What is the DPM test?
The medium DCP (DPM test) has a hammer mass that is too large to be comfortably operated by hand for effcient use but too small for use with a drill rig and a conventional SPT hammer. Several confgurations of this test have been reported as summarized in Table 1. Figure 1 shows a schematic of a portable DCP rig mounted on a trailer.
Triggs & Liang (1988) presented results using a small commercially available penetration rig with a 30kg (66 lbs) hammer that can be transported in components and assembled at a site by a two-person crew. The equipment is manufactured in Italy and can be used for both static and dynamic penetration. In the dynamic mode, the hammer is operated by a small gasoline engine and an automatic lift/drop mechanism. The cone may be either fxed to the rods or may be expendable.
In the UK, a medium DCP (DPM15) with a cone diameter of 43.7mm (1.72in.) (giving a cone area of 15cm2) is sometimes used (Butcher et al. 1995). Because of the larger area of the cone, the DPM15 has a specifc work per blow twice that of the DPL.