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By Antonio Kodsy, Lutful Khan

A research was carried out to test the possibility of reducing the pullout resistance of metal sheet piles driven in clay soils using Electrokinetic (EK) conditioning. The hypothesis was applying an electric gradient for a certain period of time should reduce the adhesion between the clay soil and the sheet piles. Tests were conducted on bench scale thin stainless-steel metal plates embedded in pure kaolinite clay, and mixtures of kaolinite clay and sand. The pullout resistances were determined after 20, 40, and 60 minutes residence times of steel plates in the soils before and after EK conditioning under an electric gradient of 1500 V/m. In kaolinite clay, the pullout resistance showed linear reduction with the duration of EK conditioning and about 60 % reduction in pullout resistance was observed after 60 minutes EK conditioning. For the kaolinite-sand mixtures, the pullout resistances were reduced by about 70% and 80% for 20% and 30% sand contents respectively after 20 minutes EK conditioning and showed no significant improvement with the increase in conditioning duration. It was concluded that the proposed electrokinetic conditioning process could potentially reduce the pullout resistance of metal plates embedded in clay and clayey soils. SHEET PILE WALLS Sheet pile walls are typically used at waterfronts as retaining structures or during the construction phase to shore the soil and avoid collapse of the excavations. When used as permanent structures, sheet pile walls are not removed after the completion of the project. However, as temporary support, they are extracted after the completion of the project and reused. In pure clay soils the extraction processes often becomes a challenge requiring very large pullout forces which could damage the sheet piles. There is a research need for developing an efficient method of sheet pile extraction from clay soils addressing the issue of pullout force reduction. However, very few researches have been conducted regarding the extraction techniques of sheet piles and their economic effect on the cost of a project. In this study a novel method for reducing the pullout resistance of sheet piles in clayey soils using electrokinetic conditioning was explored. The hypothesis of this research is that the electrokinetic process in soil/water system, specifically electrophoresis and electroosmosis, could be used to loosen the sheet pile walls embedded in cohesive soil and hence reduce the required force of extraction. The aim of this study was to test this hypothesis through laboratory tests carried out on steel plates embedded in cohesive soil samples. The pullout forces of the steel plates before and after varied duration of electrokinetic (EK) conditioning were evaluated and compared. The process was also investigated for clay-sand mixtures.

Jan 1, 2019

By Edmund Cardoza

In the spring of 1993, construction began on an ambitious building project in Boston, Massachusetts. The Shriners organization committed to offer state-of-the-art adolescent burn treatment and rehabilitation in its Boston facility by expanding in a most unusual way. In short, the concept included installation of caisson foundations and perimeter slurry wall panels to enable construction of a completely independent structure around and above the existing, continually functioning, hospital. Two distinct phases of work were detailed in the Contract Documents. At the completion of the first phase, patients will be moved into the new building, above, and demolition of the old structure, beneath, will be performed. In Phase I, sections of the slurry wall and caissons, located outside the footprint of the existing building, were planned. The next phase of the work includes the installation of the remaining caissons and slurry wall. Once excavation is completed, the balance of the new hospital structure will be constructed from the bottom upward, connecting to the under side of the new structure.

Jan 1, 1994

By T. Matsui

Many existing bridge abutments on the soft ground laterally move and their many damage examples have been reported. An essential cause for the troubles of the lateral movements may be the lack of examinations for the lateral earth pressure acting on its foundation piles. In the present paper, actual movement condition of existing bridge abutments is first summarized, and then the author establishes a practical and systematical design method for bridge abutment foundation piles, including the examination for the passive pile.

