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By Antonio Zechini, Giuseppe Iorio, Massimo Grisolia

"The new C Line of the Rome Metro runs northwest to southeast across the city center, with 30 new stations and a total length of more than 15.5 mi (25 km). Due to the presence of a dense urban environment, the selected solution for the construction of the stations consists of a cutand- cover excavation, which is retained by multipropped diaphragm walls to minimize settlement and prevent damage to the nearby structures. The bottom of the excavation of the underground stations are about 82 ft to 98 ft (25 m to 30 m) below ground surface, and about 66 ft to 82 ft (20 m to 25 m) below the groundwater table. To ensure dry conditions and to prevent hydraulic base heave instability, deep well systems were designed and used to lower groundwater level and piezometric head during excavation. The dewatering field tests showed how the local stratigraphy strongly affects the dewatering efficiency. Finite element modeling (FEM) of steady state filtration were used to compare the soil permeability with Lefranc in-situ test results and to verify the efficiency of the grouted plugs. The geological sequence along the new C Line consists of a very heterogeneously layered deposit. The base deposit of stiff overconsolidated clay (“APL,” Pliocene age) is overlain by fluvio-palustrine very dense sandy gravels (“SG,” Pleistocene age), which are then overlain by medium stiff clayey silts or dense sandy silts (“AR” or “ST,” Paleotevere units). These deposits are overlain by covered by pyroclastic volcanic soils, tuff, silty sand and sandy silt (Middle to Upper Pleistocene) deriving from the Colli Albani apparatus. A layer of made ground (“R”) of varying thickness covers the stratigraphic sequence and the natural soil profile everywhere.The local hydrogeological framework is very complex and characterized by a double groundwater system. The upper main aquifer is mainly represented by the “pozzolane sequences” (“PR/PN”), while the lower aquifer consists of a deposit of sandy gravel (“SG,” Pleistocene), which is underlain by marine claystone bedrock (“APL,” Pliocene). The pyroclastic deposits (e.g., pozzolane, lithoid and pseudolithoid tuff and clayely tuff) show large variations in permeability due to porosity, compaction processes, sealing and secondary fracturing. Permeability values for each soil type were determined using Lefranc tests at variable head and using pumping tests. The Lefranc tests indicated a wide range of permeability."

Jan 1, 2017

By Paola Campana, Maurizio Lenzi

"In the paper a non linear model for the analysis of the pile response to the axial loads is presented. The study aims to find a general analytical solution concerning the pile-soil interaction modeled by means of the method of the load transfer curves. It makes use of a criterion based on the plastic and on the hardening work locally done by the shear stresses and due to the current elastic shortening of the shaft. Then a specific solution, denoted fractal model, is found applying recurrent relations that link the shaft shear stresses and the tip normal stresses to the pile settlements. These relations are based on that one proposed by Kondner in modeling the soil samples response in the triaxial tests and then used by Chin in the inverse slope method in estimating the pile capacity by the load test results. The comparison between the model predictions and the load tests measures validate the fractal model.INTRODUCTIONThe behavior of the axially loaded piles is known to be characterized by a highly non linear trend caused by the onset of plastic and irreversible deformations in the soil starting just from the first load levels. With the purpose to reach a deeper understanding of the pile-soil interaction, the influence of the soil inelastic properties on the distribution of the axial loads and of the vertical displacements is investigated. The research starts analyzing the behavior of an infinitesimal length of a pile embedded in a non linear homogeneous soil. That initial study leads to a criterion based on the plastic and on the hardening work locally done by the shear stresses and that allows to find the axial loads as a function of the elastic shortenings of the shaft. The relation that links the pile axial load to the elastic strain of the pile material is then used. That allows to find the vertical displacements and the axial loads as function of the depth in a parametric form in which the tip settlement acts as an independent parameter. The method of the load transfer curves is used and the effects of the pile technology are included in the soil constitutive relations. The analysis is then extended to the non-homogenous soils in a very effective way. The solution is applied taking as constitutive relations of the pile-soil interface the one proposed by Kondner to analyze the soil triaxial tests and by Chin to interpolate the pile response measured in the load tests."

