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By Alexander Filotti, Richard Kalson

"In the last decade, the construction industry has witnessed significant changes in the project delivery systems and contractual relationships between the general contractors (GC) and Deep Foundation Specialty Contractors. The Deep Foundation industry, especially including industry specialty subcontractors, have experienced a significant increase in requests that project risks be transferred through contract documents to subcontractors and suppliers with a decrease in margins for the industry. GCs regularly revise their form subcontracts to take into account recent experiences/contractual trends and newly issued judicial precedent, an exercise that is less frequently undertaken by subcontractors and suppliers. These contradictory trends are at the base of the ethical analysis of subcontracts that comprises the subject matter of this paper. Using contracts as a risk management tool in order to mitigate the general contractor’s risks in the context of dynamic changes in the legislative environment will also be addressed. Furthermore, another possibility for risk mitigation for the industry is to actively promote the introduction of the latest technical developments into the contract documents.CONTRACTS’ ETHICSFor thousands of years, ethics have been a constant presence in our lives and have been debated by different branches of philosophy. In modern times, ethics in business started to be an imperative for the success of a globalized economy.“Ethics are standards by which one should act based on values. Values are code beliefs such as duty, honor, and integrity that motivate attitudes and actions.” (Rumbaugh 2004). Some of these values and actions have been carved in legislation in general and in business legislation in particular. More and more, unethical business practices (e.g., corruption) are identified as the root cause of poverty, underdevelopment, and war around the world. In the context of contract ethics, three aspects are of interest:•,Ethics of contract construction•,Ethics of contracting processes•,Ethics of risk allocation in contracts"

Jan 1, 2016

This specification, along with the drawings, encompasses all designs, materials, products, accessories, tools, equipment, services, transportation, labor and supervision, installation techniques, and testing procedures required for the installation of soil nail excavation support or earth retention systems. This is a Guide Specification designed to assist in the development of project specifications for soil nail excavation support and earth retention systems. This Model Specification is based on generally accepted industry standards but may require modification by the specification writer to accommodate unusual and/or unforeseen site and subsurface conditions and the particular circumstances of the project. Care must be taken to avoid internal inconsistencies. It contains language allowing for a Contractor-Designed Soil Nail Wall, which would be removed if the design is provided by the Owner (e.g. See Sections 1.2 and 4.1).

Jan 1, 2010

By Nikolas Schmitz

For today’s construction industry, large-diameter piles are common practice, as they are more competitive than drilling a larger number of smaller piles. More and more piles are installed by drilling rigs, replacing the installation by hammer, vibrators or caisson. Equipment capabilities and technics with rotary drill rigs are highly developed, but very costly and time-consuming when it comes to rock drilling, large diameters and deep foundations. Pile top drill rigs (PBA), based on reverse circulation drilling (RCD) technology, overcome these challenges and are an efficient solution for large diameter drilling (0.6 m to 8.0 m/19.7 ft to 26.3 ft) and drilling depths of up to 500 m (1,640 ft.)in various geological conditions onshore and offshore. The paper will explain benefits of RCD technology and prove this with figures from the Mumbai Trans Harbour Link project.

Nov 1, 2022

By Rob van Dorp

"AbstractThe Monitoring & Instrumentation Committee (MIC) of DFI Europe has the objective to support DFI members in concern of risk management of geotechnical matters, where monitoring and instrumentation have added value.Work of the CommitteeA study by the committee showed that there are already several existing (national) guidelines. They all have their strengths and limitations and their focus may vary a little per country due to local regulations and typical local building activities, but the main question remains what added value another new guideline would have. More likely it would add to the confusion instead of providing overview.Companies with larger experience in geotechnical monitoring (often larger consultancy firm, contractors or clients) are already quite familiar with its benefits do not really need a new guideline in how to design and effectively apply sophisticated geotechnical monitoring systems for special projects.Therefore the aim of the MIC is to focus a little more towards smaller organizations - that are less familiar with monitoring and instrumentation - and the more ‘regular’ type of project that they are mainly involved in. The MIC wants to create a tool which helps them to create risk awareness, to understand the benefits of geotechnical monitoring and to provide them information about how and where to find the right partners and equipment to setup and apply appropriate monitoring systems for their projects.Monitoring and instrumentation benefits are for example:• Risk control during construction stage;• Costs reduction in design and construction (taken limitation of geotechnical aspects into account).• Prevent of unnecessary delays in construction work• Increasing general awareness of geotechnical risks and possibilities of monitoring.The cost of monitoring compared to the cost of failure and/or the savings that can be achieved play a role in the work of the committee. DFI members benefit from the shared knowledge by the MIC on monitoring and instrumentation within their process of risk management."

