Search Documents

By Swaminathan Srinivasan, Aaron J. Muck

"When an opportunity arises to combine state-of-the-art concepts with advanced modeling tools, engineers need to take what they know and apply forward thinking to geotechnical solutions to promote the state-ofpractice. Such an opportunity was seized during the design and construction of the Great American Tower in Cincinnati, Ohio. The forty-one story Great American Tower at Queen City Square – currently the tallest building in Cincinnati – has not only changed the downtown skyline, it is also contributing to the advancement of the state-of-the-art use of auger cast-in-place (ACIP) piles as settlement reducers. Predicted settlements of a traditional mat foundation were excessive, and the costs and construction time associated with traditional ACIP piles extending to bedrock were not preferred. A mat supported on a limited number of ACIP piles, with the piles primarily acting as settlement reducers, was evaluated as the preferred foundation type.Promoting the unique soil-structure interaction of the foundation system with confidence required the use of sophisticated numerical modeling tools. Traditional standard penetration test boring data (SPT) was initially used to develop a numerical analysis of the soil-structure interaction using FLAC 3D software. The model was further modified with cone penetration (CPT) and pressuremeter testing (PMT), along with actual load test results on several ACIP pile elements of varying lengths, but all tipping above bedrock. Through a combined design team effort, and detailed numerical modeling analysis, ACIP piles were recommended for reducing mat foundation settlement. Instrumentation during and post-construction confirmed design assumptions and predictions. Integrating sound geotechnical concepts, and using advanced geotechnical analysis and design methods, traditional mat and ACIP pile foundations were successfully integrated into a unique foundation support system.INTRODUCTIONThe Great American Tower at Queen City Square in Cincinnati, Ohio is located within a region dissected by historical geologic deviances associated with the meander of the Ohio River and glacial progression/recession. Combining a challenging geology, with the development of a high-rise office building afforded the design team an opportunity to combine state-of-the-art soil-structure interaction concepts and method with traditional geotechnical engineering concepts. Such a combination required a variety of field tests, collaboration with the design team and owner, and geotechnical-structural modeling during the design phase. During construction, in addition to materials testing and observation, a variety of instrumentation systems were employed. Together, the data was used to corroborate the design model and make adjustments during construction and further substantiate design assumptions following construction."

Jan 1, 2015

By Sastry Putcha, Santosh Mummaneni, Avasarala Swamy

"Inspection of bored pile hole bottom prior to placement of concrete is one of the most crucial element of foundation design and construction, especially for end bearing piles. Pile hole bottoms that are not cleaned well for sediments could potentially result in settlement. Although many projects have specifications in-place for drilled pile hole inspection, they are rarely implemented as the current available tools are either unsafe or cumbersome and costly, thus making it very unattractive for owners and contractors. Further, sometimes the post-construction nondestructive quality control testing such as PIT or sonic logging on piles resulted in unanswered questions related to soft bottom. This generates costly disputes with additional testing including concrete coring and possible repairs. Currently, there are several bored pile bottom inspection devices in USA, namely, SID, DID, and SQUID which can either provide video and photo documentation or measure sediments.“ShaftCam”, a patented advanced Digital Borescope, was invented to address the issues related to pile hole bottom inspection with its ability to measure sediments as well as photo and video documentation. Shaftcam device consists of 8-inch diameter bell with a camera, led lights, air hose connection and penetrometer with digital measurement that are connected to a control power box and laptop through a cable. The bell is fitted with a round clear open fiberglass skirt to form an open chamber. A simple motorized winch frame allows the user to lower the ShaftCam equipment gently to the bottom of the shaft at the desired location. Once the bell with camera is lowered to the bottom of the hole, air is pumped into the clear chamber to displace the water/slurry/polymer and get a clear view of the hole bottom to record the conditions and measure the sediment thickness and resistance. The skirt can also be enclosed and lowered to the desired location to allow for inspection of shaft walls.ShaftCam weighs less than 15 lbs. (6.8 kgs) in water and allows for inspection of the hole by one person in less than 30 minutes. Use of ShaftCam has saved significant time and money and thus allowed owners and contractors to readily accept and implement the quality control measures in many projects in USA over past few years."

