Research On Self-Stabilizing Ability Of Ancient Landslide Based On Stiffness Degradation Of Sliding Zone

With the development of the national strategy,the large-scale infrastructure construction will be carried out in the mountainous areas in the west,and the construction of highway traffic is the most important one.During the process of highway construction,the excavation and construction of subgrade will disturb the ancient landslide,leading to changes in the critical disturbance load,structure cracking,and the scale of disasters in the revival of take-off,which may trigger the resurrection of ancient landslides.In order to better strengthen the ancient landslides,the project must first assess the stability of the ancient landslide itself.Therefore,the study and assessment of the ability of the ancient landslide to be self-stabilizing has a certain guiding role in the urgent need of large-scale mountain engineering construction.This paper focuses on the stability of ancient landslides in terms of theoretical derivation,numerical simulation,and model tests,around the ancient landslide,a special geological body.The main research contents are as follows:First,the current research results on the stability analysis of ancient landslides,the locking effect of sliding belts,and the strengt h reduction method are systematically summarized by reading a large number of references at home and abroad,and the ancient landslides in the topography,rock sequence,and the sliding body,landslide fissures,landslide walls,landslide steps,slip zones etc are discussed.Combined with the formula of classical soil mechanics,the concept of the ability of the ancient landslide to stabilize itself is proposed,and it is deduced that the Poisson's ratio must be increased when reducing the internal friction angle of the landslide.Therefore,the change of the Poisson's ratio and the elastic modulus must be considered in the process of strength reduction,that is to say,the effect of stiffness degradation should be considered,and the specific coupling metho d of strength reduction and stiffness degradation is also given in the paper.It is divided into four stages: initial consolidation,constant-speed creep,sub-accelerated deformation,and accelerated deformation according to the classic ancient landslide i nstability deformation curves.On this basis,the concept as well as determination methods of the warning displacement for the ancient landslide and the ultimate displacement of the self-stabilization capacity are proposed.Comparing and analysing the thre e different simulation methods combining with engineering examples,the superiority of the coupling method can be reflected compared to the single method.Then,taking Yinjiangyankou landslide as the prototype,a mechanical analysis model of the "straight shear by layer" type locking landslide was established.And the expression of the stability coefficient of this kind of landslide was deduced,and the factors affecting the stability of the landslide was analyzed.Afterwards,the role played by the distribution of the locking segment in the stability of the landslide was analyzed.The results showed that the locking segment had a significant control over the displacement of the landslide body and the stress distribution in the slope is changed.The overall stability of locking landslides is related to the distribution characteristics and strength characteristics of the locking segment.Finally,an indoor landslide model with an elliptical sliding surface was constructed.The disturbance of the excavation and filling of the upper and middle parts of the landslide and the graded excavation of the slope foot were performed.In addition,the displacement data obtained from the external photogrammetry system was analyzed.