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By Julie Clarke

In 1939 Dr. Ralph Peck criticized the Civil Engineering community for taking a bifurcated approach to the prediction of building damage due to subsurface geo-technical works. Specifically, he observed that Geotechnical Engineers concerned themselves only with subsurface issues implying that their results were largely independent of the presence and condition of the structures above. He continued that Structural Engineers charged with risk assessment of buildings approached their work nearly in isolation of below ground activities. Seventy years later, although the state-of-the-art has enabled a better understanding of soil-structure interaction, the reality remains that risk assessment from subsurface construction, is not yet an integrated activity when done on a large-scale basis. To help move beyond this, this paper proposes a new, integrated methodology for preliminary assessment that considers a three-stage process that involves the following: (1) traditional empirical relationships for predicting ground movement from tunneling, (2) recent advances in condition assessments, and (3) architectural designators related to usage and historic preservation listings. The methodology is applied to a study area of nearly 260 buildings in the city center of Dublin Ireland, in an area slated for an upcoming metro. The results are com-pared to the Environmental Impact Statement issued for the official project. Al-though the test case is for tunneling, the approach may be adapted to other subsurface construction activities including excavation and piling.

Jan 1, 2009

Technically speaking, the concept of NDT sounds like the "magic bullet" when faced with a questionable drilled shaft. All the Contractor or Engineer needs to do is select an NDT method, apply it, understand the details and extent of the defect and determine whether it will impact the load carrying capacity of the shaft during it’s design life. Unfortunately, it is not that simple. NDT is a tool utilized to indirectly assess the condition of the completed drilled shaft. For the most effective interpretation, NDT data should be correlated with the subsurface information, visual observation, and detailed shaft installation records. The basis for acceptance or rejection of drilled shafts should not be solely based on NDT. The parties responsible for specifying, interpreting and using the NDT results must understand the capabilities and limitations of the method to be utilized, in conjunction with the relevant subsurface conditions of the site, before selecting and specifying a system and acting on the results. This is necessary so that an appropriate NDT method can be specified and contracted. In this manner the results and roles of the responsible parties can be clearly defined.

Jan 1, 2004

By Bengt H. Fellenius

.1.1 Prior to commencement of pile installation operation, submit to [Engineer] for [approval] [review], details of equipment for installation of piles. SPEC NOTE: The information requested in 3.1 .1.2 is necessary as input to a detailed wave equation analysis of the pile driving. .1.2 For impact hammers, give manufacturer's name, type, maximum rated energy and rated energy per blow at normal working rate during easy and at termination driving, mass of striking parts of hammer, mass of driving cap, and type and elastic properties of hammer cushion. .1.3 For non-impact methods of installation, such as drilling, jacking, jetting, use of vibratory hammers, or other means, give full details of characteristics necessary to evaluate performance. .2 Impact Hammer SPEC NOTE: Do not exclude a hammer type unless for very specific reason. .2.1 [Drop hammers will not be permitted.] [Diesel hammers will not be permitted.] For final driving of [TYPE] piles, provide a hammer capable of delivering to the pile a non-erratic impact stress not smaller than [VALUE] Pascal and transferring a non-erratic energy not smaller than [VALUE] Joules per blow to the pile head at normal working rate.

Jan 1, 1991

By Debra F. Laefer

Jet grouting is a ground improvement technique that has become widely adopted over the past three decades, yet relatively little data has been published about performance characteristics of mixes under adverse conditions, such as the inclusion of clay lenses. This paper presents an experimental investigation on the impact of clay on the strength of jet grouting. A total of 150 grout samples were subjected to 0-10% levels of Kaolinite and Bentonite inclusion. While the Bentonite was introduced as a pre-hydrated slurry, the Kaolinite was mixed in two ways: in a pulverized condition and as large chunks. Sample strength and stiffness were measured at multiple dates within the first 28 days. With 10% clay inclusion all samples exhibited significant strength and stiffness losses. With some, substantial losses began with as little as 4% clay. Even a 1% clay inclusion tended to decrease strength and stiffness between one-quarter and one-third of the control sample. Depending upon clay type and inclusion method, results differed significantly with respect to strength and stiffness development and failure mechanism. Petrographic analysis is used to provide further insights as to apparently divergent behaviors.

