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By Kazimierz Gwizdala

In the paper the method for estimation of settlement of vertically loaded piles in a group is presented. The method is generally based on the hybrid procedure with non-linear solution for single piles and with interaction between them for the low-strain shear modulus. Some attention is paid to the influence of deformation and strength parameters used in calculations. The applied model is verified in the framework of the research programme carried out recently in the Geotechnical Department of Gdansk Technical University. It concerns monitoring and analysing the settlements of the existing structures on piles. A comparison of calculation and measurements results for two tested buildings is presented as an example.

Jan 1, 2002

By Naresh Koirala

The Greater Vancouver Regional District completed installation of a 2.5 Km long, 2400 mm diameter concrete sewer in Delta, British Columbia in 2000. The sewer traverses through area of peat and soft ground. The ground investigation along the sewer alignment consisted of cone penetration tests and auger drilling with standard penetration tests. The gravity sewer is supported on precast, pretensioned spun concrete piles imported from Malaysia which had never been used for a major project in North America. The capacities of the installed piles were tested using pile driving analyzer (PDA) and three static load tests. A total of 46 PDA tests were carried out during pile installation. The paper describes the pile vetting process the owner went through prior to accepting the piles for use in the project and performance of the piles. It compares the pile capacity estimated from the PDA tests with that estimated from soil mechanics methods using data from cone penetration tests and standard penetration tests. The ranges of estimated capacities calculated by different methods are discussed from design capacity selection considerations.

Jan 1, 2004

By Martin J. Pedley

The use of soil nailing has grown steadily in the UK over the last 15 years and it has recently become more popular in the Republic of Ireland. This paper presents three soil nailing temporary works case histories where the technique has been used to support steep excavations in difficult ground conditions. It demonstrates the effectiveness of soil nailing when applied in appropriate conditions. Details of design methods and construction techniques are described and those aspects of soil nailing that will benefit from further study and development are identified.

Jan 1, 2000

By Za-Chieh Moh

This paper presents a summary of the current pile foundation practice in Taiwan. Constructions of driven piles, drilled shafts, and barrette foundations are reviewed. This paper also briefly summarizes the pile works of four major construction projects in Taiwan, namely, Hsin-Ta Power Plant, Taichung Power Plant, Taipei Transit Systems, and Taiwan High Speed Rail.

Jan 1, 1996

By Shaw-Shong Liew

This paper presents the processes of investigation, analysis, design, construction and monitoring of soil nail stabilisation work to facilitate a 14.5 m deep excavation at an uncontrolled fill ground. An extensive instrumentation programme had been implemented to monitor the performance of the stabilisation solution, to provide validation for the designed nail resistance and groundwater variation. From the monitoring results, it was proved that the soil nail stabilisation technique is effective for loose saturated fill provided that substantial care is taken during implementation. Construction difficulties, solutions to overcome the problems and lessons learned will be discussed in the paper.

Jan 1, 2006

This Workshop was held at the Doubletree Inn, Seattle, Washington from September 26 to 28, 1997. Run under the auspices of the Deep Foundations Institute (DFI), it was co-funded by the newly formed Japanese Association of Micropiles (JAMP), and the Federal Highway Administration (FHWA). The Workshop was jointly organized and facilitated by Fujita Research Corporation and ECO Geosystems, Inc., with close support by Donald B. Murphy Contractors, Inc. DFI kindly consented to publish these Proceedings. As is clear from the list of attendees, 42 specially invited engineers from all aspects of micropile technology were present, representing Japanese, European and American practice. This proved to be a most friendly and interactive group of people, who freely exchanged ideas, views and close comradeship, not only during the technical sessions, but (and especially!) during the numerous social events. Perhaps the best illustration of this came in Day 2 when the attendees were divided into five competing teams, each comprising representatives from the different geographic groupings. These teams had to quickly devise solutions to two technical problems (using standard data previously provided. A team of "referees" (who also acted as "coaches") later determined the most apposite response, based on constructability design concept, cost, schedule and so on. Not only were the winning team very liberal in distributing the prize (vintage California champagne) among themselves, but the whole Workshop soon benefited from their generous division of the spoils of victory.

