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By Ronald E. Walkington

The U.S. Department of Energy (DOE) is building the world's newest accelerator-based, pulsed-neutron system, called Spallation Neutron Source (SNS). The facility, located in Oak Ridge, Tennessee, is a partnership of six DOE national laboratories - Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge. Oak Ridge has the responsibility for managing the partnership and ultimately operating SNS. SNS will provide opportunities for up to 2,000 researchers each year from universities, national laboratories and industry from around the world for basic and applied research and technology development in the fields of materials science, magnetic materials, polymers and complex fluids, chemistry and biology. When completed, this state-of-the-art research facility will provide neutron beams that are 12 times more intense than any other such source in the world. Most of the world's neutron sources were built decades ago. Therefore, it is easy to understand how SNS will provide new research opportunities unavailable elsewhere, and at the same time restore United States leadership in neutron sciences. Neutron scattering research provides valuable information about materials that cannot be obtained through microscopy, X-rays, spectroscopes, or other techniques. The information gained from neutron scattering research leads to improved materials that are used in high-temperature superconductors, powerful lightweight magnets, aluminum bridge decks, jet aircraft, compact and computer discs, magnetic recording tapes, shatter-proof windshields, and many other applications. SNS is like a flashing strobe light providing high-speed illumination of an object and will record the structure of physical and biological materials from plastics to proteins. Because neutrons have no charge, they can penetrate more deeply into materials than do X-rays, light, or electrons and thus reveal bulk structure and properties of materials. SNS will help to understand and "engineer" better materials and the manufacture of better products at the atomic level. Our high-technology society demands new materials that are stronger, lighter, and cheaper yet perform well under severe conditions. SNS, which is designed with the future in mind, will be the leading neutron research facility for many years to come.

Jan 1, 2001

By Aly M. Mohammad

Croton Point Avenue Bridge carries Croton Avenue over Metro-North main tracks at Harmon Rail Yard in Westchester County, New York. The new bridge is 1100 foot long and 36 foot wide nine span structure with three spans continuous units. The spans are steel multi-stringers, composite with concrete deck. The piers are solid wall piers and the foundations are spread footings. During the design of the bridge foundations it was determined that the relatively loose to medium dense sand layer is susceptible to liquefaction under a design earthquake with a seismic coefficient of 0.15g. Several foundation options were considered for the new bridge including both shallow and deep foundations. It was determined that the most cost effective alternative is to use spread footing foundations supported on densified soils. Vibratory probes were utilized to densify the loose to medium dense sand layer and reduce the risk of liquefaction. Densification test sections were performed to determine the optimum spacing for the vibro probes. The test sections included performing piezocone tests before and after the densification to compare the increase in relative density of the sand. In addition, ground surface settlement due to the vibro probes was measured and correlated to the increase of soil relative density. The paper will present the results of the ground improvement method utilized and correlate the spacing of the vibro probes and the increase in relative density and the results of the piezocone tests performed before and after the densification. It was found that the vibro probes are not as effective as thought at shallow depth below the ground surface. It is believed that the results and finding presented in this paper will benefit both the design and construction industries by providing a relatively cost effective means to improve the soils

Jan 1, 2007

By G. L. Sivakumar Babu, P. Chaithra

"Raft foundations which are used against differential settlements and for carrying heavy loads can still be subjected to excessive settlements even if it is safe against bearing capacity consideration. Providing additional piles under the raft can reduce such settlements to acceptable values. In addition to settlements, the piles also relieve the raft a part of the total load and thus the bearing capacity of the Combined piled raft foundation (CPRF) is improved. Parametric study of response of piled raft foundation has been conducted and the results have been presented. The study is conducted using finite element based software, PLAXIS 2D. The main objective of the paper is to evaluate the parameters that affect the performance of piled raft for an economical and effective design. It has been shown that piled rafts are an economical solution in foundation design compared to raft foundation, for the soil conditions considered in the paper.1. INTRODUCTIONThe aim during the design and construction process of high-rise building foundations in urban areas is to ensure the lifelong safety and serviceability of the new and existing buildings in the neighborhood. In order to realize this aim in a cost-optimized manner, the combined pile raft foundation (CPRF) was developed (Katzenbach et al., 2005). For the foundation of high rise buildings with good subsoil, the simplest structure considered is a raft. But when the subsoil near the ground surface has low load-bearing capacity, high-rise structures are often rested on piled foundations.A piled raft and pile group serves similar purposes, but there are essential differences between them. A pile group is a set of piles that have a pile cap. The piles would be designed to share the pile load at ultimate state. The pile cap would be designed to link the piles together but the contribution of the pile cap to bearing capacity will not be included in the design. On the other hand, a piled raft is a foundation, wherein piles are provided along with the raft so that the total load acting is shared partly by the raft and partly by piles, rather than being dominated by the piles (as in a pile group). Piled raft foundations utilize pile support for control of settlements with piles providing most of the stiffness at serviceability loads, and the raft element providing additional capacity at ultimate loading (Poulos, et al., 2011). Therefore, piles are included in a foundation for two main design purposes: to provide adequate bearing capacity and to bring down the settlements to an acceptable level."

