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By Dan A. Brown, Rich A. Lamb, Paul J. Axtell

"Over the last 10 years, the Minnesota Department of Transportation (Mn/DOT) has had a very active program of replacing many major bridges, large structures spanning the Mississippi River. The deep foundations for these new structures include both drilled shafts and large diameter open-ended driven steel pipe piles. Most of these projects included load tests, both axial and lateral.The geology of this area of Minnesota includes some interesting foundation challenges, including highly organic and compressible very soft silts and clays to very dense sand and gravel overlying sedimentary bedrock. In some cases scour requires embedment into rock, and the bedrock formations may range from very soft sandstone to very hard dolostone. Artesian groundwater conditions can sometimes complicate drilled shaft construction, but the rock is otherwise very favorable for drilled shafts. Experience with the open-ended driven steel pipe piles (typically 42 and 48 in, 1.07 and 1.2 m diameter) suggest that these piles most often penetrate even dense granular materials to achieve bearing on rock. Experiences with drilled shafts socketed into the soft sandstones demonstrate that these rocks provide very favorable conditions for drilled shafts, so long as suitable construction practices are followed. Here we present several recent case histories regarding the foundation design and construction of major bridge projects in the vicinity of Minneapolis, Minn., including the Wakota Bridge, the I-35W replacement, the Lafayette Bridge, the Hastings Bridge and the St. Croix Bridge. Some lessons learned from construction and load testing of both types of foundations are described along with implications for design in similar soil and rock conditions."

Jan 1, 2013

By Michael J. Atwood

Many buildings in Boston are founded on untreated wood piles, which can deteriorate and lose their structural capacity if groundwater levels are lowered below the tops of the piles, exposing the wood to air in the unsaturated soils that surround the piles. The problem of wood pile deterioration due to lowered groundwater levels in Boston first became evident in 1929 following discovery of rotten piles beneath walls of the Boston Public Library building. Repairs to reconstruct the library building?s wood pile foundations were made in 1930 using pit underpinning methods. Today, more than 80 years later, the subsurface conditions beneath several of Boston?s historic neighborhood areas continue to be plagued with low groundwater levels - regrettably resulting in ongoing deterioration to the wood piles that support some of Boston?s oldest and most beautiful buildings. Pit underpinning is still recognized as the preferred approach to repair wood piles and restore uniform foundation support beneath the impacted buildings. This paper provides a brief historical review of the land filling in Boston through the early 1900s that led to the use of wood piles as building foundations. Also discussed is the impact that groundwater level can have on the long term performance of wood pile foundations and the pit underpinning procedures used to reconstruct decayed wood pile foundations in 1930 beneath the Boston Public Library, and today beneath some of Boston?s oldest buildings. Also included are discussions on engineering controls and permitting requirements that help ensure safety and protection to the workers and buildings during underpinning, and some procedures being used to supplement and improve the loading capacity of the reconstructed foundations and facilitate construction of new useable below-grade space.

Jan 1, 2011

By F. Keith Jacobson

To be involved in the construction of a deep dredged caisson for a major bridge pier is one of the most rewarding and professionally challenging experiences one can have in the bridge construction business. That experience was doubled in the construction of the two deep dredged caissons for the Highway 82 Bridge over the Mississippi River near Greenville, Mississippi. The challenges and the construction risks associated with constructing these two dredged caisson pier foundations highlight the construction engineering innovation associated with major bridge pier construction. The 1,378-foot Main Span of the Highway 82 Bridge makes it the longest cable stayed bridge span over the inland rivers of the United States. The main piers for this bridge are supported on two dredged caissons measuring 80-feet by 122-feet in plan, founding 200-feet and 170-feet below the river surface. The challenges of constructing these caisson structures, sinking them through 70-feet of water to the river bottom and then excavating and further sinking them to the founding grade without exceeding the design tolerances, were enormous. The construction engineering opportunities for innovation included major breakwater structures to create a friendly environment in 11 fUsec currents, the first time use of Articulated Concrete Mattresses for river bottom scour control, unique air dome design to maximize the buoyancy of the caisson structure while floating, a caisson guide system to assure positive control and positioning of the caisson during the initial sinking phases. and a comprehensive sinking plan to assure maximum control and minimum risk. Many of the innovative solutions to the construction challenges on this bridge will be incorporated into future caisson construction projects on the lower Mississippi River.

