| With the rapid development of construction in China,it is inevitable to cut the mountain slope manually,and the landslide phenomenon caused by improper cutting process often occurs.As one of the most common types of slope,the material composition of accumulation landslide is loose,and it is easier to induce landslide by cutting and excavating this kind of slope.Therefore,how to establish appropriate and effective stability evaluation model according to the law of landslide disaster caused by cutting slope has become one of the major issues that need to be studied and solved in the field of landslide stability evaluation.In this study,based on the characteristics of accumulation landslides and sliding effect caused by slope cutting instability,the high and steep slope formed by the excavation of Chaqishan ancient landslide of Sichuan Province was taken as the research object,and the variation law of the stress field,displacement field,plastic zone and stability during the slope cutting process was explored by using Midas GTX NX finite element software.Based on the theory of loading unloading response ratio of landslide,we established the evaluation parameter and model of slope cutting dynamic loading displacement response ratio,and the basic principles of damage mechanics was applied to establish the judgement standards of instability of slope cutting dynamic loading displacement response ratio.At the same time,we redesigned four kinds of slope cutting schemes for Chaqishan ancient landslide.The stability of each design scheme was compared and analyzed from the the aspects of evaluation model of slope cutting dynamic loading displacement response ratio,residual anti-skid force,stability coefficient and the amount of slope cutting,and the optimal slope cutting scheme was determined.The above research results verified the effectiveness of the evaluation model of slope cutting dynamic loading displacement response ratio,and also provided a reference for slope cutting engineering of ancient Caiqishan landslide.The main research results are as follows:(1)Based on the material composition characteristics and the excavation deformation characteristics of Chaqishan ancient landslide,the stress field,displacement field,plastic zone and stability evolution law of the ancient landslide during the first and second slope cutting process were analyzed in detail by using Midas GTS NX finite element software.The results are as follows:(1)During the cutting process of ancient landslide,the horizontal and vertical stresses of each cut slope layer decreased gradually,and the slope body changed from compression state to tension state.(2)The maximum shear stress of each cut slope layer decreased gradually when the slope was not cut,and then increased and tended to be stable after slope cutting,and the shear failure was easy to occur at the foot of the cut slope layer.(3)The maximum principal stress of each cut slope layer decreased gradually.(4)The horizontal and vertical displacements of each cut slope layer gradually increased on the whole,and uplift occurred on the surface.Some cut slope layers produced negative displacements due to being in the interior of the slope,and eventually these negative displacements changed into positive displacement.(5)The statue area of each cut slope layer developed and penetrated gradually,and the stability coefficient decreased gradually.(6)Under the condition of rainstorm,the overall stability coefficient of the ancient landslide was 1.05,which belongs to unstable state.(2)Based on the basic deformation law of accumulation landslide and the theory of load unload response ratio of landslide,the dynamic factor(slope cutting excavation)as well as its displacement response law of slope instability were quantitatively studied.Taking the slope cutting process as the dynamic loading process,the dynamic change value in the process of slope cutting as the loading parameter,and the displacement change value caused by dynamic change as the response parameter,the slope cutting dynamic loading displacement response ratio evaluation parameter and model were established.Based on the basic principles of damage mechanics,the quantitative relationship between the stability coefficient of slope and the slope cutting dynamic loading displacement response ratio was established by taking the damage variable as the correlation parameters.Then,based on stability coefficient,the judgement standards of instability of slope cutting dynamic loading displacement response ratio was determined,providing the slope cutting dynamic loading displacement response ratio with stability evaluation significance and value equivalent to that of the landslide stability coefficients.(3)According to the general situation and the numerical simulation results of slope cutting stability of chaqishan ancient landslide,it was found that the slope cutting rate of the ancient landslide was large and the stability was low,which brings serious safety hidden danger to the highway construction project at the foot of the landslide.Therefore,under the assumption that the ancient landslide has not been cut,four kinds of slope cutting schemes were redesigned.Through numerical simulation analysis of each scheme and substituting the simulation results into the evaluation model of the slope cutting dynamic load displacement response ratio,the change curve of the slope cutting dynamic load displacement response ratio of each scheme was obtained.Through comparative analysis,it was found that the dynamic loading displacement response ratio change law in the process of slope cutting of each scheme was basically consistent with the stability coefficient evolution law.Among them,the maximum displacement response ratio of slope cutting dynamic loading in schemes 1 to 4 were7.51,7.11,5.88 and 2.77 respectively,and the corresponding stability coefficients were1.09,1.12,1.14 and 1.20 respectively,showing an obvious negative correlation between them.(4)Under the condition of limit equilibrium method,the residual anti-skid force and stability coefficient of each design scheme were calculated,and it was found that the residual anti-skid force and stability coefficient of scheme 4 were the largest.Through the above research,it was found that the slope cutting dynamic loading displacement response ratio of each design scheme was consistent with the evolution law of residual anti-slip force and stability coefficient under the calculation condition of limit equilibrium method,which further verified that the slope cutting dynamic loading displacement response ratio evaluation model can reasonably and effectively evaluated the stability of slope in the process of slope cutting.(5)Based on the comprehensive analysis of the stability of various design schemes of chaqishan ancient landslide,it was found that scheme 4 has the smallest slope cutting dynamic loading displacement response ratio,slope cutting volume,and the largest residual anti-slid force and stability coefficient.Therefore,scheme 4(slope ratio 1:1.75)was the optimal slope cutting scheme which meet the safety requirements and was economical and reasonable. |
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