P- and S-Wave velocity and Indirect Tensile Measurements for Alluvium in Support of the Source Physics Experiments

Abstract

Mechanical properties on alluvium blocks and core samples were determined to support the Source Physics Experiment Dry Alluvium Geology experimental series. Because material was not available directly from the experimental location, the alluvium blocks and core samples are intended to serve as surrogate material . P - and S - w ave velocity was measured on cubes cut from the alluvium blocks and core with the intention to study variation from water content and measured direction (material anisotropy). Indirect tensile tests were conducted dry and with moisture ranging from 6 to 9.1%. For the range of water content tested, increasing moisture level resulted in slower P - and S - w ave velocities. P - and S - w ave variability is less influenced by material hete rogeneity than moisture content. P - w ave velocity ranges from 629 m/s to 2599 m/s and S - w ave velocity ranges from 288 m/s to 1200 m/s. Counter to the velocity measurement findings, material variability on indirect tensile strength has a greater effect than moisture content. Compared to dry strength and at moisture levels from 6 to 9% the block ? s tensile strength was lowered by at least a factor of 5. Indirect tensile strength for the first block averaged 0.35 MPa and 0.25 MPa for dry and 8.9% moisture resp ectively. For the second block indirect tensile strength averaged 0.05 MPa for both dry and 6.4% moisture.