Effect of plant root system on shear strength characteristics of soil specimens with layered structure

Abstract

Surface failure sliding at the boundaries of slopes and vegetation works covering the slopes or at extremely shallow layer of slopes happens frequently in cold and snowy regions, possibly thereby forming weak areas. As a basis to clarify the phenomenon, two-layered soil specimens having different soil properties and degree of compaction (D_c) were used. A constant pressure direct shear test was conducted at the boundary of the two layers as the shear position to identify the effect of root systems of herbaceous plants on the layer boundary. X-ray CT scan was conducted to check if the root system reached the lower layers of the specimens. The experimental results show that if root systems of herbaceous plants reach the soil of the lower layer, the boundary layer will be reinforced, thereby improving the tenacity.