Research On Flabellate Landslide Mechanism Of Bedding Rock Slope In Redbeds

In the thesis,we use the landslide of excavate-caused flabellate slope at the westside of the Sinopec supplies reserve center in Northeast Sichuan as the object ofstudy,discuss the formation mechanism of it by analysing the regional geologicalbackground conditions,characteristics of rock and soil structure and weakdiscontinuity,deformation feature and the monitoring data.And then we use FLAC3Dtoanalyse the deformationprocess and failure mode of this landslide,propose theconsideration of the exploring and design process in monoclinic forward slopes in theterrain area with parallel ridge valley and lowmountain hill of EastSichuan.Meanwhile,we put forward the selection method of the parameter of the weakdiscontinuities(bands) and the analytical methods and recommendations of monitoringand early warning in engineering construction.The research results of this paper are as follows:1.Engineering geological and enviromental conditions of the study area:includingthe natural geographical and environmental conditions,landform and geologicalbackground conditions; 2.Through analysing the characteristics of rock and soil structure and weakdiscontinuities,it is indicated that the interbedded joints of sandstone and mudstone aremainly including bedding planes and tectonic fissures in redbeds regions.And theprimary weak discontinuities(bands) are highly weathered layers and argillizationinterlayers in shallow mudstone;3.By analysing the monitoring data,it is evinced that the landslide is a typicalbeddingslip of monoclinic bedrock slope,and the deformationprocessis:stableâ†'abruptly changingâ†'moderately changingâ†'abruptly changingâ†'failure andsliding.In the first "abruptly changing" of the deformationprocess,the distortion isbasically equivalent,but in the "abruptly changing" before severe sliding,the distortionincreases exponentially.And the moderate changing between the two processes of"abrupt changing" represents the transition of shear strength declined from peak valuesto salvage values;4.The analysis of the mechanism demonstrates that the controllable factor of thelandslide formation is the monocline forward structure and the weak interbedding inthe terrane,and the main incentive is the excavation digged at the leading edge of theslope,and the role of water is the main effect factor of the formation of this landslide;5.By analyzing the FLAC3D numerical simulation method, we could reveal thatas a result of the excavation at the forward edge of the slope, the slope front is in thestate of stress concentration, and the slope mass is in the tensile-shear stress and doubletensile stress state. There was a tension zone at the edge and the top of the excavationslope. Additionally, due to the soft rock strata exert a great influence on stressdistribution, the deformation and failure inside the slope rock mass were under thecontrol of its lower soft rock strata, and its failure mode is bedding sliding andfracturing;6.We suggested that it is should be paid great attention to the slope investigationand assessment in the monoclinic consequent slope area, where there are some of theengineering construction projects. The strength parameter of the weak structuralsurface，such as the red bed mudstone waste, argillic interbed and so on, should bedetermined by considering the feature of its components, and the correlative parameter of its counterpart. And we need to accurately confirm and judge the rate ofdeformation and distortion in every stage of the slope monitoring and early warning,and make some appropriate adjustments of monitoring work arrangement in time, inorder to improve the accuracy of the slope monitoring and early warning.