Insitu Vane Shear Test

The Insitu Vane Shear Test gives the in place shearing resistance of soft, saturated clays which are sensitive and are susceptible to sampling disturbances. The test give undrained shear strength of soil, along a cylindrical surface without change in volume or soil structure.

The test consists of pushing a vane with four blades into soil and rotating it till the cylindrical surface in soil fails in shear. The torque or turning moment required to cause this failure is measured on a Torque Meter.

The maximum moment of the total shear mobilized about the axis of rotation is equal to the applied torque. The unit shear resistance of the cylindrical surface can thus be computed.

IS:4434 specifies two methods, namely testing at the bottom of a bore hole and testing by direct penetration from the ground surface. HS 34.140 is used in bore holes and HS34.145 for direct penetration from ground surface.

Insitu Vane Shear Apparatus

HS 34.140

The apparatus is suitable for testing at the bottom of a bore hole.

This consists of Torque Applicator mounted on a detachable stand. By applying torque, deformation of torque ring can be read on a dial gauge. From the calibration curve, deformation can be converted into torque in Kg. Cm.

  • Torque applicator assembly, 2000 kg cm – 1 No.
  • Vane 37.5 mm x 75 mm high complete with vane rod and one dummy rod – 1 set.
  • Vane 50 mm dia x 100 mm high, complete with vane rod and one dummy rod.
  • Extension rods one meter long threaded, quick coupling type. 25 Nos.
  • Extension rods half meter long threaded, quick coupling type 10 Nos.
  • Spikes – 4 Nos.

Insitu Vane Shear Apparatus

HS 34.145

Known, as Norwegian Vane Borer, this is simple and rugged in design and is meant for penetration boring. It can be used without casing down to 30 meters depth. The lower part of the apparatus is forced down, with the vane withdrawn into a protection shoe. At the desired depth the vane is unlocked and pushed into the undisturbed soil and rotated at a constant rate of strain of 60 /min or 0.10 per second.

The maximum torque is recorded on the torque meter.

The equipment comprises the following :-

  • Torque applicator assembly, capacity 600 kg cm, complete with a metal case.
  • Vane with vane rod 37.5 mm dia x 75 mm high.
  • Vane with rod 50 mm dia x 100 mm high.
  • Vane protection shoe assembly with sleeve.
  • Extension rods 0.5 meter long 10 Nos.
  • Extension rods, 1 meter long 25 Nos.
  • Extension rods, one each 7.5 cm, 15 cm, 25 cm & 40 cm long.
  • Extension tubes, 1 meter long 25 Nos.
  • Extension tubes, ½ meter long 10 Nos.
  • Set of tools 1 set.

Spares

  • 37.5 mm dia x 75 mm vane with vane rod.
  • 50 mm dia x 100 mm vane with vane rod.
  • Extension tube 1 meter long set of 5.
  • Extension tube ½ meter long set of 5
  • Extension rod ½ meter long set of 5.