This paper studies the use of gravel drains as a means of mitigating earthquake-induced liquefaction in non cohesive soils. The study is performed numerically using the 2D finite difference code FLAC and a recently proposed bounding surface plasticity model for non cohesive soil behavior under cyclic loading. The reliability of the numerical methodology is verified via the simulation of a centrifuge test for a uniform 19m-thick liquefiable sand layer that was improved with gravel drains and subjected to earthquake motion. The comparison of data to simulations is performed in terms of time histories of accelerations and excess pore water pressure ratios at various locations within the sand layer and is found satisfactory. Given the accuracy of the methodology, parametric analyses were performed for the study of the merely horizontal dissipation of excess pore pressures provided by gravel drains in a thin liquefiable sand layer enclosed in practically impermeable clay layers. The emphasis of the analyses is the rate of excess pore pressure buildup in the improved ground, as compared to the recommendations of available methods for design of gravel drains. In particular, a conservatism of the design charts of Seed & Booker (1977) is explained at least qualitatively, and preliminary recommendations are provided for their future use.
|Pages||Paper no. 1548|
|Number of pages||13|
|Publication status||Published - 25 Jun 2007|
|Event||4th International Conference on Geotechnical Earthquake Engineering - Thessaloniki, Greece|
Duration: 25 Jun 2007 → 28 Jun 2007
|Conference||4th International Conference on Geotechnical Earthquake Engineering|
|Period||25/06/07 → 28/06/07|
- gravel drains
- ground improvement
- bounding surface
Papadimitrou, A., Moutsopoulou, M-E., Bouckovalas, G., & Brennan, A. (2007). Numerical investigation of liquefaction mitigation using gravel drains. Paper no. 1548. Paper presented at 4th International Conference on Geotechnical Earthquake Engineering, Thessaloniki, Greece.