GDS Unsaturated Triaxial Testing of Soil (UNSAT) is an extension to traditional triaxial testing in that soils from above the water table may be tested under conditions approaching the in-situ stress state and degree of saturation or partial saturation. All features and methods described in this datasheet can be used to upgrade GDS triaxial testing systems to enable the testing of unsaturated soil, or existing triaxial equipment from other manufacturers may be modified. Technical specification: Method A: Resolution of measurement of pore pressure/volumes (air & water): pressure = 0.2kPa, volume = 1cu mm. Accuracy of measurement of pore pressure/volumes (air & water): pressure = <0.1% full range, volume = 0.25%. Method B: Operational resolution of volume change measurement using 16 bit resolution: <10mm3. Accuracy of volume change measurement: estimated at 32mm3 or 0.04% volumetric strain for a triaxial specimen 38mm in diameter, 76mm in height. Method C: Resolution of measurement of cell volume: 1cu mm. Accuracy of measurement of cell volume: 0.25%. Method D: Resolution of on-sample displacement measurement using 16 bit data acquisition +/- 3.0mm = <0.1μm. Accuracy: Hall Effect = 0.8% FRO, LVDT = 0.1% FRO.

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