Jan 1, 2014

By Philip Derbyshire, Dale J. Scheffler

"Continuous Flight Auger (CFA) piling is a variation of Augered Cast-In-Place (ACIP) or augercast piling. In both cases a continuous auger with a hollow stem is used to drill a hole and a pile is formed by injection of cementitious material through the hollow stem as the auger is withdrawn. CFA differs from conventional American ACIP by the use of concrete rather than grout to form the pile, and by the type of equipment used to advance the auger into the ground and withdraw it. CFA installation uses a European style rig (i.e. fixed mast and rotary system) which can produce greater crowd and usually has a larger rotator or drill motor than the standard augercast setup. A standard augercast setup will consist of a lattice-boom crane and a set of leads to house the drill motor and auger. The auger size will range up to 24 inches (610mm). With CFA rigs larger diameter piles can be constructed, 24 to 36 in dia. (610mm to 915mm) are common and the technique has been applied with diameters up to 48-inch (1220mm). CFA makes use of sophisticated computer controlled monitoring systems, which have more recently been introduced for conventional ACIP piling. Developments in CFA have taken place over the last 25 years in Europe and particularly in the UK, but are relatively new in the USA. One application is in the construction of secant (overlapping) piled retaining walls. D.J. Scheffler Inc. recognized the potential of the CFA system following visits to the UK and has introduced its use into California for both secant piling and other applications.BACKGROUNDThe high price of real estate in many of the favored areas of California has increasingly led owners to want to build basements under their houses to increase the floor space available on a lot. Many of these areas are by the coast where the ground conditions are predominately granular and the water table is high. Conventional shoring and dewatering systems have often caused problems with adjoining properties. Clearly tangent walls are not suitable in these conditions because of leakage and loss of ground. The secant pile system, using CFA techniques, has proved very effective at overcoming the problems experienced by other methods. Other applications for CFA secant walls have included use for an emergency job on a highway following erosion caused by unusually heavy rainfall.METHODThe concept of secanting piles, whereby primary(female) piles are installed first and then secondary (male) piles are cut into the primary piles is not new. The method has been known for more than 30 years. Originally ‘Benoto’ grabbing rigs, developed in Japan, were used together with sectionalized double skinned casing and oscillators.This early method was slow, although very effective. More recently high torque rotary machines have been used. Contractors in the UK have increasingly used CFA techniques to further improve productivity of this type of piled wall. The improved capabilities of piling rigs available, as well as developments in concrete technology and instrumentation, have made this possible."

Jan 1, 2005

By Mike Muchard

STATNAMIC load testing augmented with embedded instrumentation has been successfully used to obtain structural and geotechnical design information on large diameter spun cast concrete cylinder piles on many large marine construction projects. The paper focuses on one particularly interesting large marine project involving a new bridge to St. George Island, Florida where instrumentation and STATNAMIC load testing was used in conjunction with static load testing on high capacity piles. The information presented includes embedded instrumentation measurements taken during pile fabrication (post-tensioning), during pile driving, during static load testing, and STATNAMIC load testing. As much of this data is the first of its kind on concrete cylinder piles, it is exciting to present the foundation industry with this additional insight as to the behavior of this pile type and the accuracy of the methods used to test them.

