Direct Shear Apparatus Manual

The Direct Shear Apparatus is a geotechnical testing instrument used to determine the shear strength parameters of soil specimens. It measures the shear resistance of soils under controlled normal stress conditions, providing data for cohesion (c) and angle of internal friction (φ). The apparatus consists of a shear box, loading frame, proving rings, dial gauges, and motorized loading system. Below are key sections for safety, features, installation, setup, operation, and troubleshooting.

1. Features at a Glance 2. Installation 3. First-Time Setup 4. Specifications 5. Controls and Settings 6. Connecting Components 7. Testing Procedure 8. Calibration 9. Care & Maintenance 10. Regulatory Information 11. Troubleshooting

Features at a Glance

Key components: Shear box assembly, Loading frame, Proving rings, Dial gauges, Motorized drive unit, Normal load application system.

Feature	Description
Shear box	Split box for soil specimen containment
Loading frame	Applies normal and shear stresses
Proving rings	Measures shear force accurately
Dial gauges	Measures horizontal and vertical displacements
Motorized drive	Provides constant rate of strain
Normal load system	Applies controlled vertical stress
Data acquisition	Manual or digital recording options
Calibration weights	For precise load application
Safety guards	Protects operator during testing
Control panel	For speed adjustment and operation control

Installation

Unpack and inspect all components. Place on stable laboratory bench.

Assemble frame: Secure loading frame to base using provided bolts.
Install shear box: Position shear box assembly in loading frame.
Connect drive unit: Attach motorized drive to shear mechanism.
Mount gauges: Install dial gauges for displacement measurement.
Connect power: Plug into appropriate power supply.

WARNING! Apparatus is heavy; use proper lifting techniques. Ensure all connections are secure before operation.

First-Time Setup

Power on apparatus; perform initial calibration.

Calibration: Use calibration weights to verify load cell accuracy.
Zero gauges: Set all dial gauges to zero reference position.
Lubrication: Apply recommended lubricant to moving parts.
Test run: Perform empty box test to verify proper operation.
Speed setting: Set appropriate shear rate for soil type.

CAUTION! Ensure apparatus is level and stable. Keep hands clear during operation.

Specifications

Shear Box Size: 60mm x 60mm standard
Normal Load Capacity: Up to 5 kN
Shear Load Capacity: Up to 2 kN
Displacement Range: 0-25mm horizontal and vertical
Shear Rate: 0.0001 to 4 mm/min adjustable
Proving Ring Accuracy: ±0.5% of full scale
Dial Gauge Resolution: 0.01mm
Power Requirements: 110-240V AC, 50/60Hz
Operating Temperature: 10°C to 40°C

Controls and Settings

Access controls via front panel. Main Controls: POWER, START/STOP, SPEED ADJUST, EMERGENCY STOP.

Settings: Shear rate adjustment, Normal load setting, Data recording interval, Maximum displacement limit.

Normal Stress: Applied through lever arm and weights. Shear Rate: Adjustable via speed control knob. Data Recording: Manual reading or automatic data logging. Safety: Emergency stop button and overload protection.

Connecting Components

Shear box to loading frame, Dial gauges to mounting posts, Proving ring to load cell, Power supply to main unit.

Turn off power before making connections.
Secure shear box in loading frame.
Mount dial gauges perpendicular to movement direction.
Connect proving ring to load application system.
Verify all electrical connections are secure.

Tip: Ensure all connections are tight and properly aligned before testing.

Testing Procedure

Standard procedure for soil shear strength determination.

Specimen preparation: Trim soil specimen to fit shear box.
Assembly: Place specimen in shear box with porous stones.
Normal stress: Apply desired normal load using weights.
Consolidation: Allow specimen to consolidate under normal stress.
Shear test: Start motorized drive at selected rate.
Data recording: Record shear force and displacements at intervals.
Completion: Stop test at maximum displacement or peak strength.
Calculation: Determine shear strength parameters from data.

WARNING! Wear safety glasses during testing. Keep clear of moving parts.

Calibration

Regular calibration ensures accurate test results.

Proving Ring Calibration: Use standard weights. Dial Gauge Calibration: Use micrometer standard. Load Frame Calibration: Verify alignment and friction. Speed Calibration: Check motor speed against timer.

Care & Maintenance

Disconnect power before maintenance. Clean after each use with soft cloth.

Daily: Wipe surfaces, check for loose components. Weekly: Lubricate moving parts, inspect electrical connections. Monthly: Full calibration check, thorough cleaning.

CAUTION! Do not use solvents or abrasive cleaners. Store in dry environment.

Regulatory Information

Complies with ASTM D3080 standard for direct shear testing of soils. CE certified for laboratory equipment safety. Manufactured under ISO 9001 quality standards. Copyright © 2025 Geotechnical Instruments Ltd. For technical support, visit www.geotech-instruments.com or contact 1-800-555-TEST.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Motor not running	Power connection/fuse	Check power supply; replace fuse if blown; verify switch position.
Irregular shear movement	Lubrication/alignment	Lubricate guide rods; check frame alignment; clean tracks.
Inconsistent readings	Calibration/gauges	Recalibrate proving rings; check dial gauge zero; verify mounting.
Excessive vibration	Leveling/loose parts	Level apparatus; tighten all bolts; check foundation stability.
Load not maintaining	Weights/system	Verify weight placement; check lever arm freedom; inspect loading system.

Reset: Power cycle unit if electronic controls malfunction.

Service: 1-800-555-TEST; www.geotech-instruments.com