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By Cristhian C. Mendoza, Renato da Cunha, Bernardo Caicedo, Max Barbosa

"Abstract This paper shows that a raft alone is not sufficiently appropriate to address the uncertainty of underlying soil variability; therefore, a piled raft system is a better option for mitigating such uncertainty. To study the variability of soil, the behavior of the Piled-Raft Foundation was analyzed with a type of self-drilling micropiles: the ""Alluvial Anker"" (common name for this pile type in Brasilia city). These micropiles have been used in the city and have the advantage that the drill pipe also serves as reinforcement. The studied parameters belong to an elastoplastic constitutive model for strain-stress analysis of soil; variability of these parameters can be intrinsic and/or epistemic. Simulations were performed for a hypothetical Piled-Raft Foundation subjected to vertical loading using the random finite element method. The average parameters of the constitutive model were obtained through laboratory tests. The simulations of the load test were compared with results of a real scale experimental test conducted exclusively for this work in the field. It is analyzed the relative importance of the variability of some geomechanical parameters and their variation with depth is considered. In addition, it is discussed a comparison between the uncertainty of the geomechanical parameters and the uncertainty of the results of the vertical loading test. Finally, this paper shows that a decrease of the safety factor may occur when taking into account the variability of the parameters.IntroductionBrasilia is located in a highly weathered residual tropical soil (lateritic & latossol on pedogenetic concepts). This soil presents high content of alumina and iron due to the lixiviation process of the upper layers. As a consequence, the cemented structure is highly unstable and it can generate strong changes of volume (i.e. collapse) due to changes in both moisture and state of stresses. Therefore, a greater understanding of the construction of Piled-Raft Foundation systems on this particular soil conditions is needed – especially because it covers more than 80% of the surface area of the Brazilian Federal District.Thereafter, this work investigates the influence of the variability of the soil parameters over the uncertainty of the Piled-Raft Foundation design. The studied parameters belong to an elastoplastic constitutive model for strain-stress analysis of soils. The simulations were performed for two hypothetical Piled-Raft Foundations subjected to vertical loading by using the stochastic finite element method. The results were compared to real load tests in Piled-Rafts with “Alluvial Anker” pile types."

Jan 1, 2014

By Arturo Ressi di Cervia

From the times when men in lacustrine environments drove wooden piles into the mud to elevate their dwellings, until the beginning of the twentieth century builders reacted to the conditions found in the location of their proposed structures by attempting to distribute their loads in ways that could be supported by the foundation's soils; or, if those were unsuitable, by moving the structure, whenever possible. While many major structures were built on stable ground (the pyramids were founded on rock), others were built on [ ]

Jan 1, 2000

By Axel J. Pollak

Since the late 1960's the Interstate Division for Baltimore City (IDBC) has been planning and developing the Interstate Highway System for the city to meet regional planning goals. The principal goals are to provide convenient access to the central business district and the port while diverting through traffic away from these congested areas. Interstate Route 95, an eight-lane highway carrying north-south traffic, has headed the city's priority list; during the 1970's its construction proceeded steadily from both east and west towards the harbor. Closing the final 8800-ft (2670-m) gap under the harbor will complete Interstate 95's construction. This final portion, known as the Ft. McHenry Tunnel project, will be built in nine construction contracts. Construction costs of the complete project are expected to exceed $700 million, making it the costliest single project in the Interstate Highway System. Full funding is being provided initially by the Federal Highway Administration (FHWA), and the Maryland Department of Transportation will re-pay the 10 percent local share from toll receipts within the first three years of operation.

