Research On Seismic Response Of Pile-supported Reinforced Embankment For High-speed Railway

China is a country prone to earthquakes.Strong earthquakes may cause serious damage to transportation facilities such as railways and highways.The pile-supported reinforced embankment has been widely used in various traffic facilities.Compared with the conventional embankment structures,the working performance of the pile-supported reinforced embankment has obvious advantages.At present,the static characteristics of pile-supported reinforced embankment have been understood to a certain extent,but the response of pile-supported reinforced embankment under earthquake conditions still lacks systematic results.In this thesis,taking the high-speed railway pile-supported reinforced embankment as the research object,the dynamic response characteristics of the subgrade structure under the action of seismic load are studied by shaking table test and numerical simulation,and the seismic stability calculation formula of the pile-supported reinforced embankment of the high-speed railway is deduced based on the limit equilibrium theory.These can provide a basis for the seismic design of similar projects.The main research contents and results are as follows:(1)Based on the background of the pile-supported reinforced embankment near the Tan-Lu fault zone of Xuyan high-speed railway,the similarity relationship of the shaking table test was deduced,and the shaking table test model of the pile-supported reinforced embankment was constructed.By applying Landers waves,artificial waves and Kobe waves with different peaks,the dynamic response law of slope acceleration,slope displacement,earth pressure and other indexes of pile-supported reinforced embankment under the action of different intensities and different types of seismic waves is obtained.(2)Combined with the shaking table test model,a three-dