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By Sven Schröer, Lilma Schimmel, Dimiter Alexiew

"The Geotextile Encased Columns (GEC) deep foundation system for embankments on soft soils was introduced some 20 years ago and is now considered State-of-the-art worldwide.The GECs consist of compacted granular fill, similar to common gravel columns, with one decisive difference: they are confined in a high-strength low-strain flexible geotextile “cylinder” (encasement). This engineered element provides a very efficient tool to control and optimize the behavior of the system. GECs perform very well even in extremely soft soils ensuring bearing capacity (stability) and reducing settlements. Due to the encasement, they a lso provide high lateral ductility. A wide range of fills including sands can be used.The remarkable reduction of vertical stresses in the soft soil surrounding the GECs results in a decrease of lateral pressure as well. Such reduction combined with the lateral ductility allow GECs to be also used for lateral pressure-relief adjacent to sensitive foundations, e.g. rigid piles. The application of GECs as lateral pressure relief was recently used in Brazil and Germany where bridge abutments were built on concrete reinforced-piles. The GECs below the bridge approaches and adjacent to the piles decreased the lateral pressure to acceptable values.This paper presents two case studies for which the most relevant parameters, the geotechnical conditions, specific problems, engineering philosophy, final solution and lessons learned are discussed. Furthermore, instrumentation programs were applied in both projects. The most important results in terms of displacements and stresses are shown, evaluated, summarized and commented upon, focusing on the lateral stress-relief, followed by conclusions and recommendations."

Jan 1, 2016

By Roy M. Schnabel

The Fashion Island Boulevard Bridge over the Marina Lagoon in San Mateo, California is an eight span precast, prestressed concrete girder bridge. It is approximately 495 feet in length and 61 feet in width. It is supported on 36" diameter octagonal, hollow precast-prestressed concrete pile columns. The bridge was constructed in 1968 and suffered considerable damage during the Loma Prieta Earthquake in 1989. A damage survey report prepared by the State's Office of Emergency Services (OES) recorded that sixteen of the twenty-one pile-columns sustained heavy to moderate damage from the Loma Prieta Earthquake. The damage consisted of cracking and spalling at the tops of the pile-columns. Spalls at the most heavily damaged columns exposed the prestressing strands and confinement reinforcing which also showed signs of corrosion.

Jan 1, 1993

By Emad Farouz, Ehab S. Shatnawi

"The increasing demand for small deformations and high-capacity drilled shafts without enlarging drilledshaft diameters has motivated the development and increasing use of a base grouting (BG) technique. This technique has been demonstrated to improve drilled-shaft capacity, especially for shafts tipped into loose cohesionless soils. Nevertheless, there remains considerable uncertainty in predicting the performance of base-grouted shafts, particularly for shafts tipped into cohesive soils. To date, there are only two documented design methods for estimating the axial geotechnical resistance of base-grouted shafts: Tip Capacity Multiplier (TCM) and Axial Capacity Multiplier (ACM) methods. A comprehensive test program was carried out during the design phase of the Wisconsin Zoo Interchange project to help optimize the flyover ramp’s foundation design. The test program included installing and testing one base grouted shaft and one ungrouted shaft at two sites with different ground conditions. Based on test results, it was concluded that prediction of the TCM method is well correlated with the measured values for both cohesive and granular soils; however, both methods tend to underestimate the axial resistance. Results also highlighted the importance of the base-grouting criteria in taking full advantage of the base grouting.INTRODUCTIONBase-grouted drilled shafts (BGDS), also known as post-grouted drilled shafts, consist of conventionally installed drilled shafts that contain access grout tubes placed within the shaft during construction. After installing the drilled shaft and achieving the pre-established concrete strength, grout is injected at the shaft tip through the access grout tubes to improve soil behavior around the drilled-shaft base. The tip grout injection improves the overall shaft capacity and reduces settlement through Densifying the in situ soils, compressing any debris left by the drilling process, preloading the soil beneath the tip to mobilize the shaft base resistance within service limits, increasing the tip area, and increasing the side resistance in the lower portion of the shaft."

