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By Franz-Werner Gerressen

As alternative energy industries pick up speed internationally, and as government regulation and restriction limit the use of impact hammers due to environmental limitation from construction induced noise during pile driving operations, unconventional solutions for more complex offshore foundation installations have become a necessity. Manufacturers and equipment suppliers race to develop alternative techniques to accommodate for offshore foundation construction in various soil conditions and at greater water depth. The FLYDRILL, and the Seabed-Drill BSD are two innovative systems for the installation of offshore monopiles with reduced environmental impact

By Jeremy G. Kress

We propose the discrete element method (DEM) as a complimentary alternative to analytical solutions and FEM models for the analysis of pile response. DEM is a novel approach to the engineering design of deep foundations which can be used to provide insight into the mechanics of soil-soil and soil-structure interaction. It is common to use analytical, empirical, and semi-empirical methods to predict pile behavior, where if granular properties, pile length, or load orientation change, then significant adjustments are made in the design sequence. DEM provides a more uniform approach in granular soils. Based on constitutive force-displacement relationships and laws of motion in rigid and elastic bodies, few changes must be made for a wide variety grain types, pile types, embedment, and load orientation. Preliminary results for simulation of a single pile are qualitatively consistent with results from conventional design procedures and also provide significant information not available from other analyses (e.g., local information about interface failure during shear). Importantly, these analyses are portable to a variety of pile types and installation procedures, which may not be the case for empirical approaches. Given consistent increases in computing power and rapid advances in model speed and sophistication, the DEM should prove to be a robust method for design and the analysis of pile response in granular soils.

Jan 1, 2010

By Jerold Bishop

The application of the ?electro-hydrodynamic effect? (EHDE) to civil engineering has been made in the construction of drilled piles. Equipment for the commercial application of this process was developed in Russia in the late 1980's. The process is approved for general use by the Russian Federation building code and numerous projects have been successfully completed with this technique. EHDE is a process by which a moderately powerful shockwave is released in the bottom of a drill hole filled wet concrete slurry. The energy is carried outward through the fluid with minimal loss because it is an incompressible medium. Repetitive discharges provides a series of energy pulses which will compact the soil along the pile shaft and at base of the pile. The process is analogous to repeated applications of low energy blast densification or to dynamic compaction. In general, the process is not depth dependent. Repeated application of this treatment in a drilled pile hole can increase soil density at the base and along the shaft of the pile, as desired. The overall result is that the geotechnical capacity can be improved significantly. Test results documenting improvements are presented and other applications considered.

Jan 1, 2007

By Jesús E. Gómez

Verification and production testing of soil nails requires debonding the upper section of the soil nail to isolate the portion of the soil nail intended for testing within a specific ground type. In pre-drilled soil nails, debonding can be accomplished relatively easily because the bar can be fitted with a debonding sheath before its installation. However, debonding of hollow core bar soil nails requires special procedures to achieve the intended result. This paper is a summary of the Federal Highway Administration (FHWA) Hollow Bar Soil Nail (HBSN) Test Program, which is described in detail in FHWA-CFL/TD-10-001. The program was developed to establish a suitable debonding procedure to test hollow core bars in soil nailing applications, and to initiate a database on typical bond values of HBSNs. The investigation showed that it is possible to debond hollow core bars for testing. It was also found that hollow core bars installed in granular soils may present ultimate bond values that are significantly higher than those typically used for design of conventional pre-drilled soil nails.

