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By Zhang Yaonian

This paper describes full-scale tests on ten large bored piles with grouted end conducted for three projects in the urban area of Fuzhou city. Test program included site investigation, pile installation and end grouting. The piles were instrumented with strain gages and load cells to determine load distribution in the piles. Test results showed that end grouting improves load-settlement performance of bored pile. End grouting significantly increases the shaft resistance near the pile end. The better the end condition, the greater the shaft resistance. The average shaft resistance of the bored piles with grouted end is much higher than that of piles without grouting.

Jan 1, 2004

By Packer M. L

Residual load development in driven precast piles has been widely researched in recent decades, however, cast-in-situ piles are often falsely assumed to be unaffected by this mechanism. In contrast to driven precast piles, driven cast-in-situ (DCIS) piles require adequate time prior to loading for the concrete hydration and curing processes to occur. The concrete-soil interaction is complex with several processes influencing the strains within the concrete pile after installation. DCIS piles are of particular interest given that residual loads can be developed during both the driving and casting phases. This paper present four instrumented end-bearing DCIS piles in which temperature and strains were monitored from installation, with the objective of identifying the processes contributing to the measured strains prior to testing. Strain gauges at all depths recorded a net compression and compressive strains continued to increase up to the commencement of load testing. Residual strains in the test piles were interpreted to be influenced by temperature (concrete and ambient soil and air temperature), consolidation of soils due to dissipation of excess pore water pressure, and swelling from absorption of groundwater. Several residual load interpretive methods are evaluated with the Siegel and McGillivray (2009) approach being consistent with the skin friction full mobilisation theory of the Unified Design method. The full-scale field tests presented herein provide a unique opportunity to examine DCIS pile behaviour, particularly given the lack of presently available published studies on these pile types.

May 1, 2022

By Allan Herse

"The years following World War II were nation building years in Australia. Soldiers returned from the European and Asian theatres of war sparking a major infrastructure construction boom. Dams and highways were built to keep up with the growth of towns and cities, which were bursting at the seams, not just from the returning soldiers settling down with their families but also from the many waves of refugees from war torn areas around the globe.The demand for electricity generation and distribution required for the growing population sparked the expansion of the national power grid with new high-voltage transmission towers appearing across the landscape. However, with an original design life of 50 years, those transmission lines constructed in the 1950s are nearing, or are at the end of, their anticipated service life.In recent years, the Australian power distribution network has changed from a period of high construction activity in greenfield high-voltage lines to a period that is now focused on reducing cost and maintaining existing assets. Replacing aboveground structural members and electrical components is relatively simple even under live conditions. However, the replacement or repair of tower foundations, many of which are in remote locations, has been a problem that has caused difficulties for power utilities trying to operate on a budget while also avoiding costly and unpopular power outages.With thousands of miles of aging transmission lines needing life extension work, Piling & Civil Australia (PCA) has developed a patented system of upgrading the foundations with micropiles while under live-line conditions without requiring costly outages. The system is seen as revolutionary by power utilities, allowing the utilities to extend the life of their existing assets until demand increases to warrant the construction of a new line. PCA has been working on a potential solution with Powerlink Queensland for the past 5 years to develop a quick and cost-effective foundation replacement system that can extend the life of its existing asset base anywhere from an additional 5 years to 50 years.With design support from Quanta Subsurface, USA, PCA recently completed the foundation replacement of 26 lattice tower foundations in the Townsville region of North Queensland. Using a steel bracket (patent pending) to connect hollow bar micropiles to the lattice towers, the installation techniques that were developed enabled the micropiles to be installed within a tolerance of less than about 3/8 in (10 mm) through the existing steel grillage foundation while maintaining live line conditions. The project was an Australian first and a trial by Powerlink for wider use within its network, and it was delivered on time and within budget at one tenth of the cost of traditional methods."

