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By Jonathan J. Dewsbury

It is argued that approximate computer based methods are only suited to modelling conventional piled rafts, for pile enhanced rafts where the interactions will be non linear three dimensional finite element analysis is required. However current 3D finite element analysis often relies on symmetry to reduce computational cost and there are concerns over the dependency of the results on the user. Therefore a new strategy within the finite element framework has been proposed. The main advantage of this strategy is that each stage of the model can be checked for consistency. There is also the added benefit that non symmetrical models can easily be constructed by tying the validated components together without dramatic increases in computational time. The proposed strategy compared well to the published results of a hypothetical example of a piled raft previously analysed with numerous methods by Poulos et al. (1997).

Jan 1, 2010

By Mark S. Greenleaf, Alec D. Smith, Mary Vittoria-Bertrand, Heather B. Scranton, Jean Louis Z. Locsin

"Rhode Island’s new $163.7 million, 2,265 ft (690 m) long, four-lane Sakonnet River Bridge sits just south of the existing bridge in Portsmouth/Tiverton. The bridge, a critical transportation system link between Massachusetts and Rhode Island, has a steel I-girder main span and concrete New England Bulb Tee approach spans. The foundation work was done between October 2009 and July 2010, and the bridge was completed in February 2014.Foundation design and construction challenges make the project noteworthy. There were thick layers of silty glacial soils with bedrock as deep as 400 ft (122 m) below the waterline, coupled with high foundation capacity demands at the river piers in 50 ft (15 m) of water. The Sakonnet was one of the first major bridge projects in the country to incorporate AASHTO Load and Resistance Factor Design (LRFD) guidelines for foundation design and construction. Because of these and other challenges, the engineers conducted two design-phase load test programs on several foundation elements. These programs were successful and allowed the engineers to adjust the final foundation design prior to the start of construction. During construction, the contractors drove thirty 6 ft (1.8 m) diameter steel pipe piles, each with a novel recessed steel plate insert, to depths of 130 to 200 ft (40 to 61 m) at the three river piers. The insert provided increased resistance of the steel pipe piles and saved about $9 million. Also, 457 14x117 en bearing or friction H-section piles were driven to between 50 and 190 ft (15 to 58 m) at five land piers. All piles were driven relatively close to the existing bridge, which remained in service during construction, due to the project team’s precautionary use of instrumentation and the installation of a jacking system.Area GeologyThe Sakonnet River is up to 60 ft (18 m) deep along the bridge alignment and is underlain by a deep bedrock valley. The bedrock valley is buried by at least 350 ft (107 m) of soil, which includes a complex sequence of interbedded glacial soils (glacial till, glaciolacustrine deposits and glaciofluvial deposits), overlain by geologically recent estuarine deposits. The soils having the greatest impact on the foundation resistance are the glaciolacustrine (fine sandy silt or silt) and glaciofluvial (silty sand with gravel, cobbles, and occasional boulders less than about 2.5 ft [0.8 m] in size). The soil overburden decreases toward the east and west banks of the river, as the bedrock surface rises."

Jan 1, 2015

By Matthew E. Meyer

Renovation, rehabilitation, restoration and expansion of existing residential, retail, commercial, hospital facilities and historic structures requires assessment and evaluation of foundation systems of various ages. The concept of demolition and reconstruction in urban areas is often more challenging, costly, and even prohibitive in some cases due to historic regulations. The authors have been involved with numerous projects related to existing foundation assessment and retrofit, including: hotel and hospital expansions, historic Art-Deco hotel renovations and expansions, garage structure expansions, additions to prominent auction houses, casinos, printing facilities; high-rise structure foundation retrofitting; and forensic evaluations of existing building and highway structure foundation systems, and marine bulkhead sheeting systems. The use of non-destructive testing techniques, high-strain dynamic load testing, full scale pile cap load testing and 3-D laser scanning technology has proved to be vital in the assessment and evaluation process, as well as design of foundation retrofit alternatives. This paper presents various methods and techniques to facilitate a phased approach for re-use of foundation systems. These methods and techniques are illustrated through the author?s experience and selected case histories from projects with varied foundation and geologic conditions.