May 11, 2007

By Ana Pereira, Naomi Norris, Donald Bruggers

The city of Christchurch, New Zealand is predominantly founded on alluvial sediments consisting of interbedded layers of loose to medium dense sand, soft to stiff silt and clay mixtures, and pockets of organics. These soil deposits have high liquefaction potential. Following the 2010/2011 Canterbury Earthquake Sequence several ground improvement trials were undertaken within Christchurch to understand the effectiveness of different types of ground improvement in these silty sand geological conditions. This paper presents a discussion of a stone column ground improvement trial undertaken at a Christchurch site with high fines content soils. Stone columns were installed using two types of installation methods and a range of Area Replacement Ratios (ARR) to assess the effectiveness of these ground improvement methods in high fines content soils as well as the influence on the type of installation method. Pre- and post-column installation CPTs, seismic Dilatometer Tests (sDMTs), cross-hole shear wave velocity tests, and plate load tests have been undertaken to assess the effectiveness of the ground improvement. Results of the testing are presented in this paper. INTRODUCTION This paper presents the results of a stone column ground improvement trial undertaken in Christchurch, New Zealand (Fig.1). In 2010 and 2011, four large earthquakes (greater than magnitude 5.9) and thousands of smaller aftershocks occurred in the greater Christchurch region. These events are referred to as the Canterbury Earthquake Sequence (CES). Liquefaction occurred across large portions of the city during the stronger earthquakes, particularly the February 2011 event. Following the CES a large amount of data was collected across the city including the location and volume of sand boils, and the location and magnitude of ground cracks. Additionally, data from thousands of ground investigations have been uploaded into a public database. As a result, there is clear evidence that silt and silty sands liquefy in addition clean sands. The CES and resulting liquefaction motivated a series of studies and trials from different organisations aiming to better understand the available technologies for liquefaction mitigation. The subject of this paper is a ground improvement trial undertaken by a local contractor specialising in deep foundations and ground improvement. They were interested in understanding the effectiveness of stone column ground improvement in high fines content (silty) soils using two different installation techniques, vibratory and non-vibratory. Different arrays and Area Replacement Ratios (ARRs) were used for each of the two methods of columns installation.

Jan 1, 2019

By Timothy Flaherty

We observed the boiling in the water very close to the water adjacent to where we were drilling. That only happened at the very beginning before it was switched to water flushing. Yes, it was performed with water flush.

Feb 10, 2003

By Kenneth Pidgeon

The Boston Marine Industrial Park (BMIP) Boat Section, which is part of contract C04A2 of the Central Artery/Tunnel (CA/T) project, is currently under construction in South Boston, Massachusetts (Fig. 1). The Boat Section is approximately 900 feet long and varies in width from about 135 to 185 feet (Fig. 2). The depth to the top of the Boat Section base slab varies from about 28 to 31 feet below final ground surface and about 23 to 26 feet below normal ground water levels. The Boat Section is supported on 578 anchors drilled into the underlying bedrock each designed for a working load of 630 kips. Design and Construction Team The owner of the project is the Massachusetts Highway Department (MHD). The owner's representative is the Management Consultant, Bechtel/Parsons Brinckerhoff. The section design consultant (SDC) consisted of HDR Engineering, Inc. with GEI Consultants, Inc. as the geotechnical subconsultant. The general contractor was the joint venture of Kiewit, Perini, Atkinson, and Cashman. The boat anchors were installed by the subcontractor Delta Geotechnical Services, Inc.