Jan 1, 2010

By Ali Ebrahimi, Meena L. Viswanath, John F. Beech, Mustafa B. Erten, Ming Zhu

"Excessive deformation of a cantilever sheetpile wall can occur due to dredging, excavation, backfilling, or long-term creep behavior of soil. A buttressing berm constructed in front of the wall can be considered as a mitigation technique to prevent or decrease the deformation by increasing the passive earth pressure and thus improving the wall stability. The effect of the buttressing berm on the stability and deformation of a sheetpile depends on the berm geometry (i.e., the thickness/depth and the width) as well as the properties of the sheetpile and the adjacent soils. A parametric study was conducted using a conventional limit equilibrium method. Design charts were prepared to evaluate the effect of a buttressing berm and the soil friction angle on the wall stability and deformation. These charts can be used as a tool by geotechnical engineers to make a quick estimate of the required size of a buttressing berm in case of calculated or unexpected excessive deformation of a sheetpile. An analysis of the effect of a buttressing berm on the stresses and deformation of a sheetpile was also compared with the results from finite element analysis. The results of this comparison are discussed.INTRODUCTIONCantilever sheetpile walls are commonly used to support excavations. Sheetpiles are hot rolled or cold formed sections of steel made to interlock with adjacent sections to form a continuous structure providing lateral support. Sheetpile walls can be cantilever walls or anchored with tiebacks. To construct a cantilever sheetpile wall, sheetpiles are driven by pile drivers or vibrated in to a design depth sufficiently below the depth of excavation. Excavation can then proceed in front of the sheetpile wall, which resists the earth pressure loading from behind the wall. The design depth and geometry of the sheetpile wall depend on the soil conditions, the depth of excavation, and the tolerable deformation. In certain cases, when a small buttress of soil can be left immediately adjacent to the sheetpile wall, the required depth or geometry of the sheetpile wall can be reduced or adjusted, which can significantly decrease the cost of procuring and installing the wall. Such a buttress can also serve as a short-term or long-term remedy in case of observed excessive deformation in a constructed wall. Traditional methods of analyzing the stability of a sheetpile wall do not account for the passive pressure effects of this small buttress. In this paper, a parametric study was performed for a variety of soil types and wall and buttress geometries by implementing traditional limit equilibrium methods in commercial software and design charts were created illustrating the effect of a buttressing berm on sheetpile deflection. Selected cases were then modeled in a finite element software to compare the results with the traditional limit equilibrium method. The resulting design charts can be used as a tool by geotechnical engineers looking to reduce the design geometry of a sheetpile wall or address observed excessive deformation in a constructed sheetpile wall."

Jan 1, 2016

By S. P. Lin

The numerical models of nonlinear piles for deep foundations are studied in this paper. The purpose of these is to clarify the mechanical behaviour of deep foundation nonlinear piles subjected to axial and lateral loadings. Based on the site data of p-y curve as well as t-z curve of foundation soils, it is possible to evaluate pile performance under above mentioned loads by means of combined FEM/FDM models. Numerical examples are presented in tall building and offshore jacket for illustrating the technique, it show high efficiency of these models. Some information to be interested by design engineers are given, especially for those who pay very concerns on the interaction behaviours of structure and its pile foundation.

Jan 1, 2010

By Z. Q. Wang

The author is trying to clarify the existing problems in designing and laying out dynamic consolidation for soft ground improvement. Field testings and observations including vibrational parameters, pore pressures, stereoscopic photogrammetry etc. were run in order to trace the real behaviour of ground movement during tamping. It is believed that all the data got from the field work are rather informative and illustrative than that from theoretical modelling in the laboratory, thus some highlights relating effective thickness of compaction, maximum spacing between compaction points, number of blows for optimum tamping and seismic attenuation for environmental consideration are given.

Jan 1, 2010

By Georg Breitsprecher

The technique of Stabilising Columns (product names are for example "Stabilisierungssaulen" (STS) or "Coplan Stabilisierungs-verfahren" (CSV)) is gradually becoming well accepted for ground improvement. The installation, dimensioning and quality control are standardized by DGGT (German Association for Geotechnique), working committee 2.8, of which until now only part one exists for dry columns. This paper describes the installation and testing of stabilising columns for a ground improvement project. To achieve comparable results in testing both ready mixed concrete and dry binder had been used for production.

Jan 1, 2006

By Michael Perlow

Helical screw piles in use since 1838 are routinely used for energy, transportation, municipal, industrial, marine and coastal infrastructure as well as for excavation support, environmental remediation, and foundation repair. They are especially well suited for work in constrained areas, renovations and structure retrofits. Helical pile design procedures over the past 10 years have gone through a remarkable evolution with the establishment of the 2007 AC358 Helical Pile Acceptance Criteria and inclusion of helical screw piles in the 2009 International Building Code (IBC). New 2009 IBC building code requirements and AC358 Acceptance Criteria are presented along with advances in helical pile design procedures, installation, QA/QC, and recommended load test verification criteria. Use of helical smart piles to validate helical pile design and verification of ultimate pile capacity is highlighted.

