Benchmark of experimental techniques for measuring and controlling suction

Abstract

The paper presents a benchmarking study carried out within the ‘Mechanics of Unsaturated Soils for Engineering’ (MUSE) network aimed at comparing different techniques for measurement and control of suction. Techniques tested by the eight ‘Mechanics of Unsaturated Soils for Engineering’ research teams include axis-translation (pressure plate and suction-controlled oedometer), highcapacity\ud tensiometer and osmotic technique. The soil used in the exercise was a mixture of uniform sand, sodium bentonite (active clay) and kaolinite (non-active clay), which were all commercially available. Samples were prepared by one team and distributed to all other teams. They were normally consolidated from slurry under one-dimensional conditions (consolidometer) to a given vertical stress.\ud The water retention characteristics of the initially saturated specimens were investigated along the main drying path. Specimens were de-saturated by applying suction through the liquid phase when using an axis-translation technique or osmotic method and de-saturated by air-drying,\ud when suction was measured using igh-capacity tensiometers. In general, the same technique was tested by at least two teams. The water retention curves obtained using the different techniques are compared and discrepancies are discussed in the paper.Peer ReviewedPostprint (published version

From saturated to unsaturated conditions and vice versa

“…13a and 14a are consistent with expected shrinkage behaviour for drying tests on normally consolidated or lightly overconsolidated reconstituted soil samples (e.g. [15,70]) and match well the experimental behaviour reported by Vicol [75], Fleureau et al [21], Marinho [42], Cunningham et al [18], Tarantino et al [69] and Al Haj and Standing [1].…”

“…[18,21,57,69,75]). To include, in such experimental investigations, the influence that dry density (or plastic volumetric strain) has on the airentry point, it is useful to conduct the same type of airdrying paths on several samples that have been previously pre-consolidated to different values of stress.…”

Benchmarking selection of parameter values for the Barcelona basic model

“…This benchmarking exercise was organised within a "Marie Curie" Research Training Network on "Mechanics of Unsaturated Soils for Engineering" (MUSE) (Gallipoli et al, 2006;Toll et al, 2009), which was supported financially by the European Commission. The activities undertaken by the MUSE Network included a variety of benchmarking exercises relating to experimental techniques, constitutive modelling and numerical modelling (see, for example, Tarantino et al, 2011 andD"Onza et al, 2011).…”

Editorial: partial saturation in compacted soils

“…It contains five articles, two related to the sub-theme 'benchmarking of techniques and models' (D'Onza et al, 2011;Tarantino et al, 2011) and three related to the sub-theme 'experimental observation and modelling' (Alonso et al, 2011;Boyd & Sivakumar, 2011;Romero et al, 2011). The next issue of Géotechnique will also be entirely dedicated to this symposium in print and will contain the five contributions related to the sub-themes 'material characterisation' and 'application to engineering problems and case studies'.…”

“…The second article, by Tarantino et al (2011), compares the water-retention curves measured on the same soil by eight different laboratories using different types of experimental equipment chosen from amongst the pressure plate, the axis-translation oedometer, the high-capacity tensiometer, the osmotic method and the dewpoint potentiometer. It is encouraging to observe that the measurements performed by different research teams appear remarkably consistent not only when the same type of equipment is used but also when different types of experimental techniques are employed.…”