An automated procedure for computing the packing properties of dense and locked sands by image analysis of thin sections

Abstract

The macroscopic mechanical behaviour of dense sands originates to a great extent from their microstructural characteristics such as the coordination number, the grain contact and the packing density indexes. The study of intergranular contacts and the reckoning of these indexes may be carried out on planar images of the grains either by means of time-consuming visual inspection assisted by CAD or by automatic image analysis. An innovative method for the automatic determination of microstructural characteristics of sands based on image analysis of thin section is proposed. Tests performed on a locked sand show that the proposed method is much more effective, convenient and faster than the usual visual inspection technique. Therefore, it can be considered an extremely useful tool for calibrating predictive models for arrangements of granular media based on computer simulations

The bearing capacity of footings on sand with a weak layer

“…The shear strength parameters of sand A vary in function of the normal stress level as shown in Figure 3 These results are in good agreement with data reported in the literature (Celauro et al, 2014;Chakraborty and Salgado, 2010;Lancelot et al, 2006;Loukidis and Salgado, 2011;Negussey and Vaid, 1990;Ponce and Bell, 1971;Rowe, 1962;Sture et al, 1998;Yamaguchi et al, 1977).…”

Microstructure and shear strength evolution of a lime-treated clay for use in road construction

“…2b shows that the dilatancy angle at failure (ν′ f = ∆δ v /∆δ h ) of the clay treated with 4% and 6% of lime, also increases as a hyperbolic function of time. The maximum value of the dilatancy angle was approximately 30°, similar to very dense silica sands (Valore et al, 2017;Ziccarelli et al; or quartz locked sands (Celauro et al, 2014). The clay treated with 2% of lime initially shows similar behaviour to the one of the samples treated with greater amounts of lime; after 14 days, the dilatancy angle, from a maximum of about 16°, decreases and, for curing times higher than 60 days, reaches a steady value equal to 12°.…”