Jan 1, 2016

By Paul A. O’Brien, Gary A. Chapman, Thomas G. Cuniowski

"The new Amcor B9 paper mill in Botany, NSW, Australia, involved the design and construction of a new paper mill founded within the Botany Basin Sediments. There were numerous design and construction challenges to address, including tight settlement tolerances for the paper machine footings (6 mm total and 1/2000 mm differential limits), high variable and cyclic loads, deep (>25 m) bedrock and uncontrolled fill material across the site. The mill structure design incorporated a deep driven precast and CFA piled foundation solution, with a comprehensive swathe of testing to validate pile capacity and expected settlements. The pile design for the mill structure included the installation of approximately 1000 piles, with pile testing comprising dynamic testing and a static load test on precast piles. With consideration of Sydney’s increasing demand for development space in relative close proximity to the city’s CBD, industrial areas in the Botany Bay area are likely to make way for heavy or complex commercial and residential structures. Therefore, a better understanding of the engineering behaviour of sediments underlying these areas would allow for efficient foundation solutions. This paper presents a discussion on effective foundation testing techniques and the effects that the behaviour and characteristics of the Botany Bay sediments impose on deep piled solutions.2 PROJECT DETAILS2.1 New paper millThe project involved the construction of the largest recycled paper machine in Australia. The paper machine is 330 m (1080 ft) long, 22 m (72 ft) high, and capable of producing 1.6 km (1 mile) of paper per minute. Construction commenced in early 2011 and new paper mill officially opened in early 2013. The early works contract was awarded to Baulderstone Construction Pty. Ltd. (Lend Lease Corp. Ltd.), with the D&C contract awarded to a consortium headed by Leighton Contractors Pty. Ltd. (CPB Contractors Pty. Ltd.), which included Golder Associates Pty. Ltd. as the geotechnical designer and reviewer.2.2 Site history and effect on local topographyThe site has been used as a paper mill since 1902, and as such, has layers of uncontrolled fill and buried objects within the upper fill materials associated with historical industrial use. The fill material generally comprised of loose and very loose sands, with isolated pockets of cohesive materials, peats, pulped paper and general construction waste. In addition, during construction, underground storage tanks were identified at depth, indicating the historical extent of filling across the site was extensive. The presence of this generally uncontrolled fill was a factor for determining that the most cost effective foundation solution for the paper mill was piled foundations, to bypass these materials."

Jan 1, 1900

By Sivilay Sayavong, David Puller, Julian Gatward, David Hard, Martin Stanley

"AbstractThe Thames Water Tideway Tunnels programme involves the upgrade of London’s combined sewer and storm water system. The first section is the Lee Tunnel between the Beckton Sewage Treatment Works (STW) and the Abbey Mills Pumping Station. This will intercept the overflows currently discharging to the River Lee and has the capacity to store and transfer 350,000m3 of storm water and sewage. The project required 4 shafts and a 6.9km 7.2m diameter tunnel. The shafts are some of the largest ever constructed in the UK, with diaphragm walls up to 98m deep and 1800mm thick. As a result of the innovative methods of diaphragm wall design and construction adopted the 4 very large and deep shafts were able to be excavated and completed safely, with minimal water ingress and with extremely high quality.MVB, a joint venture of Morgan Sindall, Vinci Construction Grands Projets and Bachy Soletanche are delivering the £635m contract with Thames Water’s Project Management Team in a collaborative manner under an NEC contract. Mott MacDonald, Morgan Sindall UnPS & Bachy Soletanche are acting as designers.Some of the important advances in diaphragm walling made included:??Diaphragm wall design to both EC2 & EC7 taking into considering the assessment of chalk stiffness, high hoop stresses, large multiple openings and non-axisymmetric loadings.??Formation of shafts as a faceted circle from a series of overlapping panels, with primary panels up to 7.2m wide demanding concrete volumes up to 1300m3 be poured in one go. Overlapping secondary single bite panels cut into the grade C50/60 concrete.??Excavation of the full geological stratigraphy of London making bentonite management complex.??Panel verticality of 1:300 required over the full depth. The results achieved this and in many cases exceeded expectations with some panels coming in at up to 1 in 800 with the majority at 1 in 400 to 1 in 500. The project is also the first in the Soletanche Bachy Group to take data from the ultrasonic drilling monitor used to check the verticalty in electronic format in order to create 3D CAD as-built drawings.??Each diaphragm wall panel was reinforced over its full depth. Up to 18 separate pieces of reinforcing cage had to be installed in primary panels. Cages underwent a full range of temporary works designs to check that lifting, splicing and placing could all be undertaken safely. Fibreglass was used in the tunnel portals in the shafts to ease breakthroughs."

