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By Andrew J. Brennan, Jonathan A. Knappett, Lewis Hamilton, Michael J. Brown

"Abstract This paper investigates the compressive behaviour of screw piles in sands and the key design parameters which control this. These types of foundation elements have typically been used as screw anchors onshore (i.e. for their tensile capacity), but there is increasing interest in their potential use as compression piles for supporting offshore marine renewable energy (MRE) devices (e.g. wind and tidal turbines) in deeper water. For such foundation applications, the compressive capacity is as important as the tensile capacity and is not well understood, particularly in cohesionless soils which are a likely seabed condition in MRE applications. A 1-g laboratory study was initially conducted on small scale model screw piles in sand beds of various relative density between 25 – 88%. These experiments were used to validate a Finite Element (FE) model having a stress-dependent constitutive model, making it useful for future up-scaling of the pile size for field applications. Following validation, the FE model was used to conduct a parametric study on the effects of flange spacing ratio (s/Dflange) and flange to shaft diameter ratio (Dflange/Dshaft). By using a validated FE model for this study, it was possible to observe the failure mechanisms (through the shear strain distribution) within the soil and correlate these with the pile capacity. This information was then used to comment on the most optimal (cost-effective) pile design for supporting compressive loads. This study represents a key step towards producing design tools appropriate for the design of screw piles in MREapplications.IntroductionAs defined in this paper, screw piles consist of a central small diameter hollow steel shaft, around which thin circular steel flanges run. Their principle of operation is that the flanges are spaced so as to trap the soil between them, thereby acting as an equivalent solid pile of the outer flange diameter, with a fully-rough ‘shaft’ interface (as shearing is soil-soil). One of the most important design decisions relates to the spacing of the flanges – if the flanges are spaced too far apart, then the soil will not be effectively trapped and the pile have a lower axial capacity and stiffness (controlled by the shaft friction along the central shaft and the bearing resistance arising from the individual flanges; If the flanges are spaced too close together, then there are potentially flanges which are not contributing to the pile capacity, therefore making the pile more expensive than it needs to be."

Jan 1, 2014

By Gustavo E. Armijo

This job was done in Morristown, NJ, with mono fluid system jet grouting for the construction of a new bank building. After the demolition of the existing two story structures, an excavation in loose sandy fill materials was necessary in order to reach the new structure basement level. Due to this jet grouting was selected as a medium to provide both excavation support and permanent underpinning, minimizing the adjacent building settlements. These two adjacent buildings were partially underpinned with a "gravity wall" made with 2 and 3 rows of secant vertical and inclined jet grout columns. Besides the classical jet grouting control methods, during the jet grouting execution, all the drilling and grouting parameters were recorded by a proprietary system called "Slogger". Additionally, after the jet grouting execution, an innovative result control technique was used by means of the application of the same parameter recording system. Some of the production columns were re-drilled and a comparison was made between the obtained drilling parameters and those obtained for the same age test columns. Under the referred existing conditions and in comparison with the conventional underpinning techniques, this project demonstrated that jet grouting, with proper execution and result control, can be faster than them and can maintain the building structural stability and act, at the same time, as a retention system minimizing the existing building settlements.

Jan 1, 2002

By Amaneh E. Kenarsari

Among the different sources of uncertainty in pile bearing capacity prediction including inherent heterogeneity, measurement and model uncertainties, the inherent heterogeneity of soil properties is of particular interest and is considered in this study. Cone tip resistance data are utilized to calculate pile bearing capacity by considering vertical soil variability. In this regard, cone tip resistance component of CPT data is assumed as a random parameter. Realizations of this parameter are achieved with the aid of local average subdivisions and random field theories. Monte Carlo simulation is used to generate different realizations of CPT or CPT-u data. Pile bearing capacity was then calculated by the use of direct method. Pile bearing capacity are predicted for a project in south of Iran using this method and probability density function for the total bearing capacity of pile is plotted. Coefficient of variation of 33% for ultimate bearing capacity shows the variability of bearing capacity due to variation of soil strength in depth. Cumulative probability chart for the ultimate bearing capacity are plotted as an efficient tool for estimating ultimate bearing capacity of piles with different desired confidence levels for vertically variable soil strength properties. Significant difference between mean value of pile bearing capacity (18 MN) and limit with 95% confidence level (8 MN) emphasizes the importance of considering soil variability.