Jan 1, 2009

By Dennis Nottingham

The need for deep compaction of submerged granular soils has led to improvements in this area. In 1971, L.B. Foster Company personnel patented a method of deep compaction using a vibratory pile hammer and pile probe. The technique had some success, but did not produce consistent results and thus found its way to obscurity. Other patents attempted to modify the technique by various probe modifications, but again without measurable improvement from a practical point of view. Solutions to economical deep compaction up to 100 foot depths particularly in saturated granular soils would have a great impact on the construction industry and new bulkhead structures being developed, thus PND was prompted into related research and development. The advent of higher horsepower vibratory hammers, coupled with PND engineers? experiments, observations and measurements, led to an ?H? pile probe design which has produced measured soil density improvements up to 250% using SPT ?N60? values as a measure.

Jan 1, 2013

By Christian Hoyme, Jochen Maurer

Most of the current foundation projects are suffering from disconnected information silos. In the first silo there is the planning of the project with corresponding data, presented by paper or digital drawings. Here will Building Information Modeling (BIM) be one of the trends for the future. We will see more and more projects leaving the “old way” of 2D drawings and moving into 3D planning including metadata of the foundations. But even with a perfect BIM model of a jobsite, we are not at final end of digitalization. While execution of the project at the jobsite, a second data silo is evolving. Data collected directly from construction equipment and manual measurements is currently undervalued in most projects. Paper is passed to the equipment operator and major data from measurements on site are noted on paper and digitized afterwards. Automatically collected data is not be used to create site progress reports or similar report. So, the real “data” just flows around without connection to any other data already existing in projects. And then the third silo arises: The documentation of the project. Data collected on paper es reentered to create some basic documentation of the work handed over to the client. Spreadsheet software is still the “tool-to-be-used” to create at least some documentation. Finally, the documentation is not connected to the data created while planning and not connected to the automatically collected data from the jobsite. A connected jobsite in the foundation industry must link these information silos and have to create a full data-workflow from the design through the execution to the as-built documentation. INTRODUCTION Building information modelling (BIM) is currently the most popular term of construction business in Germany and probably all over the world. But as often there are many different definitions out there and everyone has his own definition or at least understanding what BIM is about. But for sure it is the most relevant for the construction industry in the near future. Most popular is the digital twin for the upper structure of a building. In most cases the BIM models just shows the building itself, but there is more to be implemented. For example: projects where a special foundation is needed, BIM should include also the foundation elements with meta data. There are several advantages. Not only the clash detection of anchors, but also the possibilities to check the interaction with neighbor constructions, power lines and so on are a use case. For sure most of the special foundation elements are not relevant for the whole lifecycle of a building. But during construction and later the demolition the information about the hidden elements is important and gives a benefit to all stakeholders. In the future there will be not the question: “What is already in the ground?”. The risk for following construction projects on the same ground will be minimized.

Jan 1, 2019

By Stephan A. Jefferis

I presume that the questioner is not asking about the reduction of sulfate in groundwater to hydrogen sulfide as a result of biological activity promoted by organics in the grout hardener and that the question relates to sulfate attack on cementitious grout systems. For the project in Spain presented in my paper, we used a very high pulverized fuel ash (PFA) content in the cementitious material. This gives good sulfate resistance and indeed the chemical interaction will actually cause the permeability to drop for about 50 years without any question of sulfate attack and damage to the whole thickness of the grout - of course there will be attack at the exposed face of the grout where it is in contact with the contaminated groundwater. The mix had over 75% PFA, and also a very high overall cementitious content. The mix was the contractor's design and showed excellent behavior in laboratory proving trials. In grouts as distinct from concrete, PFA gives significantly better sulfate resistance than ground granulated blast furnace slag which is often used in Europe as a component of bentonite-cement mixes for slurry trench cut-off walls.