Jan 1, 1997

By Abhijit Saha

"The stone columns improve the performance of foundations on soft and loose soil due to the ability of composite ground to sustain increased structural loads under reduced settlements. The interaction between the two basic elements: the ambient subsoil and installed column, present a complexity of behaviour, both in terms of applied stresses and resulting strains. Moreover, as the same is provided in-group in a regular array beneath foundations, the performance of an individual column is likely to be influenced by the presence of neighbouring columns. The present paper addresses this very issue. Analysis of reported field hydro-test data of large diameter oil storage tanks in soft ground in reference to some existing theories led to the development of the stone-column ‘group efficiency factor’. In order that such factor is of general use, it was felt necessary to examine the applicability of the factor to different sizes of groups under varied subsoil conditions. With this in view, some model test results reported in literature of single and group of columns have been analysed and in the process an explicit relationship regarding the stone-column ‘groupeffect’ could be established.INTRODUCTIONThe field application of the stone column technology has gained momentum than the intricate design methodology due to its simplicity in installation and intuitive performance. The ground improvement is due to the complex interaction within the ‘unit-cell’ comprised of the installed column in ambient ground under sustained vertical stress; in association with the interdependence of problem geometry and material properties of the two different soils-one 'native' and the other 'back-filled'. The beneficial effects are increased load capacity, reduction in total and differential settlements, minimization of post construction settlements effected by accelerating consolidation, reduced risk of soil liquefaction, aiding in improvement of slope stability of embankments and natural slopes and effecting changes in the dynamic response. The ‘unit-cell’ concept of a tributary soil cylinder encapsulating an installed column with some reasonable assumptions and boundary conditions (Aboshi et al, 1979; Balaam & Booker, 1981; Van Impe & De Beer, 1983; Priebe, 1976; Saha & De, 1994; Saha; 2005, 2006, 2007, 2011, Saha & Das; 2007) deals with the load-settlement behaviour of the composite system. The present investigation is based on published field data from literature & validated with experimental study reported in literature. The study addresses the effect of group interaction of stone columns beneath a large area loading on ground settlement. The hydrotest load-settlement data of 12 large diameter oil storage tanks founded on stone column reinforced soil at Haldia1 and Kandla2 refinery sites in India; reported by Som (1997), has been analysed to quantify the group efficiency. The results as obtained are compared with experimental study on 2, 3 and 4 stone column groups at different spacing-diameter ratios in soft clay3 reported by Rao et al (1997) to validate the above analysis. A unique relationship between the column spacing and group efficiency has been obtained."

Jan 1, 2015

By David C. Kraft

Helical piles and ground anchors were used to meet critical design and constructability requirements for an urban forest Canopy Walk at the Atlanta Botanical Garden, Atlanta, GA. The 12-foot wide pedestrian walkway path was to be nestled among the treetops of a forest, extending to 600 ft. in length, and soaring 40 ft. high above the forest floor. Of particular concern during construction was that the foundation system for the temporary steel shoring system had to be non-invasive to the subsoil, could not damage the forest floor, trees, root systems, or foliage, and upon completion of the concrete walkway pour, could be removed, again without disturbing the subsoil. Accubrace, Inc. designed and installed all the helical foundation types, as well as provided steel braces, typically used in Tilt-Up building construction, for the walkway project. The braces, some extending to 43 ft. in length, were used to provide lateral support against wind loads for the walkway form. In addition, the braces acted as secondary support for lateral loads during the placement of wet concrete along the 600 ft. length of the walkway. Helical foundation products installed included vertical compression piles, ground anchors for tension rods, and ground anchors for the braces. The installation of the piles and anchors was particularly challenging since the forest floor elevation varied as much as 50 ft. due to the presence of a ravine. Information is provided on the subsoil conditions, required loads, design, installation, and acceptance criteria for each helical product type installed for the project. The results of vertical and lateral load tests on the helical piles in the pre-construction phase, conducted in conformance to project specifications are presented. Photographs to illustrate the nature and complexity of the project are included. The concrete pour for the walkway was successfully completed on December 12, 2009, and the walkway was opened for visitors in May, 2010.

Jan 1, 2011

By Bruce Haldeman

Timber has been used as pile support for structures for 6,000 years. Some means of preservation of wood go back almost that far. Timber piles support all types of structures ? some are buried below the water table; others raise a home for protection from animals or a chief's home for prestige. Millions of wood piles have been driven for bridge support. Earlier piles were driven by hand then by ingeniously raised weights. Charring, animal fats and oils have been used for preservation. Coal tar creosote and other preservative methods started only in the early 1800's and give effective protection.

Jan 1, 1984

By Jesús E. Gómez

This work is a continuation of a paper presented in the 32nd DFI Annual Conference, Colorado 2007, titled ?Hollow Core Bar Micropiles - Design parameters interpreted from 260 load tests.? The first paper presented the results of the verification and proof tests performed for the retrofit of two bridges with hollow core bars that used 260 micropiles. It included an interpretation of the unit bond values in the different soils where micropiles were installed. Recently two additional bridges within the same geological environment were also retrofitted using 144 hollow core micropiles. This paper includes the interpretation of the additional data from the proof tests performed and refines recommended values for design of hollow core bar micropiles in soils similar to those encountered in these two projects. The authors believe that the data collected will significantly add to the relatively small existing database on micropile tests and may also be useful during implementation of the LRFD design methodology.

