Experimental study of the strength properties of soft cohesive sediment subject to mechanical vibrations

• Published in: Marine georesources & geotechnology Vol. 41; no. 12; pp. 1415 - 1425
• Main Authors: Dong, Chuanming, Zhu, Yuzhu
• Format: Journal Article
• Language: English
• Published: Philadelphia Taylor & Francis 02.12.2023; Taylor & Francis Ltd
• Subjects: Cohesion; Cohesive sediment; Cohesive sediments; Fluidization; Fluidizing; Hydrostatic pressure; Laboratory tests; Microstructure; Offshore equipment; Offshore structures; Pore pressure; Pore water; Pore water pressure; Sediment; Sediments; Shear strength; Shear stress; Softening; Vibration; Vibration analysis; vibration loading; Vibrations; water content; Water pressure
• ISSN: 1064-119X; 1521-0618
• DOI: 10.1080/1064119X.2022.2145535

In a maritime environment, offshore structures are generally subject to cyclic shear stress from sources such as currents, waves, or offshore equipment loads, which may create vibration loadings on cohesive sediment around the foundations. In this study, the changes in shear strength, pore water pressure, and the microstructure of cohesive sediment under vibration loading were investigated through a series of laboratory tests, and the effect of the vibration intensity on the strength properties of the soft cohesive sediment surrounding a vibration pillar were analyzed. The soft cohesive sediment exhibited shear softening behavior in the experiments; the shear strength of the cohesive sediment significantly decreased under the vibration loading of the pillar. To explain the shear softening behavior of soft cohesive sediment, a formula was proposed for the attenuation of the undrained shear strength of cohesive sediment under vibration loading, which is related to the soil sensitivity and vibration intensity. Moreover, the formula revealed the mechanism of shear strength reduction or fluidization of cohesive sediment under mechanical vibrations, which may contribute in improving the penetration performance of vibratory piles or protecting the foundation around a pier.