Abstract

In this paper, a new innovative method of geotechnical investigation applicable to seafloor is proposed. This method is the improved version of Sampling and Cone Penetration Test (S&CPT) to evaluate geotechnical properties by Cone Penetration Test (CPT) while collecting continuous samples quickly and inexpensively for offshore geotechnical investigations. In the previous study, demonstration tests on soft cohesive soil were conducted, and some problems were found. The purpose of this study is to modify the sampler to improve penetrability, sampling performance, workability and to examine the applicability for cohesionless soils. Using the improved samplers, demonstration tests were conducted at two sand sites (loose and medium-dense) in Japan. The results of each test were used to examine: (1) sampling performance, and (2) workability. As a result, the following conclusions are drawn: 1) In loose sand, sampling of several meters is possible. In medium-dense sand, the same level of sampling may be possible by providing an appropriate shoe to prevent blockage at the sampler tip. 2) The workability of the proposed apparatus is very high compared to the conventional Cone Penetration Test and Standard Penetration Test.