Search Documents

By Chris Normand, Paul Volpe, Eric Wey, Howard Perko, Burt Ogilvie, Patrick Murray

"A refinery expansion project for Marathon Petroleum Company in Southern Louisiana required existing medium to large pipe racks to be expanded for additional capacity. Foundation modifications were necessary in order to add levels to the existing pipe racks. New piles were added and existing pile cap foundations were expanded. Several different pile types were considered. Custom designed large diameter helical piles were chosen, because they can be installed quickly with low overhead restrictions, produce minimal soil spoils, and are cost effective. The load capacity required for piles was higher than typical, off-the-shelf helical piles. In particular, the lateral load capacity demand was high due to wind loads of a hurricane prone region. Methods used to design and size helical piles are summarized including capacity to torque ratio estimation for composite helical piles. Pile load testing was performed in order to confirm design capacities of the helical piles under axial and lateral loading. Measured axial and lateral deflections compared well with predicted values. This case history evaluates the effectiveness of modern helical pile design methods within the context of a real and practical example.INTRODUCTIONAs the capacity of modern installation equipment increases, large-diameter helical piles are being used to support higher loads in more diverse applications. Currently, large-diameter high-capacity helical piles are used for electrical power transmission, power generation, high-rise buildings, bridges, and industrial applications. This case study regards a 2.5-mile pipe rack modification project within an existing refinery. One of the many challenges for engineering and construction of refinery revamp projects is determining how to effectively expand the capacity of existing foundations for additional equipment, piping, and other facilities. Custom designed large-diameter helical piles provided an effective solution to the challenges faced when expanding the capacity of existing pipe racks."

Jan 1, 2017

By Kessi E. Zicko, Eric A. Hackenberg, Paul J. Lewis

"Following snow melt and spring rains in 2011, a landslide measuring approximately 600 feet long and 300 feet in slope length occurred within the southbound roadway embankment of a heavily travelled 2-lane divided highway in North Central Pennsylvania. Driven steel piles were designed to stabilize the embankment slope. Factors affecting the selected stabilization technique included an adjacent reservoir, wetlands, the length and depth of the failure plane, extent of glacial lake deposits, excess pore pressures in the foundation soils, and an area of archaeological interest. Field reconnaissance and subsurface explorations including borings, instrumentation, geophysics, and laboratory testing indicated that glacial lake deposits were present in the toe region of the embankment. Instrumentation proved key in measuring excess pore pressures and in locating the failure plane, and geophysics was utilized to estimate the extent of the soft glacial lake deposits and to estimate pile lengths. The existing condition of the embankment was modeled in computer slope stability analyses, which were also used to help assign soil parameters. Significant costs were associated with constructing a berm due to the impacts on adjacent site features. Therefore, multiple rows of driven steel H-piles were designed for installation along the toe of the embankment. The design lateral load in the piles was based on slope stability analyses, and the pile size and number of piles were based on lateral pile computations with modified p-y curves to account for installing piles in an active landslide. The relationship between the factors of safety from slope stability and the LRFD pile design was significant in determining pile loads for lateral analyses.INTRODUCTIONA landslide developed along the lower portion of the southbound embankment of State Route 15 in Tioga County, Pennsylvania. The road passes through a steep valley and is located along the southern extent of the Tioga Reservoir. Although no damage to S.R. 15 was attributed to this landslide, the close proximity of the slide to the road posed a concern for the long-term stability of this section of roadway.This paper presents a summary of the site history; the subsurface conditions based on borings, instrumentation, a geophysical survey, and laboratory testing; slope stability analyses including alternatives assessment; and the pile design.SITE HISTORYS.R. 15 was originally located in the valley along the Tioga River and traversed through the towns of Tioga and Mansfield. Although the reason is unknown, it is interesting to note that Old S.R. 15 curved away from the river in the area of the landslide. In the mid 1970’s, S.R. 15 was relocated to the eastern hillside prior to construction of the Tioga-Hammond Reservoir by the U.S. Army Corps of Engineers. The relocated highway was constructed in stages. Two lanes of relocated S.R. 15 were initially constructed to carry one lane of northbound and one lane of southbound traffic. At this same time, the majority of the fill was placed for two future lanes immediately to the west, which would eventually allow for two lanes in each direction. The two eastern lanes would then carry northbound traffic after completion of the two southbound lanes to the west."