Jan 1, 1994

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 Peter Faust, Peter Hubbard, Kenichi Soga

The European Federation of Foundation Contractors (EFFC) and The Deep Foundations Institute (DFI) have set up a task group to compile a Guide for Working Platforms. The first edition of this Guide has been published in January 2020. The aim of the Guide is to provide reliable methods for design, testing and verification of working platforms for construction equipment, especially in the deep foundation industry where track loads can be excessive due to the nature of its operations. The Guide has identified areas where knowledge is limited. Actual track pressure and its distribution along the length of the tracks is still not well researched. Current recommendation provided in EN 16228-1 are believed to be overly simplified and may lead to conservative requirements for working platform thickness. This paper presents results of a series of field tests where the actual track pressure of a large drilling rig during operation was measured in real time together with the deformation of the working platform. Embedded, distributed fiber optic sensing (DFOS) at different depths throughout the platform allowed for a three-dimensional evaluation of the platform deformation throughout the entire operation. Results will help to develop more reliable recommendations for future safety requirements of working platforms for deep foundation equipment.

May 1, 2022

By Bret N. Lingwall, Byron Foster

The problem of reliable extreme event modeling of large diameter piles under enormous structural or kinematic loads has gained more attention in recent years. In particular, the soil response around the foundation and impacts to buried adjacent infrastructure has gained interest. One of the principal shortcomings with analysis of large diameter pile foundations under extreme event lateral loading is the reliance on conventional beam on elastic foundation methods, which do not model the soil field response around the pile. These methods are limited for large displacement problems, and for large diameter piles. However, the fundamental interactions between steel and concrete, and structure to soil are difficult to constrain, especially in large strain problems where the structural elements become inelastic. The non-linear interaction of the structural materials and soil is desirable so that assessment of stress changes in the field and effects on adjacent facilities can be modeled. A numerical modeling methodology that addresses these shortcomings has been developed. This method utilizes the interaction of brittle concrete with discrete steel reinforcing and casing in a robust manner capturing inelastic non-linearity in both soil and structure. This paper presents a comparison study of the method, wherein three different validation studies were made to data from full scale laterally loaded pile testing. INTRODUCTION Extreme event lateral loading of deep foundations comes in many forms including earthquakes, landsliding, tsunamis, hurricanes, surface fault rupture, liquefaction induced lateral spreads and many more. These extreme events induce loads on foundations far greater than service or strength loads. Perhaps the most dangerous extreme event loads are those of large soil displacements such as landslides, lateral spreads, and surface fault rupture, wherein the soil surrounding the foundations can move laterally 100 mm to 3 m! In these extreme event loading scenarios, small diameter foundations are pushed past their limits and many engineers prefer large diameter deep foundations for these situations. These deep foundations of diameter 900 mm or greater may be auger cast in place piles, cast in drilled hole piles, cast in steel shell piles, cased or uncased drilled shafts, bored precast piles, etc. For convenience in this paper, large diameter deep foundations will be referred to as Large Diameter Shafts (LDS). In LDS, steel may or may not used as a shell around the perimeter of the concrete and/or as internal tensile reinforcement. The interaction between brittle concrete and ductile steel within and/or along the perimeter of the LDS is critical to understanding the non-linear inelastic behavior of LDS for problems of large lateral displacements from extreme events.

Jan 1, 2018

By Andrew Higgins, Jamey Rosen

This presentation will demonstrate some recent advancements in the applications of Project Information Systems (PIMS) technology to seepage barrier walls in the context of evolving Owner Specifications. The use of geospatial technology in particular is used to track, visualize, and analyze data from a variety of sources and serve those data to contractors and owners via dashboards and as-built drawings. Data describing the geometry of construction elements (including diaphragm panels, secant piles, and jet grout columns) is of particular importance on these projects, and this presentation will include case studies in the United States of how these data are used to determine if a barrier wall is constructed as designed and if it meets the owner specifications with respect to tolerance (i.e., if each element is sufficiently close to vertical) and overlap (i.e., do adjacent elements overlap sufficiently to prevent leakage).

