盐分浸析作用下天然沉积海相黏土劣化性状与定量评价

It has been well reported that salt leaching often occurred for naturally deposited marine clays during the processes of transgression and regression. The soil structures become unstable and are easily destroyed under external loads. Many natural disasters and engineering problems caused by leaching, such as flow landslides and excessive or differential deformation and so on, have been documented in engineering practice for the area deposited with quick clays and sensitive marine clays. In this study, both the intrinsic compression theory proposed by Burland and the intrinsic strength line proposed by Chandler are introduced to incorporate the special methods of investigating the properties of quick clays and sensitive clays. Based on such an innovative approach, the following issues are investigated in this study: 1) clearifying the change laws in liquid limit and in in-situ water content under overburden effective pressure due to leaching; 2) investigating the change law in intrinsic compression parameters associated with leaching; 3) discussing the effects of the changes in liquid limit and in-situ water content caused by leaching on the intrinsic compression line proposed by Burland and the intrinsic strength line proposed by Chandler; 5) establishing the quantitative relationship between physical indices and mechanical behavior for leached marine clays with development of deterioration; 6) understanding the microstructure mechanism responsible for the deterioration behavior of natural marine clays through the comparison between the compression curves and the entrance pore size distributions for the natural marine clays subjected to leaching. It is expected that this study will break the bottleneck of qualitative evaluations on the deterioration behavior of quick clays and sensitive marine clays associated with the traditional analysis method. The research results obtained in this study can provide a new quantitative way of evaluating the deterioration behavior in compressibility and strength for natural marine clays subjected to leaching with considering the effects of overburden effective pressure and applied stress level.

天然沉积海相黏土受海侵海退影响经常发生孔隙水盐分浸析，土体结构在外部环境作用下容易遭受破坏，从而导致严重的工程问题。本项目耦合Burland固有压缩理论和Chandler固有强度线于流黏土劣化评价方法，研究有效上覆压力作用下盐分浸析导致天然沉积海相黏土原位含水率与液限之间的变化关系，探讨盐分浸析对固有压缩参数的影响规律，分析盐分浸析作用下物理性状改变对固有压缩线和固有强度线的影响，研究盐分浸析导致压缩灵敏度和强度灵敏度增长的规律，建立盐分浸析作用下物理性状变化与天然沉积海相黏土力学性状劣化程度之间的定量关系。同时，对比分析盐分浸析作用下天然沉积海相黏土压缩曲线变化与孔隙入口孔径分布曲线的关系，揭示盐分浸析作用下天然沉积海相黏土发生劣化的微观机理。研究成果预期突破传统流黏土研究停留于定性认识的瓶颈，为盐分浸析作用下天然沉积海相黏土力学劣化性状提供一个能够考虑埋深和应力水平影响的定量评价方法。

天然沉积海相黏土受海侵海退影响经常发生孔隙水盐分浸析，土体结构在外部环境作用下容易遭受破坏，从而导致严重的工程问题。本研究采用试验、理论分析与数值模拟相结合的方法，探讨了盐分浸析下天然沉积海相黏土物理-化学-力学性状的内在联系，明确了盐分浸析过程中天然沉积海相黏土基本不产生化学反应，揭示了盐分浸析下海相沉积黏土力学性状劣化基本上归结于物理性状变化的机理，研究了原位状态下盐分浸析过程中天然沉积海相黏土天然含水率与微观结构的变化规律，明确了盐分浸析下天然沉积海相黏土力学性状的劣化主要发生在重塑状态，探讨了盐分浸析引起的天然沉积海相黏土压缩-强度性状的劣化规律。基于Burland-Chandler固有理论，建立了盐分浸析下广义固有压缩线和广义固有强度线，提出盐分浸析下天然沉积海相黏土埋深对压缩灵敏度和强度灵敏度的影响规律，解决传统的流黏土研究没有考虑有效上覆压力影响而与实际工况不吻合的问题，建立盐分浸析作用下天然沉积海相黏土物理性状变化与力学性状劣化的定量关系，突破传统流黏土研究停留于土体内部固有有效应力评价体系的定性认识局限。