Jan 1, 2017

By Allan Herse

"The years following World War II were nation building years in Australia. Soldiers returned from the European and Asian theatres of war sparking a major infrastructure construction boom. Dams and highways were built to keep up with the growth of towns and cities, which were bursting at the seams, not just from the returning soldiers settling down with their families but also from the many waves of refugees from war torn areas around the globe.The demand for electricity generation and distribution required for the growing population sparked the expansion of the national power grid with new high-voltage transmission towers appearing across the landscape. However, with an original design life of 50 years, those transmission lines constructed in the 1950s are nearing, or are at the end of, their anticipated service life.In recent years, the Australian power distribution network has changed from a period of high construction activity in greenfield high-voltage lines to a period that is now focused on reducing cost and maintaining existing assets. Replacing aboveground structural members and electrical components is relatively simple even under live conditions. However, the replacement or repair of tower foundations, many of which are in remote locations, has been a problem that has caused difficulties for power utilities trying to operate on a budget while also avoiding costly and unpopular power outages. With thousands of miles of aging transmission lines needing life extension work, Piling & Civil Australia (PCA) has developed a patented system of upgrading the foundations with micropiles while under live-line conditions without requiring costly outages. The system is seen as revolutionary by power utilities, allowing the utilities to extend the life of their existing assets until demand increases to warrant the construction of a new line. PCA has been working on a potential solution with Powerlink Queensland for the past 5 years to develop a quick and cost-effective foundation replacement system that can extend the life of its existing asset base anywhere from an additional 5 years to 50 years.With design support from Quanta Subsurface, USA, PCA recently completed the foundation replacement of 26 lattice tower foundations in the Townsville region of North Queensland. Using a steel bracket (patent pending) to connect hollow bar micropiles to the lattice towers, the installation techniques that were developed enabled the micropiles to be installed within a tolerance of less than about 3/8 in (10 mm) through the existing steel grillage foundation while maintaining live line conditions. The project was an Australian first and a trial by Powerlink for wider use within its network, and it was delivered on time and within budget at one tenth of the cost of traditional methods."

Jan 1, 2017

By Scott Webster

Dynamic pile Monitoring Services (DMS) have been used for testing of offshore piles for several decades. However, most of this testing was to measure hammer performance and pile stresses rather than pile capacity or soil resistance. As the need for more economical solutions for foundation support increases, the use of DMS has provided a better means of evaluating in-place pile capacity for offshore structures, and therefore a method of determining pile acceptance. The authors have been involved in several offshore projects where DMS has been the primary source of data for acceptance of the driven pile foundations. The use of DMS for evaluation of offshore foundations requires considerations quite different from land applications and these considerations are often necessary for the careful and thorough analysis of the collected data in nearly real time for determination of pile acceptance. Case Method capacity estimates are often of little use due to the non-uniform cross sections of the foundation piles and their deep penetrations. Therefore, capacity assessments should be made using CAPWAP which is a signal matching program whose utility and reliability has been proven on thousands of projects every year, both on land and offshore. Depending upon the soil conditions at a given location, capacity assessment after soil setup effects may be necessary. In addition, tension capacity is often critical when pile refusal occurs significantly before the design pile penetration depth. Evaluation of uplift capacity can be accomplished by a CAPWAP analysis, which results in a total capacity prediction and its shaft resistance component. The use of hydraulic hammers for driving of these piles also adds the requirement of controlling hammer energy such that over-stressing of the pile is avoided. The calculation of non-axial stresses such as bending or eccentric stresses may also be involved in order to prevent pile damage.

Jan 1, 2010

By W. G. K. Fleming

The general history of piling is traced up to the present time with regard to the evolution of methods and materials. The processes have been strongly influenced by developments in basic equipment and industrial change. It is noticeable that in the twentieth century more progress has taken place than in the many previous centuries. It has been strongly influenced by the general development of Soil Mechanics. Test loading is probably the most effective way to assess the success of designs and many empirical relationships have been challenged through it. As we approach a new century it appears that it will be an age of rapid equipment development, with much enhancement of understanding of what has been done. Processes of automatic construction and testing will becoming commonplace. These changes will narrow the limits of conventional scatter that have come to be accepted and to a large extent will be driven by political efforts to curtail energy consumption, to raise standards of quality and reliability, and to conserve the environment. 1. Ancient history. Piling is an ancient art. Its first mention in history is from Herodotus, the first person to commit an account of his times to the written word in the years 557 to 479 BC. He evidently had a strong interest in engineering matters because he wrote of building, brick making, reinforced brickwork, river training, canal building, bridge construction, tunnelling and its acoustic detection and piling. The piling reference comes from Book 5 at paragraph 16.