Jan 1, 2017

By Mikael Calando, Thomas Joussellin

"San Francisco's rapid growth has caused the city to plan for the Transbay Transit Center Project, a visionary transportation and housing project, that will transform downtown San Francisco and the San Francisco Bay Area’s regional transportation system by creating a “Grand Central Station of the West” in the heart of a new transit-friendly neighborhood that will be home to more than 20 new towers rising a high a 1,070 ft. This paper describes the specificities of using advanced diaphragm wall technology, tooling, equipment and installation practices for deep foundation and permanent underground structures. In particular, this paper will emphasize on the urban constraints, geotechnical conditions, and the novel approaches adopted for the construction challenges of the Transbay Transit Center’s Load Bearing Elements, or Barrette PilesPaperThe Transbay Transit Center Project consists of the construction of a new multimodal, five-story Transit Center located in the South of Market neighborhood near the Financial District in San Francisco. The future Transit Center will incorporate nearly 83,000 square feet of retail, a 5.4-acre rooftop park, an extensive public arts program and bus ramps that will connect the Transit Center to a new off-site bus storage facility and the San Francisco–Oakland Bay Bridge. The new facility will accommodate more than 100,000 passengers each weekday and up to 45 million per year. Additionally, the new Transbay Transit Center will replace the since-demolished San Francisco Transbay Terminal, and nearly 20 towers, such as Salesforce Tower, will take advantage of the height increases allowed through the Transit Center District Plan.The approximately $4.5 billion project features a new five-story structure (including two underground stories) and new bus ramps which include a cable-stay bridge. The deep foundations for the pylon of the bridge (Pylon 9) consist of two each 21 ft x 5 ft barrettes (also called Load Bearing Elements in the US) extending more than 180 feet below grade and 10 feet into the bedrock. The barrettes were chosen because of the combination of high loads, significant depth and small footprint. The barrettes are installed using the Diaphragm Wall technology. Nicholson Construction was contracted by Shimmick Construction to install the cable-stay bridge’s foundation elements."

Jan 1, 2016

By Tu Bao

HP-Pile foundations are the most favorable type of foundations for bridges because of their constructability, versatility with regard to subsoil conditions, and settlement controllability. For many years, bridge engineers have puzzled over the most economical way to orient HP-Piles: Should the strong axis be oriented in the longitudinal direction or in the transverse direction? The accurate design of foundations may considerably reduce construction costs. In order to answer this question, 3-D finite element models will be set up to analyze the effects of pile orientation on bridge behavior. Because seismic loading usually controls the structural design in seismic zones, it is important to investigate the effects of pile orientation under such loading. HP-Piles are designed conservatively due to the uncertainty of the dynamic soil-structure interaction during earthquakes. For the bridge substructure, the soil?s stiffness plays an important role in load distribution as the soil and piles act as a combined system to resist the seismic loading. The dynamic soil-structure interaction mechanisms of bridges in both the longitudinal and the transverse directions will be investigated through the use of 3-D finite element models. The numerical models will realistically simulate the soil-pile-abutment-wingwall-superstructure system subjected to seismic loads. Nonlinear soil springs will be employed to model the non-elastic soil behavior. The analysis will provide theoretical support to the design practice. KEYWORDS: HP driven piles, finite element, pile orientation, soil-structure interaction

By Andrew Rietz, Yu Bao, Steven Halewski

"HP-Pile foundations are the most favorable type of foundations for bridges because of their constructability, versatility with regard to subsoil conditions, and settlement controllability. For many years, bridge engineers have puzzled over the most economical way to orient HP-Piles: Should the strong axis be oriented in the longitudinal direction or in the transverse direction? The accurate design of foundations may considerably reduce construction costs. In order to answer this question, 3-D finite element models will be set up to analyze the effects of pile orientation on bridge behavior. Because seismic loading usually controls the structural design in seismic zones, it is important to investigate the effects of pile orientation under such loading. HP-Piles are designed conservatively due to the uncertainty of the dynamic soil-structure interaction during earthquakes. For the bridge substructure, the soil’s stiffness plays an important role in load distribution as the soil and piles act as a combined system to resist the seismic loading. The dynamic soil-structure interaction mechanisms of bridges in both the longitudinal and the transverse directions will be investigated through the use of 3-D finite element models. The numerical models will realistically simulate the soil-pileabutment- wingwall-superstructure system subjected to seismic loads. Nonlinear soil springs will be employed to model the non-elastic soil behavior. The analysis will provide theoretical support to the design practice.IntroductionAs sustainability has asserted itself in the public’s eye, bridge professionals have rushed to develop criteria for sustainable bridges. The three main categories that define and distinguish sustainable bridges are: lower energy input, increased durability, and simplified deconstruction. By optimizing the structural members, the engineer is able to reduce the material quantities for the bridge, effectively reducing the energy input for the bridge (Hunt; Whittemore). A deeper understanding of soilfoundation- structure mechanism will facilitate sustainable bridge design by lowering energy input and increasing the service life of bridges (Rietz et al.)."

