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By Mohab Sabry, Emre Biringen

"Over the past decades, there has been an increasing recognition of the strategic use of pile-supported rafts in design of heavily-loaded structures to reduce total and differential settlements. However, such a hybrid foundation construction method has not been widely utilized in many countries, including the U.S., due to code limitations. In current practice, the foundation design is based on either (i) the bearing capacity of the raft supported by the subgrade soils, or (ii) solely the pile capacity. This paper addresses the potential use of such hybrid piled-raft systems, where the structural load is shared by both by the piles and the subgrade soils directly beneath the raft, in foundation design of power plant structures. The study assessed some of the characteristics of piled-raft behavior by undertaking three-dimensional finite element analyses of two raft sizes, and various pile layout patterns, including the rafts with piles distributed evenly and only in the central area of the raft. The computer software PLAXIS 3D with the Mohr-Coulomb constitutive soil model was used to facilitate the modeling of such cases. The results presented in this paper indicate how strategically locating the piles could reduce the differential and total settlements.INTRODUCTIONUnder the high applied loads coming from the superstructure, the addition of piles is primarily required to improve the factor of safety against failure when a raft does not provide adequate bearing capacity. If the bearing capacity of the raft is sufficient to carry the total load with a reasonable safety margin, then the addition of piles is usually intended to reduce the settlements to an acceptable amount. In current practice, the design process for pile-supported raft foundations conservatively concentrates on providing solely the pile capacity to carry the total structural load without taking the contribution of the raft into account. This paper addresses the potential use of hybrid piled-rafts in controlling foundation settlement of power plant structures by considering the support of both the piles and the subgrade soils beneath the raft to carry the load."

Jan 1, 2017

By Axel J. Pollak

Since the late 1960's the Interstate Division for Baltimore City (IDBC) has been planning and developing the Interstate Highway System for the city to meet regional planning goals. The principal goals are to provide convenient access to the central business district and the port while diverting through traffic away from these congested areas. Interstate Route 95, an eight-lane highway carrying north-south traffic, has headed the city's priority list; during the 1970's its construction proceeded steadily from both east and west towards the harbor. Closing the final 8800-ft (2670-m) gap under the harbor will complete Interstate 95's construction. This final portion, known as the Ft. McHenry Tunnel project, will be built in nine construction contracts. Construction costs of the complete project are expected to exceed $700 million, making it the costliest single project in the Interstate Highway System. Full funding is being provided initially by the Federal Highway Administration (FHWA), and the Maryland Department of Transportation will re-pay the 10 percent local share from toll receipts within the first three years of operation.

Jan 1, 1989

By Lok M. Sharma

Development of brownfields is of great interest in these days. Such fields are not easily adaptable for foundations of structures. The uncertainties in ground behavior present challenges of unpredictable subsidence that could be detrimental to the build up facility. A desalination plant had to be located along the seashore, close to the needy population and the existing water supply infrastructure. The available site had been developed as a recreational park area over a dumped construction demolition debris landfill along the coastline. To construct a desalination plant comprised primarily of large concrete basin tanks on slab, founded on the debris fill had its challenges. A ground improvement system in the form of vibro replacement stone columns was designed and constructed. Approximately 5,000 stone columns were installed across the site. This paper describes the analysis process, the design, field load testing, and installation of stone columns. Difficulties during construction and monitoring aspects are briefly described. The plant started operations in the summer of 2008 and to date has performed satisfactorily. When properly designed, the development of brownfields is achievable at other sites.