Jan 1, 1999

By Michael Hughes, Selva Selvamohan, Ray Costa

"Cutoff walls are commonly used to mitigate underseepage problems for levee remediation projects. At abrupt changes in seepage cutoff wall depths there is a potential for water to flow around the back of the deeper cutoff wall leading to elevated seepage pressures on the landside that could result in exit gradients exceeding design criteria. This condition is referred to as end-around-effects and is a complex problem that requires detailed and time consuming 3-D numerical modeling to represent accurately. This paper presents a simple approach for assessing end-around-effects using the results of 2- D seepage analysis to determine if lateral extension of the deeper portion of the cutoff wall is required. This simplified approach provides a pragmatic solution to a complex 3-D problem. The presented procedure was used as part of the Feather River West Levee Project in Yuba City, California, to assess end-around-effects at 26 locations. The results showed that wall extensions of up to 100 feet were needed at only 2 locations.INTRODUCTIONAs the lead geotechnical consultant for the Feather River West Levee Project, AECOM were responsible for designing levee remediation works for approximately 35 miles of levee protecting the area around Yuba City, California, and communities to the north and south. Due to land use constraints, seepage cutoff walls were the main remediation alternative selected to address underseepage issues for the project.As part of the design review process, the California Department of Water Resources (DWR) requested AECOM to look at 26 locations along the levee alignment where the depth of cutoff wall changed abruptly from shallow to deep, or vice versa. At these locations there was the potential for seepage pressures to pass behind the deeper section of cutoff wall and stress the blanket layer landward of the cutoff wall. A condition referred to as end-around-effects.End-around-effects involve complex 3-D ground conditions that have traditionally been addressed by laterally extending the deeper section of cutoff wall an arbitrary distance based solely on engineering judgment. In discussions with DWR, AECOM developed a simple procedure to provide a more objective assessment of end-around-effects without the need for detailed and time consuming analysis. This procedure allows the engineer to make an informed decision of whether end-around-effects are a problem at the location of a cutoff wall transition rather than laterally extending the deeper section of cutoff wall an arbitrary distance based on engineering judgment alone."

Jan 1, 2015

By Gerald Verbeek, Erick Baziw

Downhole Seismic Testing (DST) is an extensively utilized geotechnical tool for site characterization. DST provides low strain (<10-5) in-situ interval shear and compression wave velocity estimates. These velocities are determined by obtaining relative arrival times of source waves as they travel through the stratigraphy and are recorded by one or more vertically offset seismic sensors. The DST arrival times have associated measurements errors and resolution limitations, which become more pronounced as the depth interval of analysis is reduced. Baziw Consulting Engineers (BCE) has developed a new DST analysis technique, the so-called DSTPolyKF algorithm, whereby the arrival times of DST data set are used to define a high order polynomial. The main advantages of this new technique are four-fold: 1) the ability to utilize all arrival time estimates irrespective of measurement errors. 2) the ability to analyze the data with user specified and even small (≤ 0.5m) depth intervals. 3) the ability to apply sophisticated data fusion for significantly more accurate DST interval velocity estimation. 4) the use of polynomial regression accuracy parameters to quantify how well the “best fit” polynomial fits the acquired arrival time data sets. This paper outlines the mathematical details of the best fit polynomial where a Kalman filter formulation is implemented. The performance of the DSTPolyKF algorithm is demonstrated by processing real DST data sets.

Oct 1, 2022

By Dan Mahrt

"In June of 2009, a slope failure occurred along River Road in Bismarck, North Dakota. The slope failure affected approximately 300 feet of River Road with vertical displacements up to 3 feet, resulting in closure of the road. River Road travels along the Missouri River in Bismarck in a geologic area riddled with historic slope failures of varying sizes. River Road is a city roadway which travels along the Missouri River. The toe of the failure extended into the Missouri River, therefore methods to repair the slope needed to be constructed within United States Army Corps of Engineers (USACE) requirements, and be acceptable to the City of Bismarck. As this is a scenic area along the river, the stakeholders desired to maintain the scenic landscape along the roadway as a part of the slope stabilization.Due to the magnitude movement of the failure mass, the geometry of the failure was relatively easy to evaluate. In evaluating remediation options and collaborating with the USACE, the team determined that the scarp was situated primarily within the navigable portion of the Missouri River. This required USACE approval for any repair or remedial work downslope of the roadway. The City of Bismarck wished to reopen the roadway as soon as possible, therefore stabilization options were limited to working within the road right-of-way to avoid permitting for working within the navigable waterway.The remediation solution for this project involved a combination of driven H-pile and placement of lightweight fill to re-construct the roadway at the original grades, and avoid impacting the navigable portions of the Missouri River. This paper discusses the unique project constraints and the innovative solution using multiple technologies to successfully stabilize the slope.BackgroundIn June 2009, Bismarck, North Dakota experienced two consecutive days of significant rain resulting in over 5 inches of precipitation in a 36-hour period. Shortly after these rain events, a slope failure was noted on River Road, a city street along the Missouri River in Bismarck. Initial findings noted the slope failure affected about a 300-foot long portion of the roadway, with vertical displacements of about 2 feet. The city of Bismarck closed the roadway and began evaluating repair solutions for the road."

Jan 1, 2016

By Dario Libano, Luis Carlos Tenuta, Juliano Penteado

"Subway Line Number 4 is one of the newest additions to the Rio de Janeiro subway network. Built for the 2016 Olympic Games, the 16 km (10 mi) subway line connects the south of the city, with the famous beaches Copacabana and Ipanema, to Barra da Tijuca, west of the city, where the Olympic Village and Park are located. This new line, which is estimated to cost USD 2.2 billion, is composed of six new stations: Jardim Oceanico, São Conrado, Gavea, Antero de Quintal, Jardim de Alah (JA) and Nossa Senhora da Paz Station.Brasfond participated in the construction of foundations and retaining structures for all the stations, and each presented unique challenges. This is not surprising considering the difficulties present in a highly-dense urban environment including utilities, nearby buildings, traffic limitations and noise.Of all the stations, JA Station was the most challenging to construct. It was located in the middle of an avenue between residential high rises supported on shallow foundations as well as below sea level in sands with high groundwater. The other five stations were located in small parks and squares, with no buildings in the immediate proximity.The interaction between designer, owner, and the general and foundation contractors during execution was key in safely reducing the construction schedule. This was significant given the unforeseen construction delays the client, Linha 4 Sul JV, faced due to permitting, utility and traffic relocation so that the owner could fulfill their final goal: making the line operational by the Olympic Games. The GeologyGeologically, the state of Rio de Janeiro is formed by Pre- Cambrian crystalline basement rock. Its geological formation is very old and comprises two major orogenic cycles, a Mid-Precambrian formation, called “Transamazonian” (Proterozoic Era), and an Upper-Precambrian to Cambrian called “Brasiliano” (Proterozoic-Paleozoic). The soil structure of the city of Rio de Janeiro is represented by a core of crystalline rocks, usually granite-gneiss, covered with a layer of residual soil and/or partially weathered rock.JA Station is located in a Rio de Janeiro neighborhood called Ipanema, between the Atlantic Ocean and Lagoon Rodrigo de Freitas. Local geology is composed of a superficial soil, consisting of medium to coarse grained sands. Top of rock varied significantly from 20 m (66 ft) deep on one side of the station to 33 m (108 ft) on the other. Water is at a depth of 3 m (10 ft)."

Jan 1, 2016

By Hyu-Soung Shin

This study is concerned with the characteristics of the behavior of steel-concrete composite drilled shafts, a material that is used for large bridge foundations, and especially for weak submerged ground conditions. Depending on the loading or boundary conditions considered, the behavior of foundation will vary. The bearing capacity of steel-concrete composite drilled shaft is influenced by initiation and propagation of fractures along the interface between steel casing and filled concrete. The interface effect is taken into account with the following two simplified cases: (1) detached model with free interface (no shear stiffness of interface) between concrete core and steel casing, (2) confined model by an upper steel cap with free interface. In the confined model, it is intended to have an unified behavior of composite shaft between concrete core and steel casing but there is interface between them. Intensive numerical studies have been undertaken to investigate detailed behavior of the composite shaft. In this study, 3-D finite element analysis is employed. Ground conditions typical of those encountered for the design of drilled shaft under water are considered affecting the behavior. Also, an attempt is made to generate possible combinations of the loads which have been considered in fields. Detailed characteristics of the stress and displacement distributions are evaluated to understand the mechanisms of composite shafts.

