Sydney Soil Model. I: Theoretical Formulation

Abstract

In this paper a theoretical study of the behavior of structured soils, including both clays and sands, is presented. A new model, which is referred to as the "Sydney soil model," is formulated within the framework of critical state soil mechanics. In the proposed model, the mechanical behavior of soil is divided into two parts, that at a reference state and that attributed to the influence of soil structure. The reference state behavior is formulated according to the soil properties at the critical state of deformation, based on the concept of plastic volumetric hardening. The effects of structure are captured in the model by incorporation of the additional voids ratio that arises owing to the presence of soil structure. The formulation is generalized to include both isotropic compression and general shearing. In part I of this paper, a new theoretical framework for modeling structured soil behavior and the formulation of the proposed Sydney soil model are introduced. In part II of this paper, the Sydney soil model is employed to simulate the behavior of clays and sands, including calcareous clays and sands subjected to both drained and undrained shearing, and the performance of the model is evaluated.

A bond failure criterion for DEM simulations of cemented geomaterials considering variable bond thickness

“…This peculiar microstructure leads to several particular mechanical features, which distinguish them from uncemented geomaterials [1], such as decementation softening [2,3], high small-strain stress-independent stiffness [4], and brittle yield at low confining pressures contrasted to ductile failure at high confining pressures [5]. They attracted extensive investigations in geo-laboratory at a macroscopic level [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] using natural [2,[6][7][8] or synthetic [3][4][5][6][8][9][10][11][12][13][14][15][16] cemented soil samples, giving rise to a few constitutive models of cemented geomaterials [17][18][19][20][21][22][23][24]. All these studies reach the conclusion that, in addition to stress history and density, the evolution of intergranular bonds endows extra complexity to the macroscopic behavior of cement...…”

Mineralogy and geotechnical properties of Singapore marine clay at Changi

“…Yan and Ma (2010) characterised marine deposits in Macau. Liu et al (2011) characterised marine clays in Lianyougang. The results of these geological studies, which included the mineralogical and geotechnical investigation of shear strength, hydraulic conductivity and compression, are vital for research and design.…”

“…The results of these geological studies, which included the mineralogical and geotechnical investigation of shear strength, hydraulic conductivity and compression, are vital for research and design. An understanding of the compressive behaviour is essential for geological and geotechnical engineering purposes and is the core basis for modelling the stress-strain relationships of soils (e.g., Pestana and Whittle, 1995;Hong and Onitsuka, 1998;Potts and Zdravkovic, 1999;Baudet and Stallebrass, 2001;Chai et al, 2004;Liu et al, 2011Liu et al, , 2013.…”

Compressibility of lightweight cemented clays

“…The term "soil structure" is determined by both the particle associations and arrangements (fabric) and cementation bond (Terzaghi, 1953;Mitchell, 1996;Miura et al, 2001 andLiu et al, 2011). Fabric is reflected by the void ratio and swelling potential of clay while the level of cementation bond is by cement content.…”