Feb 10, 2003

By Matthias Pulsfort, Hanna Nissen, Markus Herten

An insufficient integrity of cast in-situ bored piles can lead to a reduction of the load bearing capacity and may require cost intensive repairs. Reasons for an insufficient pile integrity are linked to the construction process, mainly to poor concrete quality leading to bleeding and segregation of the fresh concrete. Moreover, the entrapment of soil and an insufficient concrete cover can pose a problem. Knowledge about the time-dependent development of the fresh concrete pressure during the construction process of bored piles is needed for a better understanding of the underlying processes causing these defects. Therefore, pressure measurements were carried out on different construction sites with pressure cells being installed at different depths along the reinforcement cage. The measurements revealed the maximum pressure acting on the surrounding soil. The achievement is a better understanding of the effects of the concrete placement specifically and the construction process in general on the surrounding soil to reduce the risk of pile imperfections.

Sep 8, 2021

By Robert B. Bittner

The Sutong Bridge across the lower Yangtze River in China will have, when completed, the longest span (1,088 m) and the highest towers (306 m) of any cable stayed span in the world. The foundations for this record setting span will also be record setting. They are located in water depths exceeding 30 m with maximum flows exceeding 3 m/sec. The soil at the site of the main pylons consists of layers of silty sands and silty clays extending to bed rock at 270 m below river elevation. This paper describes the innovative methods used by the team of foundation designers and constructors to support this record setting bridge at this very challenging site. This paper covers three specific topics related to the foundations of the Sutong Bridge: ? Design and construction of the 131 drilled shaft (2.8/2.5 m diameter and 114/117 m long) under each of the two main pylons, including the post-grouting of all drilled shaft tips. ? Design and construction of the scour protection for the two main pylons, ? Construction methods used to construct the waterline pile caps (113.8 m by 48.1 m by 13.3 m deep) under each pylon.

Jan 1, 2013

By Min Sunn Ye, Wei Wang, Huawen Xiao, Kai Yao, Fook Hou Lee, Siang Huat Goh

"Previous research have shown that introducing fibers to cement soil mixture is effective in improving the ductility as well as maintaining the strength of cement-treated soil. A good knowledge of stiffness of the improved soil at small strain is essential for realistic predictions of ground movements that may affect adjacent buildings or underlying infrastructure. This paper presents a triaxial system with local strain measurement developed for studying shear modulus degradation of cement treated clay with fibers. Cylinder specimens (70mm diameter by 140mm height) with 50% cement, 100% water, 0% to 1% polypropylene fibers by mass, and 7 days of curing period were used. A local strain measurement system with floating type miniature submersible LVDT is introduced in this paper. Configuration of the mounts including the pin size, length and distance are presented and discussed. Based on the experimental results, a reasonable configuration of the mounts is recommended for fiber reinforced cement treated clay. Results showed that the proposed local strain measurement system is effective for testing the shear modulus degradation of cement treated clay with fibers under both unconfined and confined condition. Comparisons with results from resonant column and bender element tests served to verify the reliability of the local strain measurements using the proposed method.INTRODUCTIONIn many geotechnical engineering problems, the operational strain domain ranges from 10-3% to 10- 1%. A good knowledge of stiffness at small strains is essential for realistic predictions of the ground movements that may affect adjacent buildings or underlying infrastructure. As such, during the last 3 to 4 decades, the importance of using the small strain stiffness of soils for the design of foundation and underground structures has widely been accepted. Triaxial testing has been widely used to study the stress-strain behavior of soil in the laboratory. However, the stiffness obtained from the conventional triaxial apparatus is usually far smaller than those back-calculated from field measurements. This is mainly attributed to the overestimation of axial strains from the external strain measurements, which usually includes compliance effects of the loading and load measuring system as well as sitting, bedding and alignment errors between sample and system (Baldi et al., 1988). The poor resolution of the external strain measurements is another important contribution. Therefore, conventional procedures are inappropriate for small-strain stiffness evaluation due to low accuracy and resolution."

