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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 Nicolas Moscoso, Gerald Verbeek, Marcel Bielefeld, Rob van Dorp

Upon recently, most offshore foundations were based on a number of driven piles that were installed with an impact hammer. With the increase in offshore windfarms two major developments have occurred: the shift from jackets to monopiles, leading to increase of the diameter of the foundation piles, and a shift from impact hammers to vibro hammers. As the use of vibratory hammers is becoming more and more common practice, the need for accurate vibro-driving simulation software has increased, which requires that the soil modelling is enhanced to address soil fatigue during pile driving and to predict reliably the soil behavior and resistance during pile driving. In addition pile driving monitoring, which is routine for piles driven with an impact hammer, needs to become common practice. This paper addresses advances in soil modelling that allows more accurate pile driving simulation as well as the application of Vibro Driving Analysis (VDA) or Monitoring (VDM) to validate the simulation results. This is illustrated by a case study of the test pile for the Delft Offshore Turbine project, a 28 m long monopile with a diameter of 4 m that was driven 15 m into dense sand layers using a vibro hammer. After some 6 months the pile was extracted, and pile driving simulations and VDA were done both for the installation and extraction phase. 1. INTRODUCTION At the end of 2017, the total worldwide offshore wind power capacity was 18.8 GW [1]. The vast majority of offshore wind farms are currently in Northern Europe, which together account for over two thirds of the total offshore wind power installed worldwide, followed by East Asia, while developments in North America are still in very early stages.

Jan 1, 2019

By Chul Soo Park, Juhyung Lee, Duhyun Baek

"In this study the preliminary design of suction pile as the supporting system of the concrete floating structures was performed at the offshore pilot project area in Korea. The suction pile of the floating structures has to satisfy the lateral resistance against external force evaluated from the marine and structure conditions, as well as the penetration ability according to the soil and seepage conditions. In the design, the required penetration depths for lateral resistance were evaluated with different diameters of cylindrical steel suction pile, and the design suction pressures at each penetrating depths were assessed through the comparison of penetration forces and penetration-resistances. Finally, the optimal dimension of suction pile for the pilot project area was proposed.IntroductionInterests in sea spaces have rapidly increased around the world due to limitations in use of lands. Such increase has resulted in construction of numerous marine structures aimed at expanding the use of sea spaces and developing marine resources. South Korea also needs to secure construction technologies for floating infrastructures on its relatively deep seas. Foundations for floating structures consist of anchors and mooring systems rather than driven piles or cast-in-place piles, due to limitations in equipment operation or economic feasibility. Anchors and foundations used on the sea include drag anchors and suction piles, but the suction piles are more widely used for reasons regarding uncertainties of calculation of bearing capacity and construction. Large-diameter suction piles are generally used to utilize fully their penetration ability, which is proportionate to the square of the foundation diameter, and the length-diameter ratio (L/D) does not exceed 6 (Randolph et al., 2005; Andersen et al., 2005). Recently, a design and construction technology using group suction piles consisting of medium-diameter suction piles and concrete pile caps is being developed as an alternative to the conventional large-diameter mono suction piles. In addition, pilot projects involving the group suction piles of mediumdiameter are currently being reviewed for the southwest coast area in Korea. In this study, therefore, preliminary design for installation of medium-diameter mono suction piles as the supporting system of the concrete floating structures was performed, and suction pressures, penetration forces and resistances, and lateral loading capacity with diameters were reviewed."

Jan 1, 2017

By Matthias Pulsfort, Jiarui Du, Torsten Wichtmann, Achim v. Blumenthal, Diethard König, Rowena Verst

The influence of the interaction between support fluid and soil, e.g., filter cake formation, on the shear stress transfer in the soil-concrete interface of diaphragm walls and bored piles is still controversially discussed. Actual research on the soil-concrete interface using bentonite suspensions indicates that shear stress transfer is underestimated by existing standards. Investigations on the soil-concrete interface using polymer solutions are rare. Therefore, complementary field investigations and systematic laboratory studies were conducted to analyse the soil-concrete interface using both bentonite suspensions and polymer solutions. Thickness and composition of real-scale filter cakes were investigated on several slurry wall construction sites, where bentonite suspensions were used. Direct shear tests (60 mm x 60 mm) were executed for soilbentonite mixtures with varying amounts of bentonite and different granular fines representing a realistic bandwidth of in-situ filter cake compositions. Larger direct shear tests (300 mm x 300 mm) with preceding horizontal penetration, subsequent vertical tremie concrete placement, and filter cake consolidation were performed using both bentonite suspensions and polymer solutions. The results support the view that shear stress transfer in the soil-concrete interface can be described by a wall friction angle in a range of 25° to 30° for bentonite suspensions and between 35° and 40° for polymer solutions in non-cohesive soils.

May 1, 2022

By Anup Kumar Mandal, Sanjoy Chowdhury, Biswajit Das

"Tailing pond of an iron ore mine necessitated raising the height of its embankment to create additional storage capacity. The tailing pond is located in eastern India and raising the height of embankment was going on during the month of January, 2014. Upstream method of construction was adopted since there was no space available at the downstream side. During the construction, about 200 m stretch of the north east embankment of height about 5.5 m failed forming a classical slip circle on the upstream side involving about half the top width of the embankment. To find out the root cause of the slope failure, detail geotechnical investigation work was carried out within the embankment as well as in the adjacent areas within the pond. About 7.5m thick very soft tailings were detected below the constructed embankment. Shear strength of the soft tailing was very low and was inadequate to sustain imposed embankment load. This resulted in the failure of the embankment. Analysis of the tailing deposit revealed that even after failure, settlement was continuing due to imposed embankment load. Under normal onedimensional consolidation, the tailing deposit would have taken about 5.7 years for 90% of primary consolidation. However, in order to mitigate the scarcity of storage space, mining plan required raising the height of the embankment within next six to eight months. Therefore, despite the fact that there was a failure, it was necessary to continue the construction on the underlying weak stratum. The system was redesigned with installation of prefabricated vertical drains (PVDs) to accelerate the consolidation process thereby gaining the in-situ strength. Strength was additionally enhanced by installing geogrids in multiple layers. It stabilized the existing embankment and also ensured construction of additional height over and above the existing embankment.INTRODUCTIONBeneficiation plant in the Iron mines enhances the mineral content by separation of contaminants and fines. The residue (waste material) is called tailings/tailings depending upon the grain sizes. These tailings in a slurry form are generally disposed in a pond called as tailing pond/tailing pond. Height of embankment of such ponds is increased either by upstream or by downstream or by centrally raising methods in different phases as quantum of deposition in the pond increases with time."

Jan 1, 2015

By Nadir Ansari, Brian W. Wilson, Marina S. W. Li

"A hybrid shoring system consisting of cast-in-place soldier piles with Cutter Soil Mixing (CSM) infill panels was constructed for temporary support of a 19.8 m (65 ft) deep excavation in Vancouver, British Columbia, Canada. Deep Mixing (DM) was completed up to 9.7 m (32 ft) in fill, peat, wood waste and clayey silt with embedment in dense till, and soldier piles constructed through the dense till extending to below final excavation level. Two trial CSM panels were installed ahead of production to assist with developing the termination criteria of the CSM panels in the dense till. The constructed depth of the CSM panels was based on interpretation of real-time monitoring data obtained through the Bauer B-tronic system. Inclinometer monitoring data from two CSM panels and two soldier piles, as well as soldier pile survey target data was used to assess and monitor the performance of the hybrid shoring system throughout bulk excavation. The objectives of this paper are to provide an overview of the design and construction aspects of the hybrid DM shoring system and to present inclinometer and pile target data to demonstrate the lateral performance of the CSM infill panels and soldier piles. This paper also discusses the merits of using real-time monitoring data as part of the engineering decision-making process for validating CSM panel construction. BACKGROUND A hybrid DM shoring design was recently completed for a high-rise development in downtown Vancouver, British Columbia for temporary support of a five level basement excavation. Deep mixing was proposed by the excavation and shoring design-build team as the preferred method to construct infill panels between soldier piles because of the speed at which the shoring system could be constructed in variable fill, peat, wood waste and overburden compared with traditional secant piling methods. The development site is generally a truncated triangle in plan, with the longest side of the triangle being approximately 115.7 m (380 ft) long and the two shorter sides being approximately 71.6 m (235 ft) (Hybrid Shoring Wall 1) to 75.0 m (246 ft) (Hybrid Shoring Wall 2) long. The site is bounded by an existing bridge off-ramp structure along its longest side, and by city streets on the other two sides, as shown in Figure 1. The truncated section is approximately 16.8 m (55 ft) (Hybrid Shoring Wall 3) long. Due to project constraints, the hybrid DM and soldier pile shoring system was only proposed for the two shorter sides of the triangle and the truncated section. Traditional secant piles were installed for the longest side. This paper focusses on the hybrid shoring system. A typical detail showing the CSM infill panel with the soldier piles is presented in Figure 2."

Jan 1, 2017

By Evangelia Ieronymaki

Civil engineering education relies on traditional methods of teaching, comprising mostly of deductive instruction by presenting the theory, followed by applications. This paper presents an alternative way for teaching foundation design to senior students, introducing a more inductive approach. The students are presented with a project/game adapted to a real-world problem at the beginning of the course. They are asked to identify the correct steps and methods throughout the lectures, for reaching an appropriate solution that they document and present at the end of the course. To make the project more enjoyable, the project has the format of a game where the students compete with each other on completing the task faster and more efficiently. The goal of this teaching approach is to enhance the ability of the students for problem solving and the engineering way of thinking, while playing a game. In the end, the students were requested to respond to a survey regarding the efficiency of this project/game on their learning. The results showed that students prefer more inductive methods for a design course, feeling that this project made them think more like engineers, while the ‘game’ twist of it made the whole course more fun. INTRODUCTION Most civil engineering courses are taught in 2019 the same way they used to be taught 40 years ago in the 80s. Classic methods are mostly deductive, where the instructor presents the theory first and then applications of that theory follow. Little or no attention is given initially to why the theory was developed or what are the problems it solves. The applications of the theory, and thus the purpose it serves, come only in the end and after methodologies have been presented, leading the students to show low interest in the material. As Albanese and Mitchell (1993) have reported, people are mostly motivated to learn things when they clearly see the need to know them. This explains the students’ little motivation that, if any, comes mainly from the fact that the material may be useful either in other courses or in their future careers. On the other hand, there are alternative inductive methods of teaching, where the role of the students is more active. A lot of researchers have highlighted the benefits of inductive methods in teaching engineering courses. Based on Prince and Fedler (2006), inductive methods include; a) inquiry-learning, b) discovery learning, c) problem and project-based learning (PBL), d) case-based teaching, and e) just-in-time learning. Inquiry-learning is maybe the most traditional method of inductive teaching/learning methods, where the instructor asks questions or poses problems and the students need to apply the theory they have learnt in order to find the solution (Bateman 1990; Prince 2004; Lee 2012). Similar to inquire-learning is the discovery learning, where students have to find the solution to a problem or answer to a question, while the instructor simply provides feedback to the students without guiding their efforts (Leonard 1988; Westbrook and Rogers 1994).

Jan 1, 2019

By Christopher J. Ramsey, Don W. Dotson

"An existing four lane section of US 27 was widened to eight lanes. The project lies in the rugged Valley and Ridge Province of the Appalachian mountains starting at the Tennessee River in Chattanooga, Tennessee and extending 2.6 km north to Signal Mountain Boulevard. This terrain presented many challenges to accommodate the road widening in the narrow, rugged topography. Multiple tiered wall systems consisting of large tieback walls, post-tensioned reaction blocks, and gravity MSE walls for a total of approximately 30 retaining walls were required. The retaining walls served to stabilize the thrust faulted geology while also minimizing right-of-way acquisitions. The cut walls consist mainly of a tiered system of tied-back soldier piles walls with cast-in-place concrete facing. Cast-in-place pile shear walls were required along the toe of existing MSE walls to maintain stability during construction. This paper discusses the design methodology, which includes a hybrid (rather than traditional) earth pressure diagram intended to reduce life-cycle maintenance and long-term performance. Further this paper addresses wall construction, slope stability analysis, landslide mitigation alternatives, soldier pile wall design features, site challenges, monitoring and performance (to date) of the wall systems.INTRODUCTIONThis project involves the proposed widening of US Highway 27 (State Route 29) from the north end of the Tennessee River Bridge at Manufacturer’s Road to State Route 8 (Signal Mountain Road), approximately 2.64 km of roadway (Fig. 1). The project site is located adjacent to the Tennessee River on the north side of downtown Chattanooga, Tennessee in Hamilton County. The existing, limited access highway is to be widened from four lanes (two northbound and two southbound) to a minimum of eight lanes. Some portions of the alignment will expand to as much as ten lanes where northbound and southbound ramp acceleration/deceleration lanes coincide.In addition to the number and heights of cuts and fills involved, a major factor in determining an economical design for the alignment is the complicated geologic conditions along the roadway alignment. The existing roadway is situated between several steep cut slopes, some of which are only marginally stable or currently exhibit signs of instability. Due to the proximity of the project to the downtown area, the steep slopes along the alignment, and the relatively dense population near the alignment, widening the pavement and constructing cut and fill slopes to a stable configuration would result in major land acquisition for slope right-of-way."