Jan 1, 2011

By Wesley Schmutzler

The Deep Mixing Method (DMM) was employed to raise and support the LPV (Lake Pontchartrain and Vicinity) -111 Levee in New Orleans. Even using innovative technologies, the tight schedule to achieve the 100 year elevation by June 1, 2011 was a daunting endeavor. The size and scope of DMM proposed for LPV-111 was on a scale never attempted outside of Japan. Over 1.65 million cubic yards of DMM was installed. LPV-111 is adjacent to the Bayou Sauvage Wildlife Refuge, which is the largest urban National Wildlife refuge in the United States. By utilizing DMM to control settlement and improve stability of the taller levee, side slopes were steepened from the conventional 1V:4H to 1V:2.85H, thus avoiding encroachment into the Bayou Sauvage and reducing the amount of clay needed for the completed levee. The COE utilized Early Contractor Involvement (ECI) for this contract. The ECI process allowed for input from the DMM contractor, TREVIICOS South, in order to optimize equipment resources and material requirements. This paper gives an overview of the extensive DMM requirements for LPV-111 and explains the benefits of the ECI process.

By Adriaan van Seters

"Abstract The content of Eurocode 7 – Part 1 and Part 2 – with respect to piled foundations is outlined. The important role of pile testing is presented and the derivation of the characteristic value of pile bearing resistance is explained. Recommendations for the use of correlation factors are given. The ongoing work of the Evolution Groups on piling is to prepare a revision of Eurocode 7 after 2019. Future topics and changes are highlighted.General outline of pile design by Eurocode 7In his paper for this conference Frank (2014) outlined the various aspects of standardisation for pile foundations, which involves Eurocode 7 as leading for pile construction in Europe. Standards for pile testing and execution of piling works were established in the last 15 years.This paper focuses on the design of piled foundations according to the design code Eurocode 7, which consists of 2 parts:EN 1997-1 Geotechnical design - Part 1: General Rules (CEN, 2004);EN 1997-2 Geotechnical design – Part 2: Ground investigation and testing (CEN, 2007) In Eurocode 7-1, Section 7 – Pile Foundations - deals with the design of piles. The safety concept for pile design is given in Section 2 – Basis of Geotechnical Design - for the three Design Approaches.In Section 7 presents the design of piles according to four methods:1. Results of static load tests2. Empirical or analytical calculation methods3. Results of dynamic load tests4. Observed performance of a comparable pile foundation.Guidelines for the ground investigation for piles is provided in Eurocode 7-2, Annex B.3. In the Annexes of Eurocode 7-2 examples of analytical methods to determine the bearing resistance of a single pile based on the results of various ground investigation techniques are given. Thus calculation models are presented based on design using the results of Cone Penetration Tests (D.6 and D.7) and Pressuremeter Tests (E.3). The Annexes of Eurocode 7-2 are informative.For the interpretation of Eurocode 7, reference is made to Frank et al (2004) and Bond and Harris(2008)."

Jan 1, 2014

By K. Viking

This article deals with some of the civil engineering related problems to be encountered when offshore wind energy projects transform from prototype offshore wind energy converter farms, developed and installed during the 1990?s, to commercial farms that?s currently planned to be built. The offshore wind energy converter (OWEC) installations encounter a wide range of problems, only partial of these are geotechnical. In Europe both onshore and offshore wind farms have, from a historical point of view, usually been founded by using the monopole technique, installed with traditional impact hammers, or by using gravitational foundations. However, the rapid development of bigger turbines and larger wind farms, together with increasing considerations of fatigue aspects, has lead to financial benefits of developing and exploring other foundation techniques. This paper reviews some Scandinavian experiences regarding critical components of the design phase in relation to connecting the superstructure to the ground, and some of the main considerations of how the loads applied to the structure are transferred to the surrounding soil.

Jan 1, 2013

By Masanoub R. Fujioka

A brief discussion of the methodologies involved in dewatering practices, particularly as used in Hawaii in coralline formations. A description of early dewatering practices includes a number of case histories; later dewatering practices also are detailed with case histories. There were disasters and some successes. Grouting generally was not successful. Deep wells are technically feasible and generally the economical solution to deep basement construction.