Jan 1, 2013

By Dr Karsten Galipp, Kai-Julian I. Hendler, Prof. Manuel G. Pinheiro, Dr Peter J. Bourne-Webb

With a share of approximately 11% of global greenhouse gas emissions, the construction industry contributes significantly towards climate change. This is why construction projects should not only be assessed on costs and technical solutions, but also on their carbon emissions. Life Cycle Assessment (LCA) is a tool which can quantify the environmental impacts of a construction project over its entire lifetime. The objective of this study was to determine the carbon footprint of three types of quay wall structures, namely sheet pile combi-walls, open piled decks and caissons using an LCA approach. Each of these quay walls were studied under the same boundary conditions, such as design life, ground conditions, dimensions, location and so on. The analysis showed that the sheet pile wall has the lowest carbon footprint whereas the open piled structure has the highest. Furthermore, it could be shown that the largest share of greenhouse gases (approximately 80%) is emitted during the production of construction materials. The transportation of materials and construction activities each contributed under 12% to total emissions. The sensitivity analysis showed that with innovative approaches, such as adapting the concrete mix design, the carbon footprint could be reduced by 26% to 40%.

May 1, 2022

By David H. Sanders, Ramin Motamed, Fahim M. Bhuiyan, Raj V. Siddharthan

Large-diameter drilled shafts (DS) are a critical part of a seismic-resistant system, and therefore it is important to be able to accurately model lateral resistance. To undertake the lateral load analysis of largediameter DS, a finite-difference p-y analysis program, NVShaft, is being developed at the University of Nevada Reno. Validation of the new program involved numerous p-y analyses using commercially available programs. Subsequent comparisons suggested the program's ability to yield reasonable predictions for typical diameter DS. Based on the I-15/US 95 load test program carried out in Las Vegas, NV, this study presents the evaluation of NVShaft in Nevada’s subsurface condition. Lateral load analyses of a 2 ft and an 8 ft diameter DS were attempted using NVShaft. The location of the applied lateral loads and the presence of cemented soil-layers were incorporated in the modeling. A good agreement between NVShaft prediction and the measured response was found for the 2 ft diameter DS. For the 8 ft diameter DS, a stiffer response was predicted. The inspections of the moment-curvature characteristics at different load levels suggested cracked response of the concrete due to prior axial load testing may be one of the reasons behind the deviation.

By Brian D. Barkauskas, Terence P. Holman

A major combined nuclear and coal-fired power plant, located in on the western coast of Florida has undergone multiple upgrades in recent years to increase power output and enhance environmental controls. Construction of new elements within the existing plant structure required working in highly congested conditions and heavy crane lifts with large picking radii. The largest crane pick involved the use of an 1800 metric tonne capacity Mammoet PTC ring crane for a single long-radius, high altitude lift of a precipitator unit. Original bid tender documents had called for drilled shaft foundation support, but the presence of many critical utilities and unfavorable access for cost effective construction led specialty contractor Moretrench American Corporation to propose an alternate micropile foundation on the basis that high capacities could be achieved in the weak limestone geology and that the smaller size of micropiles would allow for more surgical installation in the utility-congested areas. This case history describes the design and construction of seventy three (73) high capacity micropiles for the value engineering alternative and the crane foundation for this critical lift. Each micropile was founded in a competent dolomitic fossiliferous limestone unit at typical depths of 23 m below existing ground surface. Strain gauge instrumented load testing was used to validate the geotechnical design parameters in the weak limestone bedrock and resulted in the finding that the entire test load was being carried in the upper half of the bond zone. Construction of the production micropiles required numerous relocations due to utility conflicts and local reanalysis and redesign of the 1.2 m thick reinforced concrete ring beam cap. Crane foundation performance was satisfactory and the effective life of this temporary foundation was only 6 months before decommissioning and demolition.