Jan 1, 2015

By Samer Rabab’ah, John C. Niedzielski, Jason Valeria

The PHX Sky Train is an automated people mover system located at Phoenix Sky Harbor International Airport. Phase II of the PHX Sky Train includes the design of over 150 drilled shafts for support of four guideway abutments, 75 guideway piers and three proposed stations. The soil conditions in this area generally consist of alluvial Sand, Gravel and Cobbles (locally known as SGC) deposited by the nearby Salt River. The foundation system will support relatively high axial loads, lateral loads and moments due to the height of the elevated guideway above the ground surface, where it needs to pass over roadways, parking lots, an existing terminal, and other buildings. Deep foundation design involves designing drilled shafts within the SGC deposits, some of which extend below the long-term groundwater table. Such extreme design loading conditions, together with difficult ground conditions at the site, result in several challenges for the design and construction of the deep foundation system for the project. This paper will present the results of a drilled shaft load test program implemented to provide site-specific measurement of the axial and lateral performance of the project drilled shafts. The load testing program consisted of a bi-directional load cell axial load test and a lateral load test performed on an instrumented test shaft 84 inches in diameter. The development and execution of the load test program and analysis of the test results are discussed. Comparisons were developed between predicted load capacities of drilled shafts using different design methodologies and the load capacity measured from the load tests. The load test results showed that underestimation of the capacity is evident using conventional methodologies. The load testing program was important for verifying the performance of the drilled shaft foundations on the project and was used to reduce the size of the drilled shafts. INTRODUCTION The PHX Sky Train is a five-mile long automated people mover system situated at-grade and on an elevated guideway which connects terminals, parking facilities, a rental car center and the Valley Metro Light Rail system in Phoenix. The purpose of this automated train system is to provide a secondary transportation system within the airport to relieve roadway congestion, minimize wait times and travel times for passengers and provide climate-controlled waiting areas. Phase 1 opened to the public on April 8, 2013. Phase 1A opened on December 8, 2014.

Jan 1, 2019

By Stefan Schwank, Alexander Blatt, Franz-Werner Gerressen

Diaphragm wall technique is usually used to install diaphragm walls, which are known as underground structural elements commonly used for retention systems and permanent foundation elements as well as deep groundwater barriers, named Cut-Off-Walls (COW). In this exploration project, the diaphragm wall equipment was used in the 2019 summer season to perform the first part of an exploration and bulk sampling program for a potential mine on the Star Kimberlite. Beside the idea of using the diaphragm wall technique as bulk sampling equipment, the sampling program required the adaption of equipment and tools for a depth capability never reached before by a trench cutter in any commercial application worldwide. The paper will explain the development of the sampling program as well as the challenges occurred with the local geology and the specific demands of the exploration and sampling program. It will also provide an overview of the lessons learned during the 2019 season and will give an outlook to the approaches of optimization for the second phase which will be carried out in 2020.

By Hubert Law, Dan A. Brown, Kyle M. Rollins

"Soil mixing and jet grouting provide a means to significantly increase the lateral resistance of pile group foundations with relatively little investment of time, effort, and expense compared to the cost for additional piles necessary to produce the same increased resistance. Comparative field testing conducted on full-scale pile groups before and after treatment of small soil volumes showed significant improvement in lateral resistance. The lateral resistance of the pile group increased by 60% due to soil mixing and by 180% due to jet grouting. To provide additional understanding regarding the influence of the soil mix strength, depth of improvement and width of improvement, a series of parametric studies were performed using a 3D finite element model. This set of “virtual load tests” was then combined with the results from the actual field tests to help develop a simplified model to account for observed behavior. In general, the testing and analysis indicate the pile group and the surrounding improved soil block generally act as an equivalent “super pile”. The passive force, side shear and base shear on the improved soil surrounding the pile group itself increased lateral resistance. This increase in resistance from the soil block can be added to the lateral resistance of the pile group.INTRODUCTIONThe lateral resistance of pile groups is often critical to the design of bridges and high-rise structures subject to seismic, wind, wave and landslide forces. Typically, when analyses indicate that the lateral resistance of a foundation is inadequate, additional piles, drilled shafts or micro-piles are added to increase the lateral resistance. Furthermore, an expanded pile cap or connecting beam is often required to structurally connect the new piles to the existing pile group. While this approach provides the required lateral resistance, it may also be relatively expensive and time consuming. An alternative approach is to use soil improvement techniques to increase the strength and stiffness of the surrounding soil and thereby increase the lateral resistance of the pile group. The improved zone could potentially be relatively shallow because the lateral resistance of piles is typically transferred within 5 to 10 pile diameters. For example, the soil around the periphery of the foundation could be relatively easily improved for an existing foundation as illustrated in Fig. 1(a) using a variety of soil improvement techniques. Alternatively, the soil under the foundation could be improved for a new foundation or even for an existing foundation with a technique such as jet grouting (see Fig. 1(b)). Improving the soil under the foundation would have the potential for producing greater increases in lateral resistance because the improvement would reach interior piles. In addition, the process of creating a cemented “soilcrete” zone around pile foundations could potentially produce a zone which would behave like a reinforced “superpile” with increased structural stiffness."