Jan 1, 2015

By Brett K. Mainer

In the summer and fall of 2007, Drill Tech Drilling and Shoring, Inc. designed and built three 24-foot inside diameter shafts in Northern California using soil mix panels for support. The soil mixing was performed using the Bauer Cutter Soil Mix (CSM) method, by which rectangular soil mix panels up to 71 feet deep were arranged in an overlapping manner to form a 24-foot inside diameter circle. The shafts were then excavated to depths up to 51 feet. One of the shafts was a test shaft and used only the soil mix panels for support. The other two shafts were located immediately adjacent to the Mokelumne River and were used as access pits for a microtunnel drive under the river. These two shafts had wide flange beams embedded in the panels and were supported with several levels of ring steel placed during excavation. This project was the first use of the Bauer CSM method in the United States. The CSM method has been used extensively in Europe and Asia, but never for this application and never with this high a loading criteria due to water head and microtunnel reaction forces. Soil conditions at the river crossing shafts consisted of sands, gravels, and cobbles over top of sandstone and conglomerate bedrock ranging in strength up to 5,000 psi. Groundwater was within several feet of the surface. The shafts were successfully completed between October 2007 and January 2008, and the microtunnel was successfully completed in February 2008. This paper provides discussion regarding selection of the shoring type, structural design, the soil mixing method, and the mix designs. Shaft construction, shaft performance, and the capabilities of the CSM equipment are presented.

Jan 1, 2008

By P. D. Arumairaj, B. Vani

"Micropiles are small diameter cast insitu reinforced grouted piles and it has been effectively used in many applications of ground improvement. It increases the load carrying capacity of soil and reduces the settlement. It is also used in strengthening existing foundations. In this study, the effect of Solid and Hollow micropiles on the load carrying capacity of footing resting on sand is studied. The effects of solid Micropiles are investigated by conducting experimental model studies. The parameters involved in this study include the position of pile, pile length and pile spacing. Load test was carried out on a model footing resting on sand with solid and hollow micropiles. Load test trail is repeated for footing on Micropiles with varying lengths of 10, 20, and 30 times the diameter and spacing equal to 5, 4, 3, 2 times the diameter. The load-settlement behavior of each case is compared. Optimum length and optimum spacing of both the solid micropile and hollow micropile are determined. It is also observed that the effect of micropiles in the peripheral of footing resists lateral displacement of soil underneath the footing. The micropile beyond significant depth becomes redundant.INTRODUCTIONA micropile is a small diameter (less than 300 mm) drilled and grouted pile that is typically reinforced - FHWA-NHI 2005 (Federal Highway Administration-National Highway Institution). It is constructed by drilling a borehole, placing a steel reinforcing element into the borehole and grouting it. Hollow micropiles are typically reinforced by solid central bar that occupies about onethird of the hole volume. The grout is placed by gravity, under pressure methods or by a combination of both (post grouting). Thus, micropiles can be considered as small drilled-shafts that are specially drilled and grouted.Historically, micropiles have been introduced in Italy as a foundation system mainly for retrofitting and underpinning of structures that had sustained damage during World War II and access for conventional piling equipment was not possible (Bruce, 1988). The second generation of micropiles is a pressure grouted piles with a central mono all thread bar (with diameter up to 89 mm). They are installed by using either an open or cased hole drilling method.A new generation of micropiles, termed Grout injection bore micropiles (IBOR), was developed in the 1980s. The IBOR, currently named hollow bar micropiles, utilizes a continuous all-threaded hollow steel bar as the drilling and grouting conduit, which allows drilling and grouting simultaneously without the need of a casing during drilling. A sacrificial (lost) bit with openings that allow for pressure grouting of the hole is threaded onto the end of the hollow bar and is left in place following drilling. A drilling fluid (air, water, or grout) is introduced through the hollow bar and allows the spoils to flush from the borehole opening. Upon reaching the required depth, neat cement grout is then injected under high pressure into the drilled hole to fill the annulus between the bar and the soil from the bottom to the top. Due to the grouting method employed, the shape of the hollow bar micropile is expected to have a bulb shape with an enlarged base."