Jan 1, 1989

By Alfred H. Brand

New York City contains extensive deep deposits of glacial lake varved silt and clay, often overlain by organic soil. An 18 story building was proposed for Manhattan's upper East Side in one such area where bedrock is approximately 200 ft deep. Various pile and caisson alternatives were considered extending through the glacial lake soil to rock, but all proved beyond the project budget. Laboratory testing showed that the glacial lake deposits were preconsolidated. A test pile program using auger cast piles bearing in the glacial lake deposits proved that such piles could safely carry a load of 60 tons per unit. The auger cast pile scheme was estimated to be more economical than a deep pile alternative. A further benefit was that the vibration-free pile installation procedure posed less risk to adjacent structures which had been founded at shallow depth in fill above organic deposits and were stressed and cracked due to prior settlement. The project was designed with the anticipation that the glacial soils beneath the tips of the piles would produce a building settlement of 1 to 2 inches. The building was constructed in 2001 and 2002. It has been completed and is now occupied. Settlement data show that the building is performing as predicted. The auger cast pile scheme founded in a compressible stratum has proven to be successful and is a very unusual foundation alternative.

Jan 1, 2003

By Lois G. Schwarz

I did not make studies about this parameter but I can say that some researchers recommend using low C3A cements to repair masonry mortar in order to reduce a possible combination with sulphate that can be present in old mortars.

Feb 10, 2003

By Per Eriksson

For light buildings on clay, foundations on L/C-columns is in many cases a competitive alternative to piles when the thickness of the clay is moderate (<20 m). The method is applicable for the above mentioned depth when the clay is normally consolidated, and for thicker deposits when the clay is overconsolidated at depth. This case study concerns a shopping mall in Nordby, Sweden, founded on L/C-columns (5-15 m in length) and generally spaced 1.45-2.0 m (spacing 0.7 m was used below pillars). The base slab was built as a raft foundation, using fibre reinforced concrete.

Jan 1, 2000

By Maral Papazian Bedian

Construction contracts in the USA contain the clause "Value Engineering" ? an interesting and curious clause allowing contractor initiated design changes. Misleading is the interpretation of value engineering implying cost saving and sharing with the owner, and curious is the timing, just before beginning of actual construction. It is not surprising that such a clause would simply be ignored, because it involves change, often major design changes in very short time; and change is feared, moreover, it is vehemently resisted by all parties, owner, designer, contractor. The problem in the USA may lie in the divergence and separation of the two entities: Designer/Engineer and Builder/Contractor, assigned to the "one" engineering project. The priorities and incentives of these two groups are very different. The Engineer spends years, even decades, in design and prepares contract drawings often without a deep understanding of construction methods. Worse, with all the time available to him and in our era of tremendous advances in computational methods and speed, the designer turns in plans that are inexcusably exaggerated code-based design with excessive safety factors. As to the Contractor, he builds, often without appreciation of design principles or regard for design engineers. Redesign to apply a new technology or optimization of an inferior design just before construction becomes unthinkable. It is not surprising that adverse and hostile relationship between the designer and the contractor is a norm with extended disputes and claims, not to mention the cost these entail. Surprisingly, "Value Engineering" was successfully implemented in record speed on several very large projects in the metropolitan New York area. The process of change was unconventional, painful, and even comical. Four case studies are presented: two Design/Build: the 1.2 billion dollars Hudson-Bergen Light Rail Transit System in New Jersey and the 90 million dollars MTA Bus Depot in Manhattan, and two Conventional Design/Bid/Build: the 90 million dollars Queens Boulevard Bridge and the 150 million dollars Long Island Expressway.

Jan 1, 2002

By Mark R. Svinkin

Construction vibrations may be harmful to adjacent and remote structures, sensitive instruments and people. Construction vibration sources have a wide range of energy, displacement, velocity and acceleration transmitted on the ground. Effects of different dynamic sources and soil conditions on construction vibrations is analyzed. Consequences of construction vibrations are developed in various ways. It is important to assess intolerable vibrations before the beginning of construction activities. Guidelines for preconstruction survey are presented. Pre-construction survey and prediction of anticipated vibrations by IRFP method, monitoring and control of measured vibrations are important steps in preventing intolerable vibration effect.