Jan 1, 2015

By Ronnie W. Sisk

1. Troubles start early - Inadequate Geotechnical Data A. Owners think they are saving money by allowing limited soil borings at their site. This places a high gamble on the bidders and the Lump Sum Price will be higher. B. Inaccurate elevations on soil reports. a. Surprises in depths - over or under design bid bottom elevations. 1. Requires backfill and extraction of casing that is too short for the greater depth of the drilled shaft. 2. Redrill utilizing longer casings. 3. Softer earth (backfill) can cause difficulties in redrilling such as less quantity extracted on the auger and maintaining plumbness. 4. Greater concrete overrun. b. Extreme under depths. 1. Excessive concrete is placed as a result of planning for a deeper shaft. c. Geotechnical report that does not supply a layout of boring locations. d. Design Engineer does not have a basic knowledge of how a caisson is installed.

Jan 1, 1988

By Tracy Brettmann, Melis Sutman, C. Guney Olgen

"The use of energy piles for geothermal heat exchange has been steadily increasing during the last decade, yet there are still pending questions on their behavior during temperature changes. This paper focuses on the thermo-mechanical response of three full-scale energy piles installed in Richmond, TX. The behavior of test piles subjected to thermo-mechanical loadings was studied in situ with the aim of quantifying the thermal influence on the performance and capacity of energy piles. An extensive field test program, including conventional pile loading tests and application of heating-cooling cycles was conducted on the test piles during a period of six weeks. For thermal load applications, the heat exchanger fluid with maximum temperature of 113°F (45°C) and minimum of 47°F (8°C) was circulated in the geothermal loops placed at the center of the test piles. Optical fiber sensors, vibrating wire strain gages, thermistors and thermal integrity profile wires were installed to monitor the strain and temperature variations along the energy piles throughout the field tests. The strain and temperature profiles during heating-cooling cycles on the test piles under static loads and without a maintained load were monitored to investigate the effect of thermo-mechanical and pure thermal loads on the energy piles, respectively. Conventional pile load tests were applied before and after the application of thermal cycles. The results of the pile load tests are compared to evaluate the effect of temperature cycles on pile capacity.IntroductionEnergy piles are deep foundation elements designed to access and exploit the relatively constant temperature of the ground and its heat storage capacity for efficient heating and cooling of buildings. The deep foundation elements that are already in place for structural support are integrated with adsorber pipes to perform as heat exchangers connected to ground source heat pump (GSHP) systems. With the use of energy piles, the heat energy is fed into and withdrawn from the ground for cooling in the summer and heating in the winter, respectively.Energy piles present an innovative way to harvest near-surface geothermal energy and to provide lower carbon emissions, however, there are still pending question on their performance. During heating-cooling cycles, energy piles experience temperature changes, which result in expansion or contraction of the piles."