Jan 1, 2009

By Anup Kumar Mandal, Sanjoy Chowdhury, Biswajit Das

"Tailing pond of an iron ore mine necessitated raising the height of its embankment to create additional storage capacity. The tailing pond is located in eastern India and raising the height of embankment was going on during the month of January, 2014. Upstream method of construction was adopted since there was no space available at the downstream side. During the construction, about 200 m stretch of the north east embankment of height about 5.5 m failed forming a classical slip circle on the upstream side involving about half the top width of the embankment. To find out the root cause of the slope failure, detail geotechnical investigation work was carried out within the embankment as well as in the adjacent areas within the pond. About 7.5m thick very soft tailings were detected below the constructed embankment. Shear strength of the soft tailing was very low and was inadequate to sustain imposed embankment load. This resulted in the failure of the embankment. Analysis of the tailing deposit revealed that even after failure, settlement was continuing due to imposed embankment load. Under normal onedimensional consolidation, the tailing deposit would have taken about 5.7 years for 90% of primary consolidation. However, in order to mitigate the scarcity of storage space, mining plan required raising the height of the embankment within next six to eight months. Therefore, despite the fact that there was a failure, it was necessary to continue the construction on the underlying weak stratum. The system was redesigned with installation of prefabricated vertical drains (PVDs) to accelerate the consolidation process thereby gaining the in-situ strength. Strength was additionally enhanced by installing geogrids in multiple layers. It stabilized the existing embankment and also ensured construction of additional height over and above the existing embankment.INTRODUCTIONBeneficiation plant in the Iron mines enhances the mineral content by separation of contaminants and fines. The residue (waste material) is called tailings/tailings depending upon the grain sizes. These tailings in a slurry form are generally disposed in a pond called as tailing pond/tailing pond. Height of embankment of such ponds is increased either by upstream or by downstream or by centrally raising methods in different phases as quantum of deposition in the pond increases with time."

Jan 1, 2015

By Paul Doherty

It is known that the axial capacity of a displacement piles installed in clay varies with time. Consolidation theory suggests that dissipation of porewater pressure set-up during pile installation would lead to increased effective stress and hence higher pile resistance. In recent years a number of case histories have reported time dependent capacity increases for piles installed in sand. Although there is some debate regarding the physical mechanisms controlling this phenomenon, known as ageing, it is unrelated to pore pressure dissipation as piles in sand are installed in primarily drained conditions. A series of field tests designed to investigate ageing effects in soft clay are presented in this paper. Full-scale load tests on 6m long 250 mm square concrete piles, which were driven into soft clay are described. The piles were first tested approximately 100 days after installation, at which stage full equalization of the excess pore pressures had occurred. Static load tests were then performed up to 10 years after pile installation. The piles exhibited significant ageing, with their shaft resistance increasing by up to 66% over a 10 year period. Possible mechanisms for such aging characteristics are explored.

Jan 1, 2011

By Y. Z. Wang

Zhengzhou Yellow River Highway Bridge, which is under construction, has a total length of 5550 meters with bored cast-in-place concrete piles as the foundations of its piers which have a diameter of 2.20 m with a length of approximately 65 m. This paper attempts, through the introduction of the said bridge's footing pile design and construction, mainly to give an account of the following points: 1) experiment and research on deep friction pile with a large diameter, 2) calculation of vertical carrying capacity of the pile with a large diameter, 3) analy­sis of horizontal forces the footing-piles of the column-shaped piers, 4) application of normal and reverse-circulation rotary drilling technologies to the construction of bored cast-in-place concrete piles with a large diameter and 5) applying super-sonic impulse on destruction detective device to examine the quality of the pile concrete.

Jan 1, 2010

By Jack Taggart, Chris Barker

Pile load testing strategies for large infrastructure projects and multi-phase building developments have historically justified cost and programme benefits for undertaking advance preliminary and working pile load testing. However, more recently piling and pile load testing strategies have included assessment of the embodied carbon to understand and present the carbon savings that can also be achieved. This paper gives an overview of the factors contributing to carbon and emissions in the construction of bored pile foundations and presents the methodology taken in assessing embodied carbon as part of the pile load testing strategy for a multi-phased building development in London. Potential embodied carbon savings for various bored pile types and load testing strategies are discussed alongside alternatives and other considerations including pile re-use and carbon offsetting to inform continual improvement for future projects.