Jan 1, 2011

By Joseph A. Sopko

There has been a trend in recent years in performing the initial formation freezing using liquid nitrogen (LIN) and then converting the system to circulating refrigerated brine. While proponents of this method state it decreases freezing time, it can also be considered an alternative to inadequate refrigeration capacity. This method was used on several small projects in the 1980s. Problems such as broken pipes, frozen brine, and unsafe work conditions caused contractors to re-think the method. This paper discusses these problems and also presents work schedules showing no schedule reduction. In fact, this method can lead to longer time as well as significantly higher costs. BACKGROUND Ground freezing as a method to provide groundwater control and temporary earth support for excavations is completed using a relatively simple process: drilling and installing refrigeration pipes around the perimeter of the excavation and introducing a coolant into these pipes. The coolant extracts heat from the ground, converting the pore water to ice and forming a strong, impermeable material. A typical ground freezing system is illustrated in Fig. 1. SYSTEMS There are two basic types of coolant systems: circulating and direct expansion. The circulating coolant system is made of two separate, closed systems. The medium circulating is the secondary coolant. It is cooled at a central refrigeration plant, circulated through the pipes, and warms as it extracts heat from the ground. It then circulates back to the plant where it is cooled. This coolant is chilled in a heat exchanger by the primary refrigeration system where a compressor system is charged with a refrigeration gas. The heat is ultimately extracted from the ground and expelled into the atmosphere by an evaporative condenser. Secondary coolants are usually a brine or glycol chemical while the primary refrigeration gas is anhydrous ammonia or another commercially available gas.

Jan 1, 2019

By Abid O. Adekunte, David Greentree, David Hilton

"The construction industry is witnessing an upsurge in demand by property developers to have basements incorporated into their residential and commercial development schemes. This is attributable to perceived improvement to aesthetic and commercial values of buildings by underground space, amongst property owners. This trend is compelling more owners of buildings with no basements to explore the possibility of creating underground additional space beneath their existing buildings. The creation of a basement beneath an existing building entails the installation of a reinforced concrete (RC) underpinning system, temporary works, bulk excavation to basement formation level and construction of the basement structure, with associated aesthetic finishes.The L-shaped segmental RC underpins are a common system of choice for such underpinning works. They are multi-functional; providing vertical support to the existing superstructure, providing lateral support to earth and groundwater, supporting temporary and permanent surcharge loads from adjacent structures and services, whilst also forming part of the basement slab. This paper focuses on the first function of the Lshaped RC underpins; capacity under vertical compressive loading from the superstructure. The most common industry approach for the prediction of vertical capacities of L-shaped underpins is the oldfashioned Meyerhof’s (1953, 1963) effective width method, which is based on the traditional bearing capacity theory, whilst accounting for correction factors for eccentricity and foundation depth.The traditional bearing capacity formula is surrounded by a significant degree of uncertainty; estimates are highly user-dependent, as capacity prediction is sensitive to the chosen angle of shearing resistance (?), while there are difficulties in accurately measuring the in-situ ??value of cohesionless soils. In addition, the effective width approach has been shown to be very conservative by many research workers. The segmental RC underpins presented in this paper have been designed with an alternative less conservative method, which involves the use of a recently proposed consistent work-hardening plasticity model calibrated with field-based tests on footings of various aspect ratios and relative embedment in sand. The paper highlights the principles behind underpinning works for urban basement construction, the design of L-shaped RC underpins with the recently proposed plasticity model and the advantages of the method over traditional bearing capacity solutions and pre-existing plasticity models."

Jan 1, 2016

By William M. Tanner, Daniel C. Brahana

"A drilled pier foundation was originally designed to support the proposed G. Wayne Clough Undergraduate Learning Commons on the campus of Georgia Tech in Atlanta, GA. Reflective of the site geology, the original drilled pier foundation was divided into a Northern and Southern portion with an allowable end bearing capacity of 60 ksf and 100 ksf, respectively. After initial pricing on the original design, several value engineering options were submitted that featured changes to the original design capacity and construction method. The project team selected the value engineering option that involved conducting an Osterberg Load Cell test to assess end bearing of the site bedrock and skin friction. Results of the Osterberg Load Cell test justified increasing the allowable end bearing capacity of the site bedrock to 100 ksf in the Northern portion and 125 ksf in the Southern portion. Considering the final foundation design and Osterberg Load Cell test program, a net savings of approximately $259,000, or approximately 34%, was obtained over the original design.Project BackgroundThe G. Wayne Clough Undergraduate Learning Commons (CULC) is a 5-story academic building on the Georgia Tech campus in Atlanta, Georgia. The CULC was completed in 2011 and consists of a concrete frame structure supported on a drilled pier foundation.After pricing of the original drilled pier foundation design, several value engineering (VE) analyses were performed by the foundation contractor in an effort to demonstrate the potential for a reduced foundation cost. The VE analyses focused on variations in design assumptions, as well as construction techniques. This paper presents a case study that demonstrates how the value engineering process can be used to reduce foundation costs.Site Investigation and Subsurface ConditionsThe CULC building site is located within the Southern Piedmont Physiographic Province, an area underlain by metamorphic and igneous rocks. McConnell and Abrams (1984) indicate that the site is located at the boundary between two distinct geologic formations. The Northern portion of the site is underlain by the Wahoo Creek Formation while the Southern portion of the site is underlain by the Stonewall Formation. The following paragraphs briefly describe the geotechnical investigations performed by the project geotechnical engineer (GE) for the CULC."

