Abstract: Due to the regional differences in the properties in geomaterials, as well as the influence of pile type, dimension and installation methods, the empirical values for the CASE damping coefficient recommended by major research institutes and instrument manufacturers are lack of precision for geomaterials in some regions.  A typical bearing stratum for the pipe pile (strongly weathered argillaceous siltstone) in a project area was selected to conduct the dynamic and static axial load tests of three pipe piles with different diameters. The CASE damping coefficient of the bearing stratum at the pipe pile tip is back-analyzed, and the influence of the pile diameter on the damping coefficient is analyzed. The results show that the CASE damping coefficient is 0.35~0.55 when the strongly weathered argillaceous siltstone is used as the bearing layer of the pile tip in this area. But the Jc value range of strongly weathered argillaceous siltstone in the same site is more than 30% of the average value, and the data are too discrete, it is shown that the larger the pile diameter is, the smaller the Jc value is.

Key words: High Strain, Damping Coefficient, Axial Capacity, Dynamic and Static Load Testing