Jan 1, 2015

By Bradley J. Fleming

Although soil improvement and its application to deep foundations is gaining popularity in the engineering community, this technique is not widely used in high seismic regions due to lack of fundamental understanding of both the behavior of improved soils under high-strain cyclic loading and the interactions between the pile, improved soil, and unimproved soil. This paper describes part of an ongoing Network for Earthquake Engineering Simulation (NEES) project, where two identical full-scale steel pipe piles were driven at a soft clay site in Oklahoma. The soil surrounding one of these piles was improved using the cement deep soil mixing technique in order to enhance its lateral load behavior. Both piles were tested for seismic resistance using dynamic and quasi-static loading. The pile in unimproved soil provided larger displacements with limited lateral force resistance. This pile was subjected to lateral displacements of up to 400 mm, but experienced minimum inelastic actions. On the other hand, the pile in improved soil reached its lateral capacity at a displacement of 100 mm, at which point the critical region at the base of the pile just above the improved ground experienced buckling and fractured due to low cycle fatigue. Compared to the pile in unimproved soil, the improved ground increased the system strength by 42%. Although the soil was improved over 2900 mm, the effective improvement depth was approximately 1300 mm below the ground surface. In this paper, it is demonstrated that the effects of block type soil improvement of limited horizontal and vertical dimensions can be described using a simplified theoretical approach involving a modification to the well-known p-y representation of soil response. An example using this method is presented and shown to give adequate support to a standard 12-inch diameter steel pipe pile embedded in soft soil.

By Jin-Wei Huang, Bradley J. Fleming, Sri Sritharan

"Although soil improvement and its application to deep foundations is gaining popularity in the engineering community, this technique is not widely used in high seismic regions due to lack of fundamental understanding of both the behavior of improved soils under high-strain cyclic loading and the interactions between the pile, improved soil, and unimproved soil. This paper describes part of an ongoing Network for Earthquake Engineering Simulation (NEES) project, where two identical full-scale steel pipe piles were driven at a soft clay site in Oklahoma. The soil surrounding one of these piles was improved using the cement deep soil mixing technique in order to enhance its lateral load behavior. Both piles were tested for seismic resistance using dynamic and quasi-static loading.The pile in unimproved soil provided larger displacements with limited lateral force resistance. This pile was subjected to lateral displacements of up to 400 mm, but experienced minimum inelastic actions. On the other hand, the pile in improved soil reached its lateral capacity at a displacement of 100 mm, at which point the critical region at the base of the pile just above the improved ground experienced buckling and fractured due to low cycle fatigue. Compared to the pile in unimproved soil, the improved ground increased the system strength by 42%. Although the soil was improved over 2900 mm, the effective improvement depth was approximately 1300 mm below the ground surface.In this paper, it is demonstrated that the effects of block type soil improvement of limited horizontal and vertical dimensions can be described using a simplified theoretical approach involving a modification to the well-known p-y representation of soil response. An example using this method is presented and shown to give adequate support to a standard 12-inch diameter steel pipe pile embedded in soft soil,IntroductionPilings are the preferred foundation support for many civil engineering structures including highway bridges, railroad bridges, and port wharves. These structures and their foundations are subjected to forces created by earthquakes, wind, waves, water current, vessel impact, ice, and gravity. All loads applied to the superstructure must be transmitted to the foundation where they are resisted by the surrounding soil. With significant lateral loads, use of pile foundations may be the only solution to transmit large structural loads to competent soils. Piles supported by competent soils are relatively easy to design and costs are often attainable. However, thick layers of weak soils such as soft clays are widespread in high seismic areas (e.g., San Francisco, southern Nevada, Washington, Eastern Missouri, and Arkansas), exacerbating design challenges. Soft clays reduce the lateral resistance of the pile-soil system, making the pile foundation less cost effective. In this case, the current design practice is to use an increased number of larger diameter piles, which is a costly alternative (see SDC, Caltrans 2010). An innovative and more cost-efficient solution to this problem is to improve the soil within a short depth surrounding the foundation, thereby increasing its lateral stiffness. Some well-known methods for improving soil include deep soil mixing, stone columns, and simple soft soil replacement with select granular material."