Jan 1, 2008

By Jelke Dijkstra

This paper presents the results of model pile load tests in a photoelastic material. The soil in this test is represented by an assembly of photoelastically sensitive glass particles, which allows for optical measurements of stresses. In the same test setup, displacements around the pile are measured using digital image correlation (DIC). During the pile installation stresses and strains are recorded. Tests were performed in loose and medium dense particle assemblies. The development of stresses and strains around the pile tip and pile shaft are quantified and presented in this paper. For the loose conditions the results show a small influence on the stress state. For the medium dense conditions a clear stress change is observed.

Jan 1, 2006

By Karsten Beckhaus

"Abstract Tremie concrete for special geotechnical works needs special properties, especially during the casting process. Today’s execution standards for bored piles and diaphragm walls, EN 1536 and EN 1538, as well as the draft version of concrete standard EN 206, all comprise regulations for deep foundation concrete which have not been changed for decades. Considering the recent development in concrete technology at the same time and its actual state-of-the-art, it is essential to develop new normative specifications and specification requirements.GeneralTo allow the required integrity and quality after placing and hardening, concrete for structural elements like bored piles or diaphragm walls, used as foundations of high-rise buildings or as retaining structures for large and deep building pits, must have adequate workability and stability.In addition to requirements on mechanical properties and on durability, both of which have increased within the last decades, concrete must be suitable for being cast in deep or extremely deep excavations, see figure 1. Today’s specialist foundation engineering machinery makes it possible to drill or cut down to in excess of100 m depth. Concrete technology has developed and allows the use of high performance concrete for deep foundations. But is this capability represented by actual regulations?It has become very common for the industry to supply or use concrete with low water cement ratios, nevertheless highly flowable and set-retarded for several hours if needed. Very low water cement ratios allow design strength of 60 MPa or higher (Larisch, 2011), and a very low porosity which is required for a long service life in aggressive conditions, e.g. by chlorides.To achieve best performance, it is obvious that the concrete must completely fill the excavation and fully embed the reinforcement. As vibration of deep foundation concrete is (usually) not allowed and was anyway inefficient, deep foundation concrete must be designed to self-compact under hydrostatic pressure. Generally, it must be considered that after placement the concrete’s quality cannot be influenced anymore. Therefore, both the pouring procedure and the concrete quality must be adequate."

Jan 1, 2014

By Walter I. Paniagua

Drilled shafts and precast concrete piles were installed for the foundation of several structures in a reconfiguration project of a refinery in Minatitlan, Veracruz, in the Gulf of Mexico. The soils are alluvial deposits of flat land from the Coatzacoalcos River, which are embedded with layers of sand, soft clay, and peat. As part of a QC/QA program, load tests, both static and dynamic, axial and lateral, were performed. In this paper results of 32 axial tests are presented, in which typical load-displacement curves were measured at the top of the foundation elements; from the interpretation of these plots, data were recorded for ultimate side shear and in some cases for end bearing capacities, which are compared with the theoretical results of the final stage of the foundation design. The comparison shows that under allowable loads, side shear determines the bearing capacity of piles, even when the tip is embedded in a hard layer. Underestimation of the side shear is evident; therefore design criteria, as well as the methods used for obtaining soil parameters, should be reviewed.

Jan 1, 2007

By Tony Suckling

"As we head toward the United Nations Climate Change Conference in Copenhagen in December, the environment and sustainability will become headline news for a while. Governments are expected to agree to a set of binding targets to reduce carbon emissions probably before 2020, and certainly before 2050. This will, in effect, initiate a low carbon economy in many parts of the world. Sustainability has mainly been rhetoric so far, the exceptions being projects for those looking to the long-term future and not for short-term financial gains.The probabilities and consequences of negative impacts on the environment and on society over the short term and in the long term can be assessed and mitigated, but mitigation often adds cost. Also, we cannot know what technologies will be available, say 1,000 years into the future, which is about 40 generations of our society. It is easier to have a connection with 100 years into the future, which is only about 4 generations. Individuals may have a different sense of sustainability, and place a different value on mitigation, its cost, its importance and its potential impacts.Sustainability means different things to different parties on a construction project. For example, a land developer is likely to have a different view on the design in terms of sustainability than that of the designer. The developer may also likely to be more interested in sustainabiliy if there are tangible economic benefits that might accrue. Achieving sustainability on any project, leads to conflict between competing interests or demands cooperation between the economic and technical sectors involved. The foundations for a building or bridge, by definition, need to interact with the ground whose behaviour cannot be dictated by man. The aims of sustainability are the same as for the building or bridge, both of which are constructed of manmade materials, but it is less clear how they should be achieved. An example is the driven pile that does not produce spoil waste, but is likely to be too noisy to be acceptable in an urban environment. This then begs the question, should the public accept the nuisance of short-term pile driving to achieve a more sustainable foundation? Additionally, the question has to be asked, can the deep foundations industry develop its techniques and products to help make them more acceptable and appropriate more often than is possible now?"