Jan 1, 1900

By Rouzbeh Afsharhasani, Moses Karakouzian, Brandon Kluzniak

"The Vegas High Roller is the centerpiece of a new development parcel adjacent to the Las Vegas Strip. At a height of 550 feet, the High Roller is currently the tallest observation wheel in the world. The design team conducted a geotechnical site investigation to characterize the alluvial soils and cemented layers encountered and to provide foundation design recommendations for the observation wheel, boarding platform, and temporary structures needed to erect the wheel structure. This paper presents a case history of the geotechnical design process, including development of a ground model and design parameters, high-strain dynamic axial load tests, and settlement monitoring during construction. Results indicated that design parameters were conservatively assumed and that the majority of the axial load was transferred to a near surface caliche layer, thereby resulting in insignificant settlement of the foundation system.IntroductionThe engineering of the Vegas High Roller is similar in concept to that of the London Eye and the Singapore Flyer. The wheel has 28 cabins, each with a capacity of 40 persons. The top point of the structure is 550 ft above ground level at the site.A geotechnical site investigation program was undertaken and subsequent analyses were performed to provide foundation recommendations for the observation wheel legs, boarding platform columns, and temporary structures directly associated with construction of the observation wheel."

Jan 1, 2017

By Madan Kumar Annam, Hari Krishna Y, I. V. Anirudhan

"For completion of projects in time with positive results, improvements of productivity and effective project management procedures have become extremely important. This paper discusses a milestone project comprising 198 residential units of stilt plus 4 levels that highlighted the benefits of these key aspects. Success of ground modification procedure benefitting the entire cycle involving End Users, Suppliers, Bankers and Developer is discussed.Soil profile for a considerable depth comprises weak layers of silty clay and sandy clay with varying consistency. Deep foundations have been an automatic choice of foundation for major buildings constructed in similar environment. After serious geotechnical appraisal, reconsideration of the foundation system with an alternative solution of Ground Improvement was found to be optimal in terms of Cost and Time. Full raft foundation on the improved ground by installation of Vibro Stone Columns (dry bottom feed method) was considered as an alternative foundation system. The ground improvement works were completed within 6 weeks (as against 6 months to that of pile foundations) that was made possible through effective project management. Full size plate load tests were conducted to ascertain effectiveness of the ground improvement works. Success of the foundation system was proved by full scale monitoring of foundation settlement during and after completion of the project over a span of 2 years. This paper describes design considerations, quality control in the construction of Vibro Stone Columns (dry bottom feed method) and performance monitoring of the project thereafter.INTRODUCTIONGenerally in weak deposits, deep foundations like bored cast-in-situ piles and driven piles have historically been the foundation choice for major buildings and other structures. Construction of pile foundations is becoming a challenge due to their high cost, large construction time and due to severe environmental issues (noise pollution, ground vibrations and carbon footprint). Since the proposed building complex is located within the proximity of a well-developed residential locality, objections raised by neighborhoods to pile driving activities called for a rethinking on the foundation system.The top 6m to 8m of soil profile comprises of silty clay / sandy clay having highly varying consistency. GWT was encountered at 3.0m below the existing ground level. Under this situation, the reconsideration of the type of foundation system with respect to the geotechnical analysis gave a thought to assess feasibility of ground improvement system."

Jan 1, 2015

By José Carlos A. Cintra

This paper addresses a new experimental procedure to measure the shaft friction and the base resistance of bored piles during static load tests. It is proposed that a set of polystyrene foam discs, placed between the shaft and the base of the pile, be used instead of the usual instrumentation. Throughout the initial stages of the loading test, the foam discs will allow only the mobilization of the shaft friction. The load x settlement curve clearly shows that the shaft friction vanishes at low settlement values. As the load test proceeds, the base resistance is also mobilized. This procedure was used in two belled piles bored at the Experimental Foundation Field of the University of São Paulo, at São Carlos, Brazil. Both piles were 8 m long and had a shaft diameter of 0.6 m. The enlarged base had a diameter of 1.5 m and a height of 0.9 m. Twenty foam discs with a thickness of 20 mm each were placed between the enlarged base and the shaft of the pile. The load tests indicated ultimate shaft frictions of 28 and 30 kPa for measured settlements of 8.98 and 7.39 mm. Base resistance values at failure were 617 and 499 kPa, for a chosen settlement of 10% of the pile base diameter. The proposed approach seems to be straightforward, efficient and inexpensive.

