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By Arvindh Gupta

BC Hydro proposed to improve the stability of the existing Seven Mile Dam with 54 corrosion protected, re-stressable anchors comprising 92/0.6? strands each, in phase 2 of the program. Being globally the largest capacity anchors ever build, coupled with extra ordinary specifications, the project was a challenge for the entire post tensioning industry. The paper discusses the challenges associated with the anchor material supply as per specifications, extensive research and development carried out by Con-Tech Systems ltd. to overcome the challenges and contribute in making the project a success. The substance of this article is published in the Aug/Sep issue of ADSC magazine.

Jan 1, 2004

By Tony Amis

There is very limited information relating to the potential impact of temperature cycles, outside the variation that occurs naturally, on the behaviour of foundation piles. Such thermal loading occurs when piles are used as heat exchange elements within a Ground Sourced Heat Pump system, in addition to carrying building loads to competent strata. An investigation has been undertaken where a conventional load test has been extended to include a period in which the load is maintained and temperature cycles applied. Instrumentation was installed in the test pile, an adjacent borehole, two of the anchor piles and the heat sink pile in order to be able to develop an understanding of the temperature variation and associated strain changes within and between the various elements. Conventional electronic strain and temperature gauges have been used in conjunction with optical fibre sensors which also measure strain and temperature changes. The results have confirmed the validity of the assumption made in the thermo-dynamic design of the system, the compatibility of the differing measurement systems and differing installation methods for the optical fibres, and initial assessment suggests that the load-settlement response of the pile is not adversely affected by the temperature cycles applied.

Jan 1, 2008

By Brian Littlechild

Whilst there is much innovative work being undertaken in South East Asia in the space allowed in this paper we have settled on describing in more detail the work that has been done with shaft grouting of deep foundations and piles founded in rock both in end bearing and socket friction. The paper is necessarily in two parts. The first part is about the application of shaft grouting since its introduction to the region some eight years ago. It describes, for the first time, much of the detail of the different techniques used and the construction and the design benefits achieved with shaft grouting in five countries in the region. The second part outlines the enhancements achieved in the design of piles founded in rock and brings together the results of 10 years of test loading. This includes the load testing of 1.2m to 1.5m diameter piles to a maximum of 30MN on granite and a recent programme of tests on a wide range of strong rock types in Hong Kong. The ground conditions for these deep foundations vary widely, from sedimentary soils to in situ weathered granite and meta-sedimentary rocks. The construction techniques include barrettes constructed using mill techniques and bored piles formed under bentonite and water using both oscillators and rotators.

Jan 1, 2000

By Peter de Kort

Tunnels in urban areas generally require deep excavations in soils under the groundwater table. In The Netherlands uplift loads are generally taken by piles installed into dense sand layers, which are hard to penetrate. To avoid nuisance and damage to the environment, piles often need to be installed using vibration free methods, which also have the advantage of low noise levels during installation. Drilling piles and obtaining a high uplift resistance is a contradiction in itself. Franki has adopted several installation methods based on the injection of grout during drilling and/or post grouting to overcome the difficulty of hard layers. This report presents two projects, situated in Rotterdam and Sneek, where vertical tension piles in floors, subject to high uplift loads, have been used. It also explores a project in Zeebrugge (Belgium), where tension piles are installed at an inclination of 1:1 to anchor a diaphragm wall for a quay construction. Test results presented in this report show, that vibration free and soil displacing piles can be installed in very dense sand layers and that a high uplift resistance can be achieved. It is also shown, that a variety of installation methods is available, even in limited space.

