Design and Preliminary Tests of Mobile Seafloor Layer Sampler Prototypes as an Add-On Unit for Portable Free-Fall Penetrometers

摘要

Portable free-fall penetrometers (PFFP) are used as an innovative approach to investigate the uppermost seabed stratification, including the mobile layer. The aim of this study is to design an add-on sampler for PFFPs to collect simultaneously sediment, with focus on the mobile sediment layer. Here, we present three prototype designs and preliminary tests, based on the lessons learned from other systems such as gravity and piston corers. The prototypes differ in shape, sampling tube dimensions, wall thickness ratios, and core catching mechanisms. In preliminary tests, the sample quality was assessed based on visuals, recovery ratio and volume change. Promising results were achieved using suction only to hold the material in the sampling tube, causing the least sample disturbance. Still, the results showed that core catcher increased the chance of recovery of sand. Based on the results, recommendations for further sampler improvements, and particularly, a new core catcher design are given.