High-Capacity Direct Shear Machines measure the total horizontal shear resistance of large samples of soil, geosynthetic materials, or soil/geosynthetic composites. Specimens up to 12in (305mm) square are prepared in a two-piece shear box assembly, divided in half horizontally. The shear box assembly is held securely in place and a vertical (normal) load is applied to consolidate the specimen. A horizontal force is then directed against the lower half of the box to shear the specimen.
Horizontal shear forces are generated through a gearbox driven by a stepper motor and measured by an electronic load cell. Load measurements accurate to ±0.25% are displayed to two decimal places on the digital readout. Shear rates from 0.0508 to 5.08mm (0.002 to 0.2in) per minute are easily set with a rotary thumbwheel switch on the control panel. Horizontal displacement is measured by linear variable displacement transducers (LVDTs). Limit switches restrict total horizontal travel to 102mm (4in).
Vertical (normal) loads are applied using one or two large pneumatic pistons to consolidate the test specimen to a specified value before shearing. If lighter normal loads and greater accuracy and sensitivity are required, both models use two smaller pneumatic pistons that produce a total combined vertical force up to 4.4kN (1,000lbf). Precision regulators are used throughout the pneumatic systems to maintain accurate pressures. Consolidation displacement is measured by LVDTs.
HM-384 has a shear capacity of 45kN (10,000lbf) and uses one large piston to apply normal loads up to 45kN (10,000lbf).
HM-385 has a shear capacity of 90kN (20,000lbf) and uses two large pistons to apply normal loads up to 90kN (20,000lbf).
The built-in four-channel readout displays horizontal shear load and displacement, vertical displacement from normal loads, and pneumatic piston pressure in PSI. Piston pressure readings are correlated to normal loads in lbf using the datasheet supplied. Load and displacement data are uploaded in ASCII format through the mini-USB serial port to the user’s computer. The included software imports data into common spreadsheet applications for analysis and reporting. Displayed values on the readout can be viewed at any time during operation. Sample compaction, geotextile placement, and specimen preparation are performed on the compaction table. The convenient table-top rollers allow smooth and easy transfer of the specimen and shear box assembly to and from the shear machine.
HM-384 and HM-385 High-Capacity Direct Shear Machines are ruggedly designed for harsh lab environments. All steel parts are powder-coated, and aluminum components resist corrosion. Casters on the shear machine and compaction table make for easy portability in the lab. Shear box dimensions for the top half are 12x12x4in (304.8x304.8x101.6mm), and 12x16x4in (304.8x406.4x101.6mm), WxDxH for the bottom half. Each machine includes a compaction table and one shear box assembly, a partial filler block to adapt the lower shear box for soil direct shear samples, a 12in (305mm) square load pad, two 12inx12in porous stones, and software with a data cable. An additional Shear Box Assembly is available separately to maximize sample preparation efficiency. The optional Bottom Shear Box Platform Filler accessory positions geosynthetic and clay liner specimens at the correct height. Top shear box adapters allow testing of 6in (152.4mm) or 8in (203.2mm) square samples and are sold separately. A 120psi (827kPa) source of clean, dry, compressed air is required for operation. For mounting geosynthetic liners in the shear box, optional Bed of Screws mounting plates are available in two sizes. Specimens are securely mounted on screw tips protruding from these plates for testing. Inquire for customization options for specimen sizes and operating options.
- Tests large soil, geosynthetic, or soil/geosynthetic samples up to 12in (305mm) square
- Models have horizontal shear and vertical load capacities of 45 or 90kN (10,000 or 20,000lbf)
- Precision regulators control pneumatic pistons for vertical loads
- The built-in four-channel digital display on the front panel
- Compaction table for easy sample preparation and specimen positioning
- The rugged design is well-suited to withstand harsh lab environments
- 45kN or 90kN High Capacity Geosynthetic Direct Shear Machine (110V/60Hz or 220-240V/50Hz)
- Compaction Table
- Shear Box Assembly
- Water Chamber
- Filler Block
- Load Pads
- (2) 12x12x0.5in Porous Stones
- Software and Data Cable
- Calibration Chart