Jan 1, 2015

By Nathan A. Ingraffea

The use of steel sheet pile walls and drilled shaft foundation elements to enable up-down construction methods has been used successfully on recent high-rise structures with multi-story below grade parking. The John Ross Tower and The 3720 Tower in Portland, Oregon each make use of this system and are discussed in-depth. Up-Down construction involves the simultaneous construction of the building levels above and below grade instead of the standard construction technique of excavating and shoring the below grade construction before being able to build upward from the base of the excavation. Advantages of the up-down system include a shortened overall construction schedule, permanent basement walls that double as the temporary shoring walls, elimination of the typical continuous wall footing or grade beam at the building perimeter, increased use of recycled material (steel) while maintaining an overall decrease in total materials, elimination of wall forming costs, decreases in forming costs for slabs, decreases in waterproofing costs for walls and elimination of pile caps and/or footings for the building columns. Lessons learned during the construction of both buildings include the need for more extensive geotechnical boring information, descriptive sheet pile and drilled shaft specifications, a clear understanding from the design team on finished appearance of sheet pile and shafts, and careful consideration of the connection between both slabs and the sheet pile wall and slabs and drilled shafts.

Jan 1, 2008

By Ivan Hee

The 2.5km long bridge over the Beauharnois Canal and St. Lawrence Seaway is a major structure in the new Autoroute 30 project near Montreal. Foundations for the bridge consist of footings on bedrock, driven piles, and drilled shafts. This paper describes the design, verification, and construction of 1.85m diameter drilled shafts socketed into very strong and abrasive dolomitic sandstone. Two loading tests on sacrificial, heavily-instrumented, 1.18m diameter test shafts using Osterberg load cells were performed, with telltales installed to monitor a possible rock cone failure mechanism. The loading tests resulted in a revision to the initial design and provided a greater understanding of the cone uplift mechanism in rock. Insights gained are discussed and economies of the load testing program presented. Construction methodologies are also presented.

Jan 1, 2011

By Frederick C. Rhyner

The United States government sponsored the construction of a new vehicular bridge over the Diyala River in Bubriz, Iraq. This paper describes the geotechnical engineering for design and construction of drilled shaft foundations for this bridge. An Iraqi geotechnical engineering firm made borings and laboratory tests while analysis and design recommendations were provided in the United States. Despite the severe challenges of engineering in a war zone, excellent cooperation was the key to a successful effort. Three drilled shafts designs were necessary to accommodate the different subsurface conditions: a) medium-compact to compact sands, b) stiff to hard clays and c) mixed soil profile. The alpha and beta methods were used to estimate capacities for a conservative design, recognizing that quality control during construction might be less than what is normally provided in the United States. Iraq has a high seismic risk and LPILE was used to estimate the drilled shaft response during earthquake loading conditions. Settlement estimates were made using FHWA methods. Construction was carried out entirely by local Iraqi firms, despite the challenges of working in an active conflict area.

Jan 1, 2009

By D. E. Sherwood

Twelve toe grouted, and eleven ungrouted piles, founded in very dense sands have been analysed to establish how toe grouting enhances pile performance. It is shown that pile stiffness is greatly increased, and that pile bases work effectively. This is in contrast to ungrouted piles, where some milli­meters of base movement may be required before the base is mobilised. Grouting appears to recover most of the disturbance caused during construc­tion, but in general does not enhance the ultimate bearing capacity of undisturbed ground.

Jan 1, 1989

By N. V. Nayak

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

Jan 1, 1996

By Gopal Ranjan

An insitu prtotype study on precast driven spliced piles in soft marine clay deposit has been carried out to study negative drag. The drag is generated by loading the ambient clay. For reduction in negative skin friction, in addition to use of bitumen layer on piles, the ambient clay is transformed into composite mass of low compressibility by utlizing different ground imporvment techniques e.g. plain granular piles, mini grouted piles and self setting soil slurry piles. Adoption of these techniques resulted in significant reduction in settlement of ambient ground and consequently the negative drag on piles. On the basis of the study it has been established that these techniques improve ground condition resulting in lowering of down drag/negative friction.

