Naval Seafloor Soil Sampling and In-Place Test Equipment: A Performance Evaluation.

Abstract : The Naval Civil Engineering Laboratory (NCEL) has developed a stationary piston soil sampler and vane shear and cone penetrometer apparatus capable of performing to a depth of 10 feet in the seafloor. Both devices are subsystems of DOTIPOS (Deep Ocean Test-In-Place and Observation System). This equipment is used primarily as a research tool to determine the in-situ strength characteristics of seafloor sediments. The information obtained with DOTIPOS improves the Navy's seafloor foundation engineering capability. The results of tests at four seafloor sites to a water depth of 5,600 feet and the evaluation of the two subsystems are presented. The piston soil sampler and the vane shear and cone penetrometer apparatus have operated satisfactorily to a water depth of 5,600 feet. The relationships between in-situ vane shear and cone penetrometer test results from this equipment fall within the range of previous theoretical and experimental results. Laboratory and in-situ vane shear results are in reasonable agreement. The cone penetrometer is a more economical survey tool than the vane shear, but additional work is needed to further define the implications of the test results. (Author)