Automated Rock Direct Shear Tester

The Automated Rock Direct Shear Tester (CT-DSA) measures the shear strength of a rock discontinuity, such as a joint, bedding plane or fracture, under controlled normal stress. The test follows ASTM D5607 and the ISRM suggested method. Peak and residual shear strength, dilation and friction angle from this test feed slope stability, fault and discontinuity analysis. Coretest also offers a manual tester and a high-capacity automated model in the same family.

How it works

The specimen is mounted in the shear box with the discontinuity aligned to the shear plane, and the box is set in a stiff load reaction frame. A normal actuator applies normal stress across the plane and a shear actuator displaces one half of the specimen relative to the other. Both axes run under closed-loop servo control. Normal stress is held in constant-normal-load (CNL) or constant-normal-stiffness (CNS) mode, and shear rate is the second controlled variable.

Normal load, shear load, shear displacement and normal displacement are measured throughout the test. From these records the system reports peak and residual shear strength, dilation and friction angle. The standard frame has a normal load capacity of 50 kN and a shear load capacity of 100 kN, with 25 mm of normal displacement and 25 mm of shear displacement. The sample rig accepts specimens of 150 mm diameter and 150 mm height. The unit weighs 250 kg and runs on 110-220 VAC, 50/60 Hz. Load capacity and shear box size are configured per project.

What is included

• Stiff load reaction frame with normal and shear loading axes under closed-loop control
• Shear box for 150 mm diameter, 150 mm high specimens
• Load and displacement measurement on both axes
• Automated test control in CNL and CNS modes

Specify for your project

• Normal and shear load capacity required
• Specimen size and shear box size
• Test modes to be run: CNL, CNS or both
• Shear rate range and displacement range
• Supply voltage, 110 or 220 VAC

This description defines the product family. Guaranteed performance, included hardware, exclusions, interfaces and acceptance criteria are stated only in the project-specific technical proposal and approved datasheet.

Features

• Standard: ASTM D5607, ISRM
• Normal load capacity : 50 kN
• Shear load capacity: 100 kN
• Max. normal displacement : 25 mm
• Max. shear displacement : 25 mm
• Sample rig diameter : 150 mm
• Sample height: 150 mm
• Weigh: 250 kg
• Power supply: 110-220VAC, 50/60Hz

Benefits

• ASTM compliant
• Automated tests
• Stiff load reaction frame