Investigation of change in shear wave velocity with increasing applied stress for two samples from Holme Pierrepoint

The development of capability in the measurement of superficial deposit thickness has required laboratory testing to integrate with values obtained from field trials of a number of methodologies and equipment. The use of shear waves to detect the base of a deposit depends on an accurate knowledge of the internal velocities of the material in the deposit. It is also important to know the shear wave velocities of the materials at the deposit interface. The site used for initial assessment of equipment and methodologies was a series of sand, silt and gravel layers overlying a weathered mudstone. There are a number of interfingered facies within the body of the deposit, which may have differing interval velocities. The object of this laboratory study is to determine the shear wave velocities through undisturbed samples of the deposit material and the underlying solid geology. The samples under test are silty fine sand and the weathered mudstone. The gravel layers could not be sampled in an undisturbed state and have not been included in this study.