Deformation Mechanism And Engineering Prevention Of The Highway Landslide Based On Spatial Monitoring

Highway construction plays an important role in the development of national economy.In mountainou and hilly areas,the original slope that is excavated for the highway construction is easy to form the geological hazard of highway landslides under the influence of the induced factors.It is very important to carry out spatial multi-point deformation monitoring for studying the deformation mechanism of highway landslides and the optimal design of control projects.Taking Yu-Kai Highway Landslide in Guizhou Province as a typical engineering case,the study constructs the geological model through detailed in-situ investigation and establishes a spatial multi-point deformation monitoring system.The long-term displacement monitoring of the landslide is carried out by geodetic method.Combined with survey data and monitoring information,the temporal and spatial evolution process of the landslide is analyzed,and the deformation mechanism of the landslide is deeply studied by factor analysis and regression analysis.Based on the above results,the informatization construction is performed and an improved optimum design method for the plane layout of stabilizing pile is put forward.The main results are as follows.(1)Based on the data collected by the spatial multi-point monitoring system,the temporal and spatial effects of landslide deformation are amply analyzed.The curves of the cumulative surface displacement and the displacement rate with time have obvious step response characteristics.The deformation process of the highway landslide can be divided into three periods: the initial deformation period,the rapid deformation period and the gradual stabilization period.The monitoring results show that it will cause disturbance to the sliding mass which has gradually stabilized during the construction of control project.Therefore,it is necessary to carry out continuous monitoring during the construction period.The data of surface displacement monitoring show that the main slip direction of the landslide is about SW207° in the final state during monitoring period.(2)The position of the surface zone is determined synthetically according to the stratum condition and monitoring data of the borehole.The possible slip surface of landslide is analyzed as follow: the posterior slip surface is developed mainly along the tensile joint of the crosscutting layer;the middle slide surface mainly is developed along the weathering boundary,the interbedded layer and the rock plane.The leading edge displacement of the landslide is slight,and there is no obvious slip surface running through it.However,the front edge of landslide consists of loose silty clay and crushed stone,the anti-slide force is too small to balanced driving force.The potential slip surface is developed mainly along the rock plane and shears out to the weakest part of the impedance.(3)The three main influencing factors of the landslide are engineering excavation,rainfall and internal bad geological factors.The quantitative evaluation of rainfall factor and excavation factor is carried out by factor analysis and regression analysis.Firstly,the bad geological conditions are the material basis of landslide formation.Secondly,rainfall is the most important factor.The results of factor analysis show that rainfall in the previous month has a greater impact on the deformation of the landslide in that month than the rainfall in the same month.Thirdly,the results of regression analysis show that there is a significant linear relationship between the displacement of the sliding mass and the excavation distance.The deformation of the back edge of the landslide is greater than that of the foot.In addition,the displacement of the trend term and the periodic term with the fluctuation term are obtained by the FFT calculation.The time series model is used to predict the deformation of landslide,which reveals that landslide deformation tends to be stable.The prediction error obtained from the residual error series is range from-2% to 3%.(4)Based on spatial-temporal deformation characteristics of landslide at different evolution period to carry out the informatization construction.The comprehensive control schemes,including off-load,retaining wall,anchor cable,drain off water and stabilizing pile are adopted successively.The result of dynamic evaluation the control efficiency show that the engineering control measures are effective to control the deformation of the highway landslide.A plane layout optimization scheme for stabilizing piles based on the improved irregular driving force expression is proposed.Compared with the traditional layout scheme of stabilizing piles,the number of anti-slide piles can be reduced by 28.6%.Through the comparison between the monitoring data and the theoretical calculation,the above-mentioned method for calculating the irregular landslide driving force is verified.