May 1, 2022

By Moritz Schleeh, Christian Moormann

Temporary working platforms are generally required in order to ensure that heavy construction machinery such as drilling and trench wall units, pile drivers, vehicle and crawler cranes can be set up safely at the site of operation. Considering all possible operating and loading conditions, especially on ground of low shear strength and stiffness, the design and construction of temporary mobile working platforms needs to be considered more as a serious engineering task than as a second order structure of minor relevance. Working platforms reinforced with one or several geosynthetic layers have proven to be especially effective with regard to stability, serviceability and durability but their design requests even more sophisticated approaches. Existing design models are often based on simplified assumptions and do not consider the complex interaction between construction machinery, working platform and subgrade. Non-monotonic loading as well as elastoplastic and time-variant deformation of cohesive subsoil can adversely affect the base layer system and the serviceability and stability of the construction machinery operating on it. In this context, there is a need for improvement of design approaches and their optimisation considering that there are no generally accepted design approaches or technical codes of practice available for the design of temporary working platforms. The present paper deals with the multifaceted and non-trivial interaction effects of working platforms investigated by model tests, field measurements and numerical simulations to develop a design approach that ensures a safe installation and operation of heavy plants on unstable ground.

May 1, 2022

By Jeongbok Seo

The Dulles Corridor Metrorail Project (DCMP) involves the design and construction of a 23.1-mile extension of the Washington Metropolitan Area Transit Authority (WMATA) rail system. The initial 11.7-mile extension, with five transit stations and a new service and inspection yard, is to be constructed. The construction plan for the initial 11.7-mile extension includes installation of a total of an estimated 4,250 or 160,000 linear feet of driven 12x53 steel H-Piles at more than 80 different locations. At the time of this paper, approximately 40 percent of the piles have been installed and the remainder of piles will be installed by the end of 2010. This paper describes: 1) subsurface investigation program, 2) application of existing Codes and impact on the design of H-Pile, 3) design methods to determine geotechnical bearing capacity and pile tip elevation, 4) verification of capacity including PDA and Static Load Tests, 5) project specific pile load tests, and 6) QA/QC during pile driving.

Jan 1, 2010

By Alice Arana, David M. Cacoilo, Joel L. Volterra

"To make space for the new South Ferry Station in lower Manhattan, engineers and contractors carved out a new tunnel beneath three operating subway tunnels and tangentially to yet another tunnel. Creating the space required the design and construction of complex temporary excavation support and underpinning systems and the design and installation of real-time monitoring systems. Construction for the new station and tunnel was mainly cut-and cover in a mixed-face area of soil and rock approximately 2,000 linear ft long, 60 ft wide and up to 70 ft deep. Close coordination between the design/build team and the project owner, the Metropolitan Transportation Authority (MTA), was critical.With the construction of this $400 million project, the MTA and New York City Transit (NYCT) are correcting the numerous physical and operational deficiencies of the existing station and improving the lives of millions of commuters. Built in 1905, the original South Ferry Station is on the IRT Broadway–Seventh Avenue Line of the New York City Subway and is the southern terminal of the #1 subway service, which forms a loop to return uptown. The station has a sharply curved single platform on the outside of the outer track of a two track loop. This platform is short and does not allow the rear five cars of a normal 10-car subway train to load or unload. In addition, once the train stops at the station, commuters wait while retractable floor grates bridge the gap created between the platform and the subway car doors, and then they have only one exit from the station. Spray nozzles keep the tracks lubricated to reduce the train wheels’ friction caused by the tight curve. The sharp curvature of the loop and the inability to use half of the subway car doors slow train operation. With the new ADA-accessible station, 10-car trains will be able to open all doors, and additional entrances, escalators and elevators will greatly reduce travel times."

