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AFS30 - Presentations
2006 Annual Meeting
- CPT Deployment Systems
Mohammad T. Haider, P.E.
Fugro Consultants, LP
6100 Hillcroft
Houston, Texas 77081
Office Tel: 713-369-5430
Email: mhaider@fugro.com
Presentation Abstract:
This presentation will explore deployment of different types of Cone Penetrometer Testing (CPT) rigs in varying soil conditions for onshore, marshland, rivers, nearshore (over the water), and offshore applications. The presentation will focus on the feasibility of utilizing different types of equipment based on anticipated soil and site conditions. The equipment includes truck-mounted, ATV-mounted, track-mounted, and skid-mounted rigs for onshore and marshland applications. For nearshore (over the water) CPT techniques, barge-mounted and various other types of seabed systems including Sea Robin, Wheeldrive River Calf, Sea Scout, Dolphin Halibut Field Vanes, and TSP will be explored. The above-described types of CPT rigs are conventionally used in the United States. In addition to this equipment, alternative types of CPT systems used internationally for hard to access onshore, nearshore (over the water), and offshore applications will also be discussed. The presentation will also address the limitations of CPT with respect to the type of soil.
- Louisiana DOTD Experience with CPT for Driven Pile Design
Mark J. Morvant, P.E.
Associate Director, Technology Transfer
Louisiana Transportation Research Center
4101 Gourrier Avenue
Baton Rouge, LA 70808
Office Tel: (225) 767-9124 (Phone)
Email: markmorvant@dotd.louisiana.gov
Presentation Abstract:
The cone penetrometer test has been used to set pile lengths on many DOTD projects since the 1980's. During the first ten years of use, CPT technology was primarily used to identify dense sand layers required to support end-bearing piles. The CPT soundings were traditionally been taken during the construction phase to supplement a full complement of borings already in the plans.
Results of the 1998 LTRC study: Evaluation of Bearing Capacity of Piles from Cone Penetration Test Data demonstrated the capability of CPT methods in predicting the frictional capacity of precast concrete piles driven into Louisiana soils. A windows based computer program has been developed for pile load capacity prediction with CPT data. This now allows DOTD engineers to use CPT technology to set lengths for both end bearing piles and friction piles. Utilization of the CPT during the design phase can drastically decrease the number of soil borings and reduce the cost and time required for subsurface characterization.
It is well documented that CPT data can be obtained faster with less cost than conventional soil boring data. CPT soundings taken at closer intervals than traditional borings will provide more details on soil stratification and therefore less potential for error. Using CPT data can reduce the number of borings required and correlation with a test pile can provide more accurate pile lengths for additional savings.
- Use of CPT in Geotechnical Earthquake Engineering
Scott M. Olson, PhD, PE
Assistant Professor
Department of Civil & Environmental Engineering
University of Illinois at Urbana-Champaign
2230d Newmark Civil Engineering Laboratory
205 North Mathews Avenue
Urbana, Illinois 61801
Office Tel: 217-265-7584 (phone)
Presentation Abstract:
The cone penetrometer, particularly when coupled with a piezometer and geophone receivers in a seismic piezocone penetration test (sCPTu), is an excellent insitu site investigation tool for geotechnical engineering when soil conditions are suitable. The sCPTu is a rapid, cost-effective, and repeatable test that provides a large quantity of high quality data. It is particularly well suited to geotechnical earthquake engineering, as it provides data that can be used for site response analysis, liquefaction engineering (level ground liquefaction, liquefaction-induced settlement, flotation, lateral spreading, and flow failure analysis), seismic slope stability, seismic foundation and retaining structure design, and lifeline engineering. This presentation illustrates some of the uses of the sCPTu for the geotechnical earthquake engineering design of the Great River Bridge (GRB), a proposed cable stay structure that will span the Mississippi River from Desha County, Arkansas to Bolivar County, Mississippi. The proposed GRB is located approximately 200 km south of the New Madrid seismic zone, and may be subject to strong ground shaking, liquefaction, lateral spreading, and flow failure during its lifetime.
- Incorporating the CPT Into Mn/dot Site Investigations
Gary Person, P.E.
Foundation Engineer
Minnesota Department of Transportation
1400 Gervais Avenue, South
Maplewood, MN 55109
Office Tel: 651-779-5598
gary.person@dot.state/mn.us
Presentation Abstract:
In November of 2001, the Minnesota Department of Transportation (Mn/DOT) began using CPT methods in addition to traditional borehole drilling as standard practice for geotechnical site characterization. The quality of in-situ strength properties, stratigraphic characterization, investigation speed, and cost effectiveness has increased substantially.
Strength variation in granular deposits, clay strength, thickness and extent of sand seams in clay deposits, limits of organic materials, and groundwater information have been resolved with greater precision than previously possible, at reduced time and cost. Traditional sampling and lab correlation testing is now more targeted; specialized tests performed on fewer samples are providing high quality correlation data. A collection of brief case studies illustrating the use and benefit of CPT investigation techniques on Mn/DOT construction projects are discussed.
- Application of Piezocone Tests for Embankment Design During the Reconstruction of I-15 in Salt Lake City, Utah
Steven R. Saye, Sr.
Geotechnical Engineer
Kiewit Engineering Co.
1000 Kiewit Plaza
Omaha, Nebraska 68131
Presentation Abstract:
The piezocone was an important investigation tool used to characterize the subsurface conditions along the I-15 alignment in Salt Lake City, Utah for the design of the new embankments. The foundation soils consist of about 25 m of layered sediments associated with glacial Lake Bonneville and predecessor lakes. The lake sediments are known to be highly compressible.
The piezocone was an efficient tool to define the thickness and distribution of the individual units within the lake sediments. An adaptation of the SHANSEP Concept described by Ladd et al. (1998) was used to characterize the overconsolidation ratio, OCR, of the soil with the piezocone data. The compression ratio was evaluated using 1) analysis of historical settlement records, 2) oedometer and constant rate of strain consolidation tests, 3) an empirical correlation to water content, and 4) an empirical correlation to the piezocone data. Instrumentation data developed during embankment construction was used to confirm the design soil profiles developed with this approach.
The undrained strength of the lake deposits was estimated using the piezocone profiles of OCR combined with the SHANSEP approach, Ladd and Foott (1974), and correlation coefficients developed from direct simple shear testing at MIT. Stability conditions were often poor and staged embankment construction with prefabricated vertical drains was used to improve the stability conditions.
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