Soil Direct Shear Test
The GCTS Direct Shear Systems feature electro-hydraulic closed-loop digital servo control of the shear and normal load actuators. This allows for complete automation of the testing procedure, making performance of the test simple and accurate. The systems can easily perform both constant normal stiffness and constant normal stress tests. All SDS systems are hydraulically-powered, which eliminates vibrations caused by motorized systems that can disrupt granular specimens. The top shear box can be horizontally translated and the bottom shear box is mounted on pre-loaded sliding bearings to minimize horizontal friction. Set screws with nylon tips are used to adjust the shear gap and the top shear box is suspended on springs that balance its own weight. This allows for different shear gap settings and the more precise measurement and control of the normal stress. Also included is a water reservoir to submerge specimens during testing.
Loads or deformations for both the shear and normal actuators can be prescribed for automatically performing conventional direct shear tests as well as more advanced tests. This system can be easily programmed to perform tests such as the constant normal stiffness test where the normal load is a function of a prescribed stiffness for simulating actual compressibility of a ground shear plane (e.g. soil-pile interaction). All tests are set up in the software and carried out automatically, without any need for user intervention.
Relevant Standards
ASTM D3080 / D3080M Standard Test Method for Direct Shear Test of Soils Under Consolidated Drained Conditions
SDS-100
HIGHLIGHTS
- Closed-loop servo control of double-acting (push/pull) 20 kN (2 ton) shear load actuator with ±25 mm stroke & 20 kN (2 ton) normal load capacity with 50 mm stroke
- Normal load reaction support mounted on sliding bearings to minimize horizontal friction
- Accepts specimens with up to 100 mm (4 in) diameter or 70 mm (2.75 in) square specimens
- Software for automatic performance of direct shear tests with constant normal stress or constant normal stiffness
- Real time graphical display of test progress
- Mounted on a cart with casters
SDS-150
HIGHLIGHTS
- Shear load capacity of 50 kN (5 ton) with 100 mm stroke
- Normal load capacity of 50 kN (5 ton) with 50 mm stroke
- Normal load reaction support mounted on sliding bearings to minimize horizontal friction
- Cubical specimen of up to 150 mm (6 in.) sides
- Software for automatic performance of direct shear tests with constant normal stress or constant normal stiffness
- Real-time graphical display of the test progress
SDS-300
HIGHLIGHTS
- Closed-loop servo control of double acting (push/pull) 100 kN (10 ton) shear load actuator with 100 mm stroke & 100 kN (10 ton) normal load capacity with 50 mm stroke
- Normal load reaction support mounted on sliding bearings to minimize horizontal friction
- Accepts 300 mm (12 in.) square specimens
- Software for automatic performance of direct shear tests with constant normal stress or constant normal stiffness
- Available interface platens to test soils, asphalt and geo-membranes
- Other load capacities & specimen size dimensions are available, including large-scale test systems for shear loads of up to 1,000 kN (100 ton) & specimen sizes up to 300 mm diameter or side
- Shear speed variable from 0 mm/sec to 500 mm/sec