Jan 1, 2008

By Jeongbok Seo

This paper describes successful application of driven tapered-steel-pipe piles for two large-scale projects in the New York metropolitan area: Rego Park Mall, Rego Park, N.Y. and 164 Kent Avenue, Brooklyn, N.Y. The combination of side friction and end bearing resistance produced by tapered-steel-pipe piles has been well-recognized as greater than the side friction and end bearing resistance by pipe piles. Forty-four tapered piles were driven and tested at these two sites. Design pile load for the two sites was 260 kips for Rego Park Mall and 400 kips and 300 kips for 164 Kent Avenue. To measure the pile-drive hammer efficiency, the compressive stress in the pile, and to estimate the ultimate bearing capacity of the pile, dynamic load testing using a Pile Driving Analyzer (PDA) was conducted on index piles at the sites. Subsequent to the field testing, data analysis using the Case Pile Wave Analysis Program (CAPWAP) was conducted. Restrike PDA analysis and full-scale static load tests were performed on the selected test piles. Test piles at the project sites exhibited significant time-dependent increases in bearing capacity caused by the effects of "set-up" or "soil freeze." The dissipation of excess pore-water pressure in the soil, which had been disturbed and remolded by driven pile, was generally considered the primary cause of set-up. The increase at the subject sites ranged from 100 to 300 percent of the capacity measured at the initial driving. This paper discusses the results of various types of load testing on tapered piles and the set-up effects by comparing PDA test results acquired during and after pile driving. Finally, an empirical relationship for the New York metropolitan area has been offered for quantifying set-up.

Jan 1, 2008

By Jochen Maurer, Dr. Christian Hoyme, Dr. Hans Regler

Currently, it is very difficult to obtain qualitative and quantitative information about the status and production process of a construction site. As a rule, companies depend on reports from on-site experts. There is no end-to-end digitalization due to the mobility of equipment and ever-changing locations. Equipment from different manufacturers, especially in special foundation engineering, is highly specialized. Any data collected by this equipment is recorded in proprietary formats and made available on the manufacturers' platforms. This exacerbates the situation, making simple analysis of performance indicators impossible. Most functions such as construction diaries, equipment utilization analyses, etc. are implemented only as standalone solutions. This does not allow for prompt visualization and intervention in critical process sequences because the construction site process is usually managed using a cost-based method. Furthermore, special foundation engineering requires a high level of expertise in an extremely wide range of construction processes. In this article, the results from a set of non-proprietary performance analysis tools are presented using numerous practical examples. Once a construction element is completed, the equipment data is immediately transferred to the platform using the latest cloud technology. Because the data is normalized, construction progress can be documented immediately, even for mixed equipment fleets. Bottlenecks can be immediately detected by visualizing the current performance of the production process, which is broken down into individual steps. Modern analyses of this equipment data improve quality, thereby providing better information about current performance. These sets of tools are essential for changing from the current monetary or cost-based method of process management to time- and bottleneck-oriented management. This makes it much easier to identify the critical path during projects. The article shows that processes can be documented and managed.

By Chang-Yu Ou, Shao-Chi Chien, Hsuan-Hsiang Chang

"A field test was performed to investigate the applicability of electroosmosis with the injection of saline solution of Taipei silty clay. The calcium chloride solution and sodium silicate solution were used as the saline solution for the injection in this test. The results of this study indicate that injection using calcium chloride solution and sodium silicate solution during the electroosmosis to increase drained water from cathode and electro-chemical reaction can greatly improve the effect of electroosmosis and shorten the time of treatment. The results of field vane tests showed that the undrained shear strength after treatment increased an average of approximately 120% for a treatment period of 24 days.INTRODUCTIONThe first field application of electroosmosis in soil was demonstrated by Casagrande in 1939. Since then, more complete field applications of electroosmosis such as Bjerrum (1967), Fetzer (1967), and Lo et al. (1991b) have been made.The results of field electroosmotic work for a period of 120 days were presented by Bjerrum et al. ( 1967). The mean undrained shear strength, Su, increased from 18 to about 40 kPa, with a uniform surface settlement of about 0.5 m. Lo et al. (1991b), with a more sophisticated installation and a relatively larger spacing, also had positive results. For a 3 m electrode spacing during the treatment of a period of 33 days, the mean Su increased from 18 to about 25 kPa. Although the effect of the electroosmosis could be applied in the field based on the above examples, the response remained slow. For actual field work, the application of electroosmosis will be limited due to short project schedules and request of the effect of improvement."