Jan 1, 2017

By Andrew J. Ciancia

The construction of the Pennsylvania Station in Manhattan, the Beaux-Arts masterpiece, was completed in 1910. In financial ruin, the Pennsylvania Railroad Company sold the station in the 1960?s and the new Madison Square Garden and the Penn Plaza complex were constructed at the site. The demolition of Pennsylvania Station brought public awareness and outcry to protect historic structures and the Landmarks Preservation Commission (LPC) was subsequently established in 1965. In the 1960?s relatively little engineering data was available on the performance of historic structures during adjacent construction and thus, no published criteria were established by the LPC on allowable movements and vibrations. During the late 1970?s a commercial tower was planned adjacent to the landmark Fraunces Tavern Block (FTB) in lower Manhattan. Through negotiations between the LPC and the developer, Dr. M. I. Esrig and the author were retained to monitor the historic block during foundation construction. The monitoring data and building performance compiled from the project formed the basis of the published 1981 ASCE technical paper by Esrig and Ciancia entitled ?The Avoidance of Damage to Historic Structures Resulting from Adjacent Construction?. Based on the ASCE paper, the NYC Department of Buildings adopted Technical Policy and Procedure Notice #10/88 entitled ?Procedures for the Avoidance of Damage to Historic Structures Resulting from Adjacent Construction When Subject to Controlled Inspection by Section 27-724 and for Any Existing Structure Designated by the Commissioner?, June 1988. This paper describes the author?s recent experience during the installation of deep foundations within, or adjacent to, three Manhattan landmark structures. Discussions are provided on the foundation construction, monitoring programs and performances of the three structures.

Jan 1, 2008

By Lisheng Shao

Soil mixing and jet grouting have been widely used to support heavy structures such as tanks, cement silos, and storage buildings. Although the installation methods vary between soil mixing and jet grouting, the end product of soil-cement columns behaves similarly in supporting structure loads. In many cases, soil-cement mass treatment offers the owner savings over driven/drilled piles. This paper discusses the design methodology, production work, and quality control, with supporting figures, of a recent large complex tank farm project. The project consisted of constructing six above-ground steel storage tanks and an approximately 700-foot-long fill slope. The tank farm site is located in an industrial area of southern California, with highly variable subsurface conditions consisting of compressible soils and buried construction debris. The compressible soils necessitated that the new tanks be supported on deep foundations. A test pile program performed previously at the site showed that conventional driven concrete piles were not feasible because of buried construction debris, therefore a soilcrete system was proposed. Site design included evaluating the total and differential settlement and column group bearing capacity under both static and seismic loads. Extensive field and laboratory testing confirmed the design soil-cement strength and modulus of both the soil mixed and jet grouted soil-cement columns. The project operation and quality control programs are also included in this paper.