May 1, 2022

By John Mould, Gordon Chen, Michael Oakland, William McElwee

"This paper will discuss the design analysis of sheet pile cofferdams for static and dynamic blast loads. Following construction of the new Willis Avenue Bridge across the East River between Brooklyn and Manhattan, in-river piers No. 9 and No. 10 from the former bridge were demolished, partially by explosive charges. The blast at Pier 10 was conducted first and though the demolition charge was relatively small, it gave confidence that the sheeting could be designed to resist the blast load. This paper primarily summarizes our analysis and performance of a sheet pile cofferdam at Pier 9 used to withstand the larger blast loads, contain the blast debris, and allow excavation of the pier below the existing river bed mudline. The program NLFlex was used to predict stresses and deformations of the cofferdams under dynamic blast loads, using simplified equations to estimate the underwater blast pressures. Specifically, the analysis focused on the stresses in the struts, waler beam, sheet pile interlocks and connection of the sheeting to the waler beam. Design included allowing plastic deformations and limited rupture of the sheet pile interlocks under the blast loading. Comparisons are made between stresses assessed by the dynamic finite element modeling and empirical relationships used within the industry. The performance of the system after the actual blast is discussed as well as details of the performance of welded vs. bolted connections within the system. IntroductionThe Willis Avenue Bridge is one of the major access ways from the Bronx into Manhattan. The location is shown on Figure 1. The original bridge constructed in 1901 was a swing bridge over the East River. The bridge was in disrepair and outdated with regards to its ability to handle the flow of traffic resulting in numerousaccidents.In 2007, Kiewit Constructors Inc./Weeks Marine, Inc., A Joint Venture was selected to construct a replacement bridge. The $612 million project included construction of a new bridge just to the south of the original bridge. The most notable aspect of the construction was floating and lifting the new 350 ft. long swing span in place as a single piece. However, another significant challenge was using blasting to demolish two of the abandoned piers which were within the East River. The blast would be near existing structures in both Manhattan and Brooklyn and would be within 30 ft. of the new bridge."

Jan 1, 2017

By Michael Oakland

This paper will discuss the design analysis of sheet pile cofferdams for static and dynamic blast loads. Following construction of the new Willis Avenue Bridge across the East River between Brooklyn and Manhattan, in-river piers No. 9 and No. 10 from the former bridge were demolished, partially by explosive charges. The blast at Pier 10 was conducted first and though the demolition charge was relatively small, it gave confidence that the sheeting could be designed to resist the blast load. This paper primarily summarizes our analysis and performance of a sheet pile cofferdam at Pier 9 used to withstand the larger blast loads, contain the blast debris, and allow excavation of the pier below the existing river bed mudline. The program NLFlex was used to predict stresses and deformations of the cofferdams under dynamic blast loads, using simplified equations to estimate the underwater blast pressures. Specifically, the analysis focused on the stresses in the struts, waler beam, sheet pile interlocks and connection of the sheeting to the waler beam. Design included allowing plastic deformations and limited rupture of the sheet pile interlocks under the blast loading. Comparisons are made between stresses assessed by the dynamic finite element modeling and empirical relationships used within the industry. The performance of the system after the actual blast is discussed as well as details of the performance of welded vs. bolted connections within the system.

By Lisheng Shao

Soil mixing and jet grouting have been widely used to support heavy structures such as tanks, cement silos, and storage buildings. Although the installation methods vary between soil mixing and jet grouting, the end product of soil-cement columns behaves similarly in supporting structure loads. In many cases, soil-cement mass treatment offers the owner savings over driven/drilled piles. This paper discusses the design methodology, production work, and quality control, with supporting figures, of a recent large complex tank farm project. The project consisted of constructing six above-ground steel storage tanks and an approximately 700-foot-long fill slope. The tank farm site is located in an industrial area of southern California, with highly variable subsurface conditions consisting of compressible soils and buried construction debris. The compressible soils necessitated that the new tanks be supported on deep foundations. A test pile program performed previously at the site showed that conventional driven concrete piles were not feasible because of buried construction debris, therefore a soilcrete system was proposed. Site design included evaluating the total and differential settlement and column group bearing capacity under both static and seismic loads. Extensive field and laboratory testing confirmed the design soil-cement strength and modulus of both the soil mixed and jet grouted soil-cement columns. The project operation and quality control programs are also included in this paper.