Jan 1, 2015

By Jason Buenker, Molly Winston

Torque-installed piles are gaining popularity in Southern California as the go-to deep foundation element for small- to medium-capacity loads in urban environments. The torque-installed pile is a displacement- based screwed pipe pile with a closed-end conical tip welded to the bottom of the pipe. Torque-installed piles are most efficient in loose to medium dense soils with high liquefaction potential. Where used properly, torque-installed piles can be installed faster, require less clean-up, and create less onsite vibration/disturbance than other pile alternatives. However, torque-installed piles are not applicable in all soil conditions and care must be used to apply the pile effectively in the correct subsurface environment. This paper will review current Southern California state-of-the-practice for torque-installed pile design and construction, potential roadblocks to successful installation, and available capacities from load tests. INTRODUCTION Torque-installed piles are a type of full-displacement screwed pipe pile originally developed in Southern California circa 2001 by Substructure Support, Inc. The pile is unique for its proprietary closed-end conical tip shown in Fig. 1. The tip has a welded steel-helix plate and cutter teeth that allow the pile to be advanced efficiently under applied torque and down pressure (crowd). Since original development of the pile, several contractors or manufacturers have proposed similar proprietary screw-type piles with comparable conical tips. Pile installation is relatively quiet, vibration-free, does not generate spoils, and faster than comparable pile types. The pile was originally developed as an alternative to driven pile foundations and remains a critical substitute to driven foundations in urban environments. Torque-installed piles are conventionally specified as 12 ¾-inch outside diameter (OD) steel pipes with a ⅜-inch-thick wall, although larger sizes with alternative dimensions have been used outside Southern California. Pile installation lengths generally range from 30 to 50 feet but may reach 80 feet or greater where soil conditions permit. The pile is generally backfilled with concrete following installation to increase lateral pile stiffness and may incorporate rebar cages or other reinforcing steel to facilitate connections to structural elements. The pile is frequently specified using performance-based specifications that encourage contractor innovation and use of proprietary installation means and methods.

Jan 1, 2019

By Les R. Chernauskas

? What is Integrity Testing? ? Cross-Hole Sonic Logging (CSL) ? Single-Hole Sonic Logging (SSL) ? Typical Specifications ? Case Histories ? Observations and Conclusions WHAT IS INTEGRITY TESTING? General Definition ? Process in which the condition or structural makeup of an object can be evaluated with respect to defects such as a reduction in cross section (void or crack) or reduction in material strength (water, slurry, soil mixed with concrete). ? If the defect is severe enough, it can reduce or alter the load carrying ability of the object.

Jan 1, 2001

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 Karsten Beckhaus

Barrier walls in levees and dams are designed and constructed for new structures and for rehabilitation or upgrade of existing structures to control seepage. Construction methods applied are often deep soil mixing with a cementitious slurry or excavating a trench and refilling it with a plastic concrete. This paper explains the technical background of jointless cementitious barrier walls inevitably developing thermal tensile stresses and how these stresses can be controlled. The theoretical background of thermal stresses is explained based on experimental and numerical studies of essential factors. Although a low cracking risk is generally inherent, risk mitigation measures should be taken to thermal cracking and to ensure the permanent function of such walls as a low-permeability and high-deformability barriers.