Jan 1, 2010

By William H. Walton, Clyde N. Baker Jr., Darren S. Diehm

"A 51-story concrete core and steel frame commercial office tower was recently constructed on the site of the former US Gypsum building in downtown Chicago, Illinois, USA The structure foundation reused several caissons from the demolished US Gypsum building supplemented with new belled caissons bearing on silty clay hardpan. Extensive in-situ pressuremeter testing was performed during the geotechnical investigation to determine allowable bearing capacity and better estimate building settlements. Problems during foundation construction along the south side of the building frame required remediation of two caissons. One caisson was supplemented with micropiles, while the second caisson was abandoned and replaced with a straight-shaft rock socketed caisson. To determine the effectiveness of the repairs, the building foundation settlements were monitored during construction.IntroductionIn 2001, The John Buck Company began development of a new office tower at the southeast corner of West Monroe Street and South Wacker Drive in Chicago, Illinois. The site was formerly occupied by the 18-story US Gypsum (USG) building. Mr. Clyde N. Baker, Jr. (Senior Principal at STS Consultants, Ltd .) served as the foundation engineer for USG which was completed in 1962. The building was founded on a forest of belled caissons bearing at elevation -56 Chicago City Datum (CCD). For reference, the ground surface at Upper Wacker Drive is approximately elevation +20 CCD. The bearing material was a hard silty clay, locally described as Chicago Hardpan. The foundation caissons were designed using an allowable bearing pressure of 16 ksf (766 kPa). In 1996, the USG superstructure was razed, and the three-level basement was converted to an underground parking ramp.South Wacker DevelopmentThe 51-story high-rise building was completed in 2005 with a structural height of 681 feet (208 m), and an internal space of more than 1,000,000 square feet (93 ,000 square meter). The typical floor size is 27, 700 square feet (2, 570 square meter). Renderings of the building are provided in Figures 1 and 2. The largest single tenant is the accounting firm of Deloitte & Touche, which occupies roughly 45% of the building space with over 3,000 employees."

Jan 1, 2005

By Kirty Dave

Foundations in any contract are the most uncertain parts of the contract and most of the "Construction-Contract-Disputes" are either directly related to foundations or arise as 'Side-effects of changes in promises related to foundations. Foundation Engineering is defined as ' The art of selection, designing and constructing the elements that transfer the weight of structure to the underlying Soil or Rock." (Ralph B. Perk). This art started becoming a science since 1920, when scientific efforts to determine the behaviour of sub-surface materials were made. The art and science merged to give new techniques and the science started dominating the field as more and more refinement came in techniques to predict more accurately the characteristics of the sub-surface elements. Inspite of good thorough investigations and design, the contractual promises drafted could leave some room for differences between the parties and above all the prudency expected of both the parties may fall short of the expectations raised in the contract. This may give rise to disputes which may need to be resolved as per principles of law. This paper attempts to initiate a dialogue amongst Foundations-Engineers and Contractors as to how do we minimise the differences arising out of or related to contracts concerning "Foundations".

Jan 1, 1996

By Shoichi Tsukuni, Akihiko Uchida, Kazuo Konishi

"In order to investigate the effect of grid-form deep mixing walls as a countermeasure for liquefaction damage to roads and private houses in Urayasu, Japan, three dynamic centrifuge model tests were conducted. Urayasu is located in the Tokyo Bay area, and private houses in the city incurred severe damage due to liquefaction during the 2011 Tohoku earthquake. In grid-form deep mixing walls design, the distance between grid-form walls is critical to prevent liquefaction. This study clarifies the relationship between the settlement of private houses and the distance between grid-form walls under the conditions that exist in Urayasu.INTRODUCTIONMany private houses in Urayasu, Japan suffered severe damages due to liquefaction during the 2011 Tohoku earthquake (Photograph 1). Fig. 1 shows the location of Urayasu and the maximum acceleration of the observed seismic waves in the Tokyo Bay area. At Urayasu, the duration of the seismic waves (hereafter called the Urayasu Wave) was about 2 min. The maximum acceleration was 1.57 m/s2 (Fig. 2), which is relatively small. The damages occurred in the land reclamation areas that consist of loose sand with an SPT-N value less than 10.To prevent liquefaction in future, it is necessary to adopt suitable countermeasures in the areas where many private houses suffered severe damages. Grid-form deep mixing walls are one such countermeasure. Fig. 3 and Photograph 2 show grid-form deep mixing walls. Walls are constructed using the deep cement mixing method. Fig. 4 shows a plane view of planned grid-form deep mixing walls for roads and existing private houses in Urayasu."