Jan 1, 2010

By Frank Rausche, Scott D. Webster, Rozbeh B. Moghaddam

"Pile foundation driveability is a function of several variables such as subsurface characteristics, hammer type, hammer efficiency, pile type, and plugging conditions. One important phenomenon occurring during pile driving, and yet not well documented and published, is the friction fatigue, where a reduction of shaft resistance is observed as the pile is driven to greater embedment. This paper introduces current soil models developed for the assessment of friction fatigue, and further presents a comparison between predicted driveability obtained from Wave Equation Analysis Program (GRLWEAP) and field driving records. From a literature survey, and review of technical articles, a widely-used soil model known as AH-01 has been selected to analyze the friction fatigue concept. Using a WEAP software, two driveability analysis were completed using the standard approach with setup factors, and adapting the AH-01 model into the WEAP input file. Driveability predictions were compared to the driving records corresponding to a 1676-mm x 44- mm open-ended pipe pile with a total and embedment lengths of 180-m and 119-m, respectively. Results from analyses and the comparison presented in this paper provide further information regarding existing methods for the incorporation of the friction fatigue concept to the driveability analyses, and contributes to a better prediction of driveability of open-ended pipe piles. IntroductionDynamic measurements during pile installation provide more dependable information as compared to results obtained from predictive models used for design. Despite uncertainties associated with a specific project site and foundation type, measured data provides a reliable understanding of the soil resistance and its distribution throughout the length of the pile. Back-calculations or back-analyses based on a series of measured data from a pile driving process could help to obtain reliable models to better predict events related to pile installation process in spite of all variability related to fitted models. One of the widely-used analysis regarding pile driving during the design phase is the “driveability analysis” where capacity, blowcounts, maximum stresses in the pile element, and transferred energy from the hammer to the pile element are predicted using mathematical models along with a software. Such analysis requires relevant information regarding soil, pile, and hammer properties combined with a deep understanding of the level of impact each one of these properties could have on the analysis."

Jan 1, 2017

By V. A. Sernov

"One of the ways to increase the bearing capacity of a piled foundation is to take into account soil resistance in the base of the raft. Piled raft is similar to shallow foundation and can transfer significant part of the load into the base. It allows reducing number of piles in the foundation or shortening their length. As a result building terms and foundation costs reduce considerably. However, nowadays in Belarus there is no reliable and suitable in design practice methods of calculation of piled-raft foundations. In order to devise such methods we have analyzed the results of piled foundation tests fulfilled by various authors up to date and have carried out series of field and laboratory investigations in Minsk. The most important results of the investigations are provided in the article. Methods of analysis of piled-raft foundations are described.INTRODUCTIONPile foundations of late years are used extensively in connection with the increased number of storeys and load increment on the soil. Often pile foundations are applied in comparative favorable ground conditions at the surface of the base. In such cases the increase of the bearing capacity of foundations and the reduction of construction cost are questions of primary importance for designers. One of the ways to increase the bearing capacity of a piled foundation is to take into account soil resistance in the base of the raft. Piled raft is similar to shallow foundation and can transfer significant part of the load into the base. It allows reducing number of piles in the foundation or shortening their length. As a result, building terms and foundation costs are reduced considerably. However, nowadays there is no reliable and suitable in design practice methods of calculation pile foundations with bearing rafts. In order to devise such methods we have analyzed the results of piled foundation tests fulfilled by various authors up to date and have carried out series of laboratory and field investigations.Long before the constitution of the first piled-raft foundations in the Soviet Union there were attempts to consider soil resistance in the basis of isolated and strip grillages. Such bases can be considered as separate fragments of the piled-raft foundation. Prof. A. A. Bartolomey had tested more than 70 pile foundations of natural size in different ground conditions. The length of piles was 3 12 m (?????????? 1995). The observed results show that the raft carries about 10 12% of the total load applied when length of piles is over 9 m and space between piles is a=3d. Bearing capacity of the raft is about 35 40% when the length of piles is 5 8 m and a=6d. Prof. Golubkov has tested 2 prismatic piles (cross section: 350x350 mm, L=3800 m) and 2 pyramidal piles (cross section: head - 600x600 mm, foot – 100x100 mm, L=3000 m). One of the piles was tested with a raft and the other one without a raft. Significant influence of the raft on total bearing capacity was determined, the more the settlement was the more it influenced on the raft. Bearing capacity of the raft was 27,5% in foundation with prismatic pile and 42% with pyramidal pile (???????? et al. 1971)."

