Analysis of root system enhancing shear strength based on experiment and model

Based on present studies of the enhancement of root system on soil shear strength, this study investigated root reinforcement effect of six common plants, i. e. Pinusmassoniana Lamb, Cinnamomumcamphora (L.), Linderakwangtungensis (Liou) Allen, Gordoniaacuminata Presland Neolitseaaurata var. glauca, within acidic zheltozem area of Chongqing Jinyun mountain, by direct shear test and numerical modeling. This study was firstly implemented by a self-made large box direct shear apparatus, characterized by simple, economic, effective and reliable. Moreover, the root system reinforcement effect was quantified by the equipment. Besides, the root area ratio was calculated and root tensile strength was derived by laboratory test experiment. Further, the well-known Wu root-soil composite model was triggered with the same boundary condition as indoor experiment; and then the model calculations were compared with the experimental measurements. The results show that the above six types of plant roots notably enhance the soil shear strength, but with different levels. It is also demonstrated that Wu root-soil composite model overestimated soil shear strength by 90% compared with the large box shear test. In this manner, we revised the k value as 0.63 for soil textures in Jinyun mountain of Chongqing.