Jan 1, 2000

By S. Narasimha Rao

Significant amounts of lateral load may act on pile foundations supporting structures such as transmission line towers, tall structures, bridge abutments, offshore platforms, quay wails, harbour structures and anchorages for water front structures. There were several theoretical and experimental studies conducted on laterally loaded piles in clays to determine ultimate lateral capacity and deflections under working loads. Under a lateral load, a pile deflects in the direction of load application and the soil in front of the pile offers resistance to this movement. The ultimate lateral resistance of a pile can be estimated considering the statics of the pile for a known distribution of soil resistance with depth. In this paper, considering the contributions from both lateral shear drag and frontal passive earth pressure, a method has been proposed to estimate the ultimate lateral capacity of rigid piles in clays. The lateral shear drag has been estimated in terms of adhesion and shape factor. A few load tests were conducted on model piles subjected to lateral loading and these experimental values are used in verifying the proposed method. The reported results obtained from both model tests and field tests were used in support of the predictions made. In all the cases, there is a good agreement between the predicted and measured capacities.

Jan 1, 1996

By Ivan Jackson Madura

The new Paradisus Coco Beach Resort in Rio Grande (PR) is located on an old swamp area, which has been filled with relatively clean to silty sands. The swampy deposits consists of organic silts, peat and loose fine to medium sand and silty sand. The project requires the placement of 1.0 to 1.5 meters of additional fill together with the construction of light structures. The need for the fill will trigger the development of settlements in the underlaying weak and compressible stratum. Furthermore, the susceptibility of the loose sand to liquefaction during an earthquake was considered. This paper describes the soil improvement by means of vibro-replacement, the purpose of which was threefold: reduction in total and differential settlement, acceleration of settlements during the surcharge period and densification of the loose sand to reduce its liquefaction potential. The predesign is presented together with relevant construction details of the preliminary trial areas from which the final column diameter and grid spacing were derived. Instrumentation together with settlement observations during the surcharge period are presented as well and compared with the initial predictions.

Jan 1, 2002

By N. Som

The pile capacity in cohesive and granular soils depends on a number of parameters. The values of these parameters as recommended by Indian Standard Code of Practice vary over wide ranges. A designer often finds it difficult to select appropriate values of these parameters for realistic estimate of a pile capacity. The present paper makes a critical review of the values of the parameters given in Indian Standard Code of Practice and suggests a realistic approach to selecting them in the light of recent research.

Jan 1, 1996

By Martin van Staveren

In today&apos;s rapid changing construction world, the business pressures on piling and deep foundations reach sky-high levels. Ever increasing complexity of construction projects do severely contribute to these business pressures. Projects are often constructed in densely populated areas and located close to vulnerable buildings and infrastructure. The inherent uncertainty of ground conditions plays a dominating role in these foundation projects. Effective risk management is a key success factor for profitable and sustainable operations of piling and deep foundations. It starts with a fundamental requirement to be aware of risks. Next the different risk perspectives of all stakeholders in any foundation project have to be acknowledged. A simple and structured risk management approach is introduced, to demonstrate that effective risk management is not necessarily that complicated. A major element is the contractual allocation of risks, as a result from differing ground conditions. It is based on the so-called Geotechnical Baseline Report (GBR). The main objective of the GBR is to provide a clear contractual arrangement for the allocation of risks, arising from differing site conditions. The benefits of explicit risk management in general and contractual risk allocation in particular are illustrated with an example and experiences. The presented structured risk management approach, including contractual risk allocation, is still rather new. It proves to be promising for cost-effective risk control of piling and deep foundation projects, anywhere in the world.

Jan 1, 2006

By J. A. Elliot

Deep Mix-in-Place soil stabilisation is achieved by forming columns of soil/cement arranged to overlap by secant intersection. Alternate columns are constructed initially and infilled. The cementitious material injected is designed to retard the strength of the resulting mix thereby allowing satisfactory overlapping. Columns are constructed using a designed large diameter mixing auger mounted on a smaller diameter auger stem. This is firstly screwed to the design depth removing only such spoil as to enable penetration of the auger, and subsequently counter rotated and extracted in a predetermined mixing pattern and grout injection rate to ensure continuous and homogeneous treatment through each successive level. The process is performed whilst monitoring auger depth, grout flow and pressure. Cementation Piling and Foundations Limited used this technique to stabilise allu­vium and to facilitate the construction, by conventional techniques, of a circular pumping station pit of 10M diameter to 10M below ground level. The work was carried out within 3M of adjacent domestic properties, and on a very restricted site in Elland, West Yorkshire. Ground conditions consist of 2M of cohesive alluvium becoming water bearing and increasingly sandy and gravelly with cobbles which overlies the mudstones at 10.0m depth. Sandstones beneath formed an aquiclude to artesian ground water with the underside of the open excavation approxi­mately 1.0M from the top of this material. Peripheral treatment into the mudstone, coupled with pressure relief wells, proved successful and final excavation depth was achieved in "the dry".