Jan 1, 2002

By Brandon Smith, William Bohlen

Riverbank erosion along the Brazos River has modified the structural support conditions for an existing bridge structure in Southeast Texas. The 8-span, 1,200-foot long bridge was completed in 1992 along Highway 99, a key corridor for the Houston area. Foundation support conditions have been altered due to natural, ongoing river morphology for three bents on the affected riverbank. Recent events include three storms within a three-year period that each exceeded the 500-year return probability. This resulted in accelerated erosion along the northern riverbank. Over forty vertical feet of soil has been removed in some locations. Drilled shaft foundations are now functioning as columns. This review considers the behavior of columns and deep foundation elements due to the modified support conditions. The review ultimately presents a rational methodology for the review of the present and anticipated future bridge configuration with respect to current strength, service, and extreme event limits, with corresponding safety factors for the design. Introduction and Background The Fort Bend Grand Parkway Toll Road Authority (Owner) oversees the State Highway 99 Judge Jodie Stavinoha Bridge over the Brazos River. The 8-span, 1,200-foot long bridge was originally designed with four southern approach spans of 115 feet; a three-span continuous river crossing with span lengths of 195 feet-235 feet-195 feet; and a single northern approach span of 115 feet. Figure 1 provides an overview of the northern portion of the bridge. Table 1 provides a summary of the original bridge substructure configuration. When the bridge was completed, the centerline of the Brazos River was located at midpsan of the main span and the northern high bank was originally located at Bent 7. Erosion process has forced the northern high bank to Abutment 9 (also called Bent 9), and the river centerline during normal flow conditions is located south of Bent 8. The overall estimated river excursion at present day is approximately 270 feet to the north from its original location. An erosion wall that was installed in 2017 limits further erosion of the north river bank within the 300-foot width of the roadway corridor right-of-way. This study was developed to better understand the existing conditions, and to forecast the need, nature, and criteria for potential future improvements.

Jan 1, 2019

By J. Erik Loehr, Andrew Z. Boeckmann

"Poor drainage is a common cause of poor performance of earth retention systems, resulting in burdensome serviceability problems that can progress to outright failure of the retention system if not addressed. A drainage system consisting of filtered conical drains that can be installed through the face of an existing retaining wall and readily maintained was evaluated through tests of physical and numerical models. The physical models were constructed with different backfill materials in a container measuring 8 ft wide by 4 ft tall by 15 ft long. Tests were conducted by saturating the backfill under a constant water elevation atop the model, and then maintaining the water elevation until seepage from the drains reached a steady state condition. Pore pressures within the backfill and outflow from the drains were measured to facilitate calibration of numerical models that accompany the physical models. Results from the calibrated finite element models were used to develop design criteria for the drains. The design criteria establish the required drain spacing as a function of the height of groundwater above the drains and the diameter of the drain.INTRODUCTIONMany retaining wall performance problems are a result of poor drainage of the wall backfill. Consequences of poorly drained backfill include displacement and rotation of the wall face, including the extreme case of collapse, and seepage through the face of the wall, which is in turn associated with damage from corrosion, dry rot, and other forms of deterioration. A common approach to improve drainage of an existing wall is the installation of drainage features (e.g. “weep holes”) in the face of the retaining wall. Weep holes facilitate controlled seepage through the face, which relieves water pressure within the backfill and directs seepage to known locations in the wall face. Although installation of weep holes is relatively common, engineering methodologies for selecting the size (diameter) and spacing (along the wall) of facial drainage features are uncommon if not altogether non-existent. This paper documents tests of physical and numerical models of retaining walls with facial drainage features, including conventional weep holes as well as maintainable drains installed through the face and extending into the wall backfill. Results of the testing were used to develop generic design criteria, which establish the required drain spacing as a function of the height of groundwater above the drains and the diameter of the drain."