Jan 1, 1900

By Paolo Cavalcoli, Federico Pagliacci, Marco Chiarabelli

"The Sheikh Jaber Al-Ahmad Causeway Project in Kuwait is estimated at approximately $US3.7 billion and consists of constructing a causeway across the Kuwait Bay, connecting the Shuwaikh Port with the northern Subiyah area, where the new “Silk City” will be established. The $US77 billion Silk City will revive the ancient “Silk Road” trade route and will become a major free trade zone linking central Asia with Europe. The new city will be completed in 2030, it will house about 700,000 people and, furthermore, it will include the tallest tower in the world. The Causeway will stretch approximately 23.3 miles and will be composed of a combination of low-level bridges, embankments and transition islands. A bridge of about 16.8 miles in length will span the navigation channel and a free flow interchange at the Shuwaikh Port will connect the causeway to the main road network in Kuwait City. The geo-construction portion of the project involves the execution of 1,200 drilled shafts with diameters of 98 inches and 118 inches embedded to a maximum depth of about 276 feet. Details are provided concerning the subsurface conditions, the geotechnical characteristics and the strength parameters, illustrating, as well, the installation technique implemented for the construction of the drilled shafts. In addition, particular attention is paid to the description of the challenges faced while constructing the drilled shafts at a distance of about 10 miles from the shore, such as the depth of the water above the midline (more than 160 feet), an underwater current and the tidal variation.INTRODUCTIONThis paper presents an overview of the foundation works executed for a 37km causeway across the Bay of Kuwait, connecting Shuwaikh Port with Subiyah New Town Development. The project, in which Trevi is actively engaged, includes a 27 km low-level bridge across the bay, a main bridge with a span of 200 m, an overpass and a 5 km approach road onshore in Subiyah.The main purpose of this report is to provide information about the nature and features of the applied technique of bored piles, including a description of each work phase and other related details, in order to aid in the design of the foundations for the proposed construction.Works for the soil investigation were carried out in accordance with accepted geotechnical standards/guidelines. Brief descriptions of the methodology of the field are also provided in this report."

Jan 1, 2016

By Benjamin B. Buensuceso III

Crosshole sonic logging (CSL) is a popular quality assurance and quality control method used to examine the concrete quality of cast-in place deep foundations, though the evaluation of the results is subject to certain limitations. One such limitation explored in this paper is the occurrence of false positives, where signal anomalies indicated by CSL test results are not necessarily indicative of imperfections in the foundation that could affect its performance. A case study of false positives evaluated in CSL records in a major infrastructure project in Metro Manila is presented in this paper. A detailed desktop evaluation and results from complementary high-strain dynamic load testing and low-strain pile integrity testing were used to evaluate the significance of the suspected false positive signal anomalies from the CSL test results. Recommendations for the proper interpretation and evaluation of CSL test results in Philippine practice, given the method’s limitations and examples presented, are also shared.

Sep 8, 2021

By Amanda R. Parry, Chris R. Pray

Predicting and modeling the soil structure interaction of laterally loaded piles with significant unbraced lengths is one of the challenges faced in designing many waterfront structures. Designers often rely on pile specific design software to calculate forces in an embedded pile and then couple that with either a structural design software to capture the behavior of the rest of the structure or use potentially overly conservative assumptions to omit modelling the piles entirely. Given that some projects have hundreds of piles coupled with hundreds of loading conditions, the shuttling of results from the structural analysis software into the pile analysis software can become cumbersome, difficult to track and manage, and prone to user input errors. An alternative approach recently used on two large marine infrastructure projects consisted of calibrating a structural analysis software to replicate the resultant outputs from a software developed specifically for pile analysis. This calibration was done using thoughtfully placed springs along a pile modeled in the structural analysis software to replicate the soil-structure interaction of the piles. The focus of this paper will be on the methodology used to calibrate the two software programs and an evaluation of the results which showed close agreement. Based on the two case studies, calibrating a generic finite element analysis software via this method should be considered as a reasonable and time saving design approach for pile-supported structures.