Jan 1, 2014

By T. Jason Hardell

The Victory Bridge project was contracted by the New Jersey Department of Transportation. The project included the construction of two 4000-ft precast segmental concrete bridges to replace the existing Victory Bridge that was built in the 1920's. The existing bridge was a swing span bridge that was in desperate need of replacement. The project was considered high priority due to the large maintenance costs to keep the swing span operating over the busy navigational channel. In March of 2003 construction began on the first bridge and by April of 2005 all of the segments were set for the second bridge. On September 5 of 2005 the second bridge was open to traffic. The total cost of the project was $110-million. The two new bridges required the construction of 24-eight foot and 32-six foot diameter-drilled shafts with rock sockets. All of the shafts were constructed in the tidal Raritan River working from barges. What will follow is a description of the construction techniques that were used to build these drilled shafts, the anticipated and unanticipated challenges that were encountered during the project, and the lessons learned.

Jan 1, 2005

By Reza Y. Khaksar

Presented is a rigorous solution for the three-dimensional stability analysis of vertical shafts (excavations) subjected to the self-weight of the soil based on the upper-bound theorem of limit analysis approach. A rigid-block translational collapse mechanism is assumed, with energy dissipation taking place along planar velocity discontinuities. This mechanism is optimized to obtain the critical failure mechanism giving the lowest factor of safety for stability of shafts. Based on comparisons with other solutions, the method is generally found to be accurate in predicting the stability of vertical cuts.

Jan 1, 2006

By Sumit Kumar Biswas, Moyukh De, Sibapriya Mukherjee

"The piles often are also subjected to lateral (horizontal) forces and moments. In fact, there are some structures where the primary function of piles is to transfer lateral loads to the ground. Proper analysis of laterally loaded piles is very important to the geotechnical and civil engineering profession.In the present investigation an experimental study has been carried out with free head short model cast iron hollow piles of outer diameter of 24 mm and L/d ratios of 8, 10, and 15. The experimental results have been supplemented by numerical techniques using PLAXIS-3D Foundation version 2.1 software. The results have been found to agree reasonably well with the experimental results. Further finite difference approach has been adoptedto reduce the computational time and to calculate the coefficient of modulus of subgrade reaction (?h) from the load- deflection data obtained from PLAXIS output at different pile depths. The parametric study has been extended for the non-dimensional form defined as flexibility ratio (F.R.),where ?h, L, Ep and Ip are the coefficient of modulus of sub-grade reaction, the embeddedlength of model pile, elastic modulus of pile material and the moment of inertia of model pile about the central axis respectively).The variation of coefficient of horizontal modulus of sub-grade reaction (?h) has been studied with respect to the following parameters for homogeneous soil system: relative density andL/d ratio. It has been found that the logarithm of flexibility ratio increases with increase inrelative density and increase inL/d Ratio. The values of ?h obtained by the proposed method have been, found to be close to the numerical results.As output of this research, graphs have been generated in respect of different parametric variations to gain an insight into behavior of piles under lateral load for short piles."

Jan 1, 2015

By Mohammad Nasim

Vertical expansion of existing structures frequently requires foundation retrofitting to enhance the capacity of existing foundations for supporting additional loads. Owing to their small diameter, a variety of suitable drilling methods available for installation, and smaller installation equipment capable of operating under limited headroom conditions, micropiles are often preferred for foundation retrofitting. This paper presents a case history demonstrating application of micropiles to underpin the existing foundation of the Washington D.C. Children?s National Medical Center (CNMC) for its future expansion. Located at 111 Michigan Avenue in northwest Washington, DC, portions of the hospital currently extend five stories above grade and three levels below-grade as parking garages. The hospital intends to expand the surgical wing up to the current build out (five stories) above the remaining portion of the existing parking garage. The original foundations consist of 80-ton Raymond Step-Tapered piles. New loading on the foundations required each Raymond pile to be capable of supporting 150 tons. Results from quick load tests on existing piles indicated that two entire column lines (Column Line A and B) would experience loads beyond their capacity, requiring enhancement of the existing foundation at these locations. The design and construction of the foundation upgrading work was particularly challenging due to various project constraints related to a high groundwater table, micropile installation under limited head room, and ensuring that the parking garage remained fully operational for the entire duration of construction. The paper presents the challenges faced during testing of existing foundations amid a high groundwater table, design developments of underpinning options to support the additional column loads, difficulties and challenges encountered during installation of the micropiles and construction of the micropile pilecaps, and value engineering options developed during various phases of the project. Understanding that micropiles are often a preferred option for foundation retrofitting, the case history is expected to provide a baseline design approach and innovative solutions to typical challenges faced during construction, thereby reducing potential cost overruns during design development and construction of similar future projects.