Jan 1, 2009

By Ross T. McGillivray, David S. Graham, Dan A. Brown, Steven D. Dapp

"The Selmon Expressway includes an elevated structure extending across several miles of weathered karstic limestone geology, and represents a challenge for design because of the high variability of the material and the difficulty in characterizing the strength. The nature of the epikarst in this region of Tampa is such that variability can be extreme within distances of only a few feet. The weathered rock includes extremely soft soil infill within solution features on and within the formation. The limestone is so weathered that coring typically does not yield useful samples for strength testing, and in-situ Standard Penetration Testing (SPT) tests often encounter refusal blow counts. Thus the challenge for foundation design includes two components of reliability risks: the uncertainty associated with the ground conditions at a given foundation location plus the uncertainty associated with the foundation performance at a given location even when the stratigraphy is determined.This paper describes the design approach that has been implemented successfully for two projects at the Lee Roy Selmon Crosstown Expressway (LRS) in Tampa, Florida: the assessment and remediation of the reversible elevated lane (REL) foundations constructed in 2004, and the elevated expressways widening project constructed in 2012. Included in this design approach is a method developed for computing axial resistance in this local geology. Design for axial loading relies primarily on the development of side resistance, which was considered less subject to performance risks than base resistance. The calculation method incorporates a statistical analysis of SPT data, tempered by engineering judgment, to characterize stratigraphy at a given location into either soil, intermediate geomaterial (IGM) or rock.IntroductionThe subsurface stratigraphy of sites underlain by weathered limestone formations can be highly variable with respect to material layer thicknesses and strengths, even over short horizontal distances. This is the case for much of Florida, and particularly the Tampa area. These conditions present a challenging environment for the design of drilled foundations because of the need for a reliable determination of subsurface conditions at each foundation location, as they relate to the expected axial performance. Contributing factors include:"

Jan 1, 2015

By Robert B. Bittner

The new gated dam on the Monongahela River at Braddock, Pennsylvania, was built for the US Army Corps of Engineers using an innovative ?In-the-Wet? technology. A key feature of this technology involves construction of the foundations through the water and later mating the completed structure or a shell of the structure to the pre-installed foundation. This paper presents a description of the structure, its foundation, construction sequence and design details required to successfully implement this technology.

Jan 1, 2013

By Walter G. Brusey

This paper describes a comprehensive pile test program conducted at John F. Kennedy International Airport (JFKIA) to evaluate pile types and design capacities ranging from 890 to 4450 KN (100 to 500 tons). Driven cased piles and drilled shafts, both standard construction and post-grouted after installation, were tested with platform loads extending to 8900 KN (1,000 tons). Alternate load test procedures were developed, extensive structural integrity testing and dynamic load tests were performed on selected shafts. A brief update is provided covering the application of results of the test program to pile selection for support of major structures incorporated in the on going redevelopment of JFKIA.

Jan 1, 2000

By F. Keith Jacobson

To be involved in the construction of a deep dredged caisson for a major bridge pier is one of the most rewarding and professionally challenging experiences one can have in the bridge construction business. That experience was doubled in the construction of the two deep dredged caissons for the Highway 82 Bridge over the Mississippi River near Greenville, Mississippi. The challenges and the construction risks associated with constructing these two dredged caisson pier foundations highlight the construction engineering innovation associated with major bridge pier construction. The 1,378-foot Main Span of the Highway 82 Bridge makes it the longest cable stayed bridge span over the inland rivers of the United States. The main piers for this bridge are supported on two dredged caissons measuring 80-feet by 122-feet in plan, founding 200-feet and 170-feet below the river surface. The challenges of constructing these caisson structures, sinking them through 70-feet of water to the river bottom and then excavating and further sinking them to the founding grade without exceeding the design tolerances, were enormous. The construction engineering opportunities for innovation included major breakwater structures to create a friendly environment in 11 ft/sec currents, the first time use of Articulated Concrete Mattresses for river bottom scour control, unique air dome design to maximize the buoyancy of the caisson structure while floating, a caisson guide system to assure positive control and positioning of the caisson during the initial sinking phases, and a comprehensive sinking plan to assure maximum control and minimum risk. Many of the innovative solutions to the construction challenges on this bridge will be incorporated into future caisson construction projects on the lower Mississippi River.

Jan 1, 2013

By Hamed Ardalan, Mohamed Ashour

"CHAPTER 1INTRODUCTIONThe use of piles to stabilize active landslides or to prevent instability in currently stable slopes has become one of the most important innovative slope reinforcement techniques over the last few decades. Piles have been used successfully in many situations in order to stabilize slopes or to improve slope stability, and numerous methods have been developed for the analysis of piled slopes (Ito et al., 1981; Poulos, 1995; Chen and Poulos, 1997; Zeng and Liang, 2002; Won et al., 2005).The piles used in slope stabilization are usually subjected to lateral force through horizontal movements of the surrounding soil; hence they are considered to be passive piles. The interaction behavior between the piles and the soil is a complicated phenomenon due to its 3-dimensional nature and can be influenced by many factors, such as the characteristics of deformation and the strength parameters of both the pile and the soil. The interaction among piles installed in a slope is complex and depends on the pile and soil strength and stiffness properties, the length of the pile that is embedded in unstable (sliding) and stable soil layers, and the center-to-center pile spacing (S) in a row. Furthermore, the earth pressures applied to the piles are highly dependent upon the relative movement of the soil and the piles."