Jan 1, 2011

By Andrew R. Klaetsch, Peter W. Deming

"The Washington Avenue tunnel in Kingston, NY was completed in 1912 to convey combined storm water and sanitary sewage. Over a mile in length, the tunnel was driven almost entirely in bedrock, with the exception of an approximately 170 foot long brick arch segment constructed in soil. About 90 years after the tunnel was put into service, persistent subsidence problems and sinkholes were observed in Washington Avenue above the shield-driven soil tunnel segment, eventually causing the important traffic thoroughfare to be closed. Subsequent tunnel inspections revealed a breach in the brick arch and a significant volume of fine soil within the tunnel. A two-phase remediation program was implemented to control seepage, reduce soil migration, and remedy sinkhole problems. The first phase included in-situ soil densification by vibratory pile probe driving to improve density in shallow sandy soil loosened by ground loss. The second phase included installation of a continuous soilcrete arch structure over and alongside the tunnel, extending to rock or compact glacial till and spanning the length of the soil tunnel segment. Overlapping vertical soilcrete columns were installed through interlayered sandy and clayey silt by jet grouting to form a continuous arch structure, using grout parameters verified by full scale field testing.PROJECT BACKGROUNDThe Washington Avenue tunnel in Kingston, NY (Figure 1) was completed in 1912 to convey combined storm water and sanitary sewage to Rondout Creek by the Board of Water Supply of the City of New York. The tunnel is over a mile in length and constructed primarily in rock. Contract documents indicate the tunnel was designed with a horseshoe shape at least 3 ft wide and 5.5 ft high."

Jan 1, 2016

"Integrity tests refer to a variety of non-destructive tests (NDT) whose purpose is to measure or determine the quality and uniformity, and some- times dimensions, of cast-in-place concrete foundation elements. The tests are primarily aimed at detecting zones of poor quality concrete, voids, bulges, and/or necking.The non destructive integrity testing techniques in this section most generally used for drilled shaft testing are based on one of two physical principles - stress wave propagation or nuclear radiation. All of the stress wave methods involve monitoring a deliberately created vibration, usually of very low amplitude (strains on the order of ??). Some methods rely on direct transmission of the signal, while others rely on processing reflections of the imposed signal.The stress wave methods are inherently sensitive to vibrations from other sources, especially at frequencies that fall within the range of interest for the particular test being applied. Construction activity near the shaft being tested; such as: demolition jack-hammering, pile-driving, casing vibration, excavation and movement of track-vehicles are all known sources of interference that might render test data useless. The actual effect of such vibrations will vary with the type of activity, soil conditions and distance from the testing. The test operator must be able to recognize such interference, and the contractor should be prepared to cooperate with the testing personnel by stopping or moving the source of vibration. If this cannot be done immediately, testing should be postponed until the work in question is finished and the vibration source moved or shut down.NDT methods are not suitable substitutes for routine "topside" construction inspection as described in the Drilled Shaft Inspector’s Manual. However, these NDT methods do allow measurements of the quality of concrete placed in drilled shafts, which cannot be made from "topside" construction inspection. They should be considered supplemental to routine construction inspection as they do provide an additional level of quality control."

Jan 1, 2004

By Anne Lemnitzer

Experimental data are the cornerstone of scientific research, providing empirical evidence to validate hypotheses, test theories, inform decision-making and help develop innovative design and analysis methods. However, beyond traditional empirical validations, experimental data have also become the most crucial component of AI algorithms, measuring the algorithms' effectiveness, and allowing engineers to ensure their reliability and applicability. The DFI "Rock Socket Project," awarded in the spring of 2018 allowed for the indispensable, experimental data-based validation of structural shear magnitudes, which have been hypothesized and discussed for years within the deep foundations community and cautiously approached by many design engineers. The fundamental project idea, i.e., the investi- gation of pile shear magnitudes through experimental research, was sparked during a heated discussion in the October 2016 Drilled Shaft Committee meeting in New York. Should we design for amplified shear at the rock socket of a drilled shaft or is this merely an artifact of the p-y design approach? Data were needed to provide consensus.