Jan 1, 1989

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 Eugene Mirsky, Eloy Ramos, May ElKhattab, John Wise, Terrence Carroll, Jose Torres

In 2017, Nicholson Construction Company completed a $72.1 million design-build contract for Miami Dade Water and Sewer Department to replace an existing 54-inch diameter pre-stressed concrete force main that runs from the Virginia Key Central District Wastewater Treatment Plant, under the Biscayne Bay at Norris Cut, to Fisher Island. In order to install the new sewer pipe below the bottom of Biscayne Bay, a tunnel boring machine (TBM) was launched from a 42ft diameter and 89ft deep shaft on Virginia Key and a precast segmentally lined tunnel was constructed towards a 28ft diameter and 72ft deep retrieval shaft on Fisher Island. Both shafts were constructed through sand and highly permeable limestone, primarily the Fort Thompson Formation which is part of one of the most permeable aquifers in the United States and two different techniques were used to ensure a water-tight shaft at each end of the tunnel drive. The launch shaft structure was built using the secant pile technique, wet excavation and a tremie plug. For the tunnel break-in a soil freeze block was installed after the ground was treated with low mobility grout. The retrieval shaft was built using the Deep Soil Mixing (DSM) technique and excavated in the dry. Precedence of any other structure built this deep through hard layers (UCS over 3,000 psi) using this technique was not found. This case study addresses the challenges of constructing watertight underground structures in highly porous ground for launching and retrieving a TBM. Design challenges from complex asymmetric loading, selection and comparison of the construction techniques, the installation and excavation of both shafts, and their performance are also discussed herein.

Jan 1, 2018

By John R. Grillo, Gordian Ulrich, Franz-Werner Gerressen

Most geotechnical construction professionals are aware of piling using hydraulic drill rigs and the so-called Kelly drill mode. Kelly drilling has many advantages as it can work with a wide range of tools facing almost all types of soil and rock conditions. Kelly drilling can also deal with diameters up to 10 ft (3.00 m) and bigger or depths of more than 330 ft (100 m). Nonetheless, there is a concern about Kelly drilling as it is a relatively slow installation process. Therefore, an alternative piling method like Cased CFA (CCFA) Piles (Cased Auger Cast Piles) provides a significant advantage in terms of installation performance, schedule and cost saving potentials. Major application for the Cased CFA system is the secant pile wall construction. Against the traditional secant pile wall systems like fully cased bored piles or CFA secant piling the Cased CFA secant pile wall system has the advantage in cost and time against the fully cased system and in quality against the standard CFA system. This paper will describe the methodology and installation process in general as well as first reference projects carried out in the United States. This paper will present the results in cost and schedule saving using this method. In addition, we will also describe the limitations of this method. INTRODUCTION In the changing construction environment, companies are searching for new technologies or improvement of existing technologies to complete their projects in shorter time frames to provide a good economic solution. Especially with the focus of increasing urbanization, the aim of fast construction becomes more and more important. When thinking of piling, most people will have the same picture in mind: that of a hydraulic drill rig working in Kelly drilling mode; however, the perpetual drill rig development provides a number of options for the execution of specialist foundation projects, either for foundations or for pile walls when using single pass applications like CFA, Cased CFA and Full Displacement Piling (FDP). Single pass means, in general, that the tool is pushed and rotated into the ground to the final depth in one stroke. After reaching the final depth, concreting is started and concrete is pumped continuously while the tool is withdrawn.

