Experimental study on shear strength of root-soil composite of Robinia pseudoacacia

The stability of vegetation slope is closely related to the shear strength of the root-soil composite, which is mainly affected by the action of roots and the action of water. In this study, the effects of root content and water content on the shear strength and its indexes were analyzed by direct shear test and soil-water characteristic curve test, and a strength calculation model of the root-soil composite was derived. The results show that the roots of Robinia pseudoacacia can significantly enhance the shear strength of the soil. The cohesion first increases and then tends to be flat with the increase of root content, and the internal friction angle increases with the increase of root content, but the growth rate is small. The shear strength decreases rapidly with the increase of water content. The changing trend of cohesion and internal friction angle is consistent with the shear strength, but the change range of the internal friction angle is small. The influence of root content and water content on the shear strength of soil is mainly reflected in the change of cohesion. The root-soil composite is regarded as unsaturated soil containing roots, and the strength calculation model of the root-soil composite is derived. The calculated value of the strength model is close to the measured value of test. The research has a certain reference value for the strength calculation of the root-soil composite.