Earthquake retrofit of highway/railway embankments by sheet-pile walls

A series of highly instrumented dynamic centrifuge model tests were performed to investigate the potential of using sheet-pile walls for mitigating the adverse effects of foundation liquefaction on overlying highway embankments. The response of a prototype 4.5 m high cohesive highway embankment supported on a 6 m thick loose saturated sand layer was analyzed under dynamic base excitation conditions. In a series of four separate model tests, this embankment-foundation system was studied first without, and then with the following three different liquefaction countermeasure techniques, all involving sheet-piles: (a) sheet-pile extending to the foundation surface, (b) sheet-pile with toe area gravel surcharge berm, and (c) sheet-pile with toe area gravel surcharge berm extending into the foundation. Model response was monitored by numerous accelerometers, pore pressure transducers, and displacement gages. The underlying mechanism and effectiveness of each countermeasure is discussed based on the recorded dynamic response. All of the implemented countermeasures were found to significantly reduce embankment deformations. Particularly in the case of the sheet-pile with toe area gravel berm, cracking and lateral spreading of the embankment were practically eliminated. This revised version was published online in July 2006 with corrections to the Cover Date.