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.