Sep 8, 2021

By Michael Shedlosky, Sonia Sorabella Swift, Nina Carney, David Tarasovic

Rigid inclusions were used to support roadway fills and mechanically stabilized earth (MSE) walls for the South Capitol Street Corridor project. The first phase of this two-phase, nearly $1 billion project will include the replacement of the Frederick Douglass Memorial Bridge, including two approach ovals east and west of the Anacostia River, the replacement of the I-295/Suitland Parkway Interchange, and the construction of several traffic ramps. The bridge itself carries over 70,000 drivers daily and is expected to open in 2021. Ground improvement is required over a portion of the project footprint. Within the ground improvement area, the construction includes MSE walls up to 35 feet high and embankment fills up to 28 feet for which CMC rigid inclusions (RIs) were used to mitigate settlement and stability. The proposed construction runs over multiple old, in-service utilities that the project requirements indicate could not tolerate any stress or settlement due to the construction. As such, solutions that spanned the utilities were required. A concrete slab of varying thickness was used to span a fragile 108-inch-diameter sewer pipeline and 48- inch-square-precast-concrete box beams were used to span twin utilities that were buried just a few feet below current working grades on site. Unreinforced RIs were used to support these structures. The center to center spacing of the RIs perpendicular to the pipe run was 26.5 ft for the concrete slab and 62 feet for the precast--concrete box beams. The axial forces on the RIs were up to 267 kips. The RIs were not structurally connected to the slab or box beams. A single-element load test was performed to confirm the load-carrying capacity of the RIs. This paper will focus on the utility protection slab over the twin utilities and provide an overview of the design of the structural and geotechnical solutions and will present the results of the load test performed. INTRODUCTION The new Frederick Douglass Memorial Bridge (FDM Bridge) and reconstruction of the Suitland Parkway/ I-295 interchange (South Capitol Project) is a part of the Anacostia Waterfront Initiative (AWI) Program, whose goal is to transform the shores of the Anacostia River. The existing FDM Bridge is approximately 70-years old and has been classified as “functionally obsolete”. The completed South Capitol Project will improve the multi-modal transportation options, increase pedestrian and vehicular safety and provide additional green space. The proposed FDM Bridge, a rendering of which is shown in Fig. 1, is designed to become a landmark bridge in the Washington, D.C. area.

Jan 1, 2019

By Zachary Q. Maassen

Upon approval from the Las Vegas Convention and Visitors Authority (LVCVA), Turner/Martin Harris, A Joint Venture began construction on the estimated $860 million expansion for the Las Vegas Convention Center District Plan. Totaling around 600 shafts (60 feet depth and 3-foot diameter), the foundation installation completed via uncased drilled shaft operation, spanned from October to December of 2018. During this installation, flowback water from the water table was encountered that contained various solids ranging from cobbles to clays to silts, as well as trace amounts of contaminants of concern (COCs) left behind as a result of previous business that used to occupy the same real estate as the current expansion; more specifically, Perchloroethylene (PCE), an organic chemical widely used as a solvent and degreaser. With over 2.5 million gallons of waste slurry to be treated, technologies were deployed to reclassify the waste from liquid to solid waste as well as recover and treat the water for reuse in land spraying applications. Utilizing these technologies, it is estimated that 1.2 million gallons of water was able to be reclaimed along with over 6,400 tons of solids; resulting in hundreds of thousands of dollars in cost and environmental savings. PROJECT OVERVIEW Amidst its famous attractions from gambling to world class entertainment, Las Vegas has long been highlighted as the “No. 1 trade show destination in North America for 24 consecutive years” (LVCVA, 2018). Each year, Las Vegas hosts approximately 22,000 meetings, conventions and trade shows, which support an estimated 65,000 jobs paying $2.7 billion in wages and salaries. In 2017, the Las Vegas Convention Center hosted 21 percent of convention attendees traveling to southern Nevada, which supported approximately 13,800 jobs, paying more than $576 million in wages and salaries. Including indirect and induced impacts, the Las Vegas Convention Center’s attendees generated $2.1 billion in economic impact for the local economy (LVCVA, 2018) . This substantial economic impact of course due in part to the attractions Las Vegas offers to its trade show attendees, along with Las Vegas’ easy accessibility to major metropolises along the West Coast and reasonable travel prices offered if coming in from the East, allows for a very attractive venue. And while being a famous destination is great for business, the city wants to further distinguish itself by offering the best venue as well. For this reason, the Las Vegas Convention and Visitors Authority (LVCVA) approved a three-phase expansion plan for the Las Vegas Convention Center District totaling well over a billion dollars, slated for completion by 2023.