Sep 8, 2021

By Krishna R. Reddy, Jyoti K. Chetri, Girish Kumar

Geotechnical engineering encompasses a major portion of the civil and infrastructure projects. The large amounts of energy and resources typically used in these projects leads to undesirable emissions and wastes which contribute substantially towards global environmental impacts (e.g., global climate change). This could further include secondary economic and societal issues which are often unaccounted in traditional engineering design of the geotechnical projects. In order to address this issue, it is imperative to integrate the broader environmental, economic and social implications into decisions of a geotechnical project. Recent years have seen a major impetus on life cycle assessment to evaluate the environmental sustainability of the geotechnical designs. However, there are no tools that can quantify the life cycle triple bottom line sustainability of potential design alternatives in a project with holistic considerations towards broader economic (indirect costs and benefits) and social impacts (stakeholder preferences, socio-environmental and socio-economic impacts). This study presents a new framework for quantitative assessment of life-cycle sustainability (QUALICS) for alternative designs in engineering projects. The framework integrates two multi-criteria decision analysis methods namely, the Integrated Value Model for Sustainable Assessment (MIVES) and Analytic Hierarchy Process (AHP), to support decision making on the potential design alternatives. In this study, a brief overview of the framework is presented. A case study demonstrating the use of QUALICS framework is discussed with its application to the sustainability assessment of two deep foundation systems, caissons and piles, over their design life. The technical designs of both systems are developed based on bearing capacity, both primary and secondary settlements, and structural integrity. The results from the sustainability assessment of the two deep foundation systems are discussed, and the most sustainable option based on different stakeholder preferences and site-specific conditions are identified.

Jan 1, 2019

By Bernardo J. Jiménez Vega, Edy L. T. Montalvan

Rammed stone columns and similar reinforcement systems are used worldwide more frequently as a cost-effective method for improvement of foundations on soft soils. The effectiveness of the treatment method is evidenced by the increase in bearing capacity and reduction of compressibility of the treated ground. In this study, two job sites with over 500 stone columns were studied. On both jobs sites, shallow soft silty soils were found and stone columns were designed to support the foundations of MSE walls, which serve as abutments for viaducts. In order to verify the soil improvement efficiency CPT tests were performed before and after the construction of stone columns, also plate load tests were performed on both job sites to verify the deformation modulus of the stone columns. From CPT data it was observed an increase up to 30% of sleeve friction and 20% of tip resistance, which demonstrated a higher deformation modulus maintaining the same strength in the soil after stone columns construction. The plate load tests yield load-deformation curves which indicated that the original assumed modulus was conservative. As a result of these findings, optimization of the settlement reduction ratios was conducted using the modified values of deformation modulus for the soil and stone column, obtaining a reduction up to 30% of stone columns for further job sites with similar soil conditions.

Sep 8, 2021

By Oladayo O. Komolafe and Majid Ghayoomi

p-y curves have been used over the years to determine the lateral resistance of piles. This method is popular among practicing engineers due to its simplicity and its ability to determine the slope, displacement, shear force, and bending moment for various depths along the pile. The ultimate lateral load resistance is a key component of p-y curve formulation. The p-y curve formulation by Reese et al. (1974) does not consider the effects of soil’s degree of saturation on theoretical ultimate lateral resistance of the failure wedge. This limits an accurate assessment of the lateral soil resistance near the ground surface and the consequent p-y curves. This paper extends the existing approach for determining the failure wedge in unsaturated cohesionless soils with suction dependency, especially for the depths that are above the water table within the wedge. The modification to the failure wedge analysis was made by considering the variation of the degree of saturation which affects effective stress and lateral earth pressure. Through a set of parametric analyses, the impact of incorporating principles of unsaturated soil mechanics in the estimation of theoretical ultimate lateral resistance is examined, and its implications on lateral pile response are discussed.

