| The deformation characteristics of landslide will be different before,during and during the trial operation,and the early warning values of different stages are also different and In order to provide design basis for comprehensive treatment of landslides,judge the stability of landslides during the construction period,so as to ensure the construction safety and evaluate the comprehensive treatment effect of landslides,taking the landslide on the west side of Minjiang electrochemical as an example,the mechanism of landslide instability and failure is obtained through field investigation and analysis of influencing factors.A monitoring system is built to analyze the dynamic deformation characteristics of landslide in three stages from a large number of real-time monitoring data.Then,the FLAC software is used to model the landslide,and the strength reduction method is used to obtain the reduction coefficient and the corresponding slope displacement of the landslide in the two stages of the comprehensive treatment construction period and after the comprehensive treatment construction.After considering the anchoring effect of pile and anchor cable,combined with the slope displacement during the failure of stability,the early-warning values of deformation at three monitoring points during the comprehensive treatment construction period are obtained;The early-warning value of deformation of three monitoring points in the post construction stage of comprehensive treatment of landslide only considers the slope displacement when the landslide is unstable.Through the statistical analysis of the monitoring value of the deformation rate of the landslide and the displacement ratio method,the early warning value of the deformation rate of the landslide in these two stages can be determined.The main conclusions are as follows:(1)The deformation mechanism of the landslide is: the front edge of the main landslide is the free face generated by excavation,and the rock mass is mainly phyllite with weak rock quality.Under the influence of rainfall,the front edge of the main landslide is deformed first,and then the rear and both sides of the slope are deformed.The landslide mode is traction type landslide.Due to the traction of the front edge,the scope of the landslide is expanding,resulting in the increase of the residual sliding force of the landslide,which exceeds the anti sliding ability of the original design of the anti sliding pile.At the same time,the mechanical property of the rock mass in the embedded section of the anti sliding pile is poor due to rainfall,which makes the anti sliding The deformation of the pile is inclined;the pressure of the plate between the piles exceeds the design value.Because the deformation modulus of the plate between the piles is far lower than that of the anti slide pile,under the same pressure,the deformation of the plate is larger,resulting in the failure of the plate and the anti slide pile.(2)In terms of time,the deformation of landslide before construction increases gradually with time under the effect of rainfall.During the construction period,the deformation is further increased due to construction disturbance,but during the post construction trial operation period,the engineering effect of comprehensive treatment measures is gradually reflected,and the deformation is gradually reduced,even less than before construction.(3)From the perspective of space,landslide is affected by the existing anti slide piles in the front edge.In these three periods,the displacement and time rate are decreasing from the back edge to the front edge,and the "braking effect" phenomenon is significant.(4)Based on the strength reduction method and the displacement ratio method based on the deformation rate monitoring data,the early warning thresholds of the slope surface displacement deformation and the slope surface deformation rate in the two stages of the comprehensive construction period and the trial operation period after the comprehensive treatment are obtained. |
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