Jan 1, 2016

By Clyde Baker

Drilled shafts for many situations offer an economical alternative to driven piles. The Federal Highway Administration (FHWA) has spent considerable time and money in research and developing design and construction guidelines for drilled shafts. However, the full potential of the technology may not be realized because of the uncertainty of the effects of construction on the actual service behavior and the lack of either reliable quality control tests to check for or evaluate defects, or inexpensive load test procedures. Static load testing is very expensive and it is not feasible to load test each shaft on a project. Therefore, other means are necessary to confirm or evaluate the integrity of the completed drilled shaft or to determine the capacity of the completed shaft.

Jan 1, 1989

By Sanket Rawat, Ravi Kant Mittal, Vikash Prasad

"The understanding of the response of pile foundations under various types of loads is a necessary prerequisite to analyze and design them properly. Therefore, this paper highlights and compares the provisions available in Indian Standard IS 2911:2010 to estimate the capacity of laterally loaded pile foundation with the provisions available in different country codes and existing literature. Comparisons are made between the Indian standard method, Broms method and Matlock & Reese method for the analysis of laterally loaded piles due to popularity and prevalence of the later methods in design offices worldwide. This has been achieved using a parametric study on pile embedded in pre-consolidated clay and sand for both fixed head and free head case in terms of displacement and ultimate load capacity. It has been found that there are various limitations to the Indian Standard method associated with various cases such as short pile analysis, complete moment distribution etc. Therefore, suitable recommendations have been made on the basis of the above comparison to improve the accuracy of the design in Indian perspective. The proposed comparison and subsequent area of improvements will present the design engineers all across the globe, a broad sight of design specifications of laterally loaded piles.INTRODUCTIONPiles in groups are very often subjected to both axial and lateral loads. In the 1960’s, designers used to assume that the piles could carry only axial loads and the lateral load is to be carried by batter piles. However, later, a large number of load tests authenticated that vertical piles also can transfer lateral loads through shear, bending, and lateral soil resistance rather than purely acting as axially loaded members. Initial attempts to analyze laterally loaded piles used the finite-difference method, as described by Howe (1955), Matlock and Reese (1960), and Bowles (1968). Matlock and Reese (1956) used the finite difference method to get a series of non-dimensional curves to enable the user to input the appropriate curve with the given lateral load and estimate the ground-line deflection and maximum bending moment in the pile shaft. Later, Matlock and Reese (1960) extended the earlier curves to include selected variations of soil modulus with depth."

Jan 1, 2017

By S. Chilka, I. Maloney, J. Brady

"The purpose of this project was to design the Electrical Service Platform (ESP) for the Cape Wind Offshore Wind Farm. The ESP structure comprises two primary parts: the topside platform housing the electrical equipment and the two jacket substructures providing foundation support to the platform. The topside is supported only by the two inner legs of each jacket. The site water depth is relatively shallow and the seabed comprised of loose sediment subject to severe local scour up to 18 feet. The piles are designed for local scour, storm conditions, vessel impact, ice loads and pile installation fatigue. This paper focuses on the design and construction aspect of this project.PROJECT DESCRIPTIONBackgroundThe Cape Wind project will be located in Nantucket Sound between Cape Cod on the Massachusetts mainland (northeastern coast of the USA) and the Islands of Martha’s Vineyard and Nantucket (Fig. 1). The project is to be sited on Horseshoe Shoal, about equal distances from the mainland and the two islands. The project will produce 75% of the electricity used on Cape Cod and the Islands of Martha’s Vineyard and Nantucket with zero pollution emissions and resulting in the reduced operations, fuel consumption and pollution emissions from the fossil fuel power plants in the region. The wind farm, if constructed per plan, is expected to be America’s first offshore wind farm.The wind farm will consist of an array of 130 Siemens 3.6-megawatt offshore wind turbines with a combined production capacity of 468-megawatts. The offshore wind turbine towers will be bolted onto the transition pieces supported by monopile foundations driven into seabed. The power from the 130 wind turbine generators will be delivered to the Electrical Service Platform (ESP) by an array of up to 14 seabed conductors."

