Loess Landslide Stability Analysis With Highly Accurate Monitoring Information

China has the largest loess distribution in the world.Due to the unique geological structure of loess,geological disasters in the loess-covered areas are frequent,among which the landslide disaster is the most serious,seriously threatening the safety of people's lives and property and the sustainable development of the regional economy.Therefore,in order to evaluate the stability and development trend of landslides,the study of the stability of loess landslides has important practical and theoretical significance for the timely warning of landslide disasters and the research on disaster prevention and mitigation.Landslide stability research has always been one of the hot topics in the field of engineering geology.However,the current research on the stability of landslides only focuses on the instability of landslides under the influence of different geological parameters and external environmental factors from the perspective of pure numerical simulation.It does not take into account the external characterization information of the intrinsic deformation mechanism of the landslide that can be reflected by the external deformation information of the landslide.Therefore,it often leads to the inconsistency between the results of the evaluation of landslide stability and the actual situation.The high-precision landslide deformation monitoring data obtained by geodetic methods is the most direct external characterization information of the landslide intrinsic deformation mechanism and can reflect the multi-stage characteristics of the actual deformation of the landslide,which has important reference value to analyze the stability of the landslide at different stages.Aiming at the problems existing in the study of the landslide stability mentioned above,this paper selects the typical loess landslide in the South Jingyang plateau of China,using the high-precision monitoring data obtained from the landslide monitoring network to carry out in-depth research on landslide stability analysis with constraints of deformation monitoring information outside the landslide and fully taking into account the differences in the impacts of different inducing factors(eg,irrigation,rainfall,etc.)on the stability of the landslide in different stages of the landslide,analyzes the internal stress and the internal characteristics of stability changes in the process of landslide dynamic development.The main results obtained are as follows:(1)Based on the regional environmental geology,using regional imaging data and field survey results,an accurate 2D and 3D finite element model of the landslide area was established;The different induced factors of the landslide,especially the influence of the inducing factors on the stress and displacement of the landslide,were simulated and analyzed.Derived the mechanism of landslide instability gradually caused by landform ? groundwater ? irrigation ? rainfall.(2)Using the landslide deformation monitoring network laid out,high-precision deformation information was obtained during landslide development.Using displacement time curve analysis,numerical simulation aided analysis and displacement vector angles,etc.,the dynamic development process of landslides was analyzed;the mechanism of integral deformation under unbalanced force ? upper tensile fracture ? lower extrusion lock ? shear failure was induced;the inversion results of landslides have been optimized using finite element numerical simulation methods.A more reliable landslide parameter dynamic inversion result has been obtained.(3)A landslide finite element model with additional external high-precision monitoring data constraints was established;the characteristics of changes in internal stress and stability during landslide development were analyzed,and the influencing mechanisms of landslide deformation on internal stress changes in landslides were derived;Further,under different saturations,the process characteristics of internal stress and stability change at different stages of landslide development are obtained.It is concluded that when a small change in saturation occurs,a stronger promoting effect on well-developed landslides would happen and when there is a large change in saturation,the effects of landslides of different developmental states are basically the same,providing a reference for the interpretation of “slight rain-smoothing” and "No rain sliding".