Analysis of Cyclic Shear Stress-Displacement Mechanical Properties of Silt-Steel Interface in the Yellow River Delta

Pile foundations of offshore structures are often subjected to cyclic loads under storm loads, thus reducing their vertical bearing capacity. Therefore, studying the cyclic shear behavior of the soil-structure interface is important for maintaining the stability of offshore structures. A series of cyclic shear tests of the silt-steel interface were carried out using a large interface shear apparatus. The effects of various factors (i.e., normal stress, shear displacement amplitude, roughness, and water content) on the shear stress characteristics of the silt-steel interface were investigated. The stress-displacement model of the cyclic shear silt-steel interface was deduced. The results showed that the shear stress at the silt-steel interface was softened, and the type of bulk deformation was shear shrinkage under cyclic shear. With the increase in shear amplitude, the hysteresis curve gradually developed from parallelogram to shuttle and hysteresis cake. With the increase in normal stress and roughness and the decrease in water content, the interfacial shear strength, volume displacements growth rate, and growth rate increased. The stress-displacement mathematical model of the silt-steel interface based on the modified hyperbolic model was in good agreement with the test data.

Automated summary

The study found that under cyclic shear in offshore structures, the shear stress at the silt-steel interface softens, and the overall deformation shows shear shrinkage. Additionally, with an increase in shear amplitude, as well as in normal stress and roughness, the interfacial shear strength increases.