Here is your complimentary issue of "The Foundations Report," an e-newsletter produced by your friends at National Driller magazine. Each month, we'll be sending you an update on the latest happenings in the foundation drilling industry. If you have anything you'd like to share with fellow foundation aficianados, kindly send along your news, announcements, photos, comments and anything else of interest to ettlingg@bnpmedia.com.
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Looking for Special Projects
The Deep Foundations Institute (DFI) is seeking nominations for its Outstanding Project Award. Criteria include size, scope and challenges of the project, degree of innovation and ingenuity exercised and the uniqueness of the solution to the difficulties of the job. The award may be presented to the contractor or to the engineer, or both. Any type or size deep foundation project completed within the previous three years is eligible. Consideration is given to ingenuity of design, ingenuity of the construction technique, how the design meets the owner's needs, and how the design or technique solved geotechnical conditions. All organizations with a DFI corporate or individual membership are
eligible to submit projects, and submissions must be received by May 31. For complete details and an entry form, visit www.dfi.org.
Last year's award went to Langan Engineering & Environmental Services for the Rion-Antirion Bridge (pictured above), the longest cable-stayed bridge in the world.
Huge Drilling Rig Used for Bridge Piles
As part of BHP Billiton Iron Ore's planned major increase in iron ore production, the Turner River Rail Bridge project is a dual-track bridge (738 ft. long) alongside the existing (384 ft. long) single-track bridge built 38 years ago. The contract includes dismantling the old bridge and restoring the river to its original width.
The new bridge superstructure consists of 15 pairs of 50-foot-long pre-stressed concrete trough girders, each weighing 95 tons, supported on fabricated steel headstocks, and tubular steel piles socketed into granite bedrock. The total number of piles is 58 - in two abutments and 14 piers.
The bridge foundation design called for the driving of tubular steel piles to competent partially weathered granite bedrock. The possibility of encountering large boulders above the bedrock at pile locations, which is common in granite areas, made top driving the piles a risky method, as the pile can refuse, and the pile toe can be deformed if a large boulder is encountered. After considering various piling options under such conditions, the bridge contractor selected the Numa Super Jaws under-reaming method to carry the piles down to bedrock.
This method required close consultation between the designer, the contractor and Numa to develop a pile shoe which would meet the pile design specifications and be compatible with the under-reaming bit driving requirements. The resulting pile shoe was 35.4 inches (OD) and 31.5 inches (ID).
The under-reaming method requires lowering the drill tooling into the vertical pile from above, and then attaching the pile containing the tooling to the drilling rig. The circumstances of each project determine how this is done. Methods include drilling a cased rat hole of larger diameter than the pile, placing the pile in it, and lowering in the tooling in. Another method is to stand the casing above ground, present the tooling from above using a separate site crane, then move the drilling rig to the tooling and connect up. This requires working from a man basket. The contractor, John Holland Pty. Ltd., proposed building a combination drilling rig based on a large crane, with
sufficient travel in the leader to allow the drilling rig to be self contained - i.e. raise the tooling high enough in the leader to clear the pile, pitch the pile using the second crane winch, and lower the tooling into the pile, with all operations performed from ground level. The longest pile on the project (59 ft.) required a massive, custom-designed leader to accommodate the pile and the tooling above it. The specifications of the leader required that it be mounted on a large crane base. This is believed to be the largest self-propelled DTH drill rig ever built. The rig is also designed to support a 20-ton pile-driving hammer, capable of driving piles up to 92 feet long.
Piling commenced last September. After a slow start as operating personnel became familiar with a system they had not used before, piling developed into a steady routine. Piling, pier construction, placing and securing concrete deck girders and demobilization was completed on schedule in December. With experience, the drill operator became familiar with the downhole drilling conditions by constantly observing the weight and penetration rate on the electronic gauges monitoring the two main winches. By paying close attention to the gauges, optimum drilling rates could be achieved. In the upper alluvial strata penetration rates of 30 feet per hour were typical. Drilling rates higher than
this would blind the return paths and cause circulation to be lost. In the granite, typical rate in the medium to slightly weathered zone was 9 feet per hour. This was an indicator that toe level was being reached. At some pile locations, very hard granite boulders were encountered, some of which were only partially in the pile path. Patient establishment of a ledge was required to work through these obstructions. The 30.7-inch socketing bit -with sharp carbide buttons - penetrated the granite at a rate of 12 feet per hour.
The size and arrangement of the drilling rig proved to be a very stable drilling platform, and less wear was observed on components exposed to very high impact and abrasive wear - such as the leading edges on the bit reaming wings - than previously experienced with similar components.
Faculty Workshop
The International Association of Foundation Drilling (ADSC) will hold the next edition of its highly acclaimed Civil Engineering Faculty Workshop Program in Chattanooga, Tenn., June 8-14.
The ADSC is a leading provider of educational opportunities for civil engineering academicians, having inaugurated its Civil Engineering Faculty Workshop program in 1987. The ADSC will provide this 5-day program at no cost other than transportation to Chattanooga for the 50 attendees selected to attend.
The Workshop will provide the participants with all the tools needed to teach the fundamentals of drilled shaft and anchored earth retention design for foundation engineering studies at the undergraduate and graduate level. The program focus will be on drilled shafts, anchors and micropiles. In addition to the classroom experience, attendees will participate in hands-on field demonstrations of the latest construction and testing techniques.
Each participant will be provided with a complete take-home teaching package, including texts, manuals and audio-visual aids. The workshop faculty is a veritable who's-who in the field, and features the leading designers, researchers and constructors of drilled shafts, anchors and micropiles in North America.
For further information, and a chance to be among the first to apply, interested parties should send an e-mail to jhall@adsc-iafd.com.
Samoter Exposition Draws Over 100,000
The 27th edition of the Samoter show attracted more than 100,000 visitors to set record attendance figures for the tri-annual International Exhibition of Earth Moving, Site and Building Industry Machinery, which closed March 9 in Verona, Italy, after five days of intense activities. There were more than 1,000 exhibitors at the event, which returns to the same site in March of 2011.
Educational Opportunity
The Deep Foundations Institute is putting on a seminar program titled, "Practical Deep Foundation Design and Construction for Seismic and Lateral Loads." The event takes place Apr. 11 in New York. Noted professionals and industry experts will present the state-of-the-practice in analysis, design, construction and testing of deep foundations subject to seismic and lateral loads. For complete details or to register, visit
www.dfi.org.
Featured Product of the Month Hydraulically Operated Hammer The IHC Hydrohammer from Pileco is a hydraulically operated hammer designed to pile all steel piles and concrete piles - used both above and below water. It is a concept based on more than 30 years of construction and operational experience with hydraulically operated impact hammers. These Hydrohammers have a slim design and reliable strength suitable for universal use and all types of piling and foundation work. For more information visit
www.pileco.com.
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Greg Ettling is the editor of National Driller magazine and The Foundations Report newsletter. You can contact him at ettlingg@bnpmedia.com.