Jan 1, 2017

By Heinrich Majewski, Rob Jameson

"Careful review of site conditions and constraints is essential to select the appropriate shoring system for each project. Key evaluation criteria include the geotechnical profile, groundwater and environmental conditions, adjacent buildings and utilities, schedule and any project specific access or other constraints. Typical earth retention schemes range from rock or soil nail walls, through conventional anchored pile and lagging walls to deep internally braced cut-off systems. The Owner’s design team will often develop the conceptual approach under their design studies, and this is refined with Contractor input through Design-Build or Design-Bid-Build procurement. In downtown San Francisco, underground construction must accommodate a unique combination of variable fill, soil, rock and groundwater conditions, potential for severe seismic loadings, and constrained sites within a dense urban environment. The quarter square mile of San Francisco’s Transbay and Rincon Hill districts has seen repeated cycles of development, destruction and re-building through earthquakes and the economy, and has been intensely redeveloped over the last decade. Over 50 acres of this land has been reclaimed from the Bay since the Gold Rush and within 3 city blocks the bedrock slopes from over 250 FT depth below the fills up to outcrops over 100 FT above sea level. A series of project examples from within this small area illustrate how varied shoring systems have accommodated the highly variable subsurface conditions while offering best value in terms of cost, schedule and appropriate protection of adjacent facilities.INTRODUCTIONA walk of 3 blocks from Rincon Hill on San Francisco’s Harrison Street, north through the Transbay area to Mission Street will traverse an urban zone which has been reinvented twice within its 150 year history in response to major seismic events. This small area highlights the range of subsurface conditions and urban environments which are encountered and accommodated in shoring schemes throughout the city. This route down the north side of Rincon Hill overlies a steep bedrock slope, outcropping over 100 FT above sea level at its south end and dropping to over 250 FT below sea level at Mission Street. A complex overburden soil profile, shaped by seismic activity and changing sea-levels has created layered soils ranging from soft estuary muds, dense sandy strata and deep clay layers, in turn topped with urban fill, frequently contaminated with debris from the Great 1906 earthquake. This route runs parallel to, and 350 yards inland of, the San Francisco shoreline resulting in groundwater elevation close to sea level with almost limitless recharge within granular layers. On the higher slopes of Rincon Hill, groundwater is typically observed flowing on top of and periodically within the fractured bedrock formation. The Transbay and Rincon areas were developed early in the Gold Rush era of San Francisco. After destruction in the 1906 earthquake and fire, they became a transit gateway into the city throughout the 20th Century. Demolition of the Embarcadero Freeway in response to earthquake damage and social pressure has opened this large area to redevelopment within the last 20 years, creating a new commercial and residential hub for the city. In its latest wave of building, planners are developing taller structures with deeper basements, in turn creating new construction challenges. Selection of shoring systems appropriate for these developments requires detailed evaluation. The process must address both the rapid spatial changes in subsurface conditions and the constraints surrounding, and specific to, each site in order to define shoring performance requirements. This paper presents an overview of the subsurface conditions and land use development of the Transbay and Rincon Hill areas, with examples of the shoring systems selected to meet site-specific conditions and requirements. The projects cited range from soil nail wall"

Jan 1, 2017

The intent of this manual is to provide guidelines for inspectors of drilled shaft construction otherwise referred to as drilled piers, caissons or bored piles. It should also be helpful to train beginning geotechnical engineers with limited first hand experience or for geotechnical engineers who are training inspectors. It is expected that the general guidelines and procedures described here will be supplemented by local geotechnical engineers working in a particular region based on local practice and experience. Since drilled shaft construction procedures vary widely based on local geology and size of project, an all-inclusive manual is not considered practical. This manual focuses on traditional topside inspection for routine drilled shaft construction. Other inspection and evaluation methods that rely on electronic equipment are available, but these methods require extensive training and experience in the interpretation of results. These more sophisticated methods of drilled shaft inspection and evaluation are common in construction, but they are usually provided by specialty subconsultants. The subconsultant will typically submit a report for each shaft, which will be reviewed by the geotechnical engineer. Other manuals are available to describe the electronic methods of drilled shaft inspection.

Jan 1, 2004

By John C. Tosh, Peter M. Kandaris, Sheldon John

Geologic, geotechnical and hydrologic studies were performed for the design of 115 deep, large diameter drilled shaft reinforced concrete foundations (6 to 12 feet) to support tall steel monopoles for a new 13-mile long 230/69kV transmission line in southwestern Arizona. The subsurface conditions along the alignment posed a wide range of challenges for performing investigation and design studies. These conditions include saturated, loose granular flood plain deposits with generally low lateral capacity, potential ground loss up to 23 feet due to occasional river flow (scour and embankment loss), liquefaction impacts from nearby active fault seismicity that can generate magnitude 6.5-7.0 earthquakes, and unsaturated alluvial and eolian sand-dominated soils to full depth with low lateral capacity. All conditions will require significantly deeper than normal foundation embedment (depth ranging from 22 to 77 feet) and will present construction difficulty due to ground instability from groundwater and dry soil sloughing. A phased investigation was performed to accurately characterize the conditions for design and construction, and included performing a review of existing data, detailed field geologic reconnaissance, a limited number of standard exploratory borings (limited access), seismic cone penetrometer soundings (SCPT) in saturated soils to better understand liquefaction and strength loss potential, and hydrologic analyses to estimate scour/ground loss potential. This paper describes the site conditions, presents details on the investigation team’s approach, documents findings in relation to deep foundation analysis and design, and discusses recommendations for foundation construction to help in reducing risk.

