Contact
Research Director, Geotechnical Research Centre
Department of Civil and Environmental Engineering
Spencer Engineering Building
Room SEB 3010D
Western University
asadrek@uwo.ca
Advanced Testing
Several advanced and state of the art laboratory testing equipment are used in my research group. The basic features and characteristics of these equipment are summarized below.
Bidirectional Cyclic Direct Simple Shear Test
This apparatus can perform monotonic and cyclic direct simple shear tests. Most cyclic direct simple shear tests can only apply shear stress in one horizontal direction. However, this innovative device includes three perpendicular servomechanical actuators which can control vertical and two horizontal forces on a cylindrical soil sample. This mechanism allows to apply shear stress in two directions and carry out bidirectional cyclic or monotinc shear tests. Samples of 70 and 50 mm in diameter can be tested. Separate platens with peizoelectric bender elements are also available to measure shear wave velocity.
Cyclic Ring Shear Test
Ring shear testing is primariyl used to determine long displacement behavior and residual strength of soils. The ring shear apparatus can accommodate annular specimens with external and internal radii of 76.1 mm and 48.3 mm, respectively and specimen heights (h) of up to 53.3 mm. Vertical and shear stresses of up to 1,000 kPa and 1,300 kPa, respectively are applied on the specimen at a rate of 0.001 degrees/min to 360 degrees/min by an advanced electro-pneumatic servo-controlled system. A servo-controlled electrical motor applies and controls cyclic shear and vertical loads on the upper loading platen up to a frequency of 1 Hz. A combined force-torque sensor measures the vertical force (N) and the shearing torque (T) applied on the soil sample. The vertical displacement and the angular rotation (θ) of the upper platen are separately measured by a high resolution LVDT and an angular encoder, respectively. A pair of piezoelectric bender elements embedded in the upper and lower platens of the ring shear apparatus are also used to measure the velocity of a shear wave traveling through the soil specimen. A photograph of the cyclic ring shear tests is shown below. The cyclic ring shear apparatus at Western University is also equipped with a suction control and measurement system which can measure a wide range of matric suction.
Controlled-Rate of Strain Oedometer
Cyclic Triaxial Test
Shear Wave Velocity Measurement with Bender Elements
Both the cyclic simple shear and ring shear apparatus are equipped with piezoelectric bender elements for measuring shear wave velocity and determing maximum shear modulus of soil samples.
