Study Of Deformation Characteristics And Stability Of The K198～K199 Landslide In Yalu Freeway

Yalu Freeway located in Sichuan province, it is an important portion of the freeway from Beijing to Kunming. Along the road, the geomorphology is complex, which belongs to middle mountain landform caused by tectonic denudation and accumulation. There exist various type of lithology and faults. Because of artificial engineer activities, a lot of geological hazards are triggered.The study area locate at K198-K199 segment of Yalu freeway. The original deformation arise on the retaining wall after the continuous heavy rain in 2009 and gradually expanded facilitated by the continuous heavy rain. Although emergency stability structures had been done, but continues displacement were developed in the following time, which finally affect the daily function of Yalu freeway. Based on the investigation of geological conditions of study objects and spatial and historic deformation features, this research aims at exposing the deformation mechanism and stability analysis, and further put forward a set of suggestion of control measures.This landslide occurred in gravelly soil is triggered by rainfall. The lithology of in landslide body contains artificial filled soil, gravel soil in middle to high degree of density and silty clay in plastic to soft plastic state. The trailing edge is featured with half-dug half fill subgrade. The settlement deformation of road at the rear of the displaced materials and the toppling deformation of retaining wall were first occurred in September,2009, when the road was still under construction, and expanded over the following time, especially following heavy rain. The displaced material was divided into three deformation areas, and the largest deformation is located in the middle and rear of the landslide body. Comparing with the test data of deformation and regional rainfall data, the relationship between deformation and rainfall is obvious, although there exist some temporal delay.In addition, the lithology, groundwater conditions and construction loading perform important factors in the deformation of the slope.The stability of the slope is analyzed in rainstorm and natural conditions through limit equilibrium method and numerical simulation, the stability evaluation indicated that, the slope is unstable in rainfall state and stable in natural state. The largest deformation is concentrated on the middle of the slide body. Finally, the stabilization measurement, water drainaging in slope and stablizing pile retaining, are came up with to mitigate the deformation of the slope.