Jan 1, 2017

By R. K. Filip

"Steel bearing piles have long been used to carry high compressive, tensile and lateral loads. Such piles are most commonly tubular or ""H"" profile and are typically installed using percussive techniques. The noise and vibration associated with such installation techniques tends to preclude the use of steel bearing piles in urban and other sensitive areas.This paper describes the design and construction of an innovative new road bridge in Milton Keynes, UK. The steel bearing piles were required to continue out of the ground to form the bridge columns and abutments and then be cast directly into the soffit of the reinforced concrete bridge deck. This project was to be the first time in the UK, that this form of bridge design had been used.The paper shows how new installation techniques allowed the designers to use these high capacity steel elements in a sensitive urban environment without the use of percussive or vibratory installation techniques. Finally the paper shows how these quiet and vibration-less installation techniques can be extended to other applications.A UNIQUE BRIDGE SUPPORTED ON ""BOXED SHEET PILES""CONCEPT HISTORYThere are over 700 bridges in Milton Keynes. Concrete is the dominant construction material, most are single span with massive parallel wing wall retaining abutments. All have a certain uniformity of aesthetic design. Pell Frischmann Consultants Ltd (PFC) proposed to the client, English Partnerships (EP), that an ""integral bridge"" with a slender open appearance would be an appropriate aesthetic form for a new highways bridge, within the district of Westcroft (figure 1). The concept required that the bearing piles be continued up out of the ground to form the bridge columns and abutments. Four rows with four piles in each row were suggested. Each would then be cast directly into the reinforced concrete bridge deck forming a moment connection (figure 2). This concept meant that a single continuous steel structural member would replace traditional reinforced concrete bored piles, pile caps and piers. This member would carry vertical and lateral loads. The conceptual design was intended to meet the following client requirements:"

Jan 1, 2005

By Tai Luu, Michael McNicholas, James C. McIntyre

The Jersey City Municipal Utilities Authority (JCMUA), discovered that an existing sewer pipe had collapsed under the New Jersey Transit Conrail Railroad between Pine Street and Ash Street in Jersey City New Jersey. Immediate action was taken to abandon the pipe in place and install a new sanitary sewer. The borings showed 10-20 ft (3.04 m.- 6.09 m) of competent fill overlaying approximately 8 ft. (2.44 m.) of compressible peat and organics. Groundwater was at 8 ft (2.44 m) below ground level. The poor condition of the soils at subgrade could not withstand the extreme weight of the jacking machine or the thrust force required to push the casing from the launching pit to receiving pit. The support of excavation (SOE) would therefore not only need to retain the soil to allow the jacking equipment to reach subgrade at 14 ft (4.27m) below working grade, but also the back wall of the SOE would need to be sufficiently robust to function as the reaction block for jacking operations. The alignment and allowable tolerance for the jacked casing was minimal, therefore the performance of the SOE was extremely critical to the success of jacking operations. This paper will discuss in detail the design concepts that were developed and implemented by the team to overcome these obstacles. HISTORY The discovery of a collapsed section of an existing sanitary sewer led the Jersey City Municipal Utilities Authority to act on an emergency contract. The project design team was tasked with developing an abandonment plan for the broken pipe and installation of the new pipe through challenging geology. The new 180 ft.(54.96 m) long, 54-in. (1.37 m) . diameter sewer pipe was designed to be contained within a 72-in. (1.83 m) protective steel casing. The installation of the new sewer pipe would require a detailed understanding of the geology. The geotechnical subcontractor assembled a subsurface investigation report on November 2nd, 2017. It was quickly realized that the only way to replace the pipe was with a jacked pipe system since the large grade change and the Conrail Right of Way created no other alternative. Delaying or closing the railway was absolutely not an option as that particular railway served as the main heavy-haul route to and from Jersey City. It became apparent that a major obstacle to pipe jacking was the challenging geology present across and beneath the proposed sanitary sewer. The following challenges faced the design team prior to the installation of the replacement pipe:

Jan 1, 2019

By Chris L. Powell, Russell J. Denny.