Jan 1, 2019

By Abolfazl Eslami, Sepide Lotfi, Mohammad M. Eslami

"Via direct CPT methods for pile capacity prediction, correlation coefficients smaller than unity are used to relate cone tip resistance (qc) and sleeve friction (fs) to pile toe capacity (rt) and shaft capacity (rs), respectively. For linking CPT data to pile capacity, factors such as diameter, penetration rate, partial embedment of pile toe into a hard layer, mechanism of plunging, failure zone, data processing, and stress-strain conditions must be considered. The aim of this paper is to investigate the role and significance of scale effects and establish direct relation between CPT data and pile shaft capacity. A database has been compiled including 40 full scale pile load tests and CPT sounding records for calibration and validation of the proposed approach. Analytical studies demonstrate that differences between pile and penetrometer penetration rate, geometry, and stress-strain conditions influence the relation between fs and rs. By considering the determinants, a procedure is proposed from which the pile shaft capacity can be predicted. This approach demonstrates better agreement with measured capacity by static loading test and less scatter than other current CPT methods.IntroductionAmong different approaches for pile capacity prediction, in-situ tests such as SPT and CPT have been used as supplementary of static analysis. Due to similarities between CPT and pile, the measured cone tip resistance and sleeve friction can be employed for prediction of unit toe and shaft capacities, respectively.Determination of pile capacity from CPT data includes two main approaches: direct and indirect methods. Direct CPT methods apply the measured values of cone tip resistance (qc) for pile toe capacity (rt), and sleeve friction (fs) for pile shaft capacity (rs) with some modifications regarding scale effects. Indirect CPT methods employ friction angle and undrained shear strength values that have been estimated from CPT data.When using direct CPT methods to relate qc and fs to rt and rs, correlation coefficients smaller than unity are used. Factors such as diameter, penetration rate, mechanism of plunging, failure zone, data processing, and stress-strain conditions must be considered for correlation between CPT and pile capacity. The work presented in this paper aims toward ameliorating the situation in the area of pile shaft capacity prediction, based on cone sleeve friction.Case histories from full-scale tests are compiled and analyzed by means of six methods including five direct CPT methods for shaft capacity prediction and the proposed method."

Jan 1, 2015

By Aly Mohammad, Dongyi Yue

"The design of rock sockets for drilled shafts and piles proves to be a challenge for the Design Engineer. The magnitude of loads on the shaft and the behavior of the rock are critical in determining the required socket length. Several acceptable methods are available in the literature to analyze a rock socket under a combination of axial loads, lateral loads and moments. This paper will present a state-of-the-art methodology to analyze rock sockets utilizing deformation characteristics of the rock. This design methodology was implemented in the design of a major project in New York City.The project discussed herein is a marine transfer station planned for construction at East 91st Street along the East River in Manhattan. In order to support the piers and platform structures at a site with relatively shallow depth of the bedrock, rock sockets were required for the drilled shaft foundations. Rock sockets were utilized to provide the required fixity to the foundations and the structures. Acting at the top of the rock sockets are large shear forces and moments created by the lateral loads transferred from the structure.Upon review of the available techniques, a simplified method was proposed and used to analyze the rock sockets with a significant magnitude of lateral loading. The method recognizes two mechanisms through which the lateral shear and moment are transferred to the rock; a) load transfer through horizontal resistance of rock and b) the vertical shear resistance of the bond between socket and rock.The first load transfer mechanism was analyzed using the p-y curve method based on a rock model developed by Reese. The second was analyzed using a bond stiffness derived from the formula and curves utilized in the AASHTO Specifications for calculation of rock socket displacement. By comparing the two mechanisms, the main contribution to the large horizontal shear force that developed in the rock socket is identified.The paper will present a summary of the design methodology utilized in determining the length of the rock socket. It is believed that the presented method will provide substantial cost saving in selecting the most economical and efficient design length."

