Preparation of large-scale clay testbeds through suction-aided slurry consolidation

Preparation of normally consolidated (NC) claybeds under 1 g condition is a prolonged process with challenges (e.g., nonuniform settlement, formation of vertical cracks) that grow manifold with an increase in claybed dimensions. The requirements of large testbed dimensions and adequate inflight test arrangements often restrict the use of a centrifuge facility for preparation of large NC claybeds. Controlled application of an elevated hydraulic gradient across a consolidating clay slurry provides a fast and viable alternative to slurry consolidation under the sole action of gravity. This paper describes successful implementation of suction-aided consolidation in medium- and large-scale test tanks to prepare NC clay deposits with monotonically increasing undrained shear strength profiles. The developed test facilities utilized different levels of suction pressure at the bottom of a consolidating claybed. Recorded surface settlement data demonstrated that the influence of the magnitude of applied suction on the rate of clay slurry settlement increases with an increase in the claybed dimension. For the medium-scale test setup, undrained shear strength profiles in the bottom one-third of the claybeds were sensitive to applied suction pressure. Undrained shear strength s_u profiles obtained from constant-rate ball penetration tests were within the range of predictions using available empirical correlations to estimate s_u from liquidity index.