00969929

Monograph

http://onlinepubs.trb.org...ay/NCHRP94Final_Report.pdf

This Innovations Deserving Exploratory Analysis (IDEA) project evaluated the behavior of vertical composite earthquake drains under full-scale conditions, employing controlled blasting techniques to liquefy loose sand at a test site in Vancouver, British Columbia. A blast liquefaction test was first performed on an untreated site and then the same explosive charge sequence was used on two sites treated with earthquake drains, one installed with low vibration and the other with high vibration. Although the earthquake drains were insufficient to prevent initial liquefaction during the rapid loading produced by the blasts, the measured rate of dissipation was significantly greater at both drain test areas than in the untreated area. Dissipation rates were similar for both areas treated with drains. Despite the high pore pressures, the blast induced settlement in the first drain test area was only 60% of that in the untreated area. CPT soundings conducted over a two month period after blasting showed a 20 point increase in relative density for the layer where drains were installed with low vibration. This result indicates that both blast treatment and drain installation can produce significant increases in density. With minor modifications in the input parameters, computer analyses performed using FEQDrain were successful in matching measured pore pressure and settlement response during the blasting. These calibrated models were then used to model response to a variety of earthquake events. The results indicate that the drains can prevent liquefaction and excessive settlement when drain diameter and spacing are properly designed for the expected earthquakes.

This NCHRP-IDEA investigation was conducted by Brigham Young University, Provo. 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

NCHRP-IDEA Project 94

NCHRP-IDEA 94

English

107 p.

2004-2

NCHRP-IDEA Program Project Final Report

Appendices (1) ; Figures; Photos; References; Tables (8)

Calibration; Computer models; Dissipation; Earthquakes; Field tests; Ground settlement; Liquefaction; Pore pressure; Sand; Soil densification; Vertical drains

Innovations Deserving Exploratory Analysis (IDEA) (Program)

Controlled blasting; Vertical composite earthquake drains

Energy; Geotechnology; Highways; I42: Soil Mechanics

TRIS, TRB

Feb 23 2004 12:00AM