Direct Simple Shear test
In Direct Simple Shear (DSS) test intact or remolded specimen is radially constrained within a wire-reinforced membrane or normal thin membrane supported by a stack of rigid rings that can easily slide over each other. In this setup, the specimen is locked against shearing either from top or bottom and is subjected to a normal load. When shearing force is applied to the free end a simple shear state is imposed on the specimen. This test is usually conducted under constant volume condition (equivalent undrained condition). Since the specimens are radially constrained the constant volume condition is achieved by preventing any height change during shearing. The recorded normal stress during shearing accounts for excess pore pressure. DSS or cyclic DSS (CDSS) tests can be conducted in strain or stress-controlled manner (ASTM D6526).
Due to its simplicity and speed, DSS is becoming ever more popular in geotechnical engineering. DSS needs shorter specimens than that of a triaxial test and can simulate some of the field conditions more realistically.
Direct Simple Shear tests can be conducted and monitored manually or by using a fully automated testing apparatus. Regardless of the state of automation, in order to conduct a Direct Shear test the following devices and accessories are necessary:
A solid Platen to house the pedestal and specimen on top of it. It’s rigid enough to allow for proper consolidation, it provides drainage paths and can lock the bottom of the specimen onto the shearing table.
Includes caps and pedestals of different diameters, porous stones made from different materials, and different porosity, permeability, and friction (pinned or smooth).
Consists of a membrane stretcher, split mold for preparation of cohesionless and granular material, cutting ring, extruder, lathe, and others.
Load/Displacement/Pressure/volume measurement sensors/gages and data logging devices.
Direct Simple Shear device
To inquire about Orvalis (TM)’s Direct Simple Shear machines and Sensors click here.