"The remotely located Cockatoo Island iron ore mine off the Kimberly coast in Western Australia, which has been in operation since 1951, was recently expanded up to 50m below sea-level using staged construction of a rock-filled seawall around the open cut mining operation. The most recent stage of the seawall expansion required a seepage reducing cut-off barrier to be installed through the seawall into underlying seabed sediments. A line of grout holes at 1m centres was proposed to form the seepage barrier, with grouting extending 17m below the top of the seawall. Top hammer drilling techniques were used to penetrate the 12m deep rockfill to seabed level, and permeation grouting carried out within the rockfill to fill voids and stabilise material around grout holes. The local 10m tides meant that tidal washout of fines and grout would be a major risk, and so a combination of cementitious and chemical grout was used to create rapid gel times. Following permeation grouting, holes were re-opened to allow jet grouting to hydraulically mix and grout permeable seabed sediments below the seawall. Using the duplex jet grout system in a single pass to 17m below platform level, the jet grouting was extended upwards into the seawall fill itself to overlap with the earlier permeation grouting. Finally a soil/cement mixed capping trench was installed using slurry trenching techniques with soil/cement/bentonite mixed backfill in order to complete the grout treatment. The approach taken allowed considerable onsite flexibility in technique. An automated slurry batching plant allowed adjustment of mixes to suit the varying subsurface conditions which were encountered during the works.IntroductionLate in 2013 Wagstaff Piling was engaged to install a seepage barrier through a rockfilled seawall built to allow expansion of sub-sea iron ore mining operations on Cockatoo Island off the remote Kimberley coast in the North West of Western Australia. Earlier stages of seawall construction had used a variety of different construction techniques with varied success, and the history of sub-sea mining on the island had been plagued with failures, including failures in the slope of the seawall itself, hanging wall failure underneath and inside the seawall, and footwall failures as the ore was mined leaving the rock face inclined at 55 degrees, parallel to the bedding. The current expansion, known as the Stage 4 expansion, was more tightly constrained by the pit geometry and available materials than previous seawall expansion stages that adopted clay core and sheet pile seepage barrier solutions. In Stage 4, an innovative grout curtain seepage barrier solution was selected to ultimately provide the necessary cut-off to allow access to high grade ore, while protecting the mine from inundation by the sea."

Jan 1, 2016

By Donald Deardorff

"Helical piles often rely on the final installation torque for ultimate capacity verification. When helical piles are designed using traditional bearing capacity equations for deep foundations and field monitored for a specified final installation torque, a factor of safety equal to 2 is often allowed for the design. One of the more common methods of determining torque during helical pile installation is by correlating the differential pressure across a hydraulic gear motor to a torque. Most drive head manufacturers provide multipliers to convert differential pressure to torque for different drive head models. These multipliers are based on theoretical torque equations and vary with the planetary gear ratio, hydraulic gear motor displacement and drive head efficiency. Drive head manufacturers show a linear fit between the differential pressure and output torque with no scaling effect. Previous drive head testing performed by the author has confirmed that the drive head differential pressure to torque relationship is generally linear however there is a scaling adjustment needed. This results in a variation of multipliers across the differential pressure range for a given drive head.Eight hydraulic drive heads from three manufacturers were field tested by Foundation Supportworks, Inc. to compare the torque versus differential pressure curves with varying installation equipment, hydraulic line sizes and hydraulic flow rates. Differential pressure was monitored using three methods including pressure gages, PT-Tracker and an Ashcroft AT-100. Flow and temperature was measured using a Webtech system analyzer. Torque was measured using a Pro-Dig in-line torque transducer, a TruTorque indicator and a Chance Mechanical Dial in-line torque indicator. The current testing indicates that a change in installation equipment and/or a change in hydraulic flow rate may affect the torque versus differential pressure curve of a given drive head. The results of this testing also show that some of the methods for determining torque during helical pile installations may be unconservative, thereby resulting in safety factors less than required."

Jan 1, 2017

By Karsten Beekhaus, Sander W. Odijk, Rabea Bahlum, Mazin Adnan, Ayman Abdelh Al Nuaimat, Hassan Farhat

