Bioengineering Assessment on Sloppy Ground

Abstract

Problem statement: Soft engineering solution of sloppy surface utilizes mechanical and hydrological effects of vegetation. The hydrological effects driven by transpiration, induces an increase in matric suction and consequently tension also increase along with the decrease of moisture. Therefore once the horizontal stress of the soil exceeds the limit of tensile strain of the soil cracks occurs. Approach: The negative pore-water pressures estimated through an unsaturated water-uptake analysis. The results of the root water-uptake analysis are then used as an input for the prediction of displacements in a stress-deformation analysis in an uncoupled formulation. The formulation of the governing partial differential equations for both water-uptake and stress-deformation is based on the general theory of unsaturated soils. The ground displacement presented here only considers hydrological effects which are related to soil moisture variations driven by transpiration. Results: The ground displacement profiles as a result of matric suction changes at key times and at key locations have been presented. The matric suction changes induced settlements are estimated. The magnitude of the ground displacement depends on the relative position of the tree on the slope. The ground displacement depends, to some extent, on the precise position of the tree. Conclusion: These showed that excessive increase matric suction and tension due to decrease of moisture can lead settlement. Moisture reduction reaching a critical state causes cracks to be established, of course has negative consequences on sloppy ground.