Jan 1, 2008

By A. F. Deng

A general description of the project, mainly the pier foundation design of the ZHU JIANG FANYING is presented in the paper. The major contents include the foundation scheme, the evaluation of bed-rock characteristics, the allowable bearing pressure, the design and construction of pier foundation.

Jan 1, 2010

By Luo Yang

A one-dimensional wave equation based algorithm for estimation of shaft and toe resistance of driven piles using High Strain Testing (HST) data is presented. The pile is represented by a uniform elastic bar, while the soil around the pile is assumed as a homogenized isotropic medium, and Smith model is adopted to represent soil-pile interaction in the wave equation analysis. In most cases, the displacement of pile particles along pile shaft is greater than recoverable soil deformation (i.e., soil quake in Smith model). Therefore, static shaft resistance could be reasonably assumed to be totally mobilized during pile driving. Smith damping factor is used to account for combined dynamic and rate effect. Force and velocity time histories measured at the pile head are used as input boundary conditions in an analytical solution of the one-dimensional wave equation. As a result, two unknown parameters, static shaft resistance and Smith damping factor, can be incorporated into the one-dimensional wave equation and determined analytically for the time duration prior to the first downward wave reaching the pile toe. Then, soil resistance and Smith damping factor at pile toe can be further determined. The advantage of the proposed analysis technique is that the Smith damping factor and the static soil resistance can be directly determined based on the closed-form solution of the one-dimensional wave equation, which is computationally efficient. Numerical examples are given to illustrate the use of the proposed method to determine the pertinent Smith model constants and the static resistances.

Jan 1, 2006

By Lawrence F. Johnsen

In 1989, the Connecticut Department of Transportation authorized the evaluation and design for a reconstructed Route 1 bridge over the Quinnipiac River in the City of New Haven, Connecticut. The project extends from the intersection of Route 1 with East Street, easterly for approximately 3/4 mile to the intersection of Route 1 with Wheeler Street and Stiles Street. The reconstructed roadway will be relatively on-line and widened to provide for four lanes of vehicular traffic and a single-track railway line. The existing bascule bridge and approach spans, which were constructed in 1924, will be replaced by a 270-foot span lift bridge and new approach spans. The lift bridge will have a main lift span weighing approximately 3000 tons, second largest after the Burlington Northern Bridge over the Williamette River in Portland, Oregon. The new bridge will widen the navigation channel to 24 0 feet and provide vertical clearances of 13 feet when closed and 62 feet when open. The project is located in an industrial area. Adjacent properties include retail gasoline sales, auto repair, railroad transport and bulk storage of petroleum. Existing structures include the Yale Boathouse and several retaining walls serving as containment dikes for petroleum storage tanks. The Yale Boathouse, located on the east bank of the river, was constructed in 1909-1910 and is eligible for listing in the National Register of Historic Places.

Jan 1, 1993

By Hamed Layssi, Farid Moradi, Thomas Tingson

This paper describes the feasibility and pilot study of of using existing non-destructive testing solutions for evaluating structural integrity and mechanical performance of mass concrete foundations. This paper includes two pilot studies using well-known NDT methods (i.e., Crosshole Sonic Logging and seismic tomography) for new applications (i.e., NDT inspection of mass concrete foundations). In the first case, we will examine an existing mass concrete foundation block with internal cracking, which has negatively impacted the strength and stiffness of the foundation block. A combination of pulse velocity and 2D tomography was used to evaluate the structural integrity in the foundation block. In the second case, the quality and integrity of newly built mass foundations were evaluated using Crosshole Sonic Logging (CSL). The methods are combined to locate potential sub-surface defects such as large voids and discontinuities. This paper aims to study the effectiveness of the NDT methods of Deep Foundations to assess the quality and structural integrity of new and existing mass foundations and explore the opportunity to extend the capabilities of these tests beyond their conventional use.

Sep 8, 2021

By James Weaver

During the past 16 years, the authors have successfully used high-capacity rock anchors installed inside open-ended pipe piles, driven to bedrock, to provide uplift and overturning resistance for various structures including piers, bridges, power plant components and commercial buildings. These systems were ultimately used on the projects due to a combination of high uplift forces or overturning moments on the structures and the relatively poor subsurface conditions present at the sites. Other, foundation systems such as rock-socketed drilled shafts and spin fin piles were considered but were found to be economically prohibitive or not technically feasible.

