| With constantly advancing of China's "Western Development" and the "One Belt and One Road" strategy,the number and scale of engineering construction are increasing year after year..In the western China region,high mountains and deep valleys and poor geological environment often lead to frequent geological disasters such as landslides and landslides,which have brought unprecedented challenges to engineering construction.In the process of seismic landslide investigation in the Loess Plateau,it is found that the underlying bedrock of some loess landslides often develops concealed consequent fault zones.Its special structure of loess-mudstone stratum and the fracture zone in the slope control the stability and deformation failure mechanism of the slope.In particular,the western region has strong neotectonic movements and frequent earthquakes.The dynamic response of loess-mudstone slope under the action of high intensity earthquake is a hot issue in the research of engineering design and slope engineering.Therefore,it is of great practical significance and theoretical significance to study the dynamic response mechanism of loess-mudstone slopes with a dip fault under earthquakes.This article takes the background of loess-mudstone landslides in typical consequent fault zone in the Tianshui area of northwestern China as the research background.Based on the large-scale shaking table model test and FLAC3 D dynamic numerical simulation calculation,the dynamic response mechanism of the loess-mudstone slope with different inclination angles dip fault under different earthquakes was systematically studied.The specific contents and results are as follows:(1)The geological background of tianshui area is evaluated,the active fault in the area is developedand the seismic frequency is frequent,which controlling the stability and deformation failure of loess-mudstone slope in the region.(2)Taking typical loess-mudstone landslide along the dip fault in the study area as the research background,a generalized model of shaking table experiment was established based on the similarity theory,and large-scale shaking table physical model test of loess-mudstone slope with inclination angles of ?=50° and 80° dip fault under earthquake was firstly developed to study dynamic response of the loess-mudstone slope.The physical model test combined with numerical simulation reveals the dynamic response law and deformation failure modes including the laws of acceleration response,the response of soil pressure and the slope deformation characteristics of loess-mudstone slopes with inclination angles of ?=50° and 80° dip fault in different ground motions,the dynamic response mechanism of loess and mudstone slopes with different inclination angles dip fault under earthquakes is finally obtained.(3)Based on the finite difference theory,using FLAC3 D numerical simulation software carries out comparative simulation analysis of the dynamic responses of four loess-mudstone slops along the dip fault zone with no fault and inclination angles ?=50°,60° and 80° under earthquakes.The effects of different inclination angles on the dynamic response of loess-mudstone slopes are studied in terms of acceleration response,slope displacement,plastic zone distribution,shear strain increment,and permanent horizontal displacement in key parts of the slope.The results show that the accelerating amplification factor of the slope body is manifested as surface appearance effect,elevation magnification effect and lithologic combination effect,and the acceleration response is the strongest within the fault zone;the smaller the fracture angle of the fault zone is,the weaker the dynamic response is,but the amplitude increases with the seismic wave.The effect of the upper plate enlargement is stronger,and the influence on the slope stability and deformation failure mode is greater;the failure deformation of the loess-mudstone slope with dip fault under the action of earthquake are the rupture to glide slip type. |
PDF Full Text Request