5:15 PM - 6:45 PM
[SSS05-P21] Development of direct shear assembly in triaxial apparatus: preliminary results of slide-hold-slide tests on siliceous sediment
Keywords:Friction experiment, Siliceous sediment, Earthquake
A friction experiment with gouge in a triaxial apparatus is often performed by placing a gouge between two diagonally pre-cut cylindrical pistons. In this "pre-cut" assembly, higher stress can be applied to the gouge by confining pressure and axial force, and the length of the specimen can be relatively small. On the other hand, when the confining pressure is constant, the normal stress applied to the gouge is not constant, and there remains uncertainty in the estimation of some parameters such as the velocity dependence of the friction coefficient which is influenced by both the normal stress itself and its variation. In addition, a large displacement cannot be applied and consolidation and shear deformation of the sample with respect to axial displacement cannot be distinguished in the "pre-cut" assembly.
One way to solve these problems is the "direct shear" assembly. The prototype was originally proposed by Hoskins et al. (1968) and Logan et al. (1992), and has been actively introduced in laboratories around the world in recent years (e.g., Samuelson & Spiers, 2012; Sánchez-Roa et al., 2016). In the "direct shear" assembly, the confining pressure is identical to the normal stress and is kept constant with deformation. In addition, since the axial loading and the direction of deformation are the same, consolidation of the gouge due to axial displacement does not occur, allowing for more precise measurement of shear stress. At Kochi Institute for Core Sample Research of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), a "direct shear" assembly is installed in the existing oil-medium triaxial apparatus and preliminary experiments are underway. In this presentation, we report the results of preliminary experiments and summarize the "direct shear" assembly in the triaxial apparatus. We will also report the results of slide-hold-slide experiments on siliceous sediments, which are considered to be one of the causes of shallow slow earthquakes in the Japan Trench.
One way to solve these problems is the "direct shear" assembly. The prototype was originally proposed by Hoskins et al. (1968) and Logan et al. (1992), and has been actively introduced in laboratories around the world in recent years (e.g., Samuelson & Spiers, 2012; Sánchez-Roa et al., 2016). In the "direct shear" assembly, the confining pressure is identical to the normal stress and is kept constant with deformation. In addition, since the axial loading and the direction of deformation are the same, consolidation of the gouge due to axial displacement does not occur, allowing for more precise measurement of shear stress. At Kochi Institute for Core Sample Research of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), a "direct shear" assembly is installed in the existing oil-medium triaxial apparatus and preliminary experiments are underway. In this presentation, we report the results of preliminary experiments and summarize the "direct shear" assembly in the triaxial apparatus. We will also report the results of slide-hold-slide experiments on siliceous sediments, which are considered to be one of the causes of shallow slow earthquakes in the Japan Trench.