An Economical Approach to Supplement Investigations of Soil Relative Density in Forest Engineering Geology

摘要

Investigating cohesionless soil relative density and strength parameters using field data from driven (dynamic) cone penetration test (CPT) technology is a well-documented method in the standard practice for geotechnical projects. In general, CPT work is often relatively expensive, requires a wire-line system and large reaction mass. In remote forest work; access limitations, mobilizing costs and wire-line drill rig operation may be beyond the budget for many projects. We present data correlations (R~2 from 0.30 to 0.58) between the Standard Penetration Test SPT and adjacent Williamson Drive Probe WDP for recent projects in Northern California. Costs average about 3 to 6 percent of the costs to mobilize a drill for the SPT. The data should be used only with a) direct observation of subsurface conditions by the responsible professional, and b) some SPT site data for correlation. Selection of design strength parameters requires the active participation of a registered professional engineer.