Strain-Controlled Direct Shear Apparatus (Quadruple)

The QS-1A Strain-Controlled Direct Shear Apparatus (Quadruple) is designed to  measure the shear strength of soil. Four samples are tested simultaneously under  different vertical stresses, applying horizontal shear to determine the shear  stress at failure. Using Coulomb’s law, soil strength parameters—including  internal friction angle and cohesion—are calculated. This strain-controlled  direct shear apparatus is an improved design of the manual direct shear device.  Enhanced versions with dual-speed or triple-speed electric drives reduce  operator effort, improve test accuracy, and maintain manual functionality. Shear  rates comply with International Standards, and the instrument is equipped with a  limit mechanism to protect the device. It can perform both rapid and slow shear  tests.

Application

In many engineering problems such as design of foundation, retaining walls,  slab bridges, pipes, sheet piling, the value of the angle of internal friction  and cohesion of the soil involved are required for the design. Direct shear test  is used to predict these parameters quickly.

(1) Determination of soil shear strength parameters.

(2) Evaluation of cohesion and internal friction angle for geotechnical  engineering design.

(3) Laboratory testing of soil samples for foundations, slopes, and  earthworks.

(4) Civil engineering, geotechnical research, and construction material  testing.

Standards

(1) GB/T 50123 – Soil Direct Shear Test

(2) ASTM D3080 – Direct Shear Test of Soils Under Consolidated Drained  Conditions

(3) ASTM D6528 – Standard Test Method for Consolidated Undrained Direct Shear  Test

(4) ISO 17892-10 – Geo technical Investigation and Testing – Direct Shear  Test

(5) BS 1377:7 – Methods of Test for Soils for Civil Engineering Purposes:  Shear Strength Tests (Direct Shear Test)

(6) AASHTO T236 – Standard Method of Test for Direct Shear Test of Soils

(7) NF P09407-1/2 – Direct Shear Test of Soils (French Standard)

Parameters

Features

(1) Quadruple sample testing under different vertical stresses.

(2) High-performance digital stepper motor drive ensures minimal vibration in  low-speed mode.

(3) Microcomputer control allows preset shear time, shear rate, automatic  timing, automatic forward/backward shear, and automatic stop functions.

(4) Lever leveling device facilitates easy horizontal calibration.

(5) Infinitely variable speed knob enables manual adjustment of shear  rate.

(6) Stepper motor paired with a reducer provides strong power and stable  operation.

(7) Lever pivot upgraded from knife-edge to bearing type for enhanced safety,  faster response, lower noise.

(8) Pressing frame equipped with rolling bearings to follow lateral  displacement, preventing vertical pressure deviation due to frame tilting.

(9) Limit protection device prevents instrument damage in case of  overload.

(10) Retains manual functionality while complying with standard shear  rates.

(11) Compact and aesthetically designed for user-friendly operation.

Accessories

(1) Vertical load pans and weights set

(2) Shear boxes and base plates

(3) Lever and gear assembly

(4) Limit mechanism components

(5) Sample preparation tools

Test Procedures

Prepare four soil samples with a cross-sectional area of 30 cm² and height of 2 cm.

Place samples in shear boxes and install the apparatus lever and weights for the selected vertical pressures.

Select fast or slow shear mode depending on test requirements.

Apply horizontal shear force until sample failure occurs.

Record shear stress at failure for each sample.

Calculate internal friction angle and cohesion based on Coulomb’s law.

Maintenance Information

(1) Regularly clean shear boxes, base plates, and levers.

(2) Inspect and lubricate pivot points and gears.

(3) Check limit mechanisms for proper function.

(4) Store in a dry environment to prevent corrosion.

(5) Periodically verify vertical load weights for accuracy.