Jan 1, 2005

By Mehih Demirkan, Kevin Tehansky

Located about an hour drive south from Washington, D.C., the Maryland Transportation Authority (MDTA) contracted with Skanska-Corman-McLean (SCM) to deliver a new Governor Harry W. Nice Memorial/Senator Thomas "Mac" Middleton Bridge, which takes U.S. 301 over the Potomac River, spanning 1.9 mi (3 km) from Maryland to Virginia. The new bridge aimed to improve capacity, safety and access of the roadway and was planned as a four-lane span with deep foundations that would be constructed fewer than 150 ft (45 m) north of the existing alignment of the more than 80-year-old bridge. The new Harry Nice Bridge opened in the fall of 2022 with a design life of more than 100 years, servicing 12 ft (4 m) wide lanes with 2 ft (0.6m) shoulders, doubling capacity, enhancing emergency response, upgrading maintenance and inspection activity access, and featuring lane sharing for cyclists.

Apr 1, 2023

By Shoji Higashi, Nobuhiro Honda, Takeo Asanuma, Tatsuo Nagatsu, Masaki Kitazume, Sachihiko Tokunaga, Shigeru Kubo, Hidenori Takahashi, Tsuneyasu Onishi, Yoshiyuki Morikawa

"Various kinds of civil engineering structures and facilities were seriously damaged in the earthquake in Tohoku and Kanto regions of Japan on 11 March 2011 due to the greatness of its magnitude. In contrast, many structures resisted the large seismic force having been reinforced by the CDM (Cement Deep Mixing) method, which is often used for increasing the bearing capacity of ground and improving seismic performance. This paper summarizes the field survey undertaken to investigate damage to structures and facilities reinforced by the CDM method. Several prefectures and metropolitan areas were selected for the survey, based on the occurrence of strong seismic motions. A total of 847 structures and facilities were studied, in the survey using a questionnaire, which mainly inquired about the appearance of structures and facilities. Of the respondents to the questionnaire, 789 replied that there were no seriously damaged structures. The paper presents the damaged and non-damaged sites of CDM-technique sites and non-CDM-techniques sites. It can be concluded from the field survey that the CDM Method demonstrates high efficacy and durability against a strong seismic motions.INTRODUCTIONDuring the afternoon of 11 March, 2011, a huge magnitude-9.0 Mw (Category 9.0 on the Richter scale) earthquake occurred about 25 kilometers below the Pacific Ocean’s surface off the coast of Tohoku. This massive earthquake, now called the 2011 Off the Pacific Coast of Tohoku Earthquake was the largest earthquake ever observed in Japan. The seismic intensity of this earthquake was measured 7, the maximum on the Japanese intensity scale, as observed 7 in northern Miyagi Prefecture. The earthquake caused severe damage over a wide area from Tohoku to Kanto, and triggered large tsunamis that struck the Pacific coast of Hokkaido, Tohoku, and Kanto. The number of missing and fatalities caused by this earthquake exceeded 18,000 persons, making this an unparalleled earthquake disaster with a cost-in-life toll not experienced by Japan in recent years. Because of the scale of its seismic motions, the earthquake damaged facilities and structures of many kinds. In the years prior to this earthquake, the CDM method was used extensively to increase the bearing capacity of the ground as an anti-seismic countermeasure and to prevent liquefaction. Immediately after the earthquake, the CDM Association visually surveyed the state of damage to about 800 facilities in the Tohoku and Kanto regions where a seismic intensity of 5 or higher was observed. This report summarizes the survey of damage to facilities and structures constructed applying the CDM method in order to confirm the durability and performance of the method against seismic motions."