Jan 1, 1996

By Kozo Takeda, Arashi Shimano

"Dry Jet Mixing (DJM) technique is widely known as soil mitigation technique with small ground displacement during installation comparing with other techniques. Some projects involving sensitive structures, however, require smaller impact than in conventional technique. In order to reduce ground displacement during DJM installation, this paper introduces systematic mixing technique, RD-DJM (Reducing Displacement – Dry Jet Mixing). RD-DJM is characterized by injection nozzle on the rim of mixing blade and fin plate on mixing shaft. These devices contribute efficient collection of injected air toward mixing shaft and result in reduction of ground displacement. The authors demonstrate successful performance of RD-DJM indicating difference between conventional installation and RD-DJM technique.INTRODUCTIONThe Dry Jet Mixing (DJM) method is one of the most common techniques in Japanese deep soil mixing field and characterized mechanical mixing of powdery binder with in-situ ground (dry-mixing technique). It is widely believed that DJM Method has great advantages in less quantity of binder to achieve the desired strength and less waste generation during installation.DJM method can meet the required strength with less binder content than wet mixing. And volume of binder of dry mixing is absolutely less than wet-mixing injecting considerable volume of binder slurry. This means that dry mixing causes less ground displacement compared with wet mixing.As the medium for forced feeding of the binder, the DJM method uses compressed air, which is blown from the mixing blade nozzles to scatter the binder and then recovered through the periphery of the mixing shaft to the ground surface. Because the binder is injected outward from the injection orifice at the root of the mixing shaft, a part of the air may escape to untreated areas due to the blockage of air recovery path around the mixing shaft. Figure 1 illustrates possible escaped air and leakage around installation location."

Jan 1, 2015

By Michael D. Justason

This paper describes the technology behind the development of an automated energy control system for a diesel pile hammer. Some background is given on experience using an energy monitoring system on the Route 1/I-95 interchange in Alexandria, Virginia. An adjustable hammer throttle and feedback from an energy monitoring system was then used to create a fully automated hammer energy control system. The performance of this system is described in reference to a piling project in Canada where the automated energy control system was used to obtain an unprecedented level of quality control and assurance ? data and graphs from the project are presented. The hammer energy control system (ECS) was used to successfully control and maintain a prescribed impact energy for the diesel hammer. This paper presents the first ever results from a truly automated diesel pile hammer and points to a new direction in quality control and assurance in pile driving.

Jan 1, 2006

By Darrell Wilder

The Trenton Water Treatment Facility in Trenton, New Jersey, is expanding to upgrade existing facilities and to meet the increasing demands of the public. The facility sits uncomfortably between the northern bank of the Delaware River and Route 29, a busy traffic corridor. Flooding along this bank of the river occurs frequently and disrupts traffic along Route 29. The expansion plans for the facility call for several large clarifying tanks on a mat foundation covering an area of about 100 x 350 ft. The original design was to remove and replace up to 20 ft of existing fill and soft materials. Due to the close proximity to the existing structures and the Delaware River, it would be necessary to use sheet piles and tiebacks to support the proposed excavation, as well as the existing structures. The solution adopted consisted of the installation of vibro-replacement stone columns to improve the in situ soils and eliminate the need for excavation and replacement. This approach was tremendously successful. It mitigated the significant risk of flooding of the excavation, and provided a cost-effective alternative to mitigate settlement of the proposed tanks on the poor soft subgrade soils. This paper presents the details of the criteria for selection and design of the stone columns, and the process followed for installation of the stone columns and for verification of the level of soil improvement achieved. It also includes a back analysis of the results of a large scale, 10- by 10-foot plate load test performed on a group of stone columns using numerical procedures and recommendations for design and construction.

