THE IMPACT OF WATER CONTENT AND COMPACTION OF THE SOIL ON THE SLOPE PROTECTION BY VEGETATION

摘要

Slope protection by vegetation is used widely in civil engineering. The effect of it is influenced by soil water content, soil density, root distribution, plant species and plant age and other factors. In this article, using triaxial shear test, through putting rope into the soil sample to simulate the reinforcement effect of plant roots, the impact of water content and density of the soil on the reinforcement effect are studied. The results show that: the more compaction the soil has, more obvious reinforcement effect of plant root have. When soil compaction is 85%, the difference of the maximum principal stress will increase about 20% to 30%, when soil compaction is 75%, the reinforcement effect of plant roots is not obvious. Cohesion and internal friction angle also have similar preferment. Whether reinforced by plant roots or not, the cohesion of the soil firstly increase with water content, then decrease with water content after 14% water content. It is near the 14% water content that the plant root can improved the soil cohesion obviously. Internal friction angle decrease with water content increase, the greater water content of the soil is, the smaller the effect of plant root on internal friction angle is. The research results can provide basis for the design of slope protection using vegetation.