The Arab Potash Company, APC, is one of the 10 largest potash producers of the world. The solar ponds at the Dead Sea, used for the enrichment of the salt content in the brine, are of crucial importance for the first step in the exploitation of the potassium salt. Targeting at the expansion of production in the since over 50 years utilized facilities, the increase of the brine exploitation capacity, reducing the substantial brine seepage losses from the ponds, becomes a crucially required measure. In this context, the remediation measures on the over 11 km long Dyke 1, being a main dyke of the solar ponds system, became inevitable to reduce the brine losses, prevent further development of sinkholes and cavities and hence assuring the stability of the dyke. The highly aggressive environment, the acting hydraulic conditions and the sensitive stratification and nature of the existing ground represented remarkable challenges for the design, as well as its implementation by the construction activities. Royal Haskoning developed a solution addressing the challenges above and targeting at a high sustainability of the executed structure, especially in view of the various geological and hydrological hazards repeatedly occurring in this Dead Sea region, including sinkholes of several meters by diameter and depth. The construction works, consisting of a cut-off wall, with depths reaching down to 31 m, were awarded to Bauer International FZE, a subsidiary of Bauer Spezialtiefbau GmbH. Upon the execution of the first section of 4.2 km length, additional sections were subsequently commissioned, also on further dykes, totaling to about 300,000 m² of cut-off wall. The specific project conditions, such as utilization of cutter technique for the excavation in Halite rock, the stability of open trench exposed to hydrostatic pressure of salt-saturated ground water, resulted in unconventional requirements towards the supporting fluid. The extremely aggressive saline conditions –with a Dead Sea water density of 1.25 tons/m3; one of the world's saltiest water–, were further a decisive factor for the definition of the backfill material concept. Despite its clear advantage for construction of cut-off walls with installed sheet piles, the single-phase system with hardening slurries, fulfilling both functions of excavation support and cut-off wall backfill material, had to be abandoned in favor of the two-phase system, to construct a hybrid cut-off wall made of sheet piles and plastic concrete.

May 1, 2022

By J. Erik Loehr, Andrew Z. Boeckmann

"Poor drainage is a common cause of poor performance of earth retention systems, resulting in burdensome serviceability problems that can progress to outright failure of the retention system if not addressed. A drainage system consisting of filtered conical drains that can be installed through the face of an existing retaining wall and readily maintained was evaluated through tests of physical and numerical models. The physical models were constructed with different backfill materials in a container measuring 8 ft wide by 4 ft tall by 15 ft long. Tests were conducted by saturating the backfill under a constant water elevation atop the model, and then maintaining the water elevation until seepage from the drains reached a steady state condition. Pore pressures within the backfill and outflow from the drains were measured to facilitate calibration of numerical models that accompany the physical models. Results from the calibrated finite element models were used to develop design criteria for the drains. The design criteria establish the required drain spacing as a function of the height of groundwater above the drains and the diameter of the drain.INTRODUCTIONMany retaining wall performance problems are a result of poor drainage of the wall backfill. Consequences of poorly drained backfill include displacement and rotation of the wall face, including the extreme case of collapse, and seepage through the face of the wall, which is in turn associated with damage from corrosion, dry rot, and other forms of deterioration. A common approach to improve drainage of an existing wall is the installation of drainage features (e.g. “weep holes”) in the face of the retaining wall. Weep holes facilitate controlled seepage through the face, which relieves water pressure within the backfill and directs seepage to known locations in the wall face. Although installation of weep holes is relatively common, engineering methodologies for selecting the size (diameter) and spacing (along the wall) of facial drainage features are uncommon if not altogether non-existent. This paper documents tests of physical and numerical models of retaining walls with facial drainage features, including conventional weep holes as well as maintainable drains installed through the face and extending into the wall backfill. Results of the testing were used to develop generic design criteria, which establish the required drain spacing as a function of the height of groundwater above the drains and the diameter of the drain."

Jan 1, 2016

By Paul Pedini

The challenge of Contract C19E1 of Boston's Central Artery Project called for the construction of two roadways under the commuter rail yard at North Station. Two options were offered for the method of their construction: Slurry Wall Roof-First or Soft Ground Tunneling. The instability of the indigenous soils seemed to rule out the use of tunneling, so the slurry wall method was chosen. However, these soils were incapable of holding up during slurry trench excavation. After many episodes of ground loss on early panel excavations, Modem Continental Construction suggested a method of trench wall stabilization. The Contractor (MCC) both suggested wall stabilization method and requested that the owner participate in the funding for the effort. The Project and the Contractor were able to agree on a solution which resulted in collapse-free excavation...and found an innovative way to fund the solution.

