Although blast liquefaction studies have shown that vertical drains greatly increase the rate of drainage under field conditions, they have not prevented liquefaction. In addition, it is difficult to compare pore pressure development during blasting and an earthquake. At present, no direct field or laboratory data is available to confirm whether or not the drains have the ability to limit pore pressures and resulting settlement to acceptable levels. However, shaking table tests can be conducted with a large shear box (20 ft high, 9 ft wide, 16 ft long) containing drains at SUNY-Buffalo and compared with identical testing currently underway for another funded study. Tests will be performed at progressively higher acceleration levels and durations to allow comparison of performance (pore pressure & settlement) for earthquake conditions.

Perform shaking table tests on sandy soils with vertical drains installed to confirm whether or not the drains have the ability to limit pore pressures and resulting settlement to acceptable levels during the earthquake event. Three objectives are outlined for this study: 1. Evaluate the ability of earthquake drains to reduce excess pore pressure and settlement for level ground conditions at progressively higher acceleration levels. 2. Define the influence of drain spacing on the effectiveness of the drains for mitigating liquefaction hazard. 3. Provide well-documented case histories which can be used to calibrate/validate numerical models for predicting the performance of vertical drains.

The scope of work consists of eight specific tasks: 1. Perform a literature review to summarize the state of the art in the area of liquefaction mitigation through drainage. 2. Conduct level ground shaking table tests with drains at 4 ft spacing. 3. Conduct level ground shaking table tests with drains at 3 ft spacing. 4. Reduce the test data, analyze, and compare with previous test on untreated sand. 5. Evaluate predictive methods by comparing measured behavior with behavior computed using computer models and simplified models. 6. Prepare a final report on effectiveness of the drain technique. 7. Disseminate the research results. 8. Hold technical advisory committee meetings.

The Principal Investigator for this study will be Dr. Kyle Rollins, of Brigham Young University. Dr. Rollins has extensive experience with liquefaction mitigation studies, the use of vertical drains, and the simulation of earthquake conditions for research. This study promises to yield practical results. Vertical drains offer the potential to deal with liquefaction problems at 30 to 50% of the cost and time required with conventional densification techniques. Drains could also be used in combination with other improvement techniques where it might be difficult or too expensive to completely prevent liquefaction through densification. Drains are particularly attractive for marginal liquefaction problems or for locations where it might be economically difficult to justify the conventional densification procedure.