Volume 30, Issue 3 (May 2007)
Interface Direct Shear Testing of Unsaturated Soil
A commercially available direct shear apparatus was modified for testing unsaturated soil and interfaces between unsaturated soil and stainless steel. Major modifications include the addition of apparatus for suction-controlled testing using the axis translation method, and construction of shear boxes for testing unsaturated soil and interfaces. The major features of the device are described and results of performance tests are presented in this paper. In addition, typical results of tests on unsaturated clayey silt and interfaces are presented for drained tests conducted under different matric suction and net normal stress conditions. The Extended Mohr-Coulomb Failure Envelope for the soil is compared to that obtained for the rough interface. The soil/interface test results demonstrate the successful implementation of the device.