Sep 8, 2021

By DFI DFI

An Online Conference

By Mario A. Terceros Herrera, Mario Terceros Arce, Antonio Marinucci

This paper describes the general principles of the expander body with post-grouting (EBI) system, and how it is similar in nature to a large-scale pressuremeter device. The results from the installation of an EBI can be used to provide information about the stress-strain characteristics of the soil adjacent to the device and to compute estimates of nominal axial resistance. As the EBI expands during grouting, pressure is applied to the in-situ soil surrounding the device thereby compacting/densifying the soil. The nominal axial resistance for small diameter piles/ground anchors can be increased due to the greater soil stiffness and shear strength around the device, larger surface and end area, and improved soil-to-EBI interaction in side resistance. The shape of the response curves depends on the geotechnical conditions of the soil (e.g., in-situ stress state, strength, and stiffness) and the installation method of the piling/ground anchor. This technique has been used successfully with different pile types and ground anchors in a wide range of conditions from very loose sands/silts to very dense sands and medium-dense gravels as well as in soft to stiff clays. This paper also describes a mini case history in which 80 piles were installed to support an office building, and the results of the static axial compression load tests performed on a production FDP+EBI pile is also included.

By Waddah Akili

At an offshore site along the Red Sea coast of Saudi Arabia, marine structures were supported on tubular steel piles driven into coral and coral contaminated sands and silts. Surprises and disappointments faced during the installation of the piled foundation were, to a large measure, due to inappropriate design methodology and absence of proper soil information. The paper describes the design evolution process, highlights the static pile test program conducted to verify design parameters, and amplifies the need to prepare for worst possible scenario when coral deposits are encountered. Despite corrections made to the design, based on site-specific insitu parameters (skin friction, end bearing) perceived from load tests conducted on site; the final design adopted overestimated capacities in over 50 percent of total piles driven. The paper describes the changes introduced to the design during the execution of the project, highlights the pile test program conducted to verify the design, and compares pile design penetration with actual penetration depth. The unpredictable and erratic pile behavior observed, ascertains the need for more appropriate pile design and installation guidelines for driven piles in coral and coral contaminated formations.

By Daniel Ruffing, Jeffrey Evans

Vertical cutoff, or barrier, walls are an integral part of environmental site remediation efforts. Vertical barriers are commonly deployed to limit the influx of clean ground water and/or to control the off-site migration of contaminated groundwater. The level of detailed design consideration devoted to the vertical cutoff wall component varies widely from project to project and generally decreases with decreasing size and complexity. For those projects receiving minimal design effort, conservative design decisions can lead to unnecessary costs or unanticipated conflicts between the various design considerations. In this paper, the authors discuss several important design and construction aspects of vertical cutoff walls requiring particularly careful consideration during the design phase of the project. These design and construction considerations include the need for and extent of excavation for a key, project target hydraulic conductivity, the use of statistical allowances in the specifications, filter press testing, sand content of in-trench slurry, cleaning of the backfill slope, measurement of stress and strain, the additional of slag in cement-bentonite cutoff walls, and longevity of cutoff walls.

By Braxton P. Erbe, Douglas C. Brunot

A variety of systems and techniques exist to support deep excavations where sloping is not feasible. This paper will explore an example project involving the use of pre-engineered hydraulic bracing systems to support sheet pile walls. Challenges on site that drove the final design include a high water table, irregular excavation geometry, and underground obstructions. The hydraulic system, connected by pins and not requiring welds, allowed for quick deployment and the modularity to change as required due to unforeseen site conditions.

