00672562

Component

http://onlinepubs.trb.org...trr/1994/1447/1447-012.pdf

https://scholar.google.co...chey&publication_year=1994

A case history describing the use of blast densification by the Washington State Department of Transportation to densify a 40-m-deep, loose debris flow is presented. Debris flow from the 1980 eruption of Mount St. Helens would pose a high risk for liquefaction and ground settlement should a seismic event occur. A single-span bridge was to be constructed on the debris flow. It was determined that the only practical means of supporting the structure were spread footings founded on the debris flow, once improved by ground densification. Blast densification was chosen over more common means to improve the ground; it was considered the most cost-effective and feasible method of construction through boulder-laden debris flow. First, a test section was constructed to verify the blast design and to confirm its feasibility given the unusual geologic deposit. The goal was to improve the relative density of the deposit, as measured by standard penetration testing (SPT) and Becker penetration testing. Additionally, the site was instrumented to measure ground response. Instrumentation included surface and subsurface settlement devices, inclinometers, piezometers, ground-vibration instruments, and geophysical surveys. Blast densification successfully increased the SPT values of the deposit from an average N sub 1(60) = 8 to N sub 1(60) = 20 above 15 m, to N sub 1(60) = 19 below 15 m.

This paper appears in Transportation Research Record No. 1447, Design and Construction of Auger Cast Piles, and Other Foundation Issues. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved

01401277

English

p. 102-109

1994

Transportation Research Record

0309060532

Figures (9) ; References (12)

Bridge foundations; Case studies; Debris flows; Densification; Improvements; Soil penetration test; Spread footings; Volcanoes

Bridges and other structures; Design; Geotechnology; Highways; I24: Design of Bridges and Retaining Walls

TRIS, TRB

Jan 13 1995 12:00AM

• ANALYTICAL MODELING OF SPREAD FOOTING FOUNDATIONS FOR SEISMIC ANALYSIS OF BRIDGES
• ATLAS SCREW PILE: A VIBRATION-FREE, FULL DISPLACEMENT, CAST-IN-PLACE PILE
• BITUMEN COATING FOR DOWNDRAG MITIGATION IN COHESIONLESS SOILS
• BUCKLING OF FRICTION PILES SUPPORTING BRIDGE FOUNDATIONS
• DESIGN AND CONSTRUCTION OF AUGER-CAST PILES IN FLORIDA
• DESIGN AND CONSTRUCTION OF STARSOL PILES
• DETERMINING LENGTHS OF INSTALLED TIMBER PILES BY DISPERSIVE WAVE PROPAGATION
• FORMALIZED PROCEDURE FOR QUALITY ASSESSMENT OF CAST-IN-PLACE SHAFTS USING SONIC PULSE ECHO METHODS
• LRFD CODE FOR ONTARIO BRIDGE SUBSTRUCTURES
• MANAGING THE INSTALLATION OF AUGERED CAST-IN-PLACE PILES
• NEW TECHNIQUES FOR RELIABLE PILE INSTALLATION AND PILE BEHAVIOR DESIGN AND ANALYSIS
• REDUCED IMPACT ON ADJACENT STRUCTURES USING AUGERED CAST-IN-PLACE PILES
• REVIEW OF AUGERED PILE PRACTICE OUTSIDE THE UNITED STATES