Study On The Formation Mechanism And Treatment Measures Of Tianjiaba Landslide In Bazhong City,Sichuan Province

Bazhong City is located in northeastern Sichuan basin, it belongs to the red layer of the Southwest, with the typical slipperystratum-interbedded formation of the sand layers and mudstone layers. Slope stability problems is very prominent in the region, especially in the rainy season, many landslide hazards happened frequently, led serious losses to human lives and property. Tianjiaba landslide at the tow of Zaolin in Bazhong City belongs to such human activities destroyed and rain-induced red landslide.Tian jiaba mountain is the cuesta constructed of the bedding sand-shale rock, the slope toe was dug to form 25m Cutting Slope when built the Dawan(Dazhou～Wanzhou) expressway, without supporting timely. The slope slided along the boundary of the sand-shale rock and formed the large-scale rock landslide on september 18 due to the once-in-a-century torrential rains occurred in the areas of Bazhong on September 16,2011. The landslide’s volume is about 180million cubic metres, led to 20 houses were damaged and the building highway was forched to relocate, brought a serious threat to the production and life of local residents.This paper takes Tian jiaba landslide as the research object, on the basis of fully grasping of the geological conditions, analyses the formation mechanism and failure mode of the landslide, inverses the movement process of the lanslide, evaluates the stability of the existing slope, and proposes feasible measures to Tian jiaba landslide. The main research conclusions are as follows:(1) Through analysing the data about the field investigation, exploration and indoor experiment, grasps the geological backgrounds, failure characteristics, boundary features and distribution of rock of the landslide fully, and divides regions according to the strength of landslide’s deformation.(2) Based on the geological conditions, analyses the forming conditions, the causes and failure mode of the landslide by the method of geological history genetic analysis, and comes to the conclusions finally that Tian jiaba landslide is caused by interaction of heavy rainfall and excavation of the slope toe.(3) Inversing the failure process of the lanslide to restore its movement by the numerical analysis software of UDEC. The simulation mode mainly concludes natural conditions before the excavation, natural and rainy conditions after the excavation.(4) Evaluating the landslide quantitatively by transfer coefficient method, The calculation mode mainly concludes natural, heavy rain and earthquake, and calculates their thrusts.(5) Based on the residual thrust of Tan jiaba landslide and combined with its terrain features, feasible measures are put forward:anti-slide pile, retaining wall, intercepting drain and filling the fractures.