Jan 1, 2016

By H. Cheng

The Bohai Oil Company has applied all together 11 jack-up oil drilling rigs (movable platforms) (1) which can be classified in terms of their forms of foundations into two types: the integ­ral mat and the column legged, as demonstrated in figure 1. Figure 1 a) indicates the entire structure of the sunk cushion type, i.e. the one with a box-like sunk cushion serving as its foundation by directly sitting on the sea bed. The length, width and height of the outer sides for the sunk cushion stand at 45.8 x 38.0 x 3.3m ( for Rig Bohai No.2 ) and 50.6 x 33.2 x 4.88m ( for Rig Bohai No.6 ), the relative areas of theirs being 1475m2 and 2008m2 respectively and both bigger than the plane areas of the rigs. With a view to realize a convenient drainage of mud while sinking, two holes of 14 x 14m and 32 x 18m in size are constructed in the center part of the sunk cushion. When work sets off, the underside of the sunk cushion operates as a foundation, the sunk cushion being connected to the platform by hull columns which transmit the load of the platform down­wards to the sunk cushion that passes it further onto the subgrade. [ ] Column legs for rigs may also be grouped into two categories considering their features: columns with and without boots. The bodies of boot columns are made up of trusses, whose bottoms, are boot-shaped with a big diameter. The diameter of boot columns of the rigs applied by the Bohai Oil Company shows bigger and it may reach 12 or 18m. In the boot columns, the transmission of the platform's weight into soil is done by the underside areas of boots. While in the case of the vertical columns, which are of cylinder columns of steel with sealed bottom ends shaped inverted arch, the entire drilling platform is supported by the carrying force delivered by the bottoms of these steel cylinders and the frictional force rendered by their outside walls. Such a type of columns is featured by a small diameter, 3m in general. Figure 2 exhibits the schematic diagram of sections regarding the two types of column legs.

Jan 1, 2010

By Dinesh Hinduja, Pérez: Miguel

"Large structures are generally exposed to dynamic and structural loading. They require usually either foundation connected to hard rock through sockets or driven foundations, which encounter boulders as well.In this regards drilling hard-rock sockets or boulder offshore or onshore can be a challenging job especially when deep foundations are mandatory. To overcome the challenge, specialized equipment like a Pile Top Drilling rig (PBAs) can be used, which have to be correctly set-up and operated in order to get its maximum drilling performance. High performance drilling with PBAs requires maximizing key elements of its operation. The configuration and management of the drill string components are important. The key elements are constant weight on bit which is done by adjusting ballast and managing thrust force; and selection of cutters and proper flowing discharge.The methodology is based on the experience from over 40 years of building and operating PBAs for different project applications. These applications include drilling offshore and onshore for:?Superstructures and buildings?Drilling platforms, barges and jack-ups?Harbours, jetties, dry docks and dolphins?Bridges, piers and causeways?Marine sewerage diffusers?Offshore wind farms?Dam rehabilitationMHWirth documented methodologies demonstrate that by using PBAs properly it is possible to improves performance of underwater drilling for hard-rock sockets and boulders which ultimately reduces project-cost.Background. There is a significant percentage of total project cost in structural foundations. Equipment capabilities and technics to drill shaft with rock-sockets and embedded boulders onshore and offshore are highly developed due to the dramatic equipment advancement and experience in the last 40 years. Formerly, driven piles accounted for the majority of foundations either onshore or offshore, following the experience of previous practice in the market. Nowadays, deep drilled foundations can be constructed to carry the load through the overburden down to the sound load carrying rock or soil.Scope and objectives. The overall objectives of this study are:?Synthesis information on current practices to drill shaft with rock-socket and/or embedded boulders onshore and offshore with Pile Top Drill Rigs?Identify the principal challenges evolving with practice?Provide suggestions for improvements in the construction of drilled shafts through proper operation of Pile Top Drill Rigs?Convey information through case studies and experiences"