Jan 1, 2007

By Thomas L. Vande Voort

The strategic plan for bridge engineering issued by AASHTO in 2005 identified extending the service life and optimizing structural systems of bridges in the United States as two grand challenges in bridge engineering, with the objective of producing safer bridges that have a minimum service life of 75 years and reduced maintenance cost. Material deterioration was identified as one of the primary challenges to achieving the objective of extended life. In substructural applications (e.g., deep foundations), construction materials such as timber, steel, and concrete are subjected to deterioration due to environmental impacts. Using innovative and new materials for foundation applications makes the AASHTO objective of 75 years service life achievable. Ultra High Performance Concrete (UHPC) with compressive strength of 26,000 psi (180 MPa) and excellent durability has been used in superstructural applications but not in geotechnical and substructural applications. This paper explores the possibility of using precast, prestressed UHPC piles in future bridges. An H-shaped UHPC section, which is 10-in. (250-mm) deep with weight similar to that of an HP10×57 steel pile, was designed for constructability and economical reasons. Instrumented UHPC elements were cast to conduct large-scale field tests. In the field, two UHPC piles have been successfully driven in glacial till clay soil and load tested vertically. Test results, durability, drivability, and other material advantages over normal concrete and steel indicate that UHPC piles are a viable alternative to extend the life of bridge structures.

Jan 1, 2008

By Timothy C. Siegel

Accurate representation of the geotechnical resistance distribution is critical in evaluating the performance of piles and pile groups for design. A current practice is to infer the geotechnical resistance distribution based on measured changes in strain during conventional top load pile testing. Especially for drilled and bored piles, the residual load is typically assumed to be negligible both during testing and after the application of the structure load. A practical result is that the compressive structural load is anticipated to be opposed primarily by the shaft resistance with little or no mobilized toe resistance. The predicted top deflection is estimated as the combined elastic compression plus the movement necessary to mobilize shaft resistance. The development of residual load (and associated negative skin friction) results in a significantly different design condition. Negative skin friction tends to force the pile into the ground and develops residual load in the pile that contributes to the internal compressive load. Significant toe resistance can be mobilized in order to resist the combination of negative skin friction and the sustained compressive load. The pile movement becomes a function of the toe penetration required to mobilize sufficient resistance to reach a balance of forces. In an effort to study the development of residual load in augered cast-in place (ACIP) piles, the authors installed and monitored strain gages that were embedded in an 18-inch diameter ACIP pile at a site in southeast Georgia. The results of this study indicate that residual load develops over time and reaches a distribution that is consistent with the principles of the unified design of piles. It is concluded that residual load develops in ACIP piles (as well as all drilled and bored piles by the same mechanisms) and that the residual load should be considered in the interpretation of load tests and in the pile design, particularly in the estimation of the single pile and pile group settlement.

Jan 1, 2009

By Philip Derbyshire, Dale J. Scheffler

"Continuous Flight Auger (CFA) piling is a variation of Augered Cast-In-Place (ACIP) or augercast piling. In both cases a continuous auger with a hollow stem is used to drill a hole and a pile is formed by injection of cementitious material through the hollow stem as the auger is withdrawn. CFA differs from conventional American ACIP by the use of concrete rather than grout to form the pile, and by the type of equipment used to advance the auger into the ground and withdraw it. CFA installation uses a European style rig (i.e. fixed mast and rotary system) which can produce greater crowd and usually has a larger rotator or drill motor than the standard augercast setup. A standard augercast setup will consist of a lattice-boom crane and a set of leads to house the drill motor and auger. The auger size will range up to 24 inches (610mm). With CFA rigs larger diameter piles can be constructed, 24 to 36 in dia. (610mm to 915mm) are common and the technique has been applied with diameters up to 48-inch (1220mm). CFA makes use of sophisticated computer controlled monitoring systems, which have more recently been introduced for conventional ACIP piling. Developments in CFA have taken place over the last 25 years in Europe and particularly in the UK, but are relatively new in the USA. One application is in the construction of secant (overlapping) piled retaining walls. D.J. Scheffler Inc. recognized the potential of the CFA system following visits to the UK and has introduced its use into California for both secant piling and other applications.BACKGROUNDThe high price of real estate in many of the favored areas of California has increasingly led owners to want to build basements under their houses to increase the floor space available on a lot. Many of these areas are by the coast where the ground conditions are predominately granular and the water table is high. Conventional shoring and dewatering systems have often caused problems with adjoining properties. Clearly tangent walls are not suitable in these conditions because of leakage and loss of ground. The secant pile system, using CFA techniques, has proved very effective at overcoming the problems experienced by other methods. Other applications for CFA secant walls have included use for an emergency job on a highway following erosion caused by unusually heavy rainfall.METHODThe concept of secanting piles, whereby primary(female) piles are installed first and then secondary (male) piles are cut into the primary piles is not new. The method has been known for more than 30 years. Originally ‘Benoto’ grabbing rigs, developed in Japan, were used together with sectionalized double skinned casing and oscillators.This early method was slow, although very effective. More recently high torque rotary machines have been used. Contractors in the UK have increasingly used CFA techniques to further improve productivity of this type of piled wall. The improved capabilities of piling rigs available, as well as developments in concrete technology and instrumentation, have made this possible."

