Research On Engineering Geology Characteristics And Prevention Measures Of Embankment Slide In Lijiang-Panzhihua Highway

With the continuous development of western development strategy, more and more highway projects are being constructed or planned to be constructed in the southwest region. But many of the projects are subjected to the complicated conditions of southwest mountainous area and often suffer from the threat of geological disasters, such as landslide, collapse and debris flow, which seriously affect the safety of vehicles passing the highway. At the end of August 2015, a short-term heavy rainfall caused local slump of embankment slop of Yinjiang interactive interchange ramp on Lijiang-Panzhihua Highway, which resulted in road subsidence and directly threatened the safety of passing vehicles.In this paper, on the basis of consulting relevant materials and field survey, starting from the project’s geological conditions of the researched area where Yinjiang ramp embankment slope is located, according to the plane form of landslide, features of sliding surface and relevant parameters of rock-soil mass, the development characteristics of landslide is researched; The formation mechanism and inducing factors of landslide is summarized to explore its evolution process; Then qualitative and quantitative evaluations are conducted to the stability of landslide; Next, FLAC3D numerical simulation software is applied to calculate and simulate the stability of landslide under natural condition and rainstorm; Finally, two sets of comprehensive treatment project schemes are proposed for selection. The main research content and result are as follows:(1)Through field exploration survey, Yingjiang ramp landslide is "chair-like" shape, a trailing edge crack cause the subsidence of embankment, retaining wall bulging deformation of the leading edge, the lower part of the slope is no significant slippage. Landslide transverse width of 50m, a longitudinal length of about 80m, flat-affected area 3600m2, landslide thickness ranging from 5～7m, the total volume was of 1.8×104m3.(2)Yingjiang ramp landslide is artificial slope, in a natural state is already in the the maximum balance condition, as well as to the vehicle vibration, with the passage of time and the accumulation of bad factors Jagger evolution from quantitative to qualitative change, slope changes from stable state to an unstable creep state, and ultimately the formation of landslide.(3)The limit equilibrium method is applied to quantitatively calculate the stability of landslide mass. And the result shows that, landslide will be in a unstable state under short-term rainstorm, which is consistent with the actually monitored condition on landslide site.(4)FLAC3D numerical simulation software is applied for numerical simulation calculation of the stability of landslide under natural condition and rainstorm. The simulation result shows that, under natural condition, landslide displacement is small and landslide is in a stable state; under rainstorm, the shear zone will extend gradually and displacement is larger, and landslide is in an unstable state.(5)Two treatment project schemes are proposed:bridge schemed and pile-plank wall schemed. Through comparison and selection, the recommended scheme is:bridge scheme.