海洋沉积土动剪切模量与阻尼比的试验研究

动剪切模量和阻尼比是工程场地地震安全性评价及地基动力反应分析的重要动力学参数。为评价某海域海洋土的动力学特性，对10.3～84.2 m深度范围内的海底淤泥质粉质黏土、粉砂及细砂开展共振柱试验。利用双对数模型建立了最大动剪切模量随上覆压力的递增关系。研究发现，现有规范的剪切模量比与阻尼比的推荐取值并不适用于海洋沉积土，即使考虑借鉴以往研究成果也必须将其限制在一定的应变范围，并应考虑土体的天然应力状态取值。利用马丁-达维登科夫（Martin- Davidenkov）模型及阻尼比与剪应变的经验关系建立了剪切模量比和阻尼比随剪应变的变化规律，并由此提出了适用于海洋沉积土的5×10-6～10-3应变范围内剪切模量比及阻尼比的推荐值。研究成果可为海洋工程场地的设计、施工及抗震分析提供技术参考依据。

Testing study of dynamic shear modulus and damping ratio of seabed sediment

Dynamic shear modulus and damping ratio are two important parameters for seismic safety assessment of engineering site and earthquake response analysis of foundation. In order to evaluate the dynamics of seabed sediment of the selected area, the 10.3-84.2 m depth range of mucky silty clay, silt and fine sand are analyzed by using resonant column tests. The double logarithmic model has been built for the increasing trend of maximum shear modulus with overburden pressure. The research suggests that the existing standard values of shear modulus ratio and damping ratio are not suitable for seabed sediment, even the previous research results are just applied to a certain degree of strain range and natural stress state. Martin-Davidenkov model and the empirical relationship between damping ratio and shear strain has been used to build the variation law of shear modulus ratio and damping ratio with shear strain; and the dynamic shear modulus ratio and damping ratio of 5×10-6-10-3 strain range are used as recommended values. The study results may provide technical reference for marine engineering design, construction and seismic analysis.