Jan 1, 2008

By Roderic A. Ellman

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

Jan 1, 2005

By Michael W. Oakland

This paper summarizes the analysis and design of a pile foundation system for two 400 ft. diameter, 500 ft. high cooling tower using a detailed finite element analysis package. The cooling towers are at the Brayton Point Power Plant in Somerset, Massachusetts. The design-build project will convert the power plant to a closed loop cooling system to reduce return of heated water to the bay. Each cooling tower is supported on a 5 ft. thick by 16 ft. wide ring beam with 44 columns oriented in a radial pattern. The allowable lateral movement on the thin wall shell was limited to only 0.5 inches. Lateral and tension resistance were the primary concerns for the large, but lightweight structure and the critical issue was the lateral response of piles and pile groups within the system. By constructing a detailed model of the foundation system including modeling each pile as an independent element, the contribution of each element was separately assessed and the system tuned to take best advantage of the load distribution afforded by the ring beam as well as the soil structure interaction created by tangential as well as radial resistance of the pile groups. The detailed model also incorporated the lateral resistance of interior piles supporting an equipment slab within the ring beam. Simpler models analyzed the pile groups independent of the complete structure and generally only relied on radial stiffness and generally resulted in large groups of piles needed at each pier. Through a series of trial configurations, the number of piles used was optimized. Confirmatory lateral, vertical and tension load tests were conducted and final fine tuning of the model completed.

Jan 1, 2010

By Paul J. Lewis

Replacement of the Monroe Street Viaduct in southwest Baltimore City, Maryland included transforming 240 feet of the south approach from a pile-supported multi-span bridge to a mechanically stabilized earth (MSE) embankment supported by vibro-concrete columns (VCCs) and a load transfer platform. The project area was underlain with highly compressible soils which would have resulted in up to 18 inches of settlement under the proposed embankment load. Adjacent structures and critical underground utilities would have been impacteded or damaged by this settlement. Various load transfer alternatives were evaluated to mitigate the anticipated settlement by supporting the embankment on a deeper, more competent stratum. The alternatives considered included compaction grout columns, stone columns, deep soil mixing, and VCCs. Deep soil mixing was eventually selected for design, however, as part of a value engineering proposal, the general contractor Joseph B. Fay Company, with assistance from Hayward Baker and the Collin Group, prepared and submitted an alternative consisting of VCCs. This paper presents the details of the value load transfer platform and VCC design. Loading tests were utilized to confirm the VCC capacity and field changes were implemented based on the test results.

Jan 1, 2007

By Douglas L. Scaggs

Over the past several years, pile foundations have grown to meet the demands of larger and heavier structures. As the foundations have grown, so has the need for larger and more robust piles to carry the increased loads. Seismic considerations have also required larger and tougher piles to withstand the added component of supporting structures during earthquakes. While H-piles, precast concrete piles, timber piles and small pipe piles have been the product of choice, many applications are now calling for much larger piling requiring larger equipment and presenting the contractor with new challenges. This paper is not intended to be a ?how to? guide as much as a discussion on the potential pitfalls a contractor should watch out for when considering a project where mega piles are required.

Jan 1, 2013

By Franz-Werner Gerressen

In the changing construction environment clients are searching for new technology to complete their projects in shorter times. Manufacturers are therefore developing solutions to speed up established construction methods. The significant progress in recent years with the development of increasingly powerful drilling rigs is providing piling companies increase options for the execution of specialist foundation projects. The double rotary drilling methods are primarily used for the construction of pile walls as support for deep excavations. Typically these retaining walls are designed and installed as cased piles using the established Kelly drilling mode. However, more recently it is more popular to undertake these projects with the Cased Continuous Flight Auger (CCFA) system. This paper provides an overview of drilling with double rotary methods, in particular the monitoring during installation.

Jan 1, 2009

By Wolfram Groh

New underground floors comprising the complete footprint area of the building structure, were constructed under an existing building in sand, located in the Verdun district of Beirut / Lebanon. The works for the rehabilitation and extension of the Verdun 528 building were carried out between December 1999 and August 2000. A restriction of differential vertical movement of existing load bearing walls and columns had to be respected throughout the construction phase of the new basements. Support measures for the building were taken based on a underpinning system with Bauer SVV preloaded micropiles. The specialty of this underpinning job was that the building loads at the time of preloading and excavation of new basements was substantially less than at final stage. The design of the preloading system was particularly challenging in view of the transition from temporary to final load transfer under variable load conditions. Load transfer was based on the Bauer SVV micropile head system applied in several technical variants. Monitoring of levels of structural elements performed throughout the construction works confirmed that the differential movements of adjacent load bearing columns and walls were maintained within the specified limits.

Jan 1, 2002