Deformation Behavior of Saturated Marine Silt under Principal Stress Rotation as Induced by Wave Loading

Liuming Chang,Lan Cui,Zhenzhen Niu,Qian Sheng

doi:10.3390/app11209458

Abstract

An experimental study aimed at providing insights into the cyclic deformation behavior of saturated marine silt under principal rotation, as induced by wave loading, is presented. Using the GDS hollow cylinder apparatus, a series of undrained tests are performed and the specimens at identical initial states are subjected to combined axial–torsional cyclic loading that imposes different levels of stress rotation. The cumulative generalized shear strain γg is used to describe the deformation of the silt under complex stress paths. The test results show that the cumulative generalized shear strain is significantly dependent on the cyclic stress ratio (CSR) and cyclic loading amplitude ratio δ. The cumulative generalized shear strain increases with the increase in CSR and decreases with the increase in δ. The development trend of γg can be well predicted through the correct Monismith model in the non-liquefaction silt, with a low error that is generally less than 10%.

Highlights

Soft silty soils are widespread in deltas, estuaries and coastal zones, and are prone to liquefaction under cyclic wave loading because of their high natural water content and weak permeability [1,2], which may result in serious damage to marine structures, such as the instability of gravity platforms [3], large horizontal displacements of immersed tunnels [4], tilting of caissons [5], shear failure of breakwater slopes [6], shear and tensile failures of bolts [7], and floating up of pipelines [8]
This paper aims to explore the influence of wave-induced non-proportional loading patterns on the undrained deformation behavior of saturated marine silt, based on a series of undrained cyclic tests using a hollow cylinder apparatus
The typical results of the silt tested under wave loading (CSR = 0.05, δ = 1) are shown in Figure 6; the excess pore pressure u rises more rapidly at the beginning of loading

Summary

Introduction

Soft silty soils are widespread in deltas, estuaries and coastal zones, and are prone to liquefaction under cyclic wave loading because of their high natural water content and weak permeability [1,2], which may result in serious damage to marine structures, such as the instability of gravity platforms [3], large horizontal displacements of immersed tunnels [4], tilting of caissons [5], shear failure of breakwater slopes [6], shear and tensile failures of bolts [7], and floating up of pipelines [8] Such silty soils are characterized by high anisotropy of strength properties, mainly manifested as stress path dependence. This can be interpreted by the fact that under axial stress-controlled cyclic loading, sand exhibits a considerably higher contraction on the triaxial extension side, which is definitive evidence of soil anisotropy being related to the orientation of the major principal stress direction

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Results

Conclusion