Jan 1, 2017

By R. Radhakrishnan, C. Gunasekaran

"Calicut Bypass Phase-II project included construction of 7 m high embankment over soft compressible clays up to 18 m in thickness. Approx 1.5 km length of road out of a total 5 km length consisted of abandoned paddy fields which were low lying, waterlogged and marshy in nature. On the basis of excellent results achieved in earlier phases of the by-pass construction, ground improvement work by installing pre-fabricated vertical drains (PVD) was undertaken to stabilize the embankment foundation along the weak clay areas prior to road pavement construction to avoid large post construction settlement as well as to improve the lateral stability during and after embankment construction. This project perhaps stands out as one of the highway projects completed within a very short time period of total 18 months including four month long heavy monsoon period, when embankment construction was not possible and construction of two bridges across rivers. All activities including the ground improvement had to be programmed and completed within the shortest time period possible. The paper discusses details of the extensive ground improvement and soil instrumentation carried out for the project and will illustrate how careful planning and execution can reduce the period required for highway projects involving ground improvement.INTRODUCTIONPhase-II construction of Calicut by-pass was undertaken on a priority basis by the State of Kerala in 2014. The main contract was awarded to M/S ULCCS Ltd, Kozhikode, Kerala and the ground improvement work was awarded to M/S Geo-Enviro Engineers P Ltd, as specialist agency to design and execute the work.Soil investigation carried out confirmed thick soft clay deposits below GL in three areas along the road alignment totaling approx 1.5 km in length. These areas were low lying, waterlogged and marshy in nature. Highway embankment had to be constructed up to 7 m in height above existing GL to form the proposed road alignment along these areas. On the basis of excellent results achieved in earlier phases of the by-pass construction using pre-fabricated vertical drains or PVD (R. Radhakrishnan, 2006), ground improvement using PVD had been included in the contract to stabilize the embankment foundation along the weak clay areas prior to highway embankment construction to avoid large post construction settlement as well as to improve lateral stability during its construction."

Jan 1, 2015

By Hou Shitao

With the development of Wuhan's city planning in China, new buildings of moderate and high store have been increasing day by day. Precast concrete piles or cast-in-site piles were used in the major foundations of the buildings. In process of their design and construction geotechnical engineers are concerned very much about practical bearing capacity and construction quality of pile foundations. In order to grasp accurately the cases static loading or vibration test is used generally to judge them. At present, the major questions in existence are that although a load is applied directly on pile and measured datums are reliable for static loading test, it must take a lot of work and longer time and engineering cost is higher. A vibration test has the advantages of which checking up of pile quality can be performed rapidly, the test is simple and convenient, and scope measured wide. But bigger error exists generally in measured datums. Therefore, it is nesessary to make vibration test on piles more perfect for pile foundation engineering. It is stated in paper that adapted technique of vibration test on piles is quite right in developmental direction sense for pile foundation. There are a great variety of vibration test methods on piles. A few of methods which often are adapted in practice can not meet the need of different practical engineering. It is also an important question whether the instruments of vibration test and relevant computer softewares make a response accurately for practical case. Different sequence of operation and technical requirements comes into being some influence directly on the test results. Meanwhile, different combination of soil stratigraphy, soil texture, groundwater and pile could cause different error of test datum. It is necessary to analyse and judge objectively the results of vibration test. Therefore, on the basis of developing and perfecting further the technique of vibration test, the applied technique of vibration test should be standardized so that better test results can be obtained.

Jan 1, 1991