Sep 8, 2021

By Antonio Marinucci, Robin Mao

The new Hangzhou West Railway Station, which is currently in the early stages of construction, will be located in the city of Hangzhou, China. To accomplish the ambitious goals of the project, the construction work and station building was divided into three project areas. The original design utilizes 1,580 drilled shafts with diameters of either 800 mm or 1000 mm (32 or 40 inch) to support the new Station and its various ancillary structures. The drilled shafts will be tipped into the moderately weathered argillaceous siltstone a distance between 5 and 15 m (16.5 and 49 ft), resulting in an effective pile length ranging from 35 to 43 m (115 to 141 ft), respectively. For the first phase, approximately 550 production drilled shafts will be installed. Eight (8) sacrificial drilled shafts each with a diameter of 1000 mm (40 inch) were installed to a depth ranging from 50 to 57 m (164 to 187 ft), and were tested to confirm the design parameters used for the first phase, to evaluate the contractor’s installation means-and-methods, and to provide guidance whether redesign is warranted for the subsequent two phases. Bi-directional static load testing was performed using a donut-shaped Super Cell to apply unidirectional axial loads up to 13,200 kN (2,970 kip). This paper will describe the bi-directional testing and select results obtained therefrom. The axial compressive and uplift resistances determined from the testing verified that the available axial resistance of a single drilled shaft exceeded the minimum design requirements.

By Raymond J. Poletto

This paper describes the special problems that occur with the construction of diaphragm walls and discusses the lessons learned during the repairs of structural walls. Although diaphragm or slurry wall technology and equipment has vastly improved since its development in the late 1950?s, significant problems still occur. Key issues are repairs related to panel joints between wall panels, concrete defects associated with tremie concrete problems, leaks and other defects at tieback reservations or inserts, wall leaks within the plane of the wall and surface repairs. The paper supports the position that diaphragm walls are relatively watertight when properly constructed, but cautions that it is necessary to address potential problems in the design stage and allow for flexibility in construction so that the problems that occur can be corrected once encountered. Due to the fast track nature of most projects the time available for design, detailing and construction is limited. As a result, insufficient attention to detail by any of the responsible parties can lead to imperfections and defects in the wall. The authors describe the nature of these problems and their potential resolution based on ?lessons learned.? The timely response to wall problems is essential to the successful completion of a diaphragm wall project. Appropriate repairs have resulted in largely successful jobs starting with the World Trade Center in New York City. The authors? total 80 years of experience as the engineer of record and designer, inspector and contractor?s representative for the diaphragm wall results in a unique insight to deal with these problems.

Jan 1, 2011

By A. Paviani

The subject of this session is "Equipment Installa­tion, Recent Developments". This is a subject which is not usually addressed at conferences of Foundation Engineering. It is rare to find sessions dealing with the technological side of deep foundations, a subject which only recently seems to have aroused sufficient interest at national and international conferences. It is therefore natural for the subject of "Equipment", or the tools used to implement the various "technologies", to be over­looked or mentioned only occasionally during the discussion of other issues. At conferences, most of the attention is attached to research and to the theoretical interpretation of the performance and behaviour of deep foundations, as well as to establishing the most suitable calculation algorithms and approaches for the study, design and control of foundation structures. It is almost as if the subject of equipment is felt to be less important or, perhaps, that it is considered to belong more strictly to mechanical engineering than to civil engineering.

