Sliding mode and deformation law of double weak interlayer rock landslide

The bedding rock landslide has the characteristics of wide distribution,strong destructiveness and complex sliding mechanism. Its sliding is mainly controlled by weak interlayer and in natural,is often affected by double or mul- tiple weak interlayers. According to the features mentioned above, the development characteristics of bedding rock landslides in the Lvliangshan area of Shanxi Province are summarized. Based on the limit equilibrium method and con- sidering the strength attenuation of the shear strength of the weak interlayer in the different development stages of the landslide,two calculation models for the bedding rock landslide with double weak interlayer are established. The analy- sis shows that the landslide slides in different modes under different mechanical conditions and the slip mechanism of landslide is different under different modes. The first mode is caused by the softening of the upper weak interlayer. When the upper stratum starts to slide,the upper stratum loses stability first,while the lower stratum remains stable temporarily. The second mode is caused by the softening of the lower weak interlayer,and the form of instability failure is overall instability. In addition,based on the FLAC3D numerical simulation,the destruction and deformation law of the bedding rockslide with double weak interlayer is analyzed. The results show that when the landslide is controlled by the upper weak interlayer,slip layer shearing occurs at the leading edge,and the middle and trailing edges slide along the contact surface between the overlying strata and the upper weak interlayer. When the landslide is controlled by the lower weak interlayer,discontinuity changes will occur at the front section of the upper weak interlayer. If the landslide is jointly controlled by the upper and lower weak interlayer,when the upper weak interlayer first softens and starts to slip,the softening of the lower weak layer will lead to differentially slide. However,when the lower weak interlayer first softens and starts to slip,the softening of the upper interlayer does not significantly affect the overall sliding.