Jan 1, 1986

By Raffaella Granata, Wesley Schmutzler, Matteo Bertoni

"The Lower Wood River Levee system, at the confluence of the Wood River Creek and the Mississippi River, in East Alton, Illinois, has been plagued with underground seepage and, in 2010, remediation was deemed necessary by the Southwestern Illinois Flood Prevention District Council and the United States Army Corp of Engineers (USACE). The experts enlisted by the council produced a design that provided for constructing a cutoff wall approximately 2,000 feet long and up to 140 feet deep, through alluvial and outwash soils, and embedded in bedrock. This paper will describe the challenges faced by the Quality Control (QC) and Quality Assurance (QA) teams due to the complex nature of the project in conjunction with an extremely thorough QC/QA program.INTRODUCTIONThe “American Bottom” is an area of 453 km2 (175 square miles) in Southwestern Illinois, extending from Alton south to the Kaskaskia River, which is home to 156,000 people. In the 1940s and 1950s the U.S. Army Corp of Engineers (USACE) designed and built a 120 kilometer (74 mile) long levee system to protect the area from a 500-year flood event on the Mississippi River, which flows through it. The levee system has been plagued by under-seepage for several years. The phenomenon has worsened to varying degrees, depending on location, to the point that remediation was needed.The Southwestern Illinois Flood Prevention District Council (SIFPDC), to obtain Federal Emergency Management accreditation, in June 2010 commissioned a team lead by Amec Foster Wheeler for the design and management of the required levee improvements. The team presented in 2011 the project’s first set of drawings showing proposed design features throughout the levee system. The project was subdivided in four areas, based on the controlling levee districts, one of which, the Wood River Drainage and Levee District, was split into three subdivisions: Upper Wood River, East-West Forks of Wood River, and Lower Wood River.The project included the installation of a cutoff wall at the confluence of the Wood River and the Mississippi River in East Alton, IL (Fig. 1). The Engineer of Record (Amec Foster Wheeler) considered the cutoff wall as the only viable solution to stop the severe under-seepage that was undermining the integrity of the Lower Wood River Levee. The Lower Cutoff Wall (LCW) project is the subject of this paper."

Jan 1, 2017

By António A. Henriques, António Gomes Correia, Ana Teixeira

"Abstract Pile foundations are often used for important structures, and thus, reliability evaluation is an important aspect of the design. Reliability methods have become increasingly important as decision support tools in different areas. The main benefit of reliability analysis is that it provides quantitative information about the parameters (uncertainties) that most significantly influence the behaviour under study. In particular, the design of pile foundations still involves many limitations and uncertainties, particularly when there is not enough investment in soil characterisation and/or pile load tests. In addition to the uncertainties associated with soil characterisation, physical, statistical, spatial and human uncertainties exist. In this subject, the primary purpose of this paper is to demonstrate the application of reliability methods to geotechnical pile design (axial load). It also presents a simple and practical approach to performing it using Monte Carlo Simulations, intending to provide knowledge for code harmonisation and encouraging the development of such methodologies in geotechnical practice. Sensitivity analyses are shown to understand the influence of each uncertainty type coming from different sources. An application example indicates, corroborating other studies, that the model error is the most influent uncertainty. As such, when using the different models (SPT-, CPT- and PMT-based) for bearing capacity, the results emphasise the need for a well-defined and wellcharacterised resistance model, also these results allow the engineer to understand how important the load tests can be to achieve reliable results and economic designs.1 IntroductionUnlike the approach to reliability evaluation used in structural engineering, the traditional procedure used in geotechnical designs addresses uncertainties through high global or partial safety factors (SF), mostly based on past experience. However, this approach to addressing uncertainties does not provide a rational basis for understanding their influence on design.Furthermore, the new regulation codes and social concerns, such as the sustainability or the economy, are imposing geotechnical engineers to increase their ability to deal with uncertainty in a direct and more rational way. Designs should be economic, sustainable and reliable at the same time. Concerning the reliability part of design, different approaches can be done, but the most important thing to keep in mind is the simplicity and efficiency of the tools and applied methods."

