Direct and Residual Shear Testing Machines
Elite Series, Pneumatic Direct/Residual Shear Apparatus
Self-Contained pneumatic apparatus eliminates loading weights
Pneumatic, Semi-Automatic Direct/Residual Shear Apparatus
Semi-Automated with pneumatic loads controlled by manual valve controls
Elite Series UPGRADE for Pneumatic, Semi-Automatic Direct/Residual Shear Apparatus
UPGRADE your HM-2560.3F machine to the New HM-5560.3F
Dead-Weight Direct Residual Shear Machines
Dead-weight direct shear machines with analog, digital or dial gauges
Direct Shear Testing Machines, continued
After the vertical load has consolidated the sample, the two halves of the box are "pulled" apart relative to each other, which causes a shear load to be measured on a load measuring device. Once the soil has been sheared to its shear strength, there is failure and the load rapidly drops off. This procedure is repeated (usually three times) under different vertical loads. A "failure envelope" can then be drawn on a graph which allows engineers to design slopes, dams, foundations, etc.
The direct shear test is used to assess what soil strength might be in a field situation where complete consolidation has occurred under the existing normal stresses. Failure is reached slowly under drained conditions so that excess pore pressures are dissipated. The results from several tests may be used to express the relationship between consolidation stress and drained shear strength. Direct shear testing is often used when trying to determine the shear strength of sandy materials.
Direct shear devices can also be used to measure residual shear strength. Residual strength is the shear strength of the material that is exhibited after a failure (exceeding of initial shear strength) has occurred. Residual shear strength testing is very important in earthquake prone areas.