Jan 1, 2002

By Yan Lap J. Kan

"A waterfront stabilization system consisting of Deep Soil Mixing (DSM) columns, vinyl sheet pile fascia, and concrete flood walls supported on shallow footings was designed and constructed for a high-density waterfront development in Northern California. The project site is underlain by soft, compressible organic soil locally known as Bay Mud that has been capped with loose sand and imported fill. The waterfront stabilization system constructed at the site mitigates liquefaction, consolidation settlement and seismic potential slope deformation along the waterfront; the system was designed to reduce lateral displacements to tolerable amounts for the proposed structures. This paper presents the general design methodologies, construction challenges and quality control of this waterfront stabilization system.INTRODUCTIONUrban development in Northern California is fueling innovations in geotechnical engineering as more complex sites are developed. ENGEO Incorporated introduced a deep soil mixing technology from Japan to the US and designed a waterfront stabilization system for a high density waterfront development project in Redwood City, California. The approximately 12½-acre project site, as shown on Fig. 1, is surrounded by water on three sides, with an inner marina at the center of the site.The project site is located in the seismically active San Francisco Bay Area in California. The San Andreas Fault, the Monte Vista-Shannon Fault, the Hayward Fault and the San Gregorio Fault are major active faults located within 25 miles of the site. Once a former marshland with a major slough until the late 1950s, the site was reclaimed by placing imported fill over the native compressible clay deposits, locally known as Bay Mud."

Jan 1, 2016

By Rimas Veitas, James Panton, Erich Steinlechner

"Ductile Iron Piles (DIPs) are a proven, viable alternative to conventional piles, and for the past five years have been successfully used throughout New England. The installation process of DIPs lends itself to both large and small projects. Because of their installation efficiency they provide a substantial cost savings over drilled micro piles. Several New England projects (both end bearing and friction) will be evaluated, focusing on the installation and design procedures.BackgroundThe driven ductile cast iron pile (DIP) is a simple, fast and highly effective pile system. Over the last 30 years over 10 million feet of this pile system has been installed worldwide predominantly in Europe. DIPs are a prefabricated driven pile system utilizing high strength ductile iron pipes which are manufactured using a spun-cast process having outside diameters of 4 5/8” and 6 5/8 inches. The standard pile lengths are 16.4 feet long. The pipes are manufactured with a tapered socket with an internal shoulder for full engagement at the top and a tapered spigot at the bottom. The individual pile sections can be connected with this Plug and Drive® connection to drive a pile of any length.(see figure 1)The DIP system’s inherent advantage is the simplicity of the installation process. The piles are driven to refusal or to a required penetration depth with the use of a high-impact highfrequency hydraulic hammer (ie. Breaker hammer). In most applications the hydraulic hammer is mounted on an appropriately sized excavator (see Photo 2). At the completion of driving the pile, the pile is cut off (see photo 5) and the remaining section of pile is fitted with the appropriate driving shoe and serves as the lead section for the next pile. Being able to reuse the cut off section, yields minimal if any pile shaft waste. The pile is then fitted with an appropriate pile cap plate to receive the load from the superstructure."

Jan 1, 2017

By P. Middendorp, Gerald E. H. Verbeek

"INTRODUCTIONStatic Load Testing (SLT) is generally considered the pile testing method that provides the de-facto answers regarding pile capacity and load-deflection behavior. However, as this testing method is time consuming and costly, alternative pile testing methods are applied, such as High-Strain Dynamic Testing (HSDT), commonly referred to as Dynamic Load Testing (DLT), and Rapid Load Testing (RLT), which includes Statnamic Testing (STN) and the Fundex Pile Load Tester (PLT). Extensive descriptions of these pile testing methods as well as comparisons of the results from these two methods have been widely published, but little is written on the choice between HSDT and RLT. This article will address this issue for concrete piles by discussing five different aspects that should be considered when making a choice between HSDT and RLT for either cast-in-situ piles or precast driven piles. TIMINGThe timing of the pile load test is independent of the testing method. For cast-in-situ piles load testing is performed some time after the pile has been installed (to allow the pile to obtain the compressive strength required to withstand the test load), while for precast driven piles load testing is performed after a so-called set-up period following pile installation (to allow the soil to recover from driving induced disturbances and, at least in most cases,regain strength).In other words, the timing of the test does not affect the choice of the testing method.ACCURACY OF THE APPLIED LOADWhen a pile is tested by RLT the applied load is measured by a calibrated load cell placed on the pile head, just as it would be during SLT. This means that the error in the applied load value is less than 0.1% of the maximum range of the load cell.However, when a pile is tested by HSDT the load is calculated from the measured strains, which means that the outcome is dependent on the pile material properties. In this case the applied load (F) on the pile head is calculated by multiplying the measured strain (?) with either the calculated or estimated elastic modulus of concrete (E) and the pile cross section (A).The elastic modulus is generally back calculated from the (average) stress wave velocity (c), which in turn is derived from the reflection time (T) it takes for a stress wave to travel over the pile length (L) from the pile head to the pile toe and back to the pile head."