Jan 1, 2015

By Michael Arnold, Robert Bachus, Michael Bracher, Jamey Rosen, Robert Roff

"For a high hazard USACE facility, the Center Hill Dam in Tennessee, several disparate streams of data were compiled into a single geospatial and relational enterprise data management system to store, analyze, visualize and distribute the data collected during installation of a deep cutoff wall. These data streams included historical drawings and pre-construction plans and grouting records; geological data from boreholes; attributes of barrier wall elements; element verticality data analyzed from multiple measurement methods; and concrete field and laboratory analytical data. A previously developed data management system developed by the authors, WallTracker, was extensively modified to also include manually collected and real-time measurements from several types of dam monitoring instruments. The system now uses enterprise database technologies with Geographical Information Systems capabilities to manage and relate these data streams into a common platform and allows access to the raw and interpreted data via web and desktop-based interactive tools, including interactive map and cross-sectional viewers and other graphical and tabular reporting tools. One of the primary benefits of this system is the neartransparent interaction that is possible with the Nashville District of USACE on the project. These techniques can now be effectively incorporated into systems that address the unique construction and data management tracking requirements for dams, dikes, and levees.IntroductionThe Center Hill Dam rehabilitation, as with other deep foundation installations, requires the contractor to collect a substantial amount of information over the course of the project, both for internal quality control of construction progress and methods, and for demonstrating compliance with owner specifications. This paper discusses techniques used at Center Hill Dam for consolidating, visualizing and analyzing construction and instrumentation data using relational database and Geographic Information Systems (GIS) technology, collectively referred to as an Information Management System (IMS).The remainder of this paper presents the needs and objectives of the IMS, the components and data flows involved, the capabilities and user interfaces of the systems, and the benefits for the end users."

Jan 1, 2017

By Hyun. I. Park

Although numerous investigations have been performed over the years to predict the behavior and bearing capacity of piles, the mechanisms of these behavior and bearing capacity of piles have yet to be entirely understood. Bearing capacity is difficult to predict, because it is affected by many parameters, which have complex relationship with each other. The present paper describes the application of Artificial Neural Network (ANN) in dynamic load tests to predict the resistance of driven piles. The tip, shaft, and total pile resistances can be predicted only for piles with available corresponding measurements of these values. The design methodology composed of ANN and genetic algorithm (GA) is applied to find the optimal neural network model to predict pile resistance. The results of this study indicate that the neural network model serves as a reliable and simple tool for predicting the capacity of driven piles.

Jan 1, 2006

By Seiji Mizutani, Hirofumi Taguchi, Makoto Yoshida, Hidenori Takahashi, Naotoshi Shinkawa, Kazuo Konishi, Yoshiyuki Morikawa, Masaya Kawata

"The lattice-shaped cement treatment method has been used to improve the seismic performance of liquefied sandy soil in Japan. The efficacy of the method has been confirmed by the huge earthquake in Japan. In the present study, a new method to improve sandy ground by using the lattice-shaped cement treatment method is proposed as a liquefaction countermeasure. It is the floating-type and lattice-shaped cement treatment method, where cement treated soil is not fixed to an un-liquefiable stratum. In this method, a fixed-type structure such as treated soil should be formed at the side of the floating-type treated soil to reduce its lateral displacement. In the study, one-dimensional dynamic response analyses were firstly conducted to confirm the mechanism of the new method. Secondly, a series of centrifuge model tests were performed to demonstrate the effect in a proto-type scale's stress condition. The analyses and model tests confirmed the effect of liquefaction countermeasure of the new method.INTRODUCTIONLiquefaction induced by an earthquake generates sand boiling and ground settlement. Other problems have also been reported, including a decrease in bearing capacity and an increase in the horizontal earth pressure against retaining walls. To prevent these problems caused by liquefaction of the ground, various countermeasures have been proposed, such as cement deep mixing and high-pressure jet mixing methods. These methods have the big advantage of being applicable to ground that contains soil with a fine-grain fraction. Furthermore, the unnecessary displacement caused by the construction can be reduced. In Japan, a lattice-shaped cement-treatment method has frequently been used at many construction sites to prevent liquefaction, where cement-treated piles are intersected to form a lattice, as shown in Fig. 1. The lattice-shaped walls can reduce the shear stress generated by an earthquake, restricting the liquefaction at that location. However, the construction cost of the cement treatment is relatively high compared to other methods such as the sand compaction pile (SCP) method, and needs to be reduced. Therefore, decreasing the total volume of the cement treatment is necessary to reduce the construction cost."

