories from the 2016 Kaikoura earthquake and 2010-2011 Canterbury earthquakes in conjunction with comprehensive research studies including field investigations, laboratory testing, simplified analyses and advanced dynamic analyses. The objective of the talk is to use key observations and findings on soil liquefaction to scrutinize state-of-the-art methods and discuss important implications for engineering assessment and design.
Department of Earthquake Engineering
Indian Institute of Technology, Roorkee
Uttarakhand, India-247667