Jan 1, 2005

By Monique Nykamp

"INTRODUCTIONTerminal 46 is located just south of downtown Seattle, and is one of the Port of Seattle’s busiest container terminals. The Terminal 46 Redevelopment Project was undertaken to replace the existing 15-m-wide (50 ft) cranes along the apron with 30-m-wide (100 ft) cranes, which can unload larger, post- Panamax ships. The project included upgrading the existing waterside crane rail with new piles and constructing a new land-side rail behind the sheetpile bulkhead. The new piles had to be installed adjacent to the existing apron without causing damage, which was a signifi cant geotechnical challenge due to the soft soil conditions at the site. An instrumentation program performed during the test pile program evaluated this challenge and allowed for the development of specifi c production pile installation procedures that had the least possible effect on construction costs and schedule. SITE HISTORYThe site lies along the west side of Elliott Bay, north of the mouth of the Duwamish Waterway. Prior to development, this area was part of the tide fl ats where the Duwamish River drained into Elliott Bay. Prior to 1970, there were several existing timber piers and structures in the area. In the 1970s, the Port of Seattle constructed a 900-m-long (3,000 ft), 30- m-wide (100 ft) apron to support fi ve, 15-m-wide (50 ft) container cranes. The contained backland area was then fi lled with dredged spoils (sand and silt with organics) and the upper 5 to 20 m (16 to 65 ft) backfi lled with sand and gravel.The existing apron was constructed using 0.4 m (16 in) octagonal prestressed concrete piles to support the precast concrete deck and crane rails. The pile-supported bents were spaced at 6.1 m (20 ft), center-to-center, along the longitudinal direction. Pile lengths typically varied from about 20 to 40 m (65 to 130 ft) with 15 to 26 m penetration below mudline (50 to 85 ft penetration). The slope below the apron was constructed at about 1.75 horizontal to 1 vertical to allow for suffi cient water depth for cargo ships. In most areas, a riprap buttress was placed at the toe of the slope. A typical cross section of the apron is shown on Figure 2.Several stability, settlement and pile driving issues arose during the original construction of T-46 (Pita, 1983). Reportedly, movement of the submarine slope occurred during pile driving, resulting in settlement behind the bulkhead. Pile driving reportedly caused settlement of adjacent piles. In addition, some piles were “running” (dropping quickly under one hammer blow) during installation."

Jan 1, 2007

By Monique Nykamp

"INTRODUCTIONTerminal 46 is located just south of downtown Seattle, and is one of the Port of Seattle’s busiest container terminals. The Terminal 46 Redevelopment Project was undertaken to replace the existing 15-m-wide (50 ft) cranes along the apron with 30-m-wide (100 ft) cranes, which can unload larger, post- Panamax ships. The project included upgrading the existing waterside crane rail with new piles and constructing a new land-side rail behind the sheetpile bulkhead. The new piles had to be installed adjacent to the existing apron without causing damage, which was a signifi cant geotechnical challenge due to the soft soil conditions at the site. An instrumentation program performed during the test pile program evaluated this challenge and allowed for the development of specifi c production pile installation procedures that had the least possible effect on construction costs and schedule.SITE HISTORYThe site lies along the west side of Elliott Bay, north of the mouth of the Duwamish Waterway. Prior to development, this area was part of the tide fl ats where the Duwamish River drained into Elliott Bay. Prior to 1970, there were several existing timber piers and structures in the area. In the 1970s, the Port of Seattle constructed a 900-m-long (3,000 ft), 30- m-wide (100 ft) apron to support fi ve, 15-m-wide (50 ft) container cranes. The contained backland area was then fi lled with dredged spoils (sand and silt with organics) and the upper 5 to 20 m (16 to 65 ft) backfi lled with sand and gravel.The existing apron was constructed using 0.4 m (16 in) octagonal prestressed concrete piles to support the precast concrete deck and crane rails. The pile-supported bents were spaced at 6.1 m (20 ft), center-to-center, along the longitudinal direction. Pile lengths typically varied from about 20 to 40 m (65 to 130 ft) with 15 to 26 m penetration below mudline (50 to 85 ft penetration). The slope below the apron was constructed at about 1.75 horizontal to 1 vertical to allow for suffi cient water depth for cargo ships. In most areas, a riprap buttress was placed at the toe of the slope. A typical cross section of the apron is shown on Figure 2.Several stability, settlement and pile driving issues arose during the original construction of T-46 (Pita, 1983). Reportedly, movement of the submarine slope occurred during pile driving, resulting in settlement behind the bulkhead. Pile driving reportedly caused settlement of adjacent piles. In addition, some piles were “running” (dropping quickly under one hammer blow) during installation."

