CiPPT—A new in situ method for sounding and strength determination in peat

In this article, a new probe and method, CiPPT (Circular Probe Penetration Test), is presented, which was developed for sounding and strength determination in peat. The probe is an inverted cone where the horizontal end surface is pushed down into the peat during sounding. The probe is connected to the same equipment used for cone penetration testing, with the cone replaced by an inverted cone. A larger CiPPT, 140 mm diameter for research purposes, and a smaller CiPPT, 70 mm diameter for production purposes, have been developed and tested, both with either pins on the end surface or a rough end surface. Additionally, a variant of the CiPPT 140 mm diameter called double-CiPPT with an inner and outer plate has been developed to study the effect of fiber tensile strength on sounding resistance. The functionality of the double-CiPPT were verified, and the CiPPT variants were tested at three field test sites with low- and medium- humified peat. To evaluate strength, the results from the CiPPT were calibrated against triaxial compression tests. Comparisons were made with other in situ methods. Moreover, peat that was loaded and compressed over a long period below railway embankments and peat not loaded and not compressed in bogs were investigated.