Jan 1, 2005

By Osama A. Safaqah

Driven plate anchors can be used to hold in place large bridge caissons during floating construction. Their small size and simple method of installation make them a very cost effective alternative to other direct-embedment, gravity, and drag anchors. The geotechnical design of plate anchors involves the anchor geometry, embedment, drivability, and proof testing. This paper describes the experience gained with plate anchors used during construction of the new Tacoma Narrows Bridge. For this project, the anchors had to be driven in dense to very dense sands, and had to resist large forces from 7-9 knot currents.

Jan 1, 2013

By Kenton W. Braun

Concourse B at the Anchorage, Alaska International Airport is currently being renovated while retaining the original building structure and foundations. Part of the renovation includes the installation of a new, permanent baggage tunnel system beneath the existing building. Installation of this cast in place concrete tunnel, beneath the existing structure, required installation of a steel retaining wall to support footing loads above the base of the excavation. Construction of this retaining wall presented challenging and unconventional design and construction methods. Detailed discussions of the design and construction techniques utilized for this project are outlined.

Jan 1, 2008

By Benjamin Jennings, Jason Herron

In the summer of 2016 Xcel Energy experienced a storm event that resulted in the collapse of approximately 8.5 miles of a 345 KV transmission line near Rogers, Minnesota. In design of the new transmission line, Xcel Energy determined that ten tower locations would be replaced with steel H-frame structures supported by helical piles instead of wood H-frame structures supported by driven wooden piles. A steel foundation was proposed for the towers due to time constraints and site conditions unfavorable to large pile driving equipment. Xcel Energy contacted the helical pile manufacturer Hubbell Power Systems, Inc. (HPS) for aid in the design of a complete steel foundation for the structure legs. With the shear, moment, and axial loads provided, the manufacturer used pile group modeling and axial capacity software to design a four helical pile group; and used 3D modeling and finite element software to design a moment resistant grillage to connect to the tower base. The steel grillage utilizes a new moment resistant connection and clamp system to transfer loads from the piles to the grillage. This connection provides a true fixed head condition and reduces lateral deflection issues typical to smaller diameter piles in pinned head connections. The clamp is designed to deform the helical pipe pile shaft and transfer the full axial load of the structure through the mechanical and friction connection. The helical piles and the moment resistant grillage were manufactured with shorter than average lead times and a helical pile installation contractor performed the installation. An expedient plan of install was developed by the contractor that resulted in an average installation rate of one complete set of tower foundations per day. The design of the moment resistant grillage, clamping system, and excellent foundation construction by the contractor provided an expedient and efficient foundation system to be discussed in this paper.

Jan 1, 2017

"Full time inspection of drilled shafts by qualified personnel is a necessary part of construction. Detailed inspection procedures for routine inspection are provided in the Drilled Shaft Inspector’s Manual, published jointly by the DFI and ADSC: the International Association of Drilled Shaft Contractors.The use of NDT methods or other observation methods, such as probes, video camera inspection, remote shaft wall inspection devices or various calipers are not suitable substitutes for routine "topside" construction inspection as described in the Drilled Shaft Inspector’s Manual. However, these NDT and other "remote" or indirect observation methods are valuable alternatives to direct entry of personnel into drilled shaft excavations. They should be considered whenever appropriate to reduce the risks of direct entry of personnel into drilled shaft excavations.As described in the Drilled Shaft Inspector’s Manual, observations made during construction are essential for quality construction of drilled shafts. The shaft depth, diameter, plumbness, bottom conditions, reinforcement, concrete continuity, and bearing conditions are most easily checked during construction. Some of these observation methods include excavation around the shaft for relatively shallow inspection, down-hole inspection for end bearing conditions or rock sockets, and video camera devices for remote inspection. In rare circumstances, a drilled shaft can be extracted for inspection. Before concrete placement, the bottom of the shaft can also be probed by drilling or coring to determine if there are voids or soft zones in the material at the base of the shaft.The Drilled Shaft Inspector’s Manual focuses on traditional "topside" inspection for routine drilled shaft construction."

