The vane shear test is used to estimate the undrained shear strength of fully saturated clays without disturbance.
The vane shear test equipment consists of a four-blade stainless steel vane attached to a steel rod that will be pushed into the ground. Probedrill uses the GeoMil FFL 100 Vane Shear which comes with three rectangular vane types. These are:
- 70mm x 35mm;
- 100mm x 50mm; and
- 150mm x 75mm vanes.
The test starts by pushing the vane and the rod vertically into the soft soil. The vane is then rotated at a speed which can be adjusted from 0.1° per second up to 15° per second, while the sampling rate can be user defined.
The measured values are graphically visualised in real-time and plotted against the rotational angle.
Simultaneously all measured values, sample number and time are logged in a separate spread sheet.
The torque is measured at regular time intervals and the test continues until a maximum torque is reached and the vane rotates rapidly for several revolutions. At this time, the soil fails in shear on a cylindrical surface around the vane. The rotation is usually continued after shearing and the torque is measured to estimate the remoulded shear strength.
Upon termination of a shear test, an additional spread sheet allows to calculate the undrained shear strength at the point of failure by considering the rod friction.
Upon completion of the undrained shear test, the user can easily start a remould test. The vane will be turned 5 revolutions at a speed of 15° per second. To prevent damage the maximum torsion during remould is limited to 50%. After the 5 revolutions the system returns to the preset turning speed and will log the residual shear strength.
The results of both undrained and residual shear strength are presented in the same graph.
|Projects using this service|
|South Australia: 2016|
|Perth Stadium, Burswood: 2012 – 2015|
|Elizabeth Quay (Perth Waterfront) Project: 2010 – 2015|
|Forrestfield – Airport Link Project, Perth: 2014 – 2015|
|Chevron Wheatstone LNG Project, Onslow: 2009 – 2013|