CPTWD (Cone Penetration Test While Drilling) a new method for deep geotechnical surveys

摘要

CPTWD represents integration of: wire-line drilling system, standard and modified piezocone, MDW-monitoring while drilling. During the CPTWD test the cone is protruding in front of the drill bit during drilling in the same way as a corer; CPTU data are stored in memory unit. At the same time as the CPTU data are logged, drilling parameters (MWD) are also recorded. The system allows for the change between CPT testing, continuous core drilling, down-hole testing and non coring drilling with MWD. The combination of CPT parameters and drilling parameters can be a very powerful basis for interpretation of the data. The advantages of this system compared to the other down hole type CPTU is that much longer strokes than the normal 3 m can be made. In addition, the information from the drilling parameters is very useful, especially in hard formations where CPTU cannot be performed. It is expected that future development work will improve the method in terms of the test procedures and in terms of capabilities of the system itself, by adding new tools (e.g. field vane test, Permeameter, fluid sampler, thin wall samplers, dilatometer DMT).