Seismic Response of Deep Stiff Granular Soil Deposits

Seismic site response analysis is of paramount importance for many problems in earthquake engineering and has been studied extensively over the last 50 years. More recently, the observed response of deep stiff soil profiles during seismic events has indicated the possibility of significant ground amplification. In this study, a new enhanced hysteretic constitutive model is used for the evaluation of dynamic site response of deep granular soil deposits. The constitutive laws are implemented in a finite element computer code, AMPLE2000. The response of two soil profiles to different earthquake records was calculated using the newly developed model implemented in AMPLE and the computer program, SHAKE, which employs the equivalent linear procedure. The importance of soil nonlinearity with increasing levels of shaking and deposit depth on the acceleration at the ground surface is examined

Seismic Response of Normally Consolidated Cohesive Soils in Gently Inclined Submerged Slopes

The geological profile of submerged slopes on the continental shelf typically includes soft cohesive soils with layer thicknesses ranging from a few meters to tens or hundreds of meters. The response of these soils in simple shear tests is largely influenced by the presence of an initial consolidation shear stress, inducing anisotropic stress-strain-strength properties which depend also on the direction of shear. In this paper, a new simplified effective-stress-based model describing the behavior of normally to lightly overconsolidated cohesive soils is used in conjunction with a one-dimensional seismic site response analysis computer code to illustrate the importance of accounting for anisotropy, small strain nonlinearity and pore pressure development. In particular, a simple example is carried out to compare results for level ground conditions and a 10° slope. Depth profiling of the maximum shear strains and permanent deformations provide insight into the mechanisms of deformation during a seismic event, and the effects of sloping ground conditions

Investigation of the Performance of the New Orleans Flood Protection System in Hurricane Katrina on August 29, 2005: Volume 1

This report presents the results of an investigation of the performance of the New Orleans regional flood protection system during and after Hurricane Katrina, which struck the New Orleans region on August 29, 2005. This event resulted in the single most costly catastrophic failure of an engineered system in history. Current damage estimates at the time of this writing are on the order of $100 to$200 billion in the greater New Orleans area, and the official death count in New Orleans and southern Louisiana at the time of this writing stands at 1,293, with an additional 306 deaths in nearby southern Mississippi. An additional approximately 300 people are currently still listed as “missing”; it is expected that some of these missing were temporarily lost in the shuffle of the regional evacuation, but some of these are expected to have been carried out into the swamps and the Gulf of Mexico by the storm’s floodwaters, and some are expected to be recovered in the ongoing sifting through the debris of wrecked homes and businesses, so the current overall regional death count of 1,599 is expected to continue to rise a bit further. More than 450,000 people were initially displaced by this catastrophe, and at the time of this writing more than 200,000 residents of the greater New Orleans metropolitan area continue to be displaced from their homes by the floodwater damages from this storm event. This investigation has targeted three main questions as follow: (1) What happened?, (2) Why?, and (3) What types of changes are necessary to prevent recurrence of a disaster of this scale again in the future? To address these questions, this investigation has involved: (1) an initial field reconnaissance, forensic study and data gathering effort performed quickly after the arrival of Hurricanes Katrina (August 29, 2005) and Rita (September 24, 2005), (2) a review of the history of the regional flood protection system and its development, (3) a review of the challenging regional geology, (4) detailed studies of the events during Hurricanes Katrina and Rita, as well as the causes and mechanisms of the principal failures, (4) studies of the organizational and institutional issues affecting the performance of the flood protection system, (5) observations regarding the emergency repair and ongoing interim levee reconstruction efforts, and (6) development of findings and preliminary recommendations regarding changes that appear warranted in order to prevent recurrence of this type of catastrophe in the future. In the end, it is concluded that many things went wrong with the New Orleans flood protection system during Hurricane Katrina, and that the resulting catastrophe had it roots in three main causes: (1) a major natural disaster (the Hurricane itself), (2) the poor performance of the flood protection system, due to localized engineering failures, questionable judgments, errors, etc. involved in the detailed design, construction, operation and maintenance of the system, and (3) more global “organizational” and institutional problems associated with the governmental and local organizations responsible for the design, construction, operation, maintenance and funding of the overall flood protection system

The behaviour of repeat visitors to museums: Review and empirical findings

This study presents a theoretical and operational framework for analysing repeat visit to museums. Starting from the literature on repeat visit in tourism, the specificities of these cultural attractions are made explicit through a review of theoretical and applied works. Consistently with previous contributors, the paper suggests that the analysis of actual past behaviours has to be preferred to the one of attitudes. The application of proper econometric models is also remarked in order to put into account individual profiles. Information coming from three techniques is then used in an integrated way in order to provide a more comprehensive view of the phenomenon. Evidence from an ad hoc survey suggests the necessity to give a greater attention to perceived cultural value during the visit, promoting cultural events during the week and addressed to children, and taking care of those visitors that come from far places also through an integrated tourist supply. © 2013 Springer Science+Business Media Dordrecht

A practical approach for the consideration of single pile and pile group installation effects in clay: numerical modelling

In this paper, a practical approach for the consideration of single pile and pile group installation effects in clay is presented using some novel procedures implemented in the finite element (FE) software package PLAXIS 2D. Data reported at a soft clay site at Islais Creek, San Francisco are used to provide calibration for the constitutive model and to validate initial predictions of single pile installation effects. A short parametric study was then undertaken to examine the influence of a number of pile/soil parameters on the soil stresses generated around a single pile after installation and subsequent consolidation. In addition, a new simplified method is proposed to consider group installation effects over-and-above those associated with an equivalent single pile involving the volumetric expansion of tunnels within a plane-strain framework. Remarkably, results show that the installation of additional group piles has a negligible influence after consolidation.The first author gratefully acknowledges the College of Engineering and Informatics, NUI Galway, and the University of California Education Abroad Program for funding this research. In addition, the authors gratefully acknowledge the GeoEngineering department at Massachusetts Institute of Technology who compiled and provided the authors with the MITS1 dll for this research