Research On The Toppling Deformation Mechanism Of Counter-tilt Slate Slope In The Mountainous Area Of Southern Anhui

Shallow metamorphic sandy slate is widely dispersed in the mountainous area ofsouthern Anhui, the outcrop area is approximately8500km2. The most obvious platestructure in shallow metamorphic rocks is slate, and the characteristics of slate jointplane has important role in controlling rock slope deformation and destruction.Extensive field surveys show that most of counter-tilt slope occurs topplingdeformation because of the effect of parallel-plate structure, and the toppling rock andbroken surface is unique. In order to sum up the characteristics of toppling rock andbroken surface. and researches the main factors and toppling conditions in topplingdeformation of slope. It reveals the toppling deformation mechanism of slope, andalso provides a reasonable basis for treatment of these slope. On the basis of datacollected and analysis, field engineering geological survey, on-site point load testingand indoor physical and mechanical test. The paper uses some method such asmathematical statistic analysis, large deformation elastic-plasticity discrete element,mechanics analysis and so on. The system researches the characteristics of counter-tiltslate slope toppling rock and broken surface, and analyses the relationship betweenthe degree of toppling deformation, rock structure and dip angles of bedding surface,and it also establishes a numerical model in counter-tilt slate slope about thedisplacement of top and toppling deformation. Based on this model to analyze theimpact of various factors on the slope toppling deformation, and it reveals thetoppling deformation mechanism of counter-tile slate slope. The research made thefollowing achievements： (1) The toppling deformation of counter-tilt slate slope includes the dumping type of rock pillar and rock block dumping, the rock dip angle a has a negative exponential relationship, and the plane shapes of slope fracture surface are mainly straight line, broken line and curve shape.(2) It established the classification system about slate rotation angle ω and the degree of slope toppling:0～15°for slight,15～25° for medium, and more than25°for the strong toppling.(3) The rock mass structure styles of slate include the near horizontal layered rock, medium-dip layered rock, steep pitch layered rock and vertical rock; when the angle between slate joint plane and the role of the maximum principal stress is62°rock is most easily to shear failure along the slate joint plane.(4) When the slope angle or the inclination angle of slate joint plane is more than40°, it is suitable for toppling deformation of slope. In particular, when the inclination angle of slate joint plane is between50°to70°, the counter-tilt slope is most easily to toppling deformation and feature.(5) It presents a formula about the depth of slate fracture surface especially α+β=90°,(6) Using analysis of geological processes and mechanics mechanism, it reveals that the dynamic deformation process about toppling deformation of counter-tilt slate slope contains4broken processes: abending deformation, bending and toppling deformation, toppling and broken damage. The dynamic deformation-broken process of Yangtai landslide in huangshan city is showed with UDE and FLAC3D software.