By Laurel E. Blackman

The DFI Project Information Management Systems (PIMS) Committee cooperated with the US Army Corps of Engineers (USACE) to develop a specification for PIMS used on USACE projects. Once completed the Committee developed a more generic version of this specification for general use, which is contained in this document. This first edition has simply removed the USACE-related requirements from the document. The committee will continue to work on this specification to enhance the content and also incorporate recent technological development for these systems. It is the Committee's intention that a second edition will be issued in 2022.

Jan 1, 2021

By Mary Ellen Large

This publication of Deep Foundations Institute (DFI) is intended to provide project owners, design engineers and construction professionals with guidelines for selecting cutoff wall and barrier systems and a general introduction to their methods of construction. Three categories of cutoff wall and barrier construction technology (excavated cutoff systems, in situ techniques, and driven cutoff systems) are presented and parameters for evaluating their design and construction are discussed. The information presented was compiled from the opinions of practicing engineers and construction specialists from the DFI Slurry Wall Committee.

Jan 1, 2021

By R. B. King

This document was prepared by the DFI International Grouting Committee with the intent to provide a summary of main Standards and Guidelines available for the North America and Europe grouting industry. This document highlights the different approaches, methods and tools used internationally. The DFI International Grouting Committee comprises all parties involved on a grouting project: Owners, regulators, engineers, contractors, and manufacturers (equipment and materials). This document is not intended to cover every conceivable application or requirement of grouting. However, it does provide standard practice requirements for qualifications, materials, equipment, testing, and production procedures for the professional engineer to incorporate into their project specific requirements.

Jan 1, 2021

By A. Paviani

The subject of this session is "Equipment Installa­tion, Recent Developments". This is a subject which is not usually addressed at conferences of Foundation Engineering. It is rare to find sessions dealing with the technological side of deep foundations, a subject which only recently seems to have aroused sufficient interest at national and international conferences. It is therefore natural for the subject of "Equipment", or the tools used to implement the various "technologies", to be over­looked or mentioned only occasionally during the discussion of other issues. At conferences, most of the attention is attached to research and to the theoretical interpretation of the performance and behaviour of deep foundations, as well as to establishing the most suitable calculation algorithms and approaches for the study, design and control of foundation structures. It is almost as if the subject of equipment is felt to be less important or, perhaps, that it is considered to belong more strictly to mechanical engineering than to civil engineering.

Jan 1, 1994

By Michel Bustamante

The Arbre viaduct, 200 metres long, is the most important structure on the Belgian portion of the High Speed Train line between Paris and Brussels. The particular geotechnical conditions of the soil with carboniferous limestone affected by karstic phenomena, has prompted the designer to found the viaduct on systems of high capacity vertical and batter micropiles. The design of the working micropiles was validated by full scale tests performed on instrumented micropiles. The size of the structure and the deformation criteria to be met when HS trains are crossing the viaduct, together with the lack of references for such innovative structure, called for monitoring the movements of the piers as soon as the link was open to traffic. The authors report on the results of loading tests on micropiles and the results of settlement structure monitoring for a period of 4 years. Settlement of the foundation is estimated taking into account the group effect.

Jan 1, 2002

Jan 1, 1988

By B. De Paoli

At Pietrafitta, between Assisi and Perugia, ENEL (Italian National Electricity Authority) has for some time been managing a power-station operated with lignite, mined from an open mine on the way to exhaustion. A new plant is under construction which is located in the mine that was filled with tailings, mainly clays, sandy silts, lignite and ashes produced by the power-station. The soil profile is shown in Fig. 1: the thickness of the made ground is around 27 m. The foundation of the new power-station is on 320 t piles, 1.20 m diameter, embedded in the cohesive base formation at a depth of 57.5 m. 2,350 piles will be constructed for a total length of 125 km. It is therefore one of the largest pile sites at present in operation in Italy. [ ]

Jan 1, 1994