Shear strengths of undisturbed and remolded soil under typical forests in Jinyun Mountain, Chongqing City, southwest China

Abstract

To find the controlling measures in preventing soil and water loss from soil mechanics, according to the prescribed methods of soil engineering test regulations, shear strengths of undisturbed and remolded soils under five typical forests in Jinyun Mountain, Chongqing City were measured using the direct shear apparatus. Shear difference of both undisturbed and remolded soils was compared at the same vertical loading, under the condition of the same dry density and water content from the same forest land. The effect of roots (the finest roots) in soil-root composites (undisturbed soils) was analyzed. The results indicate that undisturbed soils have higher shear resistance and less shear displacement than remolded soils at the same vertical loading, when both soils have the same dry density and water content under the same vegetations. It has been shown that shear failure of undisturbed soils approximately indicate plastic failure, while shear failure of remolded soils is of the elastic nature. Shear strength of undisturbed soils has a positive correlation with root content, and relevant regression models about undisturbed soil were established from this.