Jan 1, 2017

By Frank Rausche

Why testing What tests can be done Dynamic load testing Loading device Measurements Analysis Examples

Jan 1, 2001

By Rouzbeh Afsharhasani, Moses Karakouzian, Brandon Kluzniak

"The Vegas High Roller is the centerpiece of a new development parcel adjacent to the Las Vegas Strip. At a height of 550 feet, the High Roller is currently the tallest observation wheel in the world. The design team conducted a geotechnical site investigation to characterize the alluvial soils and cemented layers encountered and to provide foundation design recommendations for the observation wheel, boarding platform, and temporary structures needed to erect the wheel structure. This paper presents a case history of the geotechnical design process, including development of a ground model and design parameters, high-strain dynamic axial load tests, and settlement monitoring during construction. Results indicated that design parameters were conservatively assumed and that the majority of the axial load was transferred to a near surface caliche layer, thereby resulting in insignificant settlement of the foundation system.IntroductionThe engineering of the Vegas High Roller is similar in concept to that of the London Eye and the Singapore Flyer. The wheel has 28 cabins, each with a capacity of 40 persons. The top point of the structure is 550 ft above ground level at the site.A geotechnical site investigation program was undertaken and subsequent analyses were performed to provide foundation recommendations for the observation wheel legs, boarding platform columns, and temporary structures directly associated with construction of the observation wheel."

Jan 1, 2017

By Joel Moskowitz, Jan Cermak

"New York City has unique geologic conditions which must be considered when designing pile foundations. Where shallow foundations are not feasible, the City's subsurface conditions require a variety of deep foundation systems, ranging from high capacity rock socketed piles, to piles end-bearing on bedrock, to friction piles bearing in alluvial or glacial deposits. Pile load testing is essential in confirming pile capacities as pile analyses include assumptions on soil and soil-pile response, and pile driving equipment. Load test results must be interpreted to estimate the long-term pile behavior. Except for lightly loaded driven piles, the New York City Building Code (the Code) requires that pile capacities be confirmed by static load testing. The Code provides the number of static load tests required, test procedures, and acceptance criteria. In the last few decades, methods other than static load testing have been developed including dynamic and rapid (pseudo-static) load tests. Recently, those methods have also been employed on several projects in New York City. The traditional approach to pile load testing in New York City is discussed herein including engineering involved in the analyses of test data with examples. In addition, several projects which included non-static load testing are discussed INTRODUCTIONPile load testing complements the subsurface information and pile design by providing further data on pile-soil interaction for the selected pile type and installation method. Traditional approaches to pile load testing in New York City involve static load tests to verify the design capacity of the piles for a given minimum factor of safety.In the late 1950's, Dr. Phillip C. Rutledge summarized his views on the philosophy of pile foundations in an unpublished, in-house document. He viewed pile foundations as good illustrations of pertinent and impertinent aspects of geotechnical engineering. In the analyses of piles he divided engineering into four general types:(a) Theoretical engineering in which decisions are made based on theoretical analyses. This represents ideal engineering, in which all factors affecting the pile design are well established or, at least, few simplifying assumptions with known effects on the analyses are made."

Jan 1, 2005

By Robert E. Schock, Eric J. Risberg

"Less than 20,000 years ago, the last of the glaciers retreated from the Chicago region. They left behind sheets of glacial clay till underlain by dense, over-consolidated till (“hardpan”) below which is the limestone bedrock, found about 100 ft (30.5 m) below street level. The most notable feature in this profile is the unusually soft clay till that has historically been called “Chicago Blue Clay.”But the founding fathers of Chicago really didn’t care about what was under the ground. They recognized the importance of the city’s location as a potential trade and transportation hub. With access to the East through the Great Lakes and access to the West through the Mississippi River system, the viability of the city was evident. Chicago’s population grew rapidly. The city continued to grow through the Civil War years, but was dealt a devastating blow in 1871 by the Great Chicago Fire, leaving the city in ruins. The Birth of the SkyscraperAfter the cleanup of the Great Fire came the first real building boom in Chicago’s history. During this era, buildings were generally founded on shallow footings bearing on sand or clay. Many multistory buildings were constructed between 1880 and 1890 on spread footings. The first tall buildings were constructed with load bearing masonry walls. These early tall buildings suffered significant settlement as the soft clay underwent consolidation.The Home Insurance Building, built in 1885, was 12-stories tall and is generally acknowledged to be the first “skyscraper” in the U.S. It was the first building constructed with an iron skeleton frame instead of load bearing masonry walls. Spread footings were used under the interior columns in an effort to better distribute the loads, but the building still experienced large settlements.Construction began for the Monadnock Building in 1891. The 17-story building was built using load bearing walls 7 ft (2.1 m) thick, supported on rail-grillage footing foundations. When completed in 1893, the Monadnock Building boasted the title “World’s Largest Office Building.” The total building settlement over the past 125 years has been measured at over 20 in (0.51 m). The engineering community in the late 19th century observed settlement, but did not yet understand the process of consolidation of the soft clay beneath the city. During this time, many of the new buildings required structural repairs during and after construction; the problem was especially acute in buildings where highrise towers joined lower podium structures."