Jan 1, 2015

By Monica Prezzi

"Auger cast-in-place (ACIP} piles and drilled displacement piles are being increasingly used as foundation elements for structures, particularly in projects requiring accelerated construction or involving the rehabilitation of foundations of existing, overstressed structures. Auger cast-in-place piles (also referred to as continuous-flight-auger piles) are widely used to construct the foundations of all types of structures. There are many different types of drilled displacement piles, with the installation methods varying according to the equipment used. Depending on the specific rotary piling technology used, responses ranging from those associated with non-displacement to those associated with full-displacement piles are obtained. Conventional pile design methods do not account for how the various construction techniques involved in auger piling change the soil state around the pile during installation and, hence, cannot accurately estimate the pile resistance in a consistent way. Research on this subject, identifying the different variables that must be accounted for in design and linking these variables to installation methods, is lacking. This paper describes the different piling methods available for auger cast-in-place and drilled displacement piles, the equipment used to install them and the quality control processes typically used. It also reviews some of the design methods currently used.IntroductionDeep foundations are extensively used in geotechnical engineering practice. The wide spectrum of piling methods results in a variety of pile types. Each type behaves differently, depending on the installation or construction methods. On one end of the spectrum are non-displacement piles, the classicql examples of which are bored piles or drilled · shafts. These piles are constructed by removing a cylinder of soil from the ground and replacing it with concrete and reinforcement. On the other end are full-displacement piles, such as closed-ended pipe piles or precast reinforced concrete piles, which are typically driven into the ground. Driven piles preload the materials below the toe of the pile and displace the soil surrounding the pile shaft laterally during the installation process. Therefore, displacement piles are, in general, more likely to have a stiffer response than non-displacement piles. This is true particularly in the case of sandy soils where displacement causes densification."

Jan 1, 2005

By Marcel Bielefeld, Joost Bakker, Rob van Dorp

Pile load testing can be performed by a static, rapid or high strain dynamic (generally designated as dynamic) testing method. The static load test is often considered the “gold standard” of testing with the other methods merely ‘alternatives’. However, the rapid load test, as a quasi-static test, has all the positive elements of the static alternative: the direct measurement of loads and displacements. Moreover as stress wave phenomena have no influence, the interpretation of rapid load test results is more straightforward than that of dynamic testing, and also independent of the person performing the interpretation. This paper will explore the Rapid Load Testing method and illustrate the advantages and limitations through a case study in Rostock, Germany

May 1, 2022

By Waddah Akili

The demand on pile installation in the offshore of the Arabian Gulf has, over the last two decades, experienced unprecedented boom, triggered by the construction of platforms, to help facilitate the production and transport of oil and gas. Available borehole data show that ground conditions for pile installation in the offshore is highly variable, resulting in misassessment of insitu conditions, leading to a huge discrepancy between ultimate pile capacities, based on design, and actual capacities after installation. The paper makes use of pile installation records derived from several platforms in the offshore of the state of Qatar, the Gulf Region. More specifically, the paper evaluates “as–installed” ultimate capacities and safety factors, recommends remedial installation procedures, and proposes a means for determining pile acceptability for piles meeting refusal short of design penetration. The paper offers what is believed to be relevant recommendations to guide the design and installation of future offshore structures; enabling the geotechnical community in the Region to solve their current offshore pile installation problems and gain an added margin of confidence regarding the ultimate capacity of installed piles.

By Amr M. Sallam

A case history of utilizing a mat foundation enhanced with ?settlement-control? piles to support a high-rise building in Downtown Orlando is presented. Original geotechnical engineering studies, performed by others, recommended pile foundations due to difficult soil conditions and highly variable loads. The value engineering study performed by the authors provided alternative foundation system of the mat foundation enhanced by ?settlement-control? piles. The alternative foundation system required few iterations of structural and geotechnical analysis. A target stiffness for the settlement-control piles was selected by the structural engineer. Pile load tests were performed to verify the recommended pile geometry. A total of 81 auger-cast-in-place settlement-control piles 45-foot long 16-inch diameter were installed. A total of 24 columns were monitored for settlement, which showed substantially less settlement than predicted. It is the authors? opinion that the ?settlement-control? piles increased the mat stiffness, relieved the concentration of contact pressures around heavily loaded columns, and reduced potential differential settlement. Mat foundation with settlement-control piles provided border-line foundation solution between shallow and deep foundations and has the potential to be widely used in Central Florida for similar subsoil and loading conditions; however a thorough analysis using three dimensional Finite Element Modeling may be needed to refine the geotechnical evaluations.