Jan 1, 1994

By Neil T. Russo, Peter M. Kandaris, Jogi S. Gadok

"Assessment of subsurface data for foundation design in support of long high voltage electric transmission lines is best accomplished using a probabilistic strategy since only a small portion of structure locations are typically sampled. Probabilistic approaches provide a tool to evaluate site uncertainty in a systematic and rational manner. This paper provides a case history of a risk-based design approach for a recently completed 191-mile long 69/161/345kV steel monopole transmission line traversing Central Iowa. The project owner made available limited subsurface information at project initiation, requiring the design team to obtain additional data within a constrained budget for 1067 large diameter, laterally-loaded deep drilled shaft reinforced concrete piers. The team commissioned a geologic desktop study to reduce uncertainty in subsurface evaluations and aid in selecting additional sample sites. In total, investigation programs tested approximately 15 percent of structure sites. The paper details the probabilistic approach used to estimate foundation geotechnical design parameters, with information from the various studies categorizing strata both laterally and with depth. Low-bound parameters were estimated via a statistical approach at a predetermined reliability level. Significant savings resulted from this approach when compared to conservative deterministic processes. Project QA/QC logged subsurface soil conditions during foundation excavation, then compared as-found conditions to the conditions assumed for design. The team redesigned foundations if either a non-conservative variance in soil conditions was observed or if bedrock elevation differed significantly from design assumptions. As a result, only 22 out of 1067 foundations required modification during construction (2% variance from initial design) with negligible impact on the construction budget and schedule.INTRODUCTIONFoundation design for long high voltage transmission lines presents a unique challenge in that the assessment of subsurface conditions typically requires substantial data that may or may not be obtainable. Investigations are usually performed well in advance of construction, often with limited access to structure sites and typically in remote areas. Probability and risk-based investigation and design strategies offer an opportunity to systematically estimate subsurface profiles and geotechnical design properties with limited data. Risk can be further reduced with dedicated field inspection of foundation construction along with good field and design team communication during construction. This paper presents a case history of probabilistic methods used for the investigation and design of electric transmission line foundations."

Jan 1, 2017

By Padmavathi V, M. Najamuddin, M. R. Madhav

Granular piles are one of the leading ground improvement techniques, adopted for the betterment of bearing capacity and reduction in settlements of the foundations and also to accelerate consolidation of the surrounding soil. In the recent past, there has been extensive research on the settlement analysis and behavior of granular piles under varied soil conditions. The application of these theoretical solutions to practical problems requires a knowledge of representative values of the deformation parameters of the ground and the granular piles. However, very little information is available on these parameters. The paper presents a new method for the estimation of the modular ratio of granular piles and modulus of deformation of the surrounding in-situ soil from the compression load tests. The load - settlement response obtained from the compression test results are used in the back analysis for estimating the modulus of deformation of the ground. The presence of granular bed, under the rigid plate for load testing, has been given due consideration in quantifying the proportion of load transferred on to the stone column. Based on these considerations a new method is developed to estimate the modulus of deformation of the ground and the modular ratio of the granular pile.

Sep 1, 2022

By Sitotaw Y. Fantaye

"The first segment of the Second Avenue Subway extension is approaching construction completion. The new extension will operate along Second Avenue from 96th Street to 63rd Street, where it will divert west along the existing 63rd Street line, stopping at the Lexington Avenue/63rd Street Station. The new line will have stateof-the-art stations at 96th, 86th, 72nd and 63rd streets.Most of the two-track, twin-tunnel subway was constructed using bored tunnel methods (Figure 1), with a tunnel boring machine (TBM). The launch and retrieving box of the TBM was strategically located at the south end of the 96th Street Station where bedrock exists approximately 70 ft (21.3 m) below street level. The TBM launch box and the 96th Street Station (Figure 2), including the ancillary facilities adjacent to the station, were constructed by the cut-and-cover method. The cut-and-cover work required the contractor to design and implement a stiff, tightlybraced retaining wall, approximately 100 ft (30.5 m) long, to tie the existing tunnel constructed in the 1970s to the new station, temporary street decking over the entire excavation, and a wide range of excavation support systems at various locations.The cut-and-cover construction posed significant challenges including: installation of street decking on busy Second Avenue, relocation and suspension of the myriad utilities beneath the streets, and configuration of a lateral support system that would minimize movement of adjacent structures but not slow down excavation activities. This article describes the innovative solutions developed to manage and facilitate safe and efficient construction without disrupting Second Avenue, a major southbound one-way thoroughfare.The work was performed in several phases involving: (1) preconstruction condition survey of existing buildings, (2) installation of instrumentation and monitoring, (3) major utility relocation efforts to move vital utilities from within the alignment of the slurry wall on both the east and west sides of the avenue, (4) implementation of maintenance and protection of traffic plans, (5) installation of temporary street decking across the entire avenue and over the excavation to allow an orderly movement of traffic and pedestrians, (6) staged excavation and installation of an intricate temporary bracing system beneath the decking (7) step-by-step construction of the new subway station’s structure and (8) staged removal of the bracing as the structure gained sufficient strength to resist the lateral loads. The main focus in this article is the design and construction of the temporary street decking and lateral bracing systems; the utility suspension system and the north tie-in that allowed the daunting task of excavation and construction of a new subway station in bustling New York City, with minimal disruption to the community, businesses and everyday traffic."