Jan 1, 2015

By Andrew Baxter

This paper focuses on the design of steel bearing plates to transfer load from tiebacks and tiedowns to a concrete mass. It lists and describes the various available procedures for design of bearing plates as well as explains the design procedure recommended by the authors, which incorporates the Post Tensioning Institute (PTI) recommendations. The paper includes a step-by-step design example following the recommended procedure that captures the most important aspects of plate design. The dimensions of the plate calculated from this example are compared to the design dimensions obtained from various other procedures, including those by American Association of State Highway and Transportation Officials (AASHTO) and VSL International, Ltd. (VSL). The paper also includes the results of numerical modeling of the plate that will help the reader understand important aspects of plate-concrete interaction. The authors envision that this paper will serve to create an understanding in the geo-industry of suitable design methods and help improve procurement of bearing plates for tiebacks and tiedowns.

By David Pierce

The Port of Seattle, one of the largest on the west coast of North America, made a strong statement regarding their support for reusing existing structures when a decision was made to rehabilitate Pier 69, on Seattle's downtown waterfront, for their new headquarters. Because of its age and location, the pier provided an unusual challenge to the Port and its consultants. The Port hired Peratrovich, Nottingham, and Drage Inc. to design the seismic strengthening of the pier itself. To remedy the lack of seismic resistance in the 70-year-old pier, PN&D designed a new steel-pipe-pile supported concrete apron next to it. The structure relied on a development by PN&D, the "spin-fin pile", to achieve the tension capacities required of the batter piles. The construction of this apron was completed in October of 1991. Another team of consultants performed the superstructure renovation design, which is now under construction.

Jan 1, 1992

By Dennis Nottingham

"Increased interest in seismic soil liquefaction and preventative soil stabilization sets the stage for improved deep compaction methods using pile driving techniques. In 1971, L.B. Foster Company personnel patented a method of deep compaction using a vibratory pile hammer and pile probe. The technique had some success, but did not produce consistent results and thus found its way to obscurity. Other patents attempted to modify the technique by various probe modifications, but again without measurable improvement from a practical point of view. Solutions to economical deep compaction up to 100-foot depths particularly in saturated granular soils would have a great impact on the construction industry and new bulkhead structures being developed, thus PND was prompted into related research and development. The advent of higher horsepower vibratory hammers, coupled with PND engineers’ experiments, observations and measurements, led to an “H” pile probe design which has produced measured soil density improvements up to 250% using SPT “N60” values as a measure. Case histories of two projects involving extensive SPT soil sampling comparative measurements will be discussed along with findings that led to the compaction success. Applications to numerous modern “Open Cell” bulkhead projects will be presented and discussed.INTRODUCTIONNecessity often is the basis for innovation and such was the case for needed cost-effective deep soil fill compaction in Open Cell bulkheads where granular fill below water levels was often placed.Open Cell bulkheads were developed by PND Incorporated starting in 1980, for the express purpose of meeting client demands for an economical, easily constructed, extremely strong structure. Earth-filled structures historically have had a long history of problems with stability, scour and settlement.Open Cells are flexible steel sheet pile membranes supported by soil contact with embedded tail anchor walls.This concept creates an integral reinforced soil system. The result is a structure that can withstand large settlement and support a variety of very large loads. In effect, viewed from above the structure becomes a series of U-shaped horizontal membranes that require no toe embedment for stability. The Open Cell bulkhead is constructed of only three components: flat sheet piles, fabricated connector wyes and anchor piles. Compared to alternative structures, several cost savings are realized from this land based construction such as, reduced sheet pile area, greater construction tolerance, minimal pile penetration, and simplified backfilling procedures. In seismic regions or weak soils, the tail walls can be extended as required to guarantee fill mass stability."

Jan 1, 2005