Jan 1, 2014

By Brock Wallis, Steve Davidow

The following text will present the concept of rock socketed drilled shafts used to support electrical substation structures, and discuss the cost and schedule risks that traditional design responses to unforeseen shallow rock can pose to a project. Design considerations will be detailed, including rock characterization, shear strength of drilled shafts, and modeling lateral resistance of the shaft and surrounding rock. The specific case of drilled shafts installed for heavily loaded structures at the Moxie Freedom Substation will provide an example of how close collaboration between the engineer and contractor to refine designs based on site-specific feedback can provide tangible benefits to the project. In this example, value engineered designs resulted in an approximate 40% reduction in shaft/concrete volume and a 60% reduction in total rock socket depth. PROJECT OVERVIEW The Moxie Freedom Project included the construction of a new 500 kV switchyard in Berwick, Pennsylvania. The foundation contractor was selected to install both small and large diameter drilled shaft foundations to support the structures within the switchyard. The small diameter shafts were utilized to support transformers, switches, bus supports and a static mast, while the large diameter shafts were used to support one 180-foot monopole and six H-Frame structures. CHALLENGES: ROCK SOCKETED DRILLED SHAFTS Available geotechnical data at the time of bid included limited borings and seismic refraction. The borings were not located at every structure, and the contractor and design engineer were left to interpret desktop studies and geophysics to determine the probable site-specific conditions at each foundation. The data suggested substantial variability in the quality and depth to bedrock across the project area, indicating significant risk of deep embedment into bedrock at all seven large diameter shaft locations. Rock socketed drilled shafts pose unique challenges for both designers and contractors, and the topic has become a focus of national foundation organizations. Traditional design models result in deeper and/or larger diameter shafts where rock is encountered. In the case where site-specific geotechnical conditions are not clearly understood and rock is encountered at shallow depths, this can lead to significant additional rock drilling, impacting overall project cost and schedule. Rock drilling can result in more than ten times the cost of soil drilling and can easily take in excess of ten times longer to excavate.

Jan 1, 2018

By G. T. Hong

A numerical model for use in design is developed to predict the stresses and axial and bending displacements in a drilled pier in expansive soils. The prediction is based on the horizontal swelling pressures and uplift forces which act on the side of the drilled pier. The exponential suction envelope with the depth within the moisture active zone is estimated based upon the equilibrium suction, moisture diffusion coefficients obtained from laboratory tests, and minimum suction at the ground surface of the site based on field conditions. The volume change of soil is based on suction variations, soil properties, overburden pressures, crack influences, and the relationship between moisture contents and suctions. Considering the movement active and anchor zones on a soil-pile system in expansive soils, horizontal swelling pressures are formulated using the shear strength of an unsaturated soil and the Mohr?s circle and failure envelope. The movement active zone has two sub-zones in which horizontal swelling pressures are attributed to passive earth pressure failure and suction change in the upper and lower sub-zones, respectively. Horizontal swelling pressures which occur in the anchor zone are assumed to be in the at rest condition. The shear stress generated on the vertical surface of a drilled pier is supported by the nonlinear curves of load transfer versus relative displacement. The axial behavior and lateral bending of the pier in expansive soils are simulated using a beam column approach. The computed axial and bending displacements and stresses are used to provide structural design of the pier. Figures of computed results for typical cases are presented.

Jan 1, 2007

By A. Mazzucato

This paper presents the experimental results of driving and load tests on an instrumented pile driven into a test pit filled with fine homogeneous sand.

Jan 1, 2010

By Lisa M. Splitter

Drilled displacement piles were constructed as the foundation for a proposed 10-story building in San Francisco, California. At the study location, the stratigraphy consists of 14 to 21 feet of fill and 13 to 23 feet of weak, compressible clay (?Bay Mud?), underlain by dense sand, stiff clay, and bedrock. A sensitive critical public utility is located within approximately 20 feet of the constructed piles along one side of the building. The utility pipeline is entirely within the Bay Mud where it is adjacent to the project site. The San Francisco Public Utilities Commission (SFPUC) developed limits on the allowable total and differential movement of the utility pipeline. As requested by the SFPUC, inclinometers and piezometers were installed to monitor the soil movement and pore pressure increases in the Bay Mud caused by the installation of drilled displacement piles. Action levels were set such that if displacement and/or pore pressures reached an action level, the installation methodology would be reevaluated and additional measures to reduce these effects would be implemented. This paper will present the sequence of pile installation near the pipeline and monitoring points, and the data collected from inclinometers and piezometers at variable depths and distances from the piles. The data will highlight the build-up and dissipation of pore pressures over time and the displacement of Bay Mud caused by the pile installation. The conclusions of the study are useful in determining sequencing, spacing, predrilling, and other measures that can be implemented to decrease the displacement potential and pore pressure build-up in soft clays.

