Large Direct Shear Machines test the shear resistance between a geosynthetic or geosynthetic clay liner (GCL) and the contact surface of a large soil sample according to test methods in ASTM D5321 and ASTM D6243. The test sample is divided horizontally and mounted in a two-piece shear box assembly. Vertical confining force is applied to the lower half.
Using a pneumatic system, the horizontal shear loads are applied to 12in (304.8mm) square samples by gear-driven pistons. Two smaller pistons apply lighter loads up to 1,000lbf (4.5kN), and either one or two larger pistons (depending on the model selected) apply loads up to 10,000lbf (45kN) or 20,000lbf (89kN).
Horizontal shear rate from 0.002—0.2in/min (0.0508—5.08mm/min) is easily set with digital thumbwheels on the control panel. Limit switches control the home position and limit total horizontal displacement to 4in (102mm). Vertical loads are controlled through a precision regulator, using the included calibration chart and are accurate to ±0.25%. Loading and unloading of the specimen and shear box assembly are simplified using the compaction table. The convenient table rollers allow the loaded shear box assembly to slide easily into and out of the chamber. Sample compaction, geotextile placement, and specimen preparation are performed on the table.
A load cell attached to the water chamber measures shear load, while linear variable displacement transducers measure consolidation and shear displacement. A four-channel readout displays vertical load, horizontal shear load, horizontal displacement, and vertical displacement. Data can be exported to a computer via a mini USB and downloaded onto a spreadsheet program such as Excel.
The rugged design of the Large Direct Shear Machine stands up to the most stringent laboratory environments. All steel parts are powder coated and all aluminum parts are anodized to resist corrosion. Locking casters on the compaction table allow it to be easily relocated.
2012 / 2012F 10,000lbf Large Direct Shear Machine comes with two large pistons that apply shear loads up to 10,000lbf (45kN).
2012-HP / 2012-HPF 20,000lbf Large Direct Shear Machine has two large pistons that can apply loads up to 20,000lbf (90kN).
- Tests shear resistance of large, 12in (304.8mm) square samples
- Pneumatic loading system
- 10,000lbf Large Direct Shear Machine
- 20,000lbf Large Direct Shear Machine
- Four-Channel Data Readout
- (2) 1in Linear Variable Displacement Transducers
- (2) 12 x 12in square 0.5in thick porous stones
- Drainage plates
- Compaction table
- Water chamber
- Calibration chart