Abstract

Coral sandy soils widely exist in coral island reefs and seashores in tropical and subtropical regions. Due to the unique marine depositional environment of coral sandy soils, the engineering characteristics and responses of these soils subjected to monotonic and cyclic loadings have been a subject of intense interest among the geotechnical and earthquake engineering communities. This paper critically reviews the progress of experimental investigations on the undrained behavior of coral sandy soils under monotonic and cyclic loadings over the last three decades. The focus of coverage includes the contractive-dilative behavior, the pattern of excess pore-water pressure (EPWP) generation and the liquefaction mechanism and liquefaction resistance, the small-strain shear modulus and strain-dependent shear modulus and damping, the cyclic softening feature, and the anisotropic characteristics of undrained responses of saturated coral sandy soils. In particular, the advances made in the past decades are reviewed from the following aspects: (1) the characterization of factors that impact the mechanism and patterns of EPWP build-up; (2) the identification of liquefaction triggering in terms of the apparent viscosity and the average flow coefficient; (3) the establishment of the invariable form of strain-based, stress-based, or energy-based EPWP ratio formulas and the unique relationship between the new proxy of liquefaction resistance and the number of cycles required to reach liquefaction; (4) the establishment of the invariable form of the predictive formulas of small strain modulus and strain-dependent shear modulus; and (5) the investigation on the effects of stress-induced anisotropy on liquefaction susceptibility and dynamic deformation characteristics. Insights gained through the critical review of these advances in the past decades offer a perspective for future research to further resolve the fundamental issues concerning the liquefaction mechanism and responses of coral sandy sites subjected to cyclic loadings associated with seismic events in marine environments.

中文翻译：

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循环荷载作用下饱和珊瑚砂土的液化敏感性和变形特征——批判性评论

摘要

珊瑚砂土广泛存在于热带、亚热带地区的珊瑚岛礁和海滨。由于珊瑚砂土独特的海洋沉积环境，这些土壤在单调和循环荷载作用下的工程特性和响应一直是岩土和地震工程界密切关注的课题。本文批判性地回顾了过去三十年来单调和循环荷载下珊瑚砂土不排水行为的实验研究进展。报道重点包括收缩-膨胀行为、超孔隙水压力（EPWP）产生模式以及液化机制和液化阻力、小应变剪切模量和应变相关剪切模量和阻尼、循环软化特征，以及饱和珊瑚砂土不排水响应的各向异性特征。特别是从以下几个方面回顾了过去几十年取得的进展：（1）影响EPWP形成机制和模式的因素的表征；(2)通过表观粘度和平均流量系数来识别液化触发；（3）建立基于应变、基于应力或基于能量的EPWP比率公式的不变形式以及新的液化阻力代理与达到液化所需的循环次数之间的独特关系；(4)建立小应变模量和应变相关剪切模量预测公式的不变形式；(5)应力诱导各向异性对液化敏感性和动态变形特性的影响研究。通过对过去几十年的这些进展进行批判性回顾而获得的见解为未来的研究提供了一个视角，以进一步解决有关液化机制和珊瑚沙地在海洋环境中与地震事件相关的循环载荷下的响应的基本问题。