Jan 1, 2013

By Denton A. Kort

Historically the visual examination of drilled shafts to determine shape was typically done under dry conditions. Many engineers believe that by using a dry method of construction, the question of shape is minimized because they can visually examine the excavation. In fact, test data suggests that slurry stabilized shafts tend to perform better than similarly constructed dry shafts. Clearly, the uncertainty of the shaft shape is magnified when constructed under slurry. Recent advancements have allowed a mechanical caliper to determine shape in wet conditions, but can be limited by certain shaft anomalies. New sonar technology can determine shaft shape, volume and verticality. The value of sonar technology to the geotechnical and foundation industry at large in terms of quality assurance for clients/owners and quality control for drilled shaft contractors is significant. This presentation will discuss the development and process of sonar calipering technology as it relates to the geotechnical and deep foundation industry. Sonar calipering results presented may include images from the following types of projects: slurry walls, bridge piers, cofferdams and secant walls. The results identify shaft anomalies in a variety of slurry environments, from water and polymer mixes through mineral slurries. Real-time in-situ images and CAD drawings will be presented illustrating the advantages of good caliper data taken during construction. This presentation will appeal to the geotechnical and structural engineers, as well as those supporting the deep foundation industry at large.

Jan 1, 2007

By Ernest Naesgaard

Post-grouted micro-piles were used for the seismic upgrading of the Vancouver International Airport Domestic Terminal Building (DTB). The micro-piles provided vertical resistance to both uplift and compression loads to supplement the existing timber pile foundations ability to resist the earthquake induced forces, and to provide foundation support at locations where the installation of traditional driven piles was difficult. This paper describes the site conditions, design rationale, installation method and quality control testing procedures. Site and Subsurface Conditions Vancouver International Airport is located within the central portion of Sea Island, Richmond, British Columbia (Fig. 1). Sea Island is bordered by branches of the Fraser River on the northeast and south sides and the Strait of Georgia along the west side. The natural grade of the island is part of a large delta that has been built up over several thousand years. The general pattern of sediment deposition has followed the direction of the Fraser River flow from east to west, and has built up soft sediments of about 200 m thickness at Sea Island (Luternauer, et al. 1993, Mathews and Shepard 1962). The original grade in 1962 prior to the existing Airport Terminal Building development was at about geodetic elevation 1.1 m with a grass and topsoil cover.

Jan 1, 2004

By George Machan

Bitumen coatings have been successfully used to significantly reduce downdrag on piles. Thicker coatings of "soft" bitumens can accommodate downdrag so well that very little downdrag load is transferred to the pile. Many of the case histories describe better than 80 percent downdrag load reduction. Bitumen coatings have been used on several projects in Oregon. On the Mocks Bottom Bridge project (see Reference 1), experimentation and instrumentation confirmed the viability of bitumen coatings and provided insights for design and construction. Subsequent bridge projects have used this information and have raised issues to be resolved.

Jan 1, 1989

By Jean Wehbe, Daniel C. Brahana

"This paper presents a case history of drilled pier construction for a new stadium in Atlanta, Georgia. The stadium structure is supported on several different foundation types, with the heaviest ""mega columns"" typically bearing on drilled pier supported mats. The project includes 141 drilled piers with design diameters of 5.5, 6 and 6.5 feet. The piers bear on bedrock at depths of 20 to 110 feet below the ground surface. Many of the piers included rock sockets with design lengths of 5 to 18 feet. A pre-production drilled pier load test program was completed including one Statnamic load test, two Osterberg Cell tests and two lateral load tests. Non-destructive testing (crosshole sonic logging and sonic integrity testing) were also performed during construction. Production pier installation with over 3800 linear feet of earth excavation and over 1350 linear feet of rock excavation was completed in a little over four months. The piers were installed using both the cased hole method and the slurry method. All cased holed required downhole inspection and slurry holes were initially inspected with a mini-SID device and subsequently by sounding. Advanced drilling equipment and tooling were used to meet the production requirements for the project. This paper reviews the highly variable soil and rock conditions encountered at the site, briefly presents the results of the load tests, and discusses pier installation procedures and the equipment used for installation. The paper also presents conclusions related to the installation and lessons learned.INTRODUCTIONWith the opening of AT&T Stadium in Dallas, a new era of stadium construction began in the U.S. The new age stadiums are larger and have more amenities than their predecessors. The new Atlanta Falcons stadium is no exception. Many of the new features, including Atlanta’s innovative retractable roof, result in extraordinary structural loads. The roof structure is supported by a series of mega columns that bear on eight large caps, six of which are drilled pier supported. Each of the pier caps contains between 8 and 16 drilled piers that bear in the underlying bedrock. The design pier diameters are 6 and 6.5 feet. Augercast piles were used to support two of the mega column caps. Drilled piers, augercast piles, aggregate piers and spread footings are used to support the more lightly loaded portions of the structure."