Jan 1, 2016

By Seiji Mizutani, Hirofumi Taguchi, Makoto Yoshida, Hidenori Takahashi, Naotoshi Shinkawa, Kazuo Konishi, Yoshiyuki Morikawa, Masaya Kawata

"The lattice-shaped cement treatment method has been used to improve the seismic performance of liquefied sandy soil in Japan. The efficacy of the method has been confirmed by the huge earthquake in Japan. In the present study, a new method to improve sandy ground by using the lattice-shaped cement treatment method is proposed as a liquefaction countermeasure. It is the floating-type and lattice-shaped cement treatment method, where cement treated soil is not fixed to an un-liquefiable stratum. In this method, a fixed-type structure such as treated soil should be formed at the side of the floating-type treated soil to reduce its lateral displacement. In the study, one-dimensional dynamic response analyses were firstly conducted to confirm the mechanism of the new method. Secondly, a series of centrifuge model tests were performed to demonstrate the effect in a proto-type scale's stress condition. The analyses and model tests confirmed the effect of liquefaction countermeasure of the new method.INTRODUCTIONLiquefaction induced by an earthquake generates sand boiling and ground settlement. Other problems have also been reported, including a decrease in bearing capacity and an increase in the horizontal earth pressure against retaining walls. To prevent these problems caused by liquefaction of the ground, various countermeasures have been proposed, such as cement deep mixing and high-pressure jet mixing methods. These methods have the big advantage of being applicable to ground that contains soil with a fine-grain fraction. Furthermore, the unnecessary displacement caused by the construction can be reduced. In Japan, a lattice-shaped cement-treatment method has frequently been used at many construction sites to prevent liquefaction, where cement-treated piles are intersected to form a lattice, as shown in Fig. 1. The lattice-shaped walls can reduce the shear stress generated by an earthquake, restricting the liquefaction at that location. However, the construction cost of the cement treatment is relatively high compared to other methods such as the sand compaction pile (SCP) method, and needs to be reduced. Therefore, decreasing the total volume of the cement treatment is necessary to reduce the construction cost."

Jan 1, 2015

By Allen B. Stanton, Parthiv Brahmbhatt, Michael Grimm, Stanley L. Worst

Constructing a circular shaft consisting of secant piles has its own complications which make it more difficult than typical drilled shaft construction. Add to that performing under low overhead powerlines and sitting inside of a 40-foot deep, 50-foot diameter shaft and it becomes more about logistics than the actual drilling. The complexities associated with the Romeo Arm Interceptor Segment 5 Lining project are the focus of this paper, delving into the details that made it work successfully.

Oct 1, 2022

By Bengt H. Fellenius

.1.1 Prior to commencement of pile installation operation, submit to [Engineer] for [approval] [review], details of equipment for installation of piles. SPEC NOTE: The information requested in 3.1 .1.2 is necessary as input to a detailed wave equation analysis of the pile driving. .1.2 For impact hammers, give manufacturer's name, type, maximum rated energy and rated energy per blow at normal working rate during easy and at termination driving, mass of striking parts of hammer, mass of driving cap, and type and elastic properties of hammer cushion. .1.3 For non-impact methods of installation, such as drilling, jacking, jetting, use of vibratory hammers, or other means, give full details of characteristics necessary to evaluate performance. .2 Impact Hammer SPEC NOTE: Do not exclude a hammer type unless for very specific reason. .2.1 [Drop hammers will not be permitted.] [Diesel hammers will not be permitted.] For final driving of [TYPE] piles, provide a hammer capable of delivering to the pile a non-erratic impact stress not smaller than [VALUE] Pascal and transferring a non-erratic energy not smaller than [VALUE] Joules per blow to the pile head at normal working rate.