Jan 1, 2015

By Jeff Wilkinson, Brandon Walter

"A&N Electrical Cooperative provides electrical service to the counties of Accomack and Northampton along Virginia’s Eastern Shore and to Smith Island in Somerset County, Md.A&N recently worked to improve the efficiency of power distribution to a small island community and marina on Tangier Island in the Chesapeake Bay. This improvement consisted of upgrading the existing distribution substation with a new 25 kV 2-bay box distribution structure. Earth Contact Products (ECP) collaborated with PowerServices, Inc. (PSI) to design and install a helical foundation support system as part of the substation upgrade. Feasibility EvaluationThroughout the design process, A&Nworked with its partners PSI (design) andT&D Solutions (installation) to identifycost-effective alternatives. Foundationsystems considered included cast-in-placereinforced concrete caissons, precastconcrete foundations, driven steel piles and helical piles. In evaluating all of theoptions, the greatest concern was gettingthe material onto the island, followedclosely by the availability of the equipmentto install the foundations. Clearly, cost,more specifically the installed cost, was asignificant consideration and decisionfactor throughout the process.There were several limiting factors that had to be considered during the design process, the most significant of which was that all of the material had to be barged to the site. With traditional reinforced concrete deep foundations in mind, the cost for installing these piles was projected to be nearly $2,000/cu yd ($262/cu m) of installed concrete. Given that approximately 5 to 6 cu yd (3.8 to 4.6 cu m) of concrete would be required for this structure, the cost was significantly high for this project. What’s more, because the components of the concrete mix would have to be barged and then hand mixed on site, there was concern regarding both the time required to complete the piles and the quality of the installed concrete. For the driven pile alternative, the availability, or lack thereof, of equipment and material cost resulted in a total cost estimate that was more expensive than that of the concrete piling alternative. The high material cost for the piles, which was more than double than the cost of concrete, was due to the number and size of piles needed to resist the overturning moment. Ultimately, the team selected the helical pile alternative. The decision to a use helical pile foundation system was based on many factors, not the least of which was the remote location of the project site and the difficulties associated with getting material, equipment and construction personnel to the project site."

Jan 1, 2017

By Michael T. Lambert

The purpose of the this paper is to demonstrate the benefits of using additional instrumentation during load tests of auger-cast-in-place piles. Traditionally, only load and butt displacement are determined during load tests. The results from and methods used to instrument 15 auger-cast-in-place (ACEP) piles as part of six projects are included herein. By instrumenting the piles, the distribution of load along the pile length and load transfer can be determined, allowing the pile capacity to be adjusted or the length/diameter of the pile to be adjusted for the a given required load. The majority of the piles tested were designed as end bearing piles on either shale or limestone bedrock. No discussion of Geotechnical Instrumentation can be started without acknowledgement of the "Red Book." The actual title of the book is Geotechnical Instrumentation for Monitoring Field Performance, by Mr. John Dunnicliff, John Wiley and Sons, 1993. Anyone undertaking an instrumentation program should thoroughly review the Red Book, paying particular attention to Chapters 3 and 4. Instrumentation should not be done just because it can be done. There must be an unanswered question or questions that can be answered with measured data before instrumentation should be considered.

Jan 1, 2000

By G. Ranjan

The designers and the practicing engineers have started using latest and cost effective techniques of ground improvements which utilise the weak and poor sub-soil deposits efficiently for the civil engineering construction. In the present investigation, a new concept of 'skirted granular piles' has been advocated. An effective method of construction of granular piles as an economical alternative to vibroflot, and the skirt has been developed. The construction technique is based on indigeneous know how which effectively utilises the man-power technology avoiding import of costly equipment suiting to the developing countries. Full scale insitu tests have been carried out at four sites, having different soil conditions, on virgin weak sub-soil, and improved ground by casting plain and skirted granular piles. Effectiveness of different types of skirt has been demonstrated through insitu tests. A simple analytical approach has been proposed to predict the ultimate pile capacity. The predicted values of ultimate capacity have been found to demonstrate a good correspondance. Granular pile behaviour in terms of pile depth, diameter, spacing and stress deformation characteristics of the improved ground have been discussed. A significant improvement in ultimate capacity in improved ground has been noted. This is further augmented when granular pile group is skirted.

Jan 1, 2010