Jan 1, 2009

By Richard E. Sylwester

Evaluating surface and subsurface conditions for marine foundations (bridges, causeways, terminals, etc.) is often done with a limited amount of data. Subsurface information for these projects is primarily acquired using traditional methods, such as boreholes, test pits or divers, which tend to be expensive and limited in the area of coverage. A number of geophysical methods, including precision bathymetry, sidescan sonar, and seismic reflection or subbottom profiling are extremely cost-effective and obtain significantly more data than can be acquired using traditional intrusive methods. These geophysical methods provide detailed surface images and continuous profiles of the subsurface stratigraphy. This information can be invaluable for selecting the best location for geotechnical boreholes and to map potential geohazards such as submarine slides and filled or open scour holes. Offshore investigations conducted for a proposed highway bridge (Knik Arm Bridge, Cook Inlet, AK), the retrofit of two existing bridge (Antioch and Dumbarton Bridges, CA) and a proposed cruise ship terminal (Ketchikan, AK) used a combination of geophysical methods to map water depth, detect and map debris on the seabed, map the thickness of unconsolidated sediment, determine the depth to bedrock and identify potential geohazards such as scour holes. The results of the geophysical investigations will be used to select locations for obtaining geotechnical borings, to extrapolate geologic information between existing or proposed boreholes, evaluate the potential depth of scour and design a pile support pier. Geotechnical engineers, offshore contractors and bridge designers are realizing the importance of the early use of offshore geophysics for (i) site characterization, (ii) to reduce the uncertainty of geotechnical conditions thus avoiding designs that may be overly conservative and thus more expensive and (iii) to assist in selecting locations for geotechnical borings.

Jan 1, 2013

By Prasanta Paul, Aminul Islam

"Nhava Sheva (India) Gateway Terminal Private Limited proposed to construct a container terminal yard, comprising a back-up area at Jawaharlal Nehru Port Terminal (JNPT), Uran, Maharashtra. The proposed container terminal yard is located on a recent reclamation on the Thane Creek, which was developed by land-based reclamation method. The underneath soft marine clay was treated, using vertical band drains and placement of surcharge upon.Settlement of the reclamation during its construction was monitored using settlement plate installed at +4.8m CD elevation which was above the highest high water level.This paper examines the settlement behaviour of the reclamation during the ground improvement works. The geotechnical parameters are back-analyzed by the authors from the field settlement results and the concerned preloading details. The back analyzed coefficients of consolidation due to horizontal flow (Ch) are compared with laboratory determined parameters and the estimated value, using Asaoka Method (1978). The authors also studied field compression ratio [CR= Cc/(1+e0)] vs. the compression ratio determined by laboratory test using back-analysis method.1. INTRODUCTIONNhava Sheva (India) Gateway Terminal Private Limited proposed to construct a container terminal yard, comprising a back-up area of approximately 27 hectares, complete with associated buildings and services on a part brownfield/ greenfield site. The back-up area shall include a heavy duty block paved pavement with band beams for electric Rubber-Tyred Gantry Crane (eRTGC) alongwith surface water drainage system and other services including area lighting, provision of fire-fighting facilities , sources for potable water and power.Based on the Employer’s Requirement and the available geotechnical investigation report, ground improvement scheme is designed by the construction contractor. Ground improvement works included the installation of prefabricated vertical drains and subsequent placement of surcharge for accelerating the consolidation of the underlying soft marine clay."

Jan 1, 2015

By Amalia Giannakou

When designing structures in seismically active areas, foundations of critical structures are typically located away from known faults. Indeed many seismic codes prohibit construction in the immediate vicinity of seismically active faults establishing minimum setbacks from the faults. However, for long structures such as bridges, tunnels and pipelines, a fault maybe unavoidable, and fault rupture risk impossible to preclude. This paper presents a case study of a bridge foundation design that incorporates the consequences of fault deformations passing through the foundation. A series of site surveys were conducted to characterize the fault environment, and fault displacement hazard analyses were conducted to develop design displacement demands. Subsequently, numerical analyses were performed to evaluate the fault rupture-induced demands on a pier foundation in terms of displacements and rotations. Initially, analyses were performed that model the free field fault rupture propagation to the ground surface of the fault to ensure that the basic site characteristics are captured. Subsequently, the foundation elements were introduced in the model and the fault rupture is simulated again. The interaction and influence of the foundation on the fault rupture propagation is calculated, and the consequent demands and distortions of the foundation block provide a basis for structural engineers to design the bridge.