闽东北软粘土中硅藻赋存对工程性质影响机制与打桩效应

生物硅质软粘土因含孔隙发育的硅藻颗粒而具备天然强结构性，由于目前缺乏对这种结构性土静动力学特性的定量化分析评价方法，且其微观结构与宏观性质间的关联也未探明，因此工程实践中常常难以应对由此带来的问题。本项研究首先以人工掺配土为对象，改变硅藻含量及各矿物组分的掺配比，探究硅藻夹杂对软粘土的微观结构和力学特性的影响规律；借助硅藻含量的快速鉴定方法，以宁德、福州地区天然沉积软黏土为对象，获得硅藻质软黏土在物理力学性质上的独特表征方法，定量化评价该软土结构性；查明动荷载作用下的微观结构及动力学性质，揭示硅藻质软黏土的动力响应特征，建立考虑粉粒组富水夹杂的动本构模型，利用国内外有关硅藻土地层中动力打桩监测资料，开展沉桩过程数值模拟，验证研究认知。研究将明晰硅藻矿物存在对软粘土静、动力学性质在宏微观层面的影响规律和机理，加深对软粘土力学行为的认识，从而提高近岸/海洋土工结构物安全和避免工程灾害。

Due to the diatom particles with flourishing pores, the bio-siliceous soft clay is a kind of strongly-structured natural sedimentary soil. At present, due to the lack of quantitative analysis and evaluation method for the static and dynamic characteristics of this kind of structural soil, meantime, the relationship between its microstructure and macro properties has not been explored, it is often difficult to deal with the resulting disasters in engineering practice. In this study, the artificial mixing soil of diatom and clay mineral is first involved. By changing the content of diatom and the mixing ratio of mineral component, the effect of diatom content in primary mineral on the microstructure and engineering mechanical properties of soft clay is explored. With the rapid identification method of diatomite content, the characterization method of physical and mechanical properties of structural diatomaceous clay from Ningde and Fuzhou will be proposed, and their structure is quantitatively evaluated. When clarifying the change of micro structure and macro dynamic properties under dynamic load, the dynamic response law of diatomaceous clay in the process of pile sinking is evaluated. Hereinafter the structural dynamic model of diatomite soft clay would be proposed, and be verified by the numerical simulation and the monitoring data during pile sinking process. The research will clarify the influence and mechanism of diatom existence on the static and dynamic properties from macro to micro scope, and deepen the understanding of the mechanical behavior of soft clay, aiming to improve the safety of marine/offshore geotechnical engineering and prevent engineering disasters.