Testing of slope stress zones and its application to unloading zonation

The stress restoring method has many advantages,such as simplicity,expeditiousness,economy and practicality,and it can be used to systemically test and study the slope stress field.The method was adopted to test the stress field of the adits with different elevations on both banks of a large hydropower station.The results indicated that the slope stress field had distinct zonation with the variety of depths.The magnitude of stress,a little low on the surface of slop,gradually increased with the depth.And it had a sudden increase at a certain position,where there would be a relative concentration of stress.Whereafter,the stress smoothly increased after a slim lower.Hereby,the stress field on superficial slope could be divided into regions of stress lowering,rising and fluctuating from the outside to the inside.The distribution of unloading zones correlated with the zonation of slope stress,the hemline of unloading zones often corresponded to the floor level of reducing stress region or outset of the rising stress region.The unloading zones were consistent with the rockmass structure,characteristics of distortion and cracking,and seismic wave speed.So,the characteristics of zonation of slope stress field could work as an index to divide the unloading zones of the slope.