Electrical resistivity and cone tip resistance monitoring by using cone resistivity penetrometer

The local soil properties become important parameters to evaluate the micro soil behavior. The smaller penetrometer has been commonly used to assess the soil properties in local area with the cone tip resistance with higher sensitivity. The objective of this study is the development and application of the new apparatus, Cone Resistivity Penetrometer (CRP) for measuring electrical resistivity and cone tip resistance of soil at the tip of the micro cone with minimum disturbance during penetration. The CRP is a micro-cone with 10 mm outer diameter (0.78 cm² in projected area). The strain gauge is used to measure the cone tip resistance and the electrode and an insulator are used to assess the electrical characteristics of soil at the cone tip. The measured voltage and electrical resistance is converted into the mechanical cone tip resistance and electrical resistivity, respectively. The CRP is tested into the layered soils consisted of sand and clay. The electrical resistivity and cone tip resistance clearly detect the soil layers. This study suggests that the CRP is a useful tool for accessing the local behavior in soft offshore soil, and effectively detects the soil layers with high sensitivity.