Nov 1, 2023

By Ryan Sullivan, Lisa Smiley, Jewels Stover

The Westerly Storage Tunnel (WST) Project is part of Project Clean lake, the North East Ohio Regional Sewer Dist years. When completed in 2020, WST will be nearly 2 miles of 25-ft diameter tunnel 200-250 ft below ground. The storage tunnel will manage higher flow volumes, keeping stormwater out of the combined sewer system reducing overflow occurrences. Three deep shafts provide access to the tunnel at the tunnel boring machine (TBM) launch and retrieval sites, as well as a vent shaft. Support of excavation for the access shafts was constructed utilizing unreinforced concrete diaphragm walls. This innovative, value-engineered alternate design significantly reduced risks associated with conventional secant piles combined with a rib and liner plate system. Implementation of the diaphragm wall technology resulted in a water tight, continuous shaft keyed into rock. This case study examines the design, methodology, and installation challenges unique to each shaft, as well as the benefits of the final product to the overall project.

By Pierre Gouvin

"This paper discusses real time monitoring of utility vaults during the reconstruction of the Elliot Bay Seawall in Seattle. The project, undertaken because deterioration of the old wall posed increasing risks to property and lives, impacts businesses, ferry terminals, a rail line, and electrical utilities that distribute power to much of the downtown area. The project, which has been fast tracked to minimize risk and commercial impacts, involves multiple contractors with heavy machinery working in an area one mile long and only a few hundred feet wide. This presented challenges to monitoring of the utilities, as will be discussed in the paper.INTRODUCTIONThe Elliot Bay Seawall (EBSW) was built in over a period of 18 years, starting in 1916. It consisted of a vertical concrete wall placed on a timber pilings and timber relieving platform. The seawall also retained fill that served as the foundation for a road known as the Alaskan Way. The seawall has performed well over the years, but now cracks in the concrete have allowed loss of fill, and the timber piles and support structures have been weakened by marine boring insects.The project to replace the seawall was undertaken because deterioration of the old wall posed increasing risks to property and lives. Because the project impacts businesses, tourism, ferry terminals, and a rail line, it was given a compressed timeline - 36 months from start to finish. In addition, construction activities have been staged carefully to minimize disruption of Salmon and other wildlife living in Puget Sound. In fact, will incorporate several habitat improvements to promote sea life, such as a nature-imitating textures in the surface of the wall and a glass deck structure that allows sunlight to reach the water. (Fig. 1) shows a schematic of the planned new wall.The sheet piling, concrete piles, jet grouting, drilled shafts, ground freezing, and demolition activities are all taking place in the narrow corridor that holds the subsurface ducts and vaults protecting Seattle’s electrical power distribution. If the network of duct bank and vaults were to experience differential settlement during work here, then most of downtown Seattle would be in the dark. Thus it was important to provide real-time displacement monitoring of these utility structures."

Jan 1, 2017

By Matthew Janes

The RC Harris Filtration Plant, which treats the majority of the fresh water for over 2.5 million Torontonians, is a Canadian Architectural Heritage site demonstrating a classic example of Art Deco Architecture. The facility is undergoing an expansion to install an underground sludge treatment capability. Perched atop a bluff on the North shore of Lake Ontario the structure enjoys a commanding presence on the Lake Ontario shoreline. A series of underground tanks were proposed for the hillside below the structure, which when covered would preserve the building?s architectural presence. However, the plan required two, stepped excavations 12 m and 10m deep into compact, wet sands over stiff clays and clayey silts. Concerns regarding the original structure influenced designers to set the lateral deflection limit for the front footing of the existing structure at 4 mm, (0.03% excavation depth). The design-build team indicated at the time of tender that the movement criteria was unattainable using the tender design. Analysis indicated installation effects and overall elastic movement of the soil mass beneath the building would result in movements of 7 to 9 mm at the structure. Through extensive FLAC analysis and a novel construction geometry the design-build team crafted an alternative that produced significant savings over the original concept. Based upon the analysis the design-build team negotiated a new deflection criteria dictating a maximum of 2.0 mm of movement across the critical expansion joint between the Filter Building front footing and the tank slab beyond. The contractor invested in additional pre tender soils investigation to support the refined design process. The FLAC analyses indicated the Filter Building movements would be elastic and distributed up to 50 m back beneath the front footing of the structure. An extensive precision monitoring program proved construction related movements of 6 to 10 mm horizontal at the front footing. Extensometers placed at two locations over the critical interior tank expansion joint showed no measurable movements. The overall monitoring program, including inclinometers, tilt meters, tie back extensometers (smart cables) and tie back load cells indicated a good match between recorded movements and loads and those predicted by FLAC Analysis.

