三峡消落带土壤结构变化与抗剪强度响应机理

Soil shear strength is closely related to soil erosion and slope stability, whose parameters (c, φ) are sensitive to the hydrological conditions and soil physical-chemical properties. Sharp changes of seasonal hydrological conditions of riparian zone of The Three Gorges Reservoir, not only make directly affected on the soil shear strength by the change of soil moisture condition, but also indirectly influence the soil shear strength by migration of soil clay and colloidal substance which led by the cycles of wetting and drying. And consequently, make a huge impact on soil erosion and slope stability of the riparian zone. The present study, based on a long-term locating observation and research data in the Three-gorge riparian Zone, will analyze the impact of long-term cycle of wet-dry on the soil texture, bulk density, aggregates, pores, clay migration and microstructure as well. Samples that in different periods or different degrees of wet-dry cycles will be collected to do some indoor simulation experiment under different water pressure conditions, testing soil mechanical parameters such as soil shear strength. It is expected to reveal the mechanism of soil structure in response to changes of shear strength, and to figure out the space-time changes law of soil structure and shear strength in the riparian zone. And further more, it could provide scientific basis for understanding of soil erosion process and slope stability assessment in the riparian zone of the Three-gorge Reservoir.

土壤抗剪强度是土壤抗冲抗蚀性与边坡稳定性研究的重要指标，其参数与土壤特性和水文状况密切相关。三峡消落带季节性约30米水位落差和干湿交替作用导致土壤结构变化或粘粒物质迁移，改变土壤抗剪强度等土力学特性，对水库土质消落带土壤侵蚀和岸坡稳定性产生重要影响。本研究基于三峡土质消落带长期定位观测研究资料和收集的土壤样品，分析长期水位变化与干湿交替作用对土壤质地、容重、团聚体、孔隙、粘粒迁移与微观结构的影响、测定土壤抗剪强度等土力学参数，阐明消落带土壤结构与抗剪强度的时空变化规律；对不同时期或不同干湿交替作用程度的土壤进行室内模拟试验，采用微观探测技术分析土壤颗粒排列、粘粒迁移、孔隙形态与联通性等特征及土壤抗剪强度的变化，揭示消落带情景下土壤结构变化与抗剪强度的响应机理。为三峡水库消落带土壤侵蚀机理研究和岸坡稳定性评价与预测提供科学依据。

本研究基于三峡土质消落带长期定位观测研究资料和收集的土壤样品，分析了长期水位变化与干湿交替作用对消落带土壤质地、容重、团聚体、孔隙、粘粒迁移与微观结构的影响，测定土了壤抗剪强度等土力学参数，阐明了消落带土壤结构与抗剪强度的时空变化规律；在野外动态观测的基础上，结合精准的情景和边界条件控制的模拟实验，采用微观CT探测技术研究了土壤在不同干湿交替作用程度下，土壤颗粒排列、粘粒迁移、孔隙形态与联通性等特征及土壤抗剪强度的变化；揭示了干湿交替条件下消落带土壤结构与抗剪强度的响应机理，为消落带土壤侵蚀机理研究和岸坡稳定性评价与预测提供了科学依据。