| Rock slope exposed to the natural environment for a long time is easy to form geological hazards,so it is necessary to protect the rock slope.As a new type of slope protection method,ecological bag slope protection can ensure that the soil layer as the foundation of plant growth will not be damaged by rainwater runoff when it is applied in rock slope engineering.There are two main laying patterns of ecological bags:stacking and tiling.Compared with stacking,the tiling pattern can not only significantly reduce the amount of construction work,but also has a higher germination rate of plant seeds in the bag,so it is still widely used in engineering.However,the stability of tiled ecobag protection on slope is poor.Therefore,this paper studies the possible stability problems of tiled ecobag on rock slope,aiming at providing certain theoretical support and technical basis for the application of tiled ecobag on rock slope.In this paper,the shear characteristics of ecobag-bedrock interface and soil-ecobag interface are analyzed,and the shear strength of the two interfaces is compared.In addition,a slope model test under the artificial rainfall is used to verify the results of ecobag-bedrock interface shear test.The main research contents and conclusions are as follows:(1)Using a self-designed shear box,the interfacial shear tests under four normal stresses are carried out with three kinds of roughness bedrock and five kinds of moisture content soil-containing ecobags.And the data of interfacial shear strength-displacement curve and interfacial shear strength were obtained.The results show that rain water pouring into the ecobag under artificial rainfall may not affect the stability of the ecobag,and may even increase the stability of the ecobag on the slope.The influence of rock surface roughness on the shear strength of the interface is not necessarily positive.Setting reasonable rock surface roughness is helpful to improve the stability of the ecobag on rock slope.(2)Interfacial shear tests under four normal stresses are carried out at interface of soil and ecobag with five water contents.And the data of interfacial shear strength-displacement curve and interfacial shear strength were obtained.The results show that the increase of soil water content has a deterioration effect on the shear strength of soil-ecobag interface.The stability of ecobag is not only affected by the shear strength of bedrock-ecobag interface,but also may be affected by the shear strength of soil-ecobag interface.With the increase of normal stress or water content of soil in ecobag,the cause of slope instability of tiled ecobag protection may change from relative slip of bedrock-ecobag interface to relative slip of soil-ecobag interface.(3)Based on the developed rock slope simulation platform with adjustable angle under extreme rainfall,two rock slope conditions and two ecological bag tiling methods were adopted to conduct tests under four rainfall intensity conditions.And the initial sliding angle of ecological bag is obtained.The results show that there is no stability problem when the slope angle is less than 30°.Rainfall can improve the stability of the ecobag on rock slope,and the calculated friction coefficient between the ecobag and slope is generally between 0.5 and 0.9,which are basically consistent with the conclusion of the ecobag-bedrock interface shear test. |
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