Best Practices
For CFA Piles

A wide variety of techniques, materials and equipment have been used to construct continuous-flight auger (CFA) piles. Some key components of good quality construction include drill rigs, drilling, cementitious materials, placement of grout or concrete, completion of the pile top, reinforcement, installation plan, and test piles and test installations. An on-line article providing an overview of the recommended practices for CFA piles is presented at National Driller's Web site. Click here to access the full article.

MCSI Hits the Slopes at Telluride Ski Resort

Mays Construction Specialties Inc. (MCSI) was able to expedite the new access trail for Telluride Ski Resort in Colorado by providing the blast hole drilling on this ridge at more than 13,000 feet elevation using its HEM-300HT drill mounted on a Linkbelt 130LX excavator. Weather conditions at that altitude in October consisted of wind gusts of more than 100 mph, and wind chill temperatures below 10 degrees F. MCSI, based in Grand Junction, Colo., has four TEI drills, and has provided the Rocky Mountain region with blast hole drilling, soil nailing, ground and rock anchors, and micropiles for almost 20 years.

DFI Hires Technical Activities Manager

After a yearlong search, the Deep Foundations Institute announces the appointment of Mary Ellen Bruce to the position of technical activities manager. Her duties include supporting the institute's technical committees by advising and assisting with their publications, seminars, short courses and other activities.

With nearly 20 years experience in geotechnical and environmental engineering consulting, Bruce has been involved in environmental regulatory projects and site assessments, dam and roadway projects; and she has authored technical papers on micropiles, deep mixing and ground anchors.

Bruce can be reached directly at mebruce@dfi.org or by phone at 724-942-4220.

Some Upcoming Industry Events

For a more extensive listing of events, click here. If you'd like to list you event with us, just send an e-mail to ettlingg@bnpmedia.com.

Featured Project of the Month

Geo-Foundations' Health Centre Effort

Meno-Ya-Win Health Centre is a hospital development situated in Sioux Lookout, Ontario. When completed, the new hospital will service northwest Ontario with 60 beds accompanied by emergency, surgery and other acute-care facilities. Thanks to the efforts of Geo-Foundations Inc., the new hospital's structure is framed by cast-in-place concrete founded partly on spread footings on rock, and partly on drilled, rock-socketed piles.

Due to the highly varying and erratic elevation of the bedrock at this site, use of strip-footing foundations over the entire footprint of the structure was neither economical nor practicable. The tendered foundation package prescribed the installation of 12-inch rock-socketed piles drilled a minimum of 8 feet into sound rock to support individual pile service loading of 1000 kN compression. Recognizing that the extreme hardness of the basalt bedrock was the defining factor in the pile installation's challenge and risk, Geo-Foundations submitted two prices at time of tender - one price for the drilled piles as specified, and a second price for a performance-based, one-for-one substitution of smaller-sized piles. The alternative pile proposal was ultimately selected, and the structure's deep foundations consist of 7-inch-diameter drilled pipe piles socketed 3 feet into rock. 

Drilling of the piles was completed using a single-head, shoeless, percussive, rotary-duplex drilling process employing NUMA's T150 Superjaws tooling. Immediately after being tremie-grouted, each pile was pressure-grouted to force grout into the annulus between the outside pipe wall and the inside of the rock socket. A premium grout blend, complete with superplasticizer and shrinkage compensating agents, was used.

The principle challenge to the successful installation of piles at this site was the varying and erratic elevation of the top of bedrock. In many instances, depth to bedrock was found to differ as much as 20 feet within a lateral distance of just 6 feet. Added to this difficulty was the hardness of the bedrock, which consumed several drill bits over the course of installing the production piles and load test tie-down anchors.

To validate the alternative pile design, two pre-production, static compressive load tests were completed to cyclically applied loading of 2000kN static compression. After load testing clearly demonstrated the adequacy of the alternative pile design, the balance of the piles were installed.

Geo-Foundations Contractors Inc. is a specialty geo-structural construction firm headquartered in Acton, Ontario. The company is committed to the implementation and further development of advanced technologies applicable to specialized geotechnical construction, with particular focus on small-diameter drilled solutions related to foundation support, ground improvement and ground treatment.

ASC Personnel News

At ASC geosciences inc., Lakeland, Fla., Christopher Basile has been promoted to chief engineer, geotechnical division. He will handle geotechnical projects for ASC throughout the southeastern United States. Also, Prashanth Vaddu has been promoted to central Florida area manager. For the past five years, Vaddu had served as senior staff engineer.

Featured Product of the Month

Steel Piling Joints Available

Emeca/SPEusa manufactures steel piling joints and rock points for casting into pre-stressed concrete piles for deep foundations. The locking joint ensures a sure and firm connection at the location of the pile joint. The joint is locked in place with four driven pins, and enables two or more sections of pile to be fastened together. Installation requires one rig and a two-person crew, and is said to take less than 5 minutes. Currently, the pile joints are available in 12-inch and 14-inch sizes; larger pile joints are in the development phase and will be available soon. For more information, visit www.emeca-speusa.com.

On the Job

Specialized Drilling Platform

The water catchments on the Rock of Gibraltar required decommissioning and stabilizing. Almost 10,000 soil-nails needed installing, requiring the use of a number of heavy-duty impact drills and the removal of thousands of corrugated tin sheets originally used to catch rainwater for the island. Access, Lifting, Pulling & Safety Ltd. supplied the specialized lifting and pulling equipment required to maneuver the 15-ton-plus rock drills up and down the ancient 45-percent sloping sand dune.

AEC Store Corner

Foundation Engineering Handbook - $127.95
The latest information on foundation engineering, design, construction and code

This practical resource offers complete coverage of foundation engineering, emphasizing the geotechnical aspects and the use of the 2006 International Building Code. Foundation Engineering Handbook explains how to develop a complete program of foundation investigation, conduct geotechnical field and laboratory studies, and analyze data for the design of foundations. Evaluating construction and preparing foundation engineering reports also is covered.

Covers these and other key topics:

• Soil mechanics
• Field testing
• Earth slope stability evaluation
• Seismic analysis
• 2006 International Building Code

CLICK HERE for more details or to purchase this book.