The Undrained Cyclic Response of Monterey Sand in Direct Simple Shear

The high impact that earthquake-induced liquefaction has on the New Zealand economy, as observed during the 2010-2011 Canterbury Earthquake Sequence in the Christchurch urban area, requires a better understanding of the undrained response of silty sands to cyclic shear loadings. This problem remains still difficult to address because progresses are hindered by the paucity of laboratory experimental data regarding silty sands. In order to address this issue, a series of triaxial tests have been performed at the University of Canterbury since 2011 on undisturbed samples recovered from seven sites in Christchurch. This study aims at using a direct simple shear device for improved evaluation of earthquake and liquefaction response of silty soils. In the first phase of the experimental programme, comprehensive calibration of the testing device and testing procedures has been performed. This paper summarizes key aspects of this important preparatory phase of the testing including description of testing procedures. Reliability of testing procedures and obtained results are assessed by means of a series of simple shear tests performed on a clean sand, whose results are compared against data from the literature.