Geotechnical Engineering Online Library

The most promising of these predictive tools incorporates the use of constitutive soil models in finite element and finite difference computer programs to solve boundary value problems. Unfortunately, the use of advanced constitutive soil models for liquefiable soils is being hampered by a lack of the high-quality laboratory testing for use in the validation of existing models and development of new ones. In particular, very little modeling-quality testing has been performed on: a) medium dense to dense sand that exhibits dilative behavior, b) sands under initial ìdrivingî shear conditions as would be found in sloping ground or under a structure, and c) sands experiencing multidirectional stress (or strain) paths. To address this urgent need for modeling-quality data a program of multidirectional simple shear testing was performed on medium to high relative density, 2 fully-saturated samples of Monterey 0/30 sand in the U.C. Berkeley Bi-directional Simple Shear Device. A variety of previously unexplored multi-directional stress paths (including bi-directional linear, oval/circular, and figure-8) were explored. Tests were performed both with and without an initial static driving shear stress in order to replicate the initial in-situ loading conditions on soils elements under both sloping and level ground conditions. Additionally, the major axis of the three loading types was oriented in both the dip and strike directions for the sloping ground cases. The results of this testing program addressed two ultimate goals. The first is the development of insight into the behavior of liquefiable soils under generalized loading conditions. The second is the development of modeling-quality laboratory data quantitatively describing the behavior of liquefiable soils for use in model development and calibration. Experimental, results are presented both as quantitative data and as insights into more generalized behavior of liquefiable materials under multi-directional loading.