Jan 1, 2009

By Robert Thurner

The underground car park "Admonterhof in the historical centre of Graz is an example for the technical and economical success of a complicated structural design using a concept on the basis of the observational method. The intention to built a 20 m deep excavation beneath a protected monument was accompanied by some essential issues: the preservation of the existing state avoiding extensive displacements by means of a girder grid of reinforced concrete, its support on large bored piles and small steel-tube piles with possible active compensation of differential settlements, the excavation support in none built-up areas with secant bored piles, the underpinning of existing buildings with different structures by means of jet grouting. Furthermore the hydraulic gradient and the permeability of a rock formation in a part of the excavation had to be explored with the purpose to control the inflow of groundwater with a level difference of more than 10 m.

Jan 1, 2006

By Jörn M. Seitz

Dynamic load testing is employed with ever increasing frequency to estimate the strength and elastic settlement behavior of piles of all types. For dynamic loading ram masses up to 20 Mg have been used and pile resistance forces up to 30 MN have been activated. Strains and accelerations induced by the impact are measured near the pile top and a load-set curve is computed by the so-called CAPWAP method. This paper briefly describes both the necessary equipment and other details of the dynamic tests and the available analytical tools for data interpretation. Furthermore the need for further research and the current status of standardization will be discussed. This paper also presents the results from several static and dynamic correlation tests on cast-in-situ piles of up to 2 m diameter and 64 m length. The results demonstrate the economical and technical feasibility of this test method.

Jan 1, 1987

By Kirk A. Mcintosh

Augered, cast-in-place (ACIP) piles have been utilized in the United States for a wide range of projects since the 1950's. Due to the cast-in-place nature of the installation method (and lack of a driving criteria); however, ACIP piles have not been readily accepted by some practicing geotechnical and structural engineers. Since ACIP piles were initially developed, the installation equipment and techniques have been improved and refined and the number of experienced contractors has significantly increased. Over the past 10 to 15 years, the pile type has experienced significant growth in the United States (particularly in Florida) because engineers have become more knowledgeable and comfortable with its use. The Miami area, in particular, has experienced considerable growth in the utilization of ACIP piles primarily due to their usage on the $1 billion Miami Metrorail System project in the early 1980s. The economic advantages over other deep foundation types, coupled with some unique installation advantages, have shown that ACIP piles can be a viable foundation alternative on many projects. Even though ACIP piles have gained respect in the private sector, the pile type has generally not been readily accepted by government transportation agencies. The reluctance to readily accept this foundation type stems primarily from the quality assurance aspect of cast-in-place pile construction. Additionally, there has not been much research activity on this foundation type, technical papers, formal associations (other than the DFI), or a concerted effort to standardize the industry. This paper serves to discuss the state of practice for ACIP pile installation in the state of Florida.

Jan 1, 1997

By Kenneth Gavin

The accurate prediction of the shaft capacity of drives piles in sand continues to present problems for foundation designers. Research in this field has been carried out for many years and has yielded a wide range of design approaches -some of which have been shown by recent experimental work to be based on questionable assumptions. This Paper reviews some of the current popular design methods for piles in sand in the context of recent information obtained from high quality field tests conducted by institutions such as Imperial College London. A database of driven piles in cohesionless soils has been compiled from well documented (and reliable) case histories that have been reported in the literature. The measured shaft capacities of the piles in this database are compared with predictions made by the various methods and an assessment is made of the predictive performance and reliability of each method

Jan 1, 1996

By Bert R. Oastler

BERT R. OASTLER: Born Atlanta, Georgia, October 19, 1933; B.S. Civil Engineering, Duke University, 1956; Doctor of Laws, Emory University, 1966; Bryan Honor Society; Associate Editor, Journal of Public Law. Partner in charge of litigation for Smith, Currie & Hancock Including federal and state courts, administrative boards, arbitration and negotiation. American Bar Association; American Trial Lawyers Association; Georgia Trial Lawyers Association. Practiced structural steel design at Newport News Shipbuilding & Drydock Company and building construction as an officer in the United States Air Force. Engaged in the building construction business in Atlanta, Georgia as estimator and project manager for five years. Lectured on construction litigation, arbitration and government contracts procurement law for Federal Publications, Inc., Associated General Contractors and other private entities on a nationwide basis. Served as guest lecturer on Government Contracts at Emory University and Georgia Institute of Technology, Atlanta, Georgia. Served as arbitrator in cases for the American Arbitration Association.

Jan 1, 1988

Jan 1, 1989