Jan 1, 2017

By Julie Hampden, Tim Dardis, Per Reinhall

"Noise from impact pile driving can harm fish, marine mammals and other sensitive wildlife over large areas. Marine pile driving is highly regulated, and regulators require sound levels to be below certain thresholds to avoid harassment and injury to sensitive marine life. In many locations, timing restrictions, use of noise attenuation technologies and extensive monitoring for impacts to wildlife are also required. As a result, permitting can be laborious and time consuming, and project implementation and scheduling can be complicated. Underwater noise levels are measured with an underwater microphone (hydrophone), which converts noise pressure to voltage and is calibrated to express the noise pressure in Pascals (Pa). The pressure is often expressed using a logarithmic scale, in decibels (dB). Several specific metrics can be used to describe underwater noise. Three common metrics are the instantaneous peak sound pressure level (dBpeak), the root mean square pressure level (dBRMS) and the sound exposure level (dBSEL) referred to as the peak, RMS and SEL levels, respectively.During impact pile driving, the peak pressure represents the instantaneous maximum pressure, either overpressure or underpressure, observed during each pile strike. The RMS level is the square root of the mean of the square of the pressure during the duration of the impulse; it is the average pressure level of the pile strike from beginning to end. The cumulative SEL (SELcum) is calculated by summing the cumulative pressure squared and integrating over time of duration of the pile strike. SEL is used as an indication of the cumulative energy of a pile driving event, which may consist of one or many pile strikes.Regulatory agencies use these metrics to help characterize the noise pressure levels that can affect sensitive species. Some of the most frequently encountered biological thresholds in the Northwestern United States that are used by regulators to describe potential impacts to sensitive species are summarized in the following table. Agencies have defined thresholds for different types of injury, either hearing or bodily harm, and for temporary injury or disturbance."

Jan 1, 2017

By Norm Kirk, Robert Bittner

"The addition of a new powerhouse at the existing Tulloch Hydroelectric site on the Stanislaus River in the western foothills of the Sierras Nevada Mountains of central California required a deep excavation in rock on the downstream face of the dam. A cofferdam (water exclusion device) was necessary to isolate the powerhouse construction site excavation from the existing Goodwin Reservoir and the turbulent discharge from the existing powerhouse. The cofferdam was positioned on a steeply sloping fractured rock surface exceeding 50 degrees.This paper describes the challenges encountered during design and construction of the cofferdam and describes the unique design features used to address these challenges including:•,The use of flat-sheet-piles to form cellular walls on the steeply sloping rock surface.•,The use of 5-ft deep tremie concrete plugs in the bottom of the sheet pocket cells to create the bottom seal of the cellular cofferdam walls against the sloping rock surface.•,The use of vertical post-tensioned rock anchors to provide shear resistance at the contact point between the base of the cellular-wall and the sloping rocksurface.INTRODUCTIONModification or expansion of existing hydroelectric power plants often require downstream cofferdams or water exclusion devices to temporarily separate new construction from turbulent downstream discharge of the existing dam. Most dams are positioned on solid rock in the narrowest and therefore the steepest section of the river. This combination of steeply slopingrock and the need for an exclusion barrier creates a challenge for the design engineer trying to maintain a safe dewatered construction site. Typical cofferdam solutions for hydroelectric dams usually use large granular filled circular sheet pile cells that perform as gravity structures. However, this type of structures is not well suited to steeply-sloping highly irregular rock surfaces in a confined area."