Jan 1, 2016

By Stephen Buttling, Zhong Rui

"A single unit gas fired power station was being built on the edge of the Gulf of Thailand in 2001. The soil conditions consisted of very soft to soft Holocene Marine Clay, and the site was part of a coast line which had been subsiding below high water mark for some time. In order to provide access around the power station a road system in a figure-of-eight formation was required, and this also needed to be above the design flood level, allowing for future settlement. A ground improvement scheme was proposed and constructed, which consisted of two spacings of prefabricated vertical drains (PVD) over two depth ranges, vacuum consolidation and pre-loading, and rigid inclusions.During the construction phase, the vacuum consolidation was applied for 202 to 221 days in different zones, and monitoring allowed a prediction that the future settlement, including secondary consolidation over a period of 25 years, would be within the range of 175 to 355 mm, which met the contract requirement of less than 400 mm.The power plant was completed and became operational in 2003. Monitoring of the road levels continued, as did the settlement, and in early 2010 the total settlement since the end of vacuum consolidation had reached about 800 mm. The monitoring data both during the ground treatment and for the following 7 years is presented and analysed. This is supported by numerical analysis using 3D finite element methods which shows good agreement with the measured data, and allows a preliminary explanation as to why the predictions were so far out.BACKGROUNDAfter a period of bidding and negotiation, the Eastern Power and Electric Co Ltd (EPEC), an Independent Power Producer, entered into an agreement with the Electricity Generating Authority of Thailand (EGAT) in November 1997 to sell them power. In 1999 an Engineering, Procurement and Construction (EPC) contract and an Operation and Maintenance contract were signed with a supplier to provide a gas-fired (with oil as a back-up fuel) 350 MW combined cycle power plant in Bang Bo, Samut Prakarn Province, east of Bangkok. The site of the plant at Bang Bo is located immediately to the east of the Samut Prakarn Wastewater Treatment Plant, adjacent to the Gulf of Thailand (see Figure 1) in an area of very soft to soft marine clay (Bangkok clay) having low shear strength and potential for excessive settlement. The site layout comprises the main Power Plant components of generating block, cooling towers, fuel unloading area and storage tanks, switchyard and administration block, separated by access roads."

Jan 1, 1900

By O. Craciun, C. A. Bridges, M. Cai, J. Sugawara

There are a number of methods that can be adopted for predicting the ultimate lateral resistance of a free-head rigid pile, from the conventional Brinch Hansen and Broms solutions to three-dimensional finite element analyses. Often these methods give rise to significantly different pile ultimate lateral capacities which could lead to either unsafe or too conservative designs. It is also well known that finding a rigorous and practical solution is challenging due to the complex three dimensional and nonlinear soil-structure interaction. This paper reviews some of the most common methods and produces results of pile ultimate lateral capacities embedded in cohesive or cohesionless soils. Subsequently, a finite element analysis is performed using PLAXIS 3D modelling under the same design conditions. Based on comparison of results, limitations and advantages are highlighted, and the most suitable method is proposed from a practical point of view.

Nov 1, 2022