EAGER: Shaking Table Testing to Evaluate Effectiveness of Vertical Drains for Liquefaction Mitigation

Brigham Young University, Provo UT

Investigators

Abstract

This Early-Concept Grant for Exploratory Research (EAGER)research study will conduct full-scale tests with vertical drains in liquefiable sand using the laminar shear box and shaking table system at NEES-Univ. of Buffalo. These tests are designed to evaluate the ability of vertical drains to prevent liquefaction and limit associated settlement and lateral deformation. In comparison with conventional densification mitigation strategies, drainage can theoretically reduce cost and treatment times by 50% to 75%. In addition, the cost and time delay associated with post-treatment verification testing is eliminated. Unfortunately, no full-scale drain installation has been subjected to earthquake induced ground motions. This lack of performance data under full-scale conditions is a major impediment to expanding the use of this technique as engineers are reluctant to take the risk of employing an untested system. Tests in this study will involve both level ground and sloping ground (2º slope) and will be integrated with a previously funded NEESR study currently underway so that the control tests without drains will already be available. The sand will be hydraulically placed at a relative density of about 40%. Sensors to monitor pore water pressure, settlement, lateral displacement, and acceleration will allow direct comparisons of performance with and without drains. This collaborative approach will significantly reduce the cost of the study in comparison to a completely independent study. In addition, it will provide a comparison between the performance of the soil profile with drains relative to subsequent tests where piles will be involved. Furthermore, detailed analyses of the test results using numerical models will be performed as part of a companion FHWA pooled fund study.