Jan 1, 2008

By Juhyung Lee

Recently, large diameter drilled shafts are often used for foundations of large-scale marine bridges with high capacity and required to resist lateral loads. Steel casings are essential in supporting the hole-diving concrete installation of the drill shafts constructed in the sea. The casings, however, are usually not considered as the structural elements and their load bearing capacity is often overlooked in the design of drilled shafts. As the diameter of drilled shafts becomes larger, there are higher demands for more efficient and economical design of large-scaled drill shafts in the sea. Steel-concrete composite columns are popular for the superstructure of bridges, and the outer steel attached to the shaft increases the shaft resistance through confining the concrete. In this study, the lateral resistance of steel-concrete composite drilled shafts was evaluated quantitatively based on the numerical analysis. When steel casings are used as structural elements such as the composite columns. Ultimate lateral bearing capacity of composite drilled shafts with various diameters was numerically calculated through the 3D finite element analysis. For that, elasto-plastic model with the perfect plasticity is involved to capture the ultimate load. A commercial FEA program, MIDAS-GTS, is used in this study. Real field conditions of the west coast, Korea were examined to set up the ground conditions and pile lengths required for this parametric studies. Detailed characteristics of the stress and displacement distributions are evaluated for the better understanding on the mechanisms of the composite shaft behavior.

Jan 1, 2008

By Jiun-Yih Chen

Pile load tests are regularly used to verify pile capacities. Sometimes, they are used to optimize pile designs. This paper presents a case study based on a real project, in which the information obtained from load tests during construction was used to shorten the design pile lengths without a formal decision analysis. In this study, a simple probabilistic model was used to assess the probabilities of failure based on design information. The Bayesian approach was used to update the probabilities given the additional information from load tests. These probabilities were then used in a formal decision analysis to determine the optimal pile lengths based on design information and based on the additional information from load tests. The optimal pile lengths are different from those implemented in the project without a formal decision analysis. The value of the formal decision analysis is illustrated by its ability to optimize the pile length in a transparent and defendable way.

Jan 1, 2009

By Piotr D. Moncarz

As major urban areas begin to run out of "good-terrain" for their expansion, they begin to claim high water-table areas within or adjacent to water fronts or swamps. Similarly, major infrastructure projects encroach on or cross high organic content areas. The associated major structures often require deep foundations located in soils investigated through core samples removed at a discrete number of locations. The investigation is nearly always preoccupied with soil mechanical properties, sometimes with soil non-organic chemistry for concrete and metal corrosion, seldom, if ever, for organic-chemistry and bio-conditions as related to concrete longevity. Not surprisingly so, bio-corrosion of concrete is one of the least understood phenomena by practicing civil engineers. This paper shows how low-iron, organic-rich sediments may trigger sulfate degradation of concrete, even when standard pre-construction chemical analyses indicate only a moderate sulfate level. The discussion is illustrated with a case of a pile foundation in the United States driven into marine channel sediments and sediment-derived fill material. The concrete piles lost their structural integrity due to secondary ettringite formation and depletion of iron in the cement paste. Disintegration of concrete occurred only where it contacted superficial marine sediments and sediment-derived fill material. Concrete in direct contact with seawater or native sand and silt materials appeared to be sound. Sediments in contact with the degraded concrete were highly anoxic and had a history of sewage contamination, contained low concentrations of total iron (<2%), Fe(III) (<0.3%) and moderate levels of sulfate (1500ppm), and exhibited high bacterial activity. This environment resulted in the microbial dissolution of Fe(lll)-rich ferrite in hardened cement paste. Iron depletion in the cement paste had made the concrete vulnerable to degradation by sulfate, even at moderate levels of sulfate concentrations in the sediments.

Jan 1, 2002

By Roderic A. Ellman

The new Woodrow Wilson Bridge (WWB) will replace the existing bridge over the Potomac River to connect Alexandria, Virginia to Prince Georges County, Maryland. The new WWB will extend approximately 1.1 miles across the river, with a 367-ft long bascule span in the main river channel where the water depth is about 36 ft. The subsurface soil profile consists of up to 50 ft of a soft organic silty clay layer that is very vulnerable to scour, underlain by a deep deposit of hard sandy clay. Foundation construction in the Potomac River required the use of cofferdams to allow structural concrete work to be performed in the dry. This paper will the present the types of cofferdams used to construct the foundations for the WWB replacement project. The bridge is primarily comprised of fixed spans in relatively shallow water and a bascule span over a navigation channel in relatively deep water. Foundation construction included the installation of 48" to 72" open end steel pipe piles and cast-in-place concrete pile caps. To achieve the desired bridge appearance, pile caps were required to extend below the water surface and below the existing river bottom in shallow water locations. Conventional steel sheet pile cofferdams with tremie concrete seal were used to construct fixed span, shallow water piers. Selection of deep water bascule span foundation cofferdams was governed by several factors including contraction scour, environmental considerations and cost. Potomac River cofferdams, i.e., relatively shallow depth cofferdams that are supported by the foundation piling were selected. This cofferdam system provided a shallow profile which minimized contraction scour and the amount of filling in the river. Design issues include load selection and cofferdam stability in very soft alluvial soils. Construction issues include erection sequence, tremie concrete mix design and placement procedures.

