ABSTRACT

The undrained shear strength of marine sediments is closely related to marine engineering construction. Based on acoustic wave propagation theory, the theoretical shear wave velocity of sediments with different physical properties was calculated. In the laboratory, a self-made apparatus was employed to measure the acoustic velocity and shear strength of replicated marine sediments, which were subsequently compared with theoretical results. The findings reveal a greater proximity of the measured values to the effective media model when the density is low, whereas the values are more akin to the porous media model when the density is high. Through the experimental results, the relationship between shear wave velocity, sediment physical properties and undrained shear strength was explored. Utilizing the regression analysis technique, two predictive models for undrained shear strength, namely single-parameter and double-parameter, were established.

INTRODUCTION

With the exploration and development of oil gradually turning to the deep sea, the marine has become more important in terms of economic resources. Marine sediment is a general term for stratum soil below the seabed, and its properties are related to the depositional environment and tectonic process. One of the important properties of marine sediments is the undrained shear strength, which is closely related to offshore oil platform spudcan penetration and the installation of jackets, or is very important in evaluating the potential for ground failure of sediments when they encounter sudden earthquakes or external forces (Oh et al., 2017). The undrained shear strength of sediments is typically divided into laboratory measurement and field in-situ measurement. Direct shear test or triaxial test are the main methods of laboratory measurement (Hong et al., 2017), while vane shear, cone penetration test, etc. are the main methods of in-situ measurement (Kruiver et al., 2021). Regardless of the method used, it will more or less disturb the sediment and affect its physical properties, and the process of each experiment cannot be repeated. In addition, the nature and structural characteristics of the sediment itself are regional. This makes the research on the undrained shear strength of marine sediments have limitations.

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