Jan 1, 1991

By Terrence M. Carroll, Chu E. Ho

"A pile installation and load testing program on driven tapered piles was undertaken at John F. Kennedy International Airport in New York City for the extension of the existing Terminal 4. As part of the program, dynamic testing by means of the Pile Driving Analyzer (PDA) was performed on several preliminary test piles as well as production piles. The results of the dynamic tests and subsequent static load tests were reviewed to develop an understanding of the pile-soil response of a tapered pile during driving and after setup. Pile setup occurred as a result of increase in shaft resistance with virtually no increase in toe resistance. More than 150 tons of additional capacity was gained after the setup time.The capacities measured during driving from the PDA are typically used as the basis for determining the pile driving set criteria, with the required initial driving capacities determined largely by the contractor’s experience. An improved appreciation of the setup phenomenon is required to better refine the driving criteria at the end of initial driving such that the required ultimate capacities can be obtained, with reasonable confidence, after a period of setup.This paper presents interpretation of pile-soil behavior from Case Pile Wave Analysis Program (CAPWAP) analyses and discusses the mechanism of increased capacity as a result of setup effects. Time-dependent capacity gain as a result of setup effects should be based on the extrapolation of the shaft resistance component rather than the total pile capacity as is commonly practiced. Prediction of pile performance using this approach was in good agreement with observed static and dynamic load test results.IntroductionTapered piles have been adopted for various projects at John F. Kennedy International Airport (JFKIA) since the late 1940’s. Initially timber piles were used exclusively, with steel Monotube piles being used from at least the 1980’s (Horvath and Trochalides, 2004). The steel Tapertube pile was developed in the mid-1990’s and has commonly been used in recent construction (Brusey and Yin, 2008). The Tapertube piles used for this project consisted of a 25 foot long tapered section that was 8 inches in diameter at the tip and 18 inches in diameter at the top. An 18 inch diameter straight pipe was welded above the tapered section."

Jan 1, 2015

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

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

Jan 1, 2015

By Stefan Larsson, Jan Ekström, Jennie Kock-Larsen, Håkan Garin

"This paper describes the testing procedure (or protocols) for quality control of dry deep mixing columns in a major ground improvement project carried out in Sweden. Quality control was mainly based on column penetration tests performed at different stages in the project and on two occasions after installation. In the paper, the results from the tests are compared with tests on the unimproved clay. As expected, the results show that the correlation between undrained shear strength in the columns and in the unimproved soft soil depends mainly on the in-situ stress. However, the correlation probably depends on when the tests were performed after mixing. When the influence of the in-situ stress was excluded from the analysis, no significant correlation could be identified. This means that the undrained shear strength in the columns and in the unimproved soft can be considered to be uncorrelated when the strengths and the corresponding variability are evaluated with depth from groups of tests.INTRODUCTIONQuality control and quality assessment of deep mixing (QC/QA) constitute a key component in verification of the limit state design. Due to the complex mixing process and varying geological conditions, it is normally not possible to sufficiently assess the strength and deformation properties in advance. In Sweden, the most commonly used QC/QA method for verification of the limit state is the column penetration test (Axelsson and Larsson 2003; Bergman et al. 2013). The method works well but is time-consuming and requires many tests since property variability is normally high. The column penetration test can be used to assess the undrained shear strength Cu,col. However, it is not clear how the strength correlates to the undrained shear strength of the unimproved soil Cu,soil. There are common factors such as the in-situ stress state and the natural water content, which makes a positive correlation probable, i.e. as Cu,soil decreases, Cu,col also decreases and vice versa. The unimproved soil has a natural spatial variability, but it is not known if the improved soil follows the same variation. The mixing process has a substantial influence on the strength variability and may supersede the influence of other factors. However, if a sufficiently good correlation exists between Cu,col and Cu,soil, information from the geotechnical ground investigations can be used in the design and planning of QC/QA of deep mixing in a more stringent manner. Information about the correlation is also essential in reliability based design, where a strong positive correlation may have a negative influence on reliability. However, as discussed by Al-Naqshabandy and Larsson (2013), this correlation may be weak or insignificant for a representative failure domain where the mixing process may have a dominant influence on the strength variability. It is thus of interest to assess the correlation."

Jan 1, 2015