Jan 1, 2006

By Bill Shea, Gordon King

"For a drainage channel built in San Juan, Puerto Rico, a value engineering (VE) proposal incorporating a secant pile top-down approach saved time and facilitated construction work on the larger flood control project. The channel, at the Bechara Industrial Area, Puerto Nuevo Port Facility and the Puerto Rico Maritime Shipping Authority Dock, was needed to allow drainage of the Rio Puerto Nuevo into San Juan Bay. The port area, one of the busiest in the Caribbean, has over 6,000 ft (1,800 m) of berthing wharves for ocean-going container ships along with over 500,000 sq ft (46,000 m²) of container loading and unloading areas, and is critical to the local economy.Planners wanted to minimize the impact of construction to the port and dock users, and developed a construction methodology and work sequencing that would prevent a complete barrier to port traffic. This plan involved non-contiguous and limited work area that “leapfrogged” along the alignment so as to prevent long barriers to lateral traffic movement across the culvert alignment.After reviewing the project plans and schedule, Morris-Shea Bridge Company (MSB) proposed an alternate design and construction approach that provided significant cost and schedule benefits, and also provided better access for the port and dock users. The alternate VE proposal involved top-down construction methodology and redesigned drainage culvert geometry with two parallel 2,000 linear ft (lf) (600 m) secant walls installed on each side of the culvert. These walls facilitated excavation and formed part of the culvert permanent walls. The result was a significantly reduced required construction right of way that allowed construction work in contiguous areas largely without impact on ongoing port activity. MSB conceived the design concept, and engineered design and construction of the VE alternate secant pile culvert.The project initially consisted of an open channel in the industrial area picking up water from the existing Rio Puerto Nuevo, transitioning to an enclosed culvert through the port and dock areas, and outfall through the existing dock. The base bid construction included three main areas of work:"

Jan 1, 2012

By Ramin Motamed, Anna Panorska``, Joseph A. W. Toth

In this study, a dataset of 145 bi-directional and static load tests was used to evaluate the load-displacement response with respect to unit side resistance for drilled shafts comprising fully and partially mobilized data. A total of 612 unit side resistance curves were calculated which included 52 fully mobilized curves showing a maximum response. A new approach using the double tangent method, is proposed in calculating the maximum unit side resistance from partially mobilized load-displacement data. The double tangent method was applied to each load-displacement response to estimate the ratio of mobilized resistance between the intersecting tangents and peak measured resistance. It is observed that as the mobilization of side shear approaches a maximum, the ratio approaches unity. Using the fully mobilized curves, regression models were developed using correlations between ratios of estimated resistance at the double tangent, peak, and maximum measured responses. Regression models are evaluated for the following factors: predominant soil type and drilled shaft construction methods. Comparisons of calculated and measured maximum values of unit side resistance are compared for each model. Although these factors each influence the load-transfer behavior, a single global regression model including all the data showed promise in yielding accurate results.

By Oladayo O. Komolafe and Majid Ghayoomi

p-y curves have been used over the years to determine the lateral resistance of piles. This method is popular among practicing engineers due to its simplicity and its ability to determine the slope, displacement, shear force, and bending moment for various depths along the pile. The ultimate lateral load resistance is a key component of p-y curve formulation. The p-y curve formulation by Reese et al. (1974) does not consider the effects of soil’s degree of saturation on theoretical ultimate lateral resistance of the failure wedge. This limits an accurate assessment of the lateral soil resistance near the ground surface and the consequent p-y curves. This paper extends the existing approach for determining the failure wedge in unsaturated cohesionless soils with suction dependency, especially for the depths that are above the water table within the wedge. The modification to the failure wedge analysis was made by considering the variation of the degree of saturation which affects effective stress and lateral earth pressure. Through a set of parametric analyses, the impact of incorporating principles of unsaturated soil mechanics in the estimation of theoretical ultimate lateral resistance is examined, and its implications on lateral pile response are discussed.

Sep 8, 2021