Dynamic characteristics of coral silt with consideration of static-cyclic loading coupling.

Coral silt, a type of coral soil with more than 50% silt content, is formed during the process of land reclamation. Given the frequent action of waves, wind, earthquakes and other dynamic loads, the cyclic dynamic shear characteristics of coral silt are important for determining the seismic safety of reef infrastructures. A series of symmetrical and asymmetrical cyclic simple shear tests were performed to characterize the cyclic behavior of coral silt with particular consideration given to the static-cyclic shear stress coupling. Two empirical formulas for the undrained peak shear strength and critical state strength in monotonic simple shear tests are proposed. For both symmetrical and asymmetrical-loading cyclic simple shear tests, a CSR threshold value lying between 0.05 and 0.075 controls the final failure. The cyclic shear stress significantly influences the cyclic deformation, cyclic pore water pressure, cyclic strength, and cyclic shear modulus of coral silt. • The undrained shear strength of coral silt can be estimated by the empirical formula: S up = 0.1992 σ v 0 ′ and S uc = 0.1435 σ v 0 ′ , respectively. • There is a threshold value of CSR between 0.05 and 0.075 that controls whether the final failure. • There is an inflection point in the cyclic shear strain development curve of all ultimate failure tests. • The cyclic pore water pressure development model and cyclic shear modulus significantly depend on CSR. • The dynamic strength of coral silt increases as the α and σ ′ v0 increase. [ABSTRACT FROM AUTHOR]