Jan 1, 2006

By Manasi Wijerathna, D. S. Liyanapathirana

"Deep cement mixing is a popular soft ground improving technology that improves the bearing capacity and settlement characteristics of natural soil. When Deep Cement Mixed (DCM) columns are installed attached to each other in a wall configuration, the walls are capable of resisting bending moments and shear forces in the direction transverse to the columns. Therefore, installing DCM walls beneath the embankment slope perpendicular to the alignment of the embankment is a proper solution to prevent excessive lateral deformations of the embankment. Previous research studies have shown that failure patterns of DCM column walls are different to failure patterns of individual DCM column rows, under lateral loads. This study investigates the failure patterns of embankments where DCM column walls are located beneath the slopes, with respect to DCM wall strength, DCM column wall width and the spacing between DCM walls. 2D and 3D numerical models developed using the ABAQUS/standard finite element programme, were used in this investigation. Results show that the DCM wall strength and width of the DCM wall have a significant influence on the failure mode and the critical failure surface of the embankment. 3D simulation results demonstrate that the failure due to soil extrusion between columns was less pronounced in embankments improved with DCM walls, due to the interaction between the DCM walls and the surrounding natural soil.INTRODUCTIONEmbankments constructed over soft ground are highly susceptible to global slope failure and excessive displacements due to combined effects of vertical and lateral loads beneath the embankment slope (Zheng et al., 2009, Han and Gabr, 2002). The overall stability of the embankment can be significantly improved by improving the soil beneath the slope of the embankment using Deep Cement Mixed (DCM) column rows or overlapped DCM column walls (Jamsawang et al., 2015, Larsson and Broms, 2000, Topolniki, 2004, Broms, 1999). According to the literature, the improved ground experience different failure modes other than shear failure, such as separation of columns, overturning, shear failure along the columns or dowel action (Broms, 1999). Some of the failure modes reported by Broms (1999) are shown in Fig. 1. The ultimate failure mode depends on the geometry and the strength of the improved ground (Jamsawang et al., 2015, Kitazume and Maruyama, 2006, Kitazume and Maruyama, 2007)."

Jan 1, 1900

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

By Patrick Granitzki, Alicia Plinio, Janitha Batagoda, Peter Howell

The City of Newark is making a comeback with new mixed-use multi-storied Residential Development projects. The majority of developers tend to use driven H-pile deep foundation systems to support their super-structures. A different approach was recommended for one particular new development near the Passaic River. The surficial geology included glacial deposits consisting of loose to dense sand overlaying relatively soft silt and clay and a lower stratum of medium-dense sand. During a preliminary site investigation for the project, bedrock was encountered at depths ranging between approximately 168 feet to 182 feet below the ground surface. Design capacity required a single pile of 200 tons. Two different pile foundation systems were evaluated in conjunction to the typical driven H-pile system in order to review potential costs and construction schedule impacts. The two alternative pile systems evaluated were tapered tube piles and drilled displacement piles. Theoretical calculations were followed by in-situ load testing. The field testing results indicated the use of drilled displacement piles as the best option for a portion of the proposed building. This paper discusses the different piles systems considered, installation and using drilled displacement piles to minimize cost and optimize construction.

Sep 8, 2021

By John P. Briand III, Douglas J. Aghjayan, Robert E. Fosse

This paper highlights the successful pile load testing program for the redevelopment of Pier One in East Boston, Massachusetts. Pier One is a 5.4-acre parcel on a dormant waterfront site used in the 1950s as a warehouse and distribution facility. The developer plans to re-use the existing 14-inch-diameter concrete-filled steel pipe piles to support four 5- to 7-story apartment buildings above a 2-story parking garage. A pile load testing program was developed to establish if the existing piles could support design loads of 240 kips for project financial feasibility and up to 300 kips for a significant reduction in future foundation costs. The Phase 1 program consisted of statnamic and dynamic load testing on two piles with two loading intervals (200 and 240 kips). Based upon the favorable results of the Phase 1 program, the Phase 2 program involved statnamic load testing on two piles and dynamic load testing on ten piles with three loading intervals (200, 240, and 300 kips). The Phase 2 program confirmed the favorable results which were applied across varying strata thicknesses and pile embedment depths. The average allowable capacity for the piles tested was greater than 300 kips with pile movement up to 0.3 inches.