Jan 1, 2009

By Y. C. Han

The advances in seismic design considering soil-structure interaction or soil-pile-structure interaction are described using a substructure approach. The nonlinearity of soil is considered approximately using a boundary zone model with non-reflective interface, and computer programs are available for practical applications. The validation of model is confirmed with dynamic tests on piles in the field, and the results for a single pile are used to compare with the predictions in this study. The liquefaction for sand soil layer can be accounted for, and a case of liquefaction is discussed. Two practical examples are examined, a vacuum tower structure supported on foundation of steel pile group and a table top structure supported on foundation of concrete pile group. To illustrate the effects of soil-pile-structure interaction on the seismic response of vacuum structure, different base conditions are considered, rigid base, i.e. no deformation of the foundation; linear soil-pile system; and nonlinear soil-pile system. The method introduced can be applied to the design of tall buildings, bridges, industrial structures and offshore platforms with soil-pile-structure interaction under seismic or dynamic loads.

Jan 1, 2010

By Paul J. Axtell

Two new railroad bridges in Kansas City, Missouri are founded on drilled shafts embedded into the soil and underlying shale. The uncertainty arising from the non-homogeneous, anisotropic nature of most shales, and the variability of shales across the U.S., makes it a difficult material to assign appropriate design properties. As was the case on this project, the uncertainty of foundation performance in shale can lead to overly conservative designs, particularly with drilled shaft foundations. An extensive Statnamic axial testing program was performed to verify that the load-settlement behavior of the drilled shafts would be acceptable for the intended railroad traffic. Axial Statnamic testing was applied in three increasing cycles of 927 kips, 1007 kips, and 3177 kips, respectively. The maximum movements recorded at the shaft head during each of the loadings were 0.052 inches, 0.062 inches, and 0.257 inches, respectively. The loads applied in each of the respective Statnamic tests were not sufficient to reach the capacity of the shaft; so direct comparison of measured and calculated capacities is not possible. However, evaluation of the estimated design capacity can be accomplished based on results from the Statnamic testing program by utilizing normalized load transfer relations presented by O?Neill and Reese (1999). Such comparisons necessarily require extrapolation of the data measured in the Statnamic tests following typical load-displacement response. Results indicate the Kulhawy and Phoon (1993) method for estimating side resistance in Pleasanton shale rock sockets, assuming a smooth socket, appears to agree well with observed behavior during Statnamic testing. Accordingly, the O?Neill and Reese (1999) method for estimating the toe resistance in intermediate geomaterials, assuming cohesive rock with Rock Quality Designation (RQD) between 70 and 100, appears to agree well with observed behavior during Statnamic testing. Finally, based on Statnamic testing at varying load magnitudes and normalized curves developed by O?Neill and Reese (1999), the contribution of side resistance to the capacity of a deep foundation can be determined assuming no load is transferred to the base of the foundation during lower magnitude testing. Furthermore, higher magnitude testing can provide a means to evaluate the accuracy of design end bearing calculations.