Jan 1, 2005

By KeerthiRaaj Subrmanian, Muthukkumaran Kasinathan

"A railway embankment is under construction between Nagapattinam to Thiruthuraipoondi covering 36.5 km. The sub-soil strata comprises of soft clay extending up to 10 m below existing ground level, which is subjected to stability and settlement problems. A trial stretch covering about 5 kilometer was improved using Prefabricated Vertical Drains (PVD) with surcharge was recommended to accelerate the consolidation settlement. The geotechnical characteristics of the subsoil are examined through laboratory tests on representative soil samples. Recent improvement in the finite element analysis has facilitated modeling of PVD in finite element software for computing the settlement magnitude and time rate of consolidation. In this study the theoretically predicted settlement magnitude and time rate of consolidation from Terzaghi.s vertical consolidation, Barron's radial consolidation are compared with the analyzed FEM results for both the cases with and without PVD improved embankment. The comparative analysis between FEM and predicted data hold good for stresses and the associated deformations. The excess pore water pressure was significantly lower and their dissipation was faster in case of embankment with vertical drains. Thus PLAXIS 2D tool shows fairly convincing results in comparison to the theoretical solutions.1. INTRODUCTIONFrom the earlier times civilization has been developed in a fashion either at the banks of river or near to the shore region, because of the easier availability of food and water. This over centuries made them as huge cities, consequently population rise made the increased necessity of highway, railways, port and even more ground for construction. As a stake researchers are pushed to make a low bearing ground into a massive carrier of skyscrapers, embankment, bridges etc. These low bearing ground suffers from total and differential settlement, slope instability. Hence, numerous ground improvement techniques were followed to eradicate these concerns which include preloading, piling, stone column, vertical drains and geosynthetic reinforcement. Among them Prefabricated vertical drain (PVD) are often used to accelerate consolidation of soft subsoil and has been the main soil improvement method used in improving the soft marine clay deposit (Chu et al.(2004); Chai (2001) and Arulrajah et al.(2003)). Literature review of embankment over soft clay deposit reveals that combination of PVD with preloading is widely considered as an economical and less time consuming ground improvement technique."

Jan 1, 2015

By Shenbaga R. Kaniraj

The pile loading tests are generally conducted to assess the safe load on piles in compression. In the Indian practice, the safe load is determined using the pile loading test data and the two criteria specified in the Indian Standard Code, IS.2911 (Part 4) -1985. For this, the test pile should have undergone a minimum displacement equal to 10% of the pile diameter. Often, the piles are not subjected loads that are sufficient to cause a displacement of this magnitude. If the settlement is at least 12 mm, then the safe load is determined based only on the first criterion. But, if the settlement is less than 12 mm, the safe load cannot be determined using the IS Code criteria. The paper presents two procedures called hyperbolic and generalized hyperbolic methods to estimate the safe load using the IS Code criteria even when the loading test data is insufficient. The data from two initial tests have been analyzed. The predicted safe loads have been compared with the actual safe loads.