Jan 1, 2017

By Fawad S. Niazi

Analysis of deep foundations in terms of axial capacity has been a topic of great interest in the soil-structure interaction problems. Soil behavior is governed by a series of complex stress-strain changes that occur during pile installation and subsequent loading. Owing to the difficulties and uncertainties on the basis of the soil strength-deformation characteristics, one of the most frequently followed design practice is to refer to the formulae correlating directly the pile axial capacity components of unit base resistance (qb) and unit shaft resistance (fp) to the data collected from cone penetration test (CPT), i.e. to the tip stress (qc or more proper qt), sleeve friction (fs), and shoulder pore water pressure (u2). The elementary basis for such formulations has been the idea of considering cone penetrometer as a mini-pile foundation. This has resulted in plethora of correlative relationships in the past over 60 years. Such correlations, although empirical, have been worked out on the basis of load test results from both instrumented and un-instrumented full scale piles and are able to accommodate many important variables. A quick review of the evolution process and development of such design formulations is presented with a view to propose recommendations for future research directions, where the latest version of CPT i.e. seismic piezocone test (SCPTu) can be used to advance from capacitysingularity to the complete axial pile load–displacement (Q–w) response.

Jan 1, 2013

By K. Oshima

In Japan, earthquakes are experienced frequently. Many buildings and structures in Japan are supported on pile foundations. For these pile foundations, the joint section between the piles and footing (hereinafter referred to as "Pile Head Joint"), where the load of the superstructure is transmitted to the ground through the piles, is important in both the design and construction of works particularly under seismic conditions. This paper discusses the state in which the force is transmitted to the Pile Head Joint, and introduces the basic construction of the Pile Head Joint, based on experimental investigation. Steel pipe piles

Jan 1, 2010

By Dan Brown

This paper provides an overview of the advantages and limitations of continuous flight auger (CFA) and drilled displacement (DD) systems compared to other deep foundation systems, along with a summary of important considerations for selection and design. Geotechnical and project considerations are described which favor the use of CFA and DD piling, and also which may be problematic for this type of construction or which may limit the practicality and competitive advantages. A brief summary of design methods for axial and lateral loading is included.

Jan 1, 2005

By George J. Tamaro

In 1967 the Port Authority of New York and New Jersey undertook the construction of the World Trade Center (WTC) diaphragm walls, installation of the lateral support system and the excavation of the site, commonly referred to as the "Bathtub". The work took two years to complete. In 2001 the City of New York undertook the re-excavation of the site after the terrorist attacks. The recovery work will take eight months to complete. This paper describes the initial work on the WTC "bathtub" in the late 1960s and the recent work during the recovery.

Jan 1, 2002

By Frederick C. Rhyner

The United States government sponsored the construction of a new vehicular bridge over the Diyala River in Bubriz, Iraq. This paper describes the geotechnical engineering for design and construction of drilled shaft foundations for this bridge. An Iraqi geotechnical engineering firm made borings and laboratory tests while analysis and design recommendations were provided in the United States. Despite the severe challenges of engineering in a war zone, excellent cooperation was the key to a successful effort. Three drilled shafts designs were necessary to accommodate the different subsurface conditions: a) medium-compact to compact sands, b) stiff to hard clays and c) mixed soil profile. The alpha and beta methods were used to estimate capacities for a conservative design, recognizing that quality control during construction might be less than what is normally provided in the United States. Iraq has a high seismic risk and LPILE was used to estimate the drilled shaft response during earthquake loading conditions. Settlement estimates were made using FHWA methods. Construction was carried out entirely by local Iraqi firms, despite the challenges of working in an active conflict area.

Jan 1, 2009

By Peter de Kort

Tunnels in urban areas generally require deep excavations in soils under the groundwater table. In The Netherlands uplift loads are generally taken by piles installed into dense sand layers, which are hard to penetrate. To avoid nuisance and damage to the environment, piles often need to be installed using vibration free methods, which also have the advantage of low noise levels during installation. Drilling piles and obtaining a high uplift resistance is a contradiction in itself. Franki has adopted several installation methods based on the injection of grout during drilling and/or post grouting to overcome the difficulty of hard layers. This report presents two projects, situated in Rotterdam and Sneek, where vertical tension piles in floors, subject to high uplift loads, have been used. It also explores a project in Zeebrugge (Belgium), where tension piles are installed at an inclination of 1:1 to anchor a diaphragm wall for a quay construction. Test results presented in this report show, that vibration free and soil displacing piles can be installed in very dense sand layers and that a high uplift resistance can be achieved. It is also shown, that a variety of installation methods is available, even in limited space.

Jan 1, 2008