Jan 1, 2019

By Tony Mazzo

It has often been said by consulting engineers that foundation contractors are in the business of taking risks. One would agree that the mere fact a foundation project can be budgeted, planned, engineered and executed solely on the reliability of eight test borings made at a proposed site having an area of approximately 19,000 square feet, is a risky proposition, in and of itself. Now imagine that this site is actually one half of a city block located in an urban setting in an old, congested, historical neighborhood, surrounded by narrow city streets and historic landmark buildings. And suppose that the required depth of excavation for the construction of the new building on this site is approximately 35 feet and the natural groundwater table is at a depth below existing grade of only 25 feet. Given the difficult site conditions outlined above, one could certainly add the words "challenging" and "complicated" to the inherent word "risky" when describing the construction techniques involved to undertake a foundation project of this magnitude. This case study will discuss in detail how the excavation, sheeting, dewatering and underpinning work was accomplished as well as the problems overcome along the way.

Jan 1, 2003

By Atta B. Yiadom, A. David Miller, Robert C. Kirby, Sean M. Todaro

"San Pablo Dam is a 170-foot (52-meter)-high earthfill embankment, located approximately 10 miles (16 kilometers) north of downtown Oakland, California, that impounds a 38,600 acre-feet (47.6 million m3) reservoir for customers in the East Bay Municipal Utility District's (EBMUD's) service area. Seismic upgrades were designed and constructed in 2008 through 2010. Work included removal of an existing 140,000 cubic-yard (107,000 m3) downstream buttress, which was replaced with an enlarged 300,000 cubic-yard (230,000 m3) buttress founded on alluvium and colluvium that were improved in-place using Cement Deep Soil Mixing (CDSM) technology. The site characterization for the project, design of CDSM, reuse of CDSM spoils as construction materials, and environmental permitting have been described in five previously published professional papers.This paper provides a brief summary of the design of the seismic upgrades and presents the results of measurements made during and/or after construction including the variation of CDSM strengths with time, piezometric levels within the dam and foundation soils, and seepage flow rates. These measured values are compared to the values estimated during design of the seismic upgrades.INTRODUCTIONSan Pablo Reservoir is located approximately 10 miles (16 kilometers) north of downtown Oakland, California, as shown in Fig 1. As many as 50 million gallons (200,000 m3) per day pass through the reservoir for treatment and distribution to a portion of the 1.3 million customers served by EBMUD. The dam is founded mainly on alluvium and was originally built in 1920 using materials excavated from the left and right abutments consisting of siltstone, claystone, fine-grained sandstone, mudstone, and shale that were excavated and placed using hydraulic fill methods. The dam is located within two miles (three kilometers) of the Hayward Fault which is capable of a moment magnitude 7.25 earthquake.Because of the foundation materials, construction method, and proximity to the Hayward Fault, the dam has undergone a series of seismic improvements, including the placement of a downstream compacted earth buttress in 1967 and an upstream compacted earth buttress in 1979. In 2002, the State of California Division of Safety of Dams (DSOD) requested that EBMUD evaluate the seismic stability of San Pablo Dam, following the results of a study that same year that indicated a 62 percent chance of a greater than 6.7 magnitude earthquake striking the San Francisco Bay region between 2003 and 2032. The dam was evaluated and it was concluded that portions of the underlying foundation soils may liquefy during the maximum credible earthquake which could cause the dam to become unstable."

Jan 1, 2015

By Roderic A. Ellman

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

Jan 1, 2013

By Y. G. Qin

In this article an experimental study of axial bearing capacity of half-closed steel pipe pile installed at BKSH dock is presented. In comparison with open and closed end piles, half-closed end pile is considered to have high bearing capacity and good penetration, that is, it not only has a capacity as twice as the same size open end steel pipe pile, but also has blow counts as half as the same size closed end steel pipe pile. It is economic to use half-closed end pile in soft ground without a deep deposit of thick stiff clay. This article also describes a large scale model pile test and preliminarily analyses mechanism of improvement of bearing capacity of half-closed end pile with emphasis on effect of squeezed soil on side friction; an empirical approach is presented in which side friction is related to density of squeezed soil and which is useful for reasonably chosing side friction of different types of piles in design of foundarion.

Jan 1, 2010