Jan 1, 1996

By R. Paul De Bruyn

A. Crane Check List -- Make -- Model -- Year of Manufacture -- Where is load chart? Is it for this crane? -- Boom style and length -- Boom tip drawing (sketch) for fixed lead connection. Has the crane manufacturer been consulted on the point of attachment? -- How many drums; diameter and length of wire rope. -- Is the single part line pull enough to lift pile or hammer on single part line? -- What is the effective weight of the whole driving system - leads, pile, hammer, etc? -- Are there any auxilliary hydraulic systems? Are the line pulls on these adequate to lift the pile or hammer? -- What is the anticipated working radius? Will the spotter collapse to that length? -- Nature of foundation under crane - barge, marsh, unstable sand, etc. -- Does the crane meet OSAH and state regulations -current certification. Note - the operator is responsible for compliance with regulations. -- Is there any extra weight added to counterweight by compressors or hydraulic systems? What does crane manufacturer say? Consult factory before adding.

Jan 1, 1990

By A. Ghorbani

The analysis of Combined Pile Raft Foundation (CPRF) is very complex due to involved interactions among components of CPRF system. Many researchers made efforts to develop sufficient methods including three dimensional finite element methods to compute these interactions. Since there are some restrictions and complexity in previous methods, in present study a new approach based on three dimensional finite difference methods is implemented to overcome some of these restrictions. The total and differential settlements of a centrifuge case study are computed using different numerical methods to show the performance of present numerical approach.

Jan 1, 2007

By A. Le Kouby

We present in this paper the results of a parametric study carried out in a calibration chamber on instrumented model piles. The aim is to point out group effect on piles within a group through their resulting shaft friction and tip resistance. The methodology relies on the study of the influence of adjacent piles on a "reference" pile. The soil used is a silica sand (Fontainebleau sand). The influence of parameters like pile spacing, number of piles and installation order are evaluated. The results show a positive effect on shaft friction of the group effect and a negative effect on tip resistance. Efficiency factors are defined in order to have a better view on the parameters influencing the response of the pile within a group.

Jan 1, 2006

By Maurice Bottiau

When dealing with displacement auger piling, some general and fundamental issues have to be considered, irrespective of the system. More than with other pile types, the interplay between the soil conditions and the design and execution is of outstanding importance. This paper intends to address these issues and to summarize some critical matters in terms of design, execution and control such as : ? Importance of a reliable soil investigation ; ? Summary of the design as it is addressed in Europe for this category of piles ; ? Criteria for a good choice and control of the correct asset of the piles ; ? Importance of the concreting phase; ? Relation between the power and the engine characteristics of the drilling equipment with the final bearing capacity. For each of these issues detailed examples will be given as well as results of load tests and in-situ control during execution.

Jan 1, 2003

By N. V. Nayak

Konkan Railway Project is one of the most ambitious railway construction projects in India, involving construction of a 760.km long, Broad Gauge (1676 mm), single track railway line, connecting Roha in Maharashtra State with Mangalore in Kamataka State. The railway line travels along the Western Coast of Indian subcontinent, through states of Maharashtra (382 km), Goa (105 km) and Karnataka (273 km) (Fig.1). The project alignment traverses through one of the most formidable terrains ever encountered, in the history of railway construction in India. In the State of Goa only, railway alignment is crossing 6 major rivers Terekhol, Chapora, Mandovi, Zuari, Sal and Talpona. Zuari Railway Bridge (1305.6 m), Mandovi Railway Bridges (I and II) (1182.7 m) rank as 2nd and 3rd long bridges, (first longest bridge being Sharavati Bridge (2.2 km} at Honavar) which have been constructed on Konkan Railway. All these three bridges have been constructed by M/s.Asia Foundations and Constructions Ltd. (AFCONS). This paper presents, case history of construction of pile/caisson foundations for Zuari and Mandovi Bridges.

Jan 1, 1996

By Barry C. Roth

Driving of large piles in water can impact marine wildlife. Bubble curtains can mitigate these adverse effects. The procedures for and preliminary results of monitoring airborne, waterborne and groundborne vibrations with and without bubble curtains on a test project involving 2.438 m piles to 110 m is reported here. We observed fish kills and sea lions apparently fleeing the area. These phenomena were presumably due to the extreme acoustic effects of the powerful hammers which generated waterborne sound intensities locally in excess of 240 dB. This waterborne pile driving noise data collection undertaking is believed to be the most extensive ever attempted.

