The Study On The Mechanism Of Loess Landslide Induced By Traffic Overload

With the rapid development of national economy in our country, a lot of roads, highways, railways were constructed. The landslide, roadbed subsidence and traffic disruption induced by long-term effects of traffic dynamical load and static pressure often happen along the road,. Studying on the failure mechanism of highway subgrade and soil of slope induced by traffic cyclic load, that can provide reference for the prevention and control of geological disasters along railway and highway.In this paper, the dynamic characteristics and the failure characteristics of loess under the cyclic loading were studied by means of dynamic triaxial and resonant column experiment. The microstructure and composition of loess was revealed with the help of scanning electron microscopy(SEM) experiment. Based on the numerical analysis, the dynamic response law and deformation characteristics of the loess slope under traffic cyclic loading were studied. With the help of research results of engineering geology, dynamic characteristics of loess, microstructure, dynamic response rules, soil strength attenuation, seismic subsidence, local liquefied, the collapsibility, the mechanism of the occurrence of No.2 landslide of Bao Ping road induced traffic overload was comprehensively analyzed. The main conclusions are as follows:(1)The loess has the following dynamic characteristics: the dynamic shear modulus obviously depends on frequency and increases with the the frequency by the form of power function. The damping ratio is negatively correlated with the frequency and is positively correlated with the amplitude of driving force; the pore pressure, shear strain, radial strain and volume strain, axial residual deformation was positively correlated with dynamic load; Compared with the unsaturated loess, the traffic cyclic loading will cause more serious impact on the saturated loess.(2)The dynamic response of loess slope to traffic load: the displacement, velocity and acceleration vibration response nearly linear increases with the increase of axial load, and nonlinear changes with frequency and the speed of vehicle. There is one frequency stage, that easily causes resonance response of the slope soil. Under the long term effect of heavy traffic cyclic loading with low frequency, loess slope prone to greater shear deformation and failure, which is bad for the long-term stability of highway subgrade and loess slope.(3) The mechanism of No.2 loess landslide of Bao Ping road induced by traffic overload: Under long-term effect of traffic cyclic loading, due to the loess unique microstructure, seismic subsidence and the local liquefaction was occurred. Furthermore, the seismic subsidence will accelerates the collapsible process of loess. Under the above mentioned factors, the strength of loess is reduced and the slope will be unstable.