Jan 1, 2004

By R. Bruce Patterson

The New Tacoma Narrows Bridge is a classic suspension bridge founded on concrete caissons. Caisson construction was complicated by the proximity of the existing bridge piers, only sixty feet away. High capacity plate anchors were used successfully to moor the new caissons in currents as strong as seven knots during construction.

Jan 1, 2013

By Thang V. Nguyen, Lisheng Shao, Gary E. Taylor

"The Community Memorial Hospital of Ventura, California, proposed to build a new state-of-the-art Cancer Treatment Center with radiation shielding walls and roof. The loose silty soils at the site had the potential to liquefy during an earthquake, which would result in significant settlement under the heavy footing loads. Treatment options included various deep foundation alternatives, as well as several ground improvement methods. The choice of wet soil mixing minimized the disturbance to the adjacent hospital during construction and potential settlement. Wet soil mixing allowed the structure to be supported on a raft foundation, meeting the stringent building total and differential settlement criteria. The authors also performed unit cell 3-D finite element analyses to evaluate the behavior of the wet soil mixing system in seismic loading conditions. This paper highlights the ground improvement design, construction, QA/QC, and the research related to evaluating the effectiveness of soil mixing for liquefaction mitigation.INTRODUCTIONThe Ventura Community Memorial Hospital proposed the construction of a new Cancer Treatment Center to replace the existing structure, which was built in 1901. The hospital complex is located in a wellestablished residential neighborhood. The soil conditions at the site of the proposed structure required ground modification to support the very heavy radiation treatment section of the building and limit settlement. Originally, 90-foot-long precast piles were considered for foundation support. Based on supplemental Cone Penetration Tests (CPTs) performed, the deepest CPT did not encounter competent pile bearing strata at a depth exceeding 30.5 m (100 ft). This could result in failure of the piles under long-term conditions, especially if hydro-consolidation occurs. The more realistic pile penetration depth would have been 36.6 to 45.7 m (120 to 150 ft). In addition, the excessive noise in association with pile driving would have been unacceptable to the community, patients, and staff of the hospital, so an alternative ground improvement solution was required.The specialty geotechnical contractor recommended wet soil mixing, an economical solution of creating a soil-cement product known as soilcrete that would significantly reduce the construction related noise and provide a more complete deep foundation for the structure.SOIL CONDITIONS AND SETTLEMENT CONCERNSThe subsurface soils were interbedded (Fig. 1) consisting of loose to medium dense silty sands, and soft to medium stiff silty clays to a depth of 30.5 m (100 ft). Groundwater was encountered at depths of 9.1 m (30 ft) and historical high groundwater was at 8.5 m (28 ft) below the ground surface."

Jan 1, 2015

By Osamu Taki

The innovative Soil-Cement Mixed Wall Technique emerged in Japan and obtained recognition in the engineering and construction communities in the 1980's. This technique was introduced to the United States in 1986. It was accepted as the most credible construction technique by the U.S. Bureau of Reclamation for ground stabilization and cutoff wall work in the Jackson Lake Dam Project, Wyoming in 1987 and 1988. It was also accepted as a remediation technique by U.S. EPA for a Superfund Innovative Technology Evaluation (SITE) demonstration on in-situ solidification/ stabilization. The Soil-Cement Mixed Wall Technique consists of mixing in-place soils with cement grout or other reagent slurries using multiple axis augers and mixing paddles to construct overlapped soil-cement columns. The overlapped column panel is then extended to form an underground continuous soil-cement wall for use as a cutoff wall or a structural diaphragm wall for groundwater control and excavation support. By arranging the column panels in various configurations, the technique becomes a versatile tool for stabilization of soft or liquefiable soils.

Jan 1, 1990