Master of Science in Civil Engineering (MSCE)
Civil and Environmental Engineering
This thesis presents the development of a True Triaxial Testing TTT Apparatus. The TTT apparatus developed has the capabilities of applying the three principal stresses to a rectangular prismoidal specimen independently. The minor principal stress is provided by the cell pressure. The major principal stress is provided by a load actuator traveling at a constant velocity. A LabView software program instantaneously reads instrumentation, makes calculations, and commands a second load actuator to induce an intermediate principal stress that maintains a constant b-value; where b-value is equal to the intermediate principal stress minus the minor principal stress divided by the major principal stress minus the minor principal stress. The development of the TTT Apparatus included; creating a robust data acquisition system to facilitate immediate readings of all needed instrumentation, manufacturing a horizontal loading system to transmit the load from the load actuator to the specimen, constructing a pressure control system capable of providing the desired confining pressure, creating a LabView software program to interface with the data acquisition system and the load actuators to record and control the test parameters. Calibration tests were performed to quantify the correction factors for the following: volume change due to volumetric expansion of the pressure jacket and loading rams, the load due to frictional forces and pressure, and the length change due to compression of the rubber cushions. True triaxial test were conducted on F-75 silica sand at various b-values as verification of the developed TTT Apparatus’s capabilities. The results of these tests compared well with the findings of other researchers conducting similar tests.
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Williams, Heath Stuart, "Development of a true triaxial apparatus for soil testing" (2004). LSU Master's Theses. 1811.