Jan 1, 2006

By Timothy C. Siegel

In response to a solicitation for ground improvement for the construction of a new hospital in Owensboro, Kentucky, the team of Berkel & Company Contractors and Dan Brown and Associates PC designed and installed lightly reinforced cast-in-place piles (known commercially as Cast-in place Ground improvement Elements or CGEs) as part of a composite ground system. The concept of the design is that the structure load is shared between the piles and the soil subgrade. The load sharing is controlled (to some degree) by the placement of a cushion between the pile head and the bottom of the overlying spread foundation. In an effort to confirm the design principles and to better understand the behavior of composite ground, the design-build team performed plate load tests on ground with a single CGE and with a group of CGEs. The small plate test (on ground with a single CGE) characterized the stiffness of the cushion. The large plate tests showed that the cushion will distribute the applied load to the CGEs and to the soil subgrade between the CGEs. On the basis of the plate tests, it was concluded that the plate stiffness can influence the test results. The use of a concrete layer was effective at supplementing the plate stiffness. The cushion was shown to be an important component of a composite ground system by allowing mobilization of the soil subgrade resistance and avoiding a stress concentration at the tops of the CGEs that would otherwise be present if the spread foundation and piles were rigidly connected. Because the composite ground system engages the resistance of the soil subgrade, the structural demand is reduced and consequently there is a potential for savings when compared to a conventional pile foundation. Several foundations for the new Owensboro hospital are being monitored for vertical movement during construction of the superstructure that will extend through 2011. At the time of this paper (mid 2011) the settlement of the foundations due to only part of the structural load (primarily the structural steel) has been negligible.

Jan 1, 2011

By Jogeshwar P. Singh, Ahmed AlaaEldin, Mohamed Ashour

The presented methodology allows the determination of the response of laterally loaded battered long piles in sandy soils based on the soil-pile interaction. The Strain Wedge (SW) model which was originally developed for laterally loaded vertical piles is modified to assess the behavior of laterally loaded battered piles with the consideration of soil and pile properties. The method predicts the pile-head response and associated p-y curves. The presented soil-pile model accounts for the variation of the direction and magnitude of the batter angles from the vertical position. Unlike current practice, the proposed technique also provides the p-y curves for battered piles in sandy soils based on soil and pile properties (i.e., sand relative density, friction angle, pile geometry, etc.). The proposed methodology has been validated through a number of comparisons with full/model-scale pile load tests. INTRODUCTION The influence of pile battering on the lateral response of piles is rarely studied in the literature. Over the last decades and as suggested by Kubo (1962) and Zhang et al. (1999), a p-y multiplier is applied to predict the response of laterally loaded battered piles from an equivalent vertical one. Several researchers conducted model-scale piles load tests to understand the behavior of battered piles subjected to lateral load (Juvekar and Pise 2008; Meyerhof and Ranjan 1973; Meyerhof and Yalcin 1994). However, such tests were conducted on model piles with diameters less than 30 mm which may not have reflected actual soil-pile interaction. Battered piles are generally categorized as positive or negative battered piles according to the angle of pile installation as shown in Fig. 1. From the small-scaled and numerical models of battered piles, it was found that the lateral capacity of negative battered piles is larger than that of vertical ones. On the other hand, the positive battered piles have lower lateral capacity when compared to vertical piles (Fan-ren and Ji-Ming 2011; Juvekar and Pise 2008; Manoppo 2010; Reese et al. 2004; and Reese and Van Impe 2011).

Jan 1, 2018

By Van E. Komurka

This paper presents a cost comparison of the driven pile foundations for two large Wisconsin Department of Transportation (?WisDOT?) projects in Milwaukee, Wisconsin: the Marquette Interchange South Leg, and the Canal Street Viaduct. The projects? geology is fairly similar, but their methods/approaches to pile foundation design and installation differ. Although the Marquette Interchange South Leg had deeper poor soils, its pile design was more-cost-effective than the Canal Street Viaduct?s. Potential reasons for cost differences between the projects are identified, and the effect of the different design and construction approaches on economics is discussed.

