| Landslide early warning and forecast is always one of the important contents in the field of the study of geological hazard, as a type of representative geological disaster of landslide, deep layer accumulation landslide is widely distributed in China's western mountain area, and has the characteristics of large scale, harmfulness. This kind of landslide material composition contains Quaternary eluvial,rockfall deposit, ice accumulation, etc, and has the characteristics of loose structure, high porosity, strong permeability and the particularities of the material composition determines that the slope is easy to lose stability and slide down under extreme conditions of rain and earthquake. Therefore, it has important theoretical and practical significance to study the landslide coordinated early warning based on multi source three-dimensional observation network for the large-scale accumulation landslide in the western mountain area.This paper taking Xishancun landslide in Li County as the main object of study. Based on the collected related geological data of Xishancun landslide and the detailed investigations of landslide morphology, characteristics of geological structure, macroscopic deformation characteristics, combined with the multi-source stereo measured data, a GMD three-dimensional numerical model that can reflect the geological characteristics, mechanism and deformation characteristics of the landslide was established. Analysis of slope deformation distribution and the law of development of the landslide in gravity condition with the creep of the sliding body in the deformation zone and the interior of the slope body. And Through the continuation of the computing time, the sliding time of this landslide is predicted based on this model, and the time and space coordinated early warning index was analyzed. The main results obtained in this paper are as follows:(1) Xishancun landslide is located in Tonghua township, Aba Li County, left of Zagunao River, the Minjiang River tributary. Landslide was "chair-shaped", the total length 3800 m, width 680~980m, average thickness 55 m, volume greater than 170 million, which belongs to giant deep accumulation landslide. Overall the landslide terrain was on "upper gentle, lower steep" poly line shape. According to the drilling, the exposed strata in the study area mainly are blue grey phyllite of Silurian and Devonian, accumulation body material structure is divided into two layers, silt with gravel, gravel soil and crushed rock, and the rock stratum varies greatly at the bottom of the landslide, which means the initial deformation of the rock mass maybe toppling.(2) Field investigation and multi-source monitoring data show that the deformation of Xishancun landslide is mainly concentrated in the front of the left of the landslide, especially in the front area. Signs of deformation contains cracks, dislocation and partial collapse, and according to the macroscopic deformation characteristics, the landslide deformation is divided into three regions. And the manner of deformation is progressive back, the deformation mechanics model is creep-cracking. The results of the surface and internal displacement monitoring of the landslide also shown that the landslide is in the stage of constant velocity deformation at present.(3) With the multi-source stereo monitoring data, in the area of the leading edge of landslide deformation, the GMD 3D numerical model was established which can reflect the geological structure, mechanical mechanism and deformation characteristics of the landslide using the FLAC3 D software, and the Cvisc creep model of the software was used for landslide simulation. The initial simulation results show that the deformation progress can be divided into two stages, the first stage is the initial stage of landslide deformation, the second stage is the creep stage, numerical simulation results and the real development process fitted well, which proves that the GMD model is reasonable and can be used to predict the sliding time of landslide and the deformation analysis.(4) According to the GMD numerical model, the landslide displacement space distribution characteristics and slope deformation evolution progress with creep time goes on was analyzed by arranging monitoring and tracking points in the surface and inside the slope body of the 3 revival deformation zones of the landslide. Study found that deformation of the landslide is mainly concentrated in the deformation zone I and II, especially the posterior of region I. Through monitoring the displacement at different depths of the slope the conclusion can be found that in the internal displacement of the landslide body basically decreasing gradually along the depth direction. And 2nd drilling displacement changes great in the range of 0~20m, the analysis suggests that the possibility of shallow slip is greater. and No. 5, 10 inside the slide body displacement changes are more uniform, performance for the overall forward creep.(5) On the basis of the landslide GMD numerical model, by the extension of calculating time to predict the sliding time of the landslide. The simulation results show that the displacement rate of deformation at No.1 monitoring points at deformation zone? has a mutation when the creep calculation time is 2380 days, the total displacement of the landslide growth accelerated, and at this time, the landslide has entered the stage of accelerated creep. Through monitoring the displacement of the internal point 1,we found that the displacement and the displacement rate has increased greatly in the deformation zone ? in 40 m depth range when the calculation time is 2380 d, and the changes of internal displacement in deformation zone II and III are much smaller. With the increase of the creep time the deformation zone? is likely to slide from deep and overall.(6) Based on the above analysis combined with the principle that the landslide early warning indicators should be easy to monitor, and has applicability, selecting the slope macroscopic deformation and failure signs, the displacement and displacement rate of a particular point and the improved tangential angle as Xishancun landslide space-time coordinated early warning indicators, and according to the division of landslide early warning level make the landslide collaborative early warning classification index. |
PDF Full Text Request