Shearing behaviour of vegetated soils with growing and decaying roots

Abstract

Nowadays Soil-bioengineering has been recognized as a green and eco-friendly slope protection alternative for shallow slope failure. However, Most of studies mainly consider strong and mature plants. In fact, natural and anthropogenic activities would lead to plant death and decomposition of root, This is another important factor that makes engineers still not confident in applying plants to improve soil slopes. In order to develop better and more sustainable mitigation strategies, the effects of root decomposition on soil properties will be considered in this study. Laboratory tests were conducted to measure effects of root growth and decay (i.e. by burning and herbicides) on the properties of soil vegetated with Cynodon dactylon. The direct shear tests were performed to observe Shear strength and Shearing behavior. The results showed that the growth of grass can Increase the shear strength of the vegetated soils during growth period. Root decay also resulted in the changes of shear strength. Upon burning, the shear strength were gradually decreased. However, with herbicides, the strength of the roots were significantly reduced. Because the herbicides cause plant to death and decay faster. The maximum shear strength of the soils was also reduced. The decrease was equivalent to soil without plants for 2 months after herbicide application and 4 months after burning.