Jan 1, 2009

By D. P. Nicholson

The current phase of office development at Canary Wharf in the London Docklands includes twelve multi-storey buildings varying from eighteen to forty stories in height. The area of Canary Wharf South comprises five multi-storey buildings with low level in fill podium and garden areas. Three of these multi-storey buildings have "pile-cap" designs where the entire building load is applied to the piles. The remaining two buildings have "piled-raft" designs where allowance is made in the design for part of the building load to be transferred to the raft formation. Using a piled-raft design approach has enabled savings to be made on the number of piles used below the raft. This paper describes the calibration analysis undertaken to validate the design method. The ground conditions at the Canary Wharf site are typically fill and recent gravel deposits over the overconsolidated clay and sand of the Lambeth Group. Below these strata is the Thanet Sand. The Lambeth Group provided the founding layer for the raft and contributed to the pile shaft resistance. The Thanet Sand stratum provided the bearing layer for the 1.5m diameter base grouted bored piles. The piled-raft design required an assessment of the building load transfer through the raft to the formation layer. This load transfer led to significant increases in effective stress in the soil below the raft and thence a corresponding increased the capacity of the piles. This interaction of the raft with the prepared formation contributed to between 27% and 45% increase in total vertical load carrying capacity of the piled-raft substructure compared with the pile-cap design method. The development of the piled-raft design was carried out in three main phases: ? Development of the approach and validation analyses. ? Design work on various schemes resulting in detailed design packages. ? Validation analyses using full 3D finite element analysis (presented herein). The validation of the piled-raft design approach was initially carried out against published case histories for piled-raft interaction. To improve on the validation work a full 3D finite element analysis of a simplified pile raft and superstructure (which contributes stiffness to the raft) was undertaken; the analysis included only a quarter of the structure due to assumed symmetry of the structure and vertical loading. This 3D validation analysis is presented herein. The analysis was carried out using the Oasys LS-DYNA finite element program. Prior to carrying out the analysis of the piled-raft an initial finite element analysis was carried out to back analyse a fully instrumented field pile test providing accurate modelling of a single pile performance. This back analysis allowed confidence in the soil parameters used in the 3D model; comparisons of shaft and base resistances between the pile test and the FE model calculations for the single pile are presented. The parameters provided in this work were then carried into the full 3D model of the piled-raft. The 3D model of the piled-raft structure included 18 piles (12 full piles and 6 half piles on an axis of symmetry of the model).

Jan 1, 2002

By Trevor L. L. Orr

"AbstractThe background to the harmonization of geotechnical standards that has taken place in recent years in Europe has been the move to more economic and political integration following World War II that has led to the formation of the European Union. Prior to 2010 the standards used in the European countries for geotechnical design, investigation and testing and for the carrying out geotechnical work, such as the installation of piles, were the different national standards, which were not harmonized. The harmonization of geotechnical standards in Europe started in 1981 with work on a model Eurocode 7 for geotechnical design that led eventually to publication by CEN, the European Committee for Standardization, of the European Standard version of Eurocode 7 in 2004. In parallel with the work on Eurocode 7, a large number of associated harmonized standards have been, and are being, prepared by CEN and by the International Standards Organization (ISO) for geotechnical investigation and testing and for the execution of geotechnical works. Standards published by CEN must be adopted by the CEN member countries and all conflicting standards withdrawn. Hence all the CEN countries have adopted the same the harmonized text of Eurocode 7, but with National Annexes that allow national choice with regard to Design Approach and partial factor values. The adoption of Eurocode 7 and its associated geotechnical standards has removed the barriers to geotechnical activity in Europe due to the presence of different national standards. It has also enhanced the ability of EU firms to compete in the global market.Background to harmonization of geotechnical standards in EuropeThe initial moves towards the harmonization of geotechnical standards in Europe can be related to the economic and political developments that took place in the period immediately following World War II to revive the economies of Western Europe. Europe at that time was divided by a political and, in many places, a physical barrier, known as the Iron Curtain, into two very different and separate zones: communist in the east and non-communist in the west. In 1952 the European Coal and Steel Community (ECSC) was formed, linking 6 countries: Belgium, West Germany, France, Italy, Luxembourg and the Netherlands, and establishing a common market in coal and steel. The ECSC was the first international organization to be established on the basis of supranational principles whereby negotiated power is delegated to an authority by the governments of the member states. In 1957 the ECSC became the European Economic Community (EEC), also known as the Common Market in the English-speaking world, with the aim to bring about economic integration. With the addition of Denmark, Ireland and the UK in 1973 and Greece in 1981, followed by Portugal and Spain in 1986, this led to the formation of the European Union (EU) in 1993. East and West Germany were reunified in 1990, following the fall of the Iron Curtain in 1989. In 1995, Austria, Finland and Sweden joined the EU, and since then the numbers of countries in the EU has increased to 28, many of which are countries that were formerly behind the Iron Curtain."

Jan 1, 2014