Jan 1, 2011

By Nabil F. Ismael

The axial capacity of step tapered bored piles in sand was examined by field tests at one site in Kuwait. Two straight piles, and two step tapered piles were load tested in compression to failure. All four piles were 3 m deep. The straight piles were 0.2 m in diameter. The step tapered piles had a diameter of 0.3 m for the upper segment which extended up to 40% of the pile length changing to 0.2 m diameter for the lower section. The soil profile consists of medium to dense sand with minor cementation and no groundwater was encountered. Both the ultimate bearing capacity and the settlement at working loads were examined. The axial capacity of the step tapered piles was greater, and the settlement at working loads was less, compared with the straight shaft piles. The increase in capacity is mainly attributed to the added side friction along the larger diameter top segment of the shaft.

Jan 1, 2008

By Nicolas Denies, Gust Van Lysebetten, Bart Lameire, Jan Maertens, André Vervoort, Noël Huybrechts, Flor De Cock

"Abstract Originally developed for ground improvement works, the deep mixing method (DMM) has increasingly been applied in recent years for the realization of soil and water retaining structures and as alternative to traditional foundation solutions. From practice, there is a real need for practical guidelines dealing with the execution, the design and the control of such applications. With the aim of developing such guidelines, the BBRI ‘Soil Mix’ project was initiated in 2009. Within this research project, deep soil mix (DSM) material from 38 Belgian construction sites has been tested. In spite of the large advances in the mechanical characterization of the DSM material, one major issue remains the representativeness of the typical core samples in comparison with the real scale behavior of the soil mix elements. There is among others the question of the influence of the unmixed soft soil inclusions on this behavior and the issue of the scale effect which must be considered in the design. In order to investigate these questions, 8 large scale UCS tests and 17 large scale bending tests have been performed on excavated soil mix elements. The present paper discusses results of this experimental campaign, presents some research perspectives and highlights different aspects related to the design of soil mix elements for the realization of retaining wall or foundation solution.INTRODUCTIONSince several decennia, the deep mixing method (DMM) has been used to improve the strength and deformation characteristics of weak soils. In recent years, deep mixing has increasingly been applied – in Belgium and in other countries – for the realization of soil and water retaining structures and alternative foundation concepts. With regard to the execution of the DMM, one can refer to the European standard EN 14679 on deep mixing (2005) that was elaborated under the umbrella of CEN TC 288 “Execution of special geotechnical works”. However, from practice, it has been experienced that this execution standard does not provide enough pragmatic information and guidelines, in particular for the more recent applications of the deep mixing method (with retaining and bearing functions). The same need by the sector for guidance rules linked to design aspects in the context of Eurocode 7 was experienced as well. With the aim of developing such guidelines and in order to provide feedback to the European standardization platforms, the Belgian Building Research Institute (BBRI) has initiated the BBRI ‘Soil Mix’ project (2009-2013) in collaboration with the KU Leuven and the Belgian Association of Foundation Contractors (ABEF), the Belgian branch of the EFFC. Within this research project, deep soil mix (DSM) material from 38 Belgian construction sites, with various soil conditions and for different execution processes (CVR C-mix®, TSM and CSM), has been tested (Denies et al., 2012)."