By Patrick K. Wong, Richard Kelly

"The variability in strength and compressibility of in situ deep soil mixing products can be greater than the variability of the natural soil. However, satisfactory performance can be achieved by careful construction and an appropriate QA/QC program. This paper presents a case study on the use of deep dry soil mixing columns to support several embankments over soft clay along a highway project. Post-construction settlement monitoring indicated that good performance is achieved where the acceptance criteria are met, except in an area with high organic content. Embankments with contrasting performance are compared to the quality control test results which comprised laboratory testing of core samples as well as in situ test results such as pull-out and push-in vanes and conventional cone penetration tests. Drawing on the performance results and quality control testing, discussions and guidelines are given on quality assurance acceptance criteria and construction control testing regime for future projects.INTRODUCTIONBetween 2008 and 2012, the largest deep dry soil mixing (DSM) contract during that time in the southern hemisphere was carried out for the Ballina Bypass project. The project, comprising 12 km upgrade of the Pacific Highway located in northern New South Wales close to the border of Queensland, was commissioned by the Roads and Maritime Services (RMS) of NSW. The ground improvement contractor was Keller Ground Engineering (KGE) Australia. Seven different types of ground improvement techniques were employed for the project, ranging from low embankment strategy with nominal preloading, to surcharge with wick drains, light weight bottom ash fill, DSM, vibro-replacement stone columns, dynamic replacement, and vacuum consolidation (installed by Menard Bachy Pty Ltd). Different techniques were chosen depending on time program, cost, and performance requirements relative to proximity to piled structures (e.g. bridge abutments) and post-construction settlement and differential settlement for either rigid or flexible pavements at different locations.DSM was the most utilized ground improvement technique employed on the project, comprising a total of about 285 km of 0.8 m diameter columns to depths up to 18 m for the purpose of supporting bridge approach embankments and culverts with embankment heights up to 6 m. DSM was chosen due to the very soft nature of the clay soil with moisture content practically at liquid limit, and the relative speed and economy of the system. Dry cement powder at rates of 160 kg/m3 to 200 kg/m3 were pneumatically discharged via the hollow stem of the mixing tool, and mixed with the soil (using multiple horizontally mounted paddles on a single vertical stem) at high speed as the mixing tool is withdrawn."

Jan 1, 2015

By Donald Bruce, Alex Reeb, George Filz, Wesley Schmutzler, Mitsuo Nozu

"One million seven-hundred thousand cubic yards of deep mixing were installed to support an elevation raise of an earthen levee known as LPV 111, which is located in east New Orleans. The deep mixing was done by two contractors using somewhat different technologies, but producing elements of the same size. As part of the quality control and quality assurance program, 507 deep-mixed elements were cored and 5,082 specimens were strength tested in unconfined compression. This paper presents data from the coring and testing program. Very high percentages of the core run lengths were recovered, except during one period for one mixing technology. The coring methods are described, and reasons for the isolated episode of low recovery are discussed. The strength data show that the specification acceptance criteria were satisfied. Statistical parameters of the strength data are provided, and trends between strength and the following factors are discussed: depth, soil type, binder factor, and project-specific experience. Photographs of longitudinal cuts of core specimens are presented. Important lessons learned from this unusually large project are described.INTRODUCTIONThe Lake Pontchartrain and Vicinity Hurricane Protection system included a project known as LPV 111, which is an approximately 5-mile long segment of levee and floodwall located in east New Orleans along the Gulf Intracoastal Waterway and adjacent to Bayou Sauvage National Wildlife Refuge (Cali et al. 2012). The majority of the project consisted of a raise of an existing earthen levee from an existing crest elevation of about 18 ft to a new crest elevation of about 28 ft. The underlying soils were weak and compressible, providing inadequate support for the raised levee. Ground improvement in the form of deep mixing was selected to provide the necessary stability and settlement control for the raised levee.The US Army Corps of Engineers (USACE), New Orleans District, was the governmental agency in responsible charge of the project, including approval of design, construction, and payment. The lead designer was URS Corporation, and the general contractor was Archer-Western-Alberici (AWA), working in alliance with TREVIICOS South (Trevi), who, together with Fudo Construction (Fudo), performed the deep mixing.As part of the quality control and quality assurance program, over 500 production deep-mixed elements were cored, the cores were carefully logged, and over 5,000 unconfined compression tests were performed. In addition, selected specimens were carefully photographed before and after longitudinal saw cuts to expose the interior of the specimens. This paper provides a summary of the coring and testing performed on the production deep-mixed elements."

Jan 1, 2015