| In a complex geological environment of the mountains of southwest in China are widely distributed a kind of mixed soil, with many origins, various compositions, multiple gradations, complex particle morphology and environment sensitivity. In engineering practice, ChuanXi slopes mostly composed of this type of mixed soil often deform and slide as a result of rainfall, earthquakes, groundwater level changes or moisture content changes caused by freezing-thawing, causing huge economic losses. A lot of practice shows that the talus mixed soil belongs to unsaturated soil under natural conditions. Therefore, carrying out experimental study on the unsaturated mechanical characteristics and their influence factors of mixed soil under various climatic hydrologic conditions has a certain theoretical and practical significance for geotechnical stability evaluation and disaster prevention projects composed of this mixed soil.In this paper, the idea can be summarized as "physical form-matric suction-shear strength". We made plenty of experimental research according to this technical route, discussing the connection between soil macroscopic phenomenon (soil water characteristics and shear strength) and meso (mineral composition) with matric suction as a link and expounding in detail their mutual relations and influential factors. The main contents and conclusions as follows:1. By carrying out experiments on the identification of mineral composition, analysis of grain composition, moisture content and density test of the three types of undisturbed mixed soil taken back in three different places, we found that these three mixed soil differ in physical form.2. By perfoming soil-water characteristic experiment on the remolded mixed soil with pressure plate test as the main method and filter paper method supplemented, we could find that soil physical form has a great influence on soil water characteristic curve and obeys certain rules, which are mainly associated with the soil composition of particle structure and pore size.3. Doing undrained triaxial shear experiment on the remolded mixed soil by the way of controlling of moisture to indirectly control the matric suction, we obtained the generalized cohesion and generalized internal friction angle are related with soil physical form and matric suction and that generalized internal friction angle is only by effected by soil particle composition, while generalized cohesion is influenced by many factors and obeys certain rules. |
