Effects of heterogeneities of soils on the stability of slopes

本研究的目的是探讨土壤的非均匀性，如表面结皮，裂缝，交通盘，硬盘，大孔隙，由于植物和土壤动物的活动和人工土屑和堤岸的稳定性的影响。得出以下三个结论：1.层状土壤中水的折射流动众所周知，饱和层状土壤中的流线作用在两种不同水力性质的介质之间的界面上，但层状非饱和土壤中流线的行为是模糊的。本文从理论和实验两方面阐明了非饱和土中水流折射的物理特性。发展了可视化技术，验证了饱和和非饱和层状土中的折射规律.非均质土壤中的优先流将优先流分为旁通流、指状流和漏斗流。利用8 mm摄像机、半导体压力传感器和染料对漏斗流的物理特性进行了实验研究，阐明了漏斗流与指状流之间的定性和定量关系。采用饱和流模型和非饱和流模型对漏斗流进行了分析.非均匀性与边坡稳定性的关系本文通过实验研究了地表结皮对水流和边坡稳定性的影响。通过实验研究了优先流对模型边坡稳定性的影响。土壤非均匀性和优先流对边坡稳定性影响的理论方面还需要进一步的研究。

The purpose of this study was to investigate the effects of soil heterogeneities such as surface crusts, cracks, traffic pans, hard pans, macropores due to activities of plant and soil animals and artificial soil cuttings and bankings on the stability of slopes. The following three conclusions were obtained :1. REFRACTION OF FLOW OF WATER IN LAYERED SOILSIt is well known that stream lines in saturated layered soils refract at the interface between two media having different hydraulic properties, but the behaviour of stream lines in layered unsaturated soils were vague. This study clarified the physical properties of refraction of water flow in unsaturated soils theoretically and experimentally. The visualization technique was developed to verify the refraction law in saturated and unsaturated layered soils.2. PREFERENTIAL FLOW IN HETEROGENEOUS SOILSPreferential flows were classified into bypassing flow, fingering flow and funneled flow. The physical properties of funneled flow were investigated experimentally by using 8 mm video camera, semiconductor pressure transducers and a dye and the qualitative and quantitative relation between the funneled flow and fingering flow was clarified. Saturated flow model and unsaturated flow model were applied to analyse the funneled flow.3. THE RELATION BETWEEN HETEROGENEITY AND STABILITY OF SLOPESThe effects of surface crust on flow of water and stability of slopes were investigated experimentally. The effect of preferential flow on the stability of a model slope was also investigated experimentally. Further investigations are required to make clear the theoretical aspects of the effects of soil heterogeneities and preferential flows on the stability of slopes.