IN-SITU VANE SHEAR TEST AZA0922

Description

Purpose and Significance

The in-situ vane shear test is a well-established field method for measuring the shear resistance of saturated cohesive soils without the need for sample extraction. By applying controlled torque to a cruciform vane embedded in the soil, the apparatus determines the soil’s resistance to shear failure directly in the ground.

The AZA0922 also enables soil sensitivity determination by measuring both undisturbed and remolded shear strength, which is critical for evaluating the behavior of sensitive clays under construction disturbance.

Applications

The AZA0922 is widely used in:

• Geotechnical site investigations

• Foundation and pile design in soft clay deposits

• Embankment and slope stability studies

• Retaining wall and excavation analysis

• Dredging and soft sediment characterization

• Infrastructure projects such as roads, bridges, dams, and buildings

Working Principle

1. A cruciform vane is pushed into the soil at the required depth.

2. Torque is applied at a controlled rate using a geared torque head.

3. Soil fails along a cylindrical shear surface around the vane.

4. Maximum torque at failure is recorded.

5. Undrained shear strength (cᵤ) is calculated using vane dimensions and applied torque.

6. For sensitivity, the soil is remolded by rapid rotation and the test is repeated.

Construction & Key Features

• Torque Applicator Assembly
  Heavy-duty, base-mounted system with geared crank for smooth and controlled torque application.

• Torque Measurement System
  Calibrated split proving ring with high-precision dial gauge and conversion chart.

• Cruciform Vanes
  Manufactured from high-grade steel for durability and minimal soil disturbance.
  Standard H/D ratio of 2:1 as per standards.

• Extension & Dummy Rods
  Square cross-section rods with secure couplings for testing at various depths.
  Dummy rods provided for friction correction.

• Low-Friction Mechanism
  Thrust collars/bearings minimize rod friction to ensure accurate torque measurement.

• Rotation Indicator
  Allows precise monitoring of angular displacement during testing.

• Detachable Stand
  Provides stable anchoring during field operation.

• Portable Design
  Supplied with a sturdy carrying case for easy transport and protection.

Standards Compliance

The AZA0922 is designed and manufactured in compliance with:

• IS 4434:1982 (Reaffirmed 2016) – Field Vane Shear Test for Cohesive Soils

• ASTM D2573 – Field Vane Shear Test in Cohesive Soil

• ISO 22476-9 – Geotechnical Field Vane Test

Specifications

Frequently Asked Questions (FAQ)

Q1: What does the AZA0922 measure?
It measures the undrained shear strength (cᵤ) of cohesive soils directly in the field.

Q2: Which soils are suitable for this test?
Soft to medium saturated clays and silts. It is not suitable for sandy or gravelly soils.

Q3: Why is in-situ testing preferred for soft clays?
Because it minimizes soil disturbance, providing more accurate strength values than laboratory tests on disturbed samples.

Q4: Can soil sensitivity be determined?
Yes. By comparing undisturbed and remolded shear strength values.

Q5: Is the apparatus suitable for field conditions?
Yes. It is robust, portable, and designed specifically for demanding field environments.