Jan 1, 2014

By Ramin Motamed, Farshid Ghazavi, Joseph A. W. Toth

"Post-disaster reconnaissance of areas affected by earthquakes has documented extensive damage to buildings with shallow foundations located in liquefaction-prone areas. Currently, estimation of liquefaction settlement is based on empirical correlations that evaluate settlement in the free-field environment and are based on one-dimensional consolidation. However, observations have shown that liquefaction settlement under buildings can be considerably greater. This research is based on a series of 1- g shake table experiments using a transparent soil box to reproduce liquefaction-induced building settlement. Building settlements were evaluated using a scaled model of a building foundation representing a 1-2 story building. Comprehensive parametric study was carried out to establish the effects of several parameters on free-field and building settlements such as building width and thickness of liquefiable soil layer. The experiments utilized accelerometers and pore-water pressure sensors to monitor ground accelerations and buildup of pore-water pressures in both the free-field and model building footprint. Results of these experiments are compared to available centrifuge tests and field observations and conclusions are drawn with respect to the potential scaling effects. Lastly, this paper discusses the feasibility of installing helical piles as a mitigation strategy to reduce the building settlements by presenting some of the exploratory experimental data obtained from this series of 1-g shake table tests.INTRODUCTIONThe 2010-2011 Canterbury earthquake sequence and the 2011 Great Tohoku earthquake are some of the most recent examples where large numbers of low-story structures sustained damage resulting from liquefaction-induced settlements. This damage has commonly been observed in residential and commercial areas developed over loose, unconsolidated and saturated coarse grained soils resulting from both natural and man-made deposits. Damages incurred from the 2010-2011 Canterbury earthquake sequence occurred in the largely unconsolidated fluvial environment bordering the Avon River in Christchurch (Henderson 2013). Similar damage was also incurred during the 2011 Great Tohoku earthquake where liquefaction of soils occurred in both young alluvial deposits and fill materials (Ashford et al. 2011). Figure 1 presents typical modes of failure to structures resulting from the effects of liquefaction. Current practices in evaluation of liquefaction settlement rely on empirical correlations (Tokimatsu et al. 1987; Ishihara et al. 1992) developed for liquefiable soils in the freefield environment (Dashti et al. 2010a). However, recent observations of the performance of foundations suggest that settlement of rigid shallow foundations in liquefiable soils are commonly greater than those predicted in the free-field. Therefore, new correlations should be developed to better predict the degree of settlement of shallow foundations in liquefiable soils. Current research is beginning to focus on the mechanisms of settlement during liquefaction in regards to confining stress, pore-water pressure and shear stress induced from foundations (Dashti et al. 2010b)."

Jan 1, 2016

By Rich A. Lamb, Paul J. Axtell, Michael K. Muchard

"Since 2010, the Minnesota Department of Transportation (MnDOT) has performed eight full-scale compressive load tests on large-diameter pipe piles at four different project locations across the state. All of the piles were 42-in diameter, open-ended pipes driven to practical refusal on sedimentary bedrock with D125-32 diesel hammers from three separate manufacturers. The rapid load test method in general accordance with ASTM D7383-10 (Statnamic method) was used along with high-strain dynamic testing and subsequent signal matching. Results of these tests indicate that the axial nominal resistance of these piles in compression is not controlled by geotechnical considerations when driven with an appropriately sized hammer and installation criterion. Rather, the predominantly elastic load-deflection behavior of the piles under compressive load suggests the axial nominal compressive resistance is controlled by the structural capacity of the pile. In all instances, the rapid load tests indicated a nominal resistance exceeding that produced by high-strain dynamic tests due to insufficient hammer energy to fully mobilize resistance. In all cases, the hammers used were able to easily install the piles through the soil overburden. Mobilizing a larger hammer simply to demonstrate high-strain dynamic resistance is not economical or practical. This paper presents the subsurface conditions at each location, the ensuing test results, and the ramifications for future projects in Minnesota utilizing large-diameter open-ended pipe piles.INTRODUCTIONThe Minnesota Department of Transportation (MnDOT) has recently performed eight full-scale compressive load tests on large-diameter pipe piles at four different project locations across the state. The four project locations described in this paper where pile load testing was performed are shown in Figure 1 and exist in the southeastern portion of Minnesota. The projects are all major bridges crossing the Mississippi River in three instances and the St. Croix River just above the Mississippi River in the other instance. The first project is the TH 61 Mississippi River crossing in Hasting, MN where two load tests were conducted. The second is the TH 36 St. Croix River crossing in Stillwater, MN where two load tests were performed. The third project is the I-90 Mississippi River crossing in Dresbach, MN where three load tests were conducted. The final project is the TH 43 Mississippi River crossing in Winona, MN where one load test was performed."

