Quality of undisturbed samples of cohesionless soils collected with advanced procedures [QUALIDADE DE AMOSTRAS INDEFORMADAS EM SOLOS NÃO COESIVOS RECOLHIDAS COM PROCEDIMENTOS AVANÇADOS]

Abstract

Over the past decade, soil-sampling techniques have evolved in order to reduce friction in the interface between the sampler and the soil, minimizing soil disturbance and collecting high-quality samples for laboratory characterisation. Under research projects focused on liquefaction studies in Portugal (LIQ2PROEARTH) and in Europe (LIQUEFACT), an experimental site was implemented in the areas of Benavente and Vila Franca de Xira, where various in situ tests (SPT, CPTu, DMT), including seismic wave measurements (SCPTu and SDMT), were performed and undisturbed samples were collected. The present work presents the experience with samplers adapted to difficult conditions, Dames & Moore and Gel-Push, in granular alluvial deposits with susceptibility to liquefaction. The handling and transportation procedures adopted are described and the performance of each technique is evaluated based on the samplers recovery capacity. Subsequently, the quality of the samples collected is evaluated by comparing the shear wave velocities obtained in the field and in the laboratory, here using bender elements. Both samplers proved to be competent in extracting samples of loose sands and silty sands of high quality. (c) 2021 Sociedade Portuguesa de Geotecnia.