Jan 1, 2001

By Gerald Verbeek

There are certain concepts that seem to invite responses from some, including some in the foundation industry and even some within DFI, that are at best surprising. Business owners and their employees share the desire that their company does well and continues to operate. Maybe company growth is not always realistic but maintaining the current level of activity is in the least what they hope for. In other words, they hope that their company is sustainable, and they are fully behind that notion. But when the concept of sustainability is raised, there is, at least with some, suddenly doubt that that is a good thing. And yet, that concept only aims to achieve at a grander scale what the owners and employees desire for their company. There are many definitions of the term sustainability, but probably the most commonly used description is that framed by the United Nations in 1987. It states that sustainability is the concept of meeting the needs of the present without compromising the ability of future generations to meet their own needs. Arguably that definition is too abstract and does not provide the type of specific goals and targets we are used to. To help with that, to some extent, in 2015 the United Nations formulated 17 Sustainable Development Goals (SDGs), to provide "a shared blueprint for peace and prosperity for people and the planet, now and into the future." And undoubtedly those SDGs are fodder for those that question the concept of sustainability in the foundation industry. How can our industry, they wonder, ensure that there is no poverty or hunger (SDG 1 and 2), and the climate action goal (SDG 13) immediately leads to the hot button topic of global warming. And maybe this is where advocates lose (some of) the sceptics of the sustainability concept, but hopefully they will continue to read this article that lays out why sustainability simply makes sense, also for the foundation industry and especially for DFI.

Nov 1, 2022

Pier, well cap and steining junction is a complicated 3-d re-ion. The prevalent design procedure for the pier, well cap and steining in isolated manner is not rational. In absence of an integrated approach for design of the junction structure, the well cap is designed uneconomical and at the same time pier and steining are left relatively unsafe. Strut-and-Tie Model based design is a simple solution to this problem. An example illustrating design of the junction structure using STM is presented. On comparison of the outcomes of the STM based design with the prevalent design, the following anomalies are found: i) For smooth flow of forces, length of pier at its base should preferably be made equal to the outer well diameter, ii) STM based design for the pier is more rational, economical and safe. iii) Due to presence of hoop stress, as indicated by the STM, the steining concrete in a depth of p times outer diameter of the well from the well cap level should be limited to M15 grade, iv) STM based design for the steining is more rational, economical and safe.

Jan 1, 1996

By W. G. K. Fleming

The codification of foundation design and construction is a subject of extensive discussion in Europe and all current code proposals are based on limit state partial factoring. For simplicity, it is claimed, simplified forms of Partial Factor use are presently being advocated but, if this is the direction which codes are to follow, then it is preferable in this age of computer technology that a true system should be adopted rather than a simplification. A philosophically satisfactory method can readily be found which can fulfilcurrent requirements and it is better that such a method should be adopted from the beginning rather than later to find it necessary to make important alterations and amendments.

Jan 1, 1996

By Naim Noori Samie

Lateral force rsistance of piles is analytically investigated by dividing the pile length to 3 segments. The first segment (Zone I) models the load eccentricity with respect to the soil and the pile-deck connection, using a third degree differential equation representing the shear variation along the pile. The soil is assumed to be uniform, homogeneous with an elastic-perfectly plastic behavior. The Top soil layer (Zone II) is assumed to be stressed beyond the elastic limit. A simple 4th degree differential equation represents this zone. The soil resistance is assumed to vary linearly with depth (or surcharge). The pile deformation and soil behavior determines the plastic zone length. In zone III the soil is assumed to behave elastically, hence its resistance is proportional to its deformation. A linear 4th degree differential equation is employed in this zone. The compatibility conditions are satisfied on each boundary. Maximum allowable moment and shear are investigated throughout the pile as the basic limiting criteria on lateral force capacity. In this paper the soil coefficients are taken from a proposal by ref(3), and the results are compared with the soil response as determined by the P-Y method as recommended by ref(2).

Jan 1, 1996