Jan 1, 2017

By Cory J. E. Yacyshyn

Anchored steel pipe piles are being used more frequently in British Columbia for shoreline projects such as public ferries, cruise ship docks, containership terminals and locally in the expansion of the Vancouver waterfront convention center. While a 36? diameter driven pile may provide adequate compression loads it will not always achieve enough penetration to provide the required tension loading. That is why bundles of threaded anchors or strands are drilled through the center, past the pile tip, and anchored into the underlying strata. Drilling up to 250 feet deep through the piles in variable water bearing strata presents challenges. Southwest Contacting Ltd. (SWC) recently completed the three largest anchored pile projects in BC; Vancouver Port and Convention Center Expansion, Vanterm Container Terminal and the new Prince Rupert Cruise Ship Terminal. This paper will present the separate challenges encountered drilling the anchors. At Prince Rupert, the recently completed Northland Cruise Ship Dock ultimately required a cased system to drill and install triple thread bar anchors. When 200 foot long steel pipe piling was unable to penetrate the highly fractured gneiss/schist bedrock to obtain a seal and consolidation grouting was unsuccessful, a modified cased system was advanced deep enough into the rock to eventually seal. The 3-#20 bars were changed to 12-strands since the bars wouldn?t fit through the smaller cased hole. The options were limited because each dolphin only had enough room for a small hydraulic drill rig that wouldn?t have the power to fully case the holes. The Canada Place Pier Extension in Vancouver?s Harbor led to the development of an innovative tip design used later at Vanterm. The 36? diameter steel pipe piles were driven closed end but modified to permit drilling through a concrete plug at the base. The driving of the piles at Canada Place often knocked out the plug so we were faced with 50 feet of sand up inside the pile when the drilling started. This led to discussions on how to safely remove the sand, solidify the tip, and continue drilling to get past the tip without undermining the pile. Finally, Vanterm Berth Extension was completed with a unique drilling system because the pile tips stopped in hydraulic sands, as opposed to the native till. We were faced with advancing the casing to the till without undermining the base of the pile. With 100 psi water pressure at the pile base after we broke through the concrete plug, the trick was to prevent charging the sand with our 250 psi air which liquefies it and forced it up our drill casing. And of course, it has to happen just before Christmas holidays!

Jan 1, 2004

By Austin Metz, Kevin Stanton, Ramin Motamed

"A recent study calibrated Load and Resistance Factor Design (LRFD) resistance factors for local soil conditions in the Las Vegas Valley. As a part of this calibration, an extensive database of drilled shaft load tests and associated subsurface soil information were collected and compiled. This database, deemed the Nevada Department of Transportation Deep Foundation Load Test Database or NDFLTD, was designed with the presentation of load test data, the subsurface soil conditions, and the spatial distribution of the data in mind. In addition, the NDFLTD was developed in a way that allows additional data to be added as it becomes available. As such, the rules of database normalization were followed to allow for additional and different types of data to be added to the database and reports. Microsoft Access was chosen to present the data because it is easily accessible to anyone with Microsoft office software, it has a quick learning curve, and it has the ability to present a relational database. The largest obstacle faced when creating the NDFLTD was normalizing the data used in the LRFD calibration, with the goal of reaching the 5th normal form.INTRODUCTIONLRFD is based on statistical performance of engineering components, as opposed to the more traditional Allowable Strength Design (ASD), which divides the strength of a component by a safety factor. Calibration of resistance factors for LRFD requires a robust statistical analysis of past performance. For drilled shafts this requires a database of full scale load tests (Abu-Hejleh et al. 2014). The FHWA developed the largest US based deep foundation load test database, deemed the DFLTD, collecting data from 1985 to 2003 when funds ran out (Abu-Hejleh et al. 2014). Recently, the DFLTD has been updated to modern standards (Petek et al. 2016). In October of 2007, the FHWA mandated state department of transportations (DOTs) to follow AAHSTO LRFD guidelines for their highway foundation designs (Abu-Hejleh et al. 2014). Since then multiple state DOTs have developed their own, region specific deep foundation load test databases. Florida has a long history of developing databases for deep foundation LRFD resistance factor calibration, with the two main databases being the FL database, and The Deep Foundations Database (Abu-Hejleh et al. 2014). Iowa developed a Microsoft Access based database in 2014 (Garder et al. 2014). Oregon developed a database compiling pertinent data from the DFLTD, Florida DOT’s Deep Foundation Database, as well as from other databases (Smith et al. 2011). Illinois developed the “International Database” for static and dynamic reliability based calibration (Long et al. 2009). Louisiana developed a database for LRFD Calibration of driven piles in 2009 (Abu-Farsakh et al. 2009). The California Department of Transportation has its own internal foundation database, which is housed within the Foundation Testing Branch archive (Smith et al. 2011). In 2016, the Nevada Department of Transportation (NDOT) presented its own LRFD calibration for the Las Vegas Valley (Stanton et al. 2017), and the NDFLTD was developed as a part of that project (Motamed et al. 2016)."

Jan 1, 2017