Jan 1, 2007

By Jon Sinnreich

Ensuring the accuracy of collected data during deep foundation static load tests is of paramount importance. Typically, pile head displacements are measured relative to a purpose-built reference system, which is assumed to be fixed. This study presents a simplified error analysis of this assumption, illustrates the potential magnitude of these errors, and proposes an improved method of pile head displacement monitoring.

Jan 1, 2009

By Chu E. Ho

This paper reviews the design of jet grouting at re-entrant corners of excavations where the diaphragm wall and secant pile wall installation were interrupted by existing utilities in the streel sidewalk. Jet grout blocks were formed to seal the gaps in the walls for excavation support, consisting of four to six columns in clusters. Jet grouting was performed around an electrical duct bank which had to be maintained. Jet grouting was executed through stratified soils using various combinations of jetting parameters for different soil strata. The installation sequence and age of the neighboring columns within a cluster will affect the jet’s ability to form subsequent columns. When jet cutting is limited next to hardened grout columns or embedded obstructions (such as diaphragm walls or secant pile walls in this case), the specific gravity (SG) of spoils would be reduced and tend toward the value of the injected grout SG. The magnitude of spoil SG is also influenced by the variability of the grout mix supplied. Specific Gravity Ratio (SGR) defined as the ratio of spoil SG to the actual grout SG at the time of jetting can be used as an indicator of successful treatment, with SGR > 1.0 indicating effective soil erosion. Verification coring and testing were implemented to confirm target column diameter and strength of grouted soils have been achieved.

May 1, 2022

By L. D. Johnson

12 groups of 12 precast prestressed (PCPS) piles were driven in the lagoon of Kwajalein Island to support a dry dock. Pre-construction investigation of the calcareous coral sands and static pile loeid tests were performed to determine if the 7.9 by 7.9 cm (20 by 20 inches) by 26 m (85 ft) long PCPS piles embedded to a depth of 16 m (53 ft) would adequately support the dry dock. Driving records for production piles indicated that the blowcounts of the piles at the fincil embedment depth became substantially less than expected as piles wssre driven further toward the lagoon end of the dry dock and decreased to as low as 2 blows/ft. A supplemental investigation that included a static load test on a production pile, the driving of an indicator pile, and restrikes indicated that the pile foundation has adequate bearing capacity. The observed bearing capacity appears to be effected by several mechanisms including breakdown of cementation between sand particles, densification of the sands during driving, and dissipation of excess pore pressures and recementation after driving.

Jan 1, 1993

By Riad Diab

In 2018 the Caisse de Dépôt et Placement du Québec (CDPQ) awarded a $6.3 billion (U.S. dollars) design-build contract to the Joint Venture (JV) team NouvLR for the design and construction of one of the largest automated transportation systems in the world, called the Réseau express métropolitain (REM). The REM project is a 67 km (41.6 mi) light rail system with 26 stations linking downtown, the airport and the greater Montreal area in Canada. Out of the 67 km (41.6 mi) network, over 25 km (15.5 mi) is being constructed on a 650- span elevated structure founded on single drilled shafts socketed into rock. Optimizing the design of the drilled shafts was one of the main objectives of the geotechnical team, as it would likely result in shorter shafts that help significantly reduce the project costs. As part of the optimization process, three static axial load tests and two fully instrumented lateral load tests were performed, during the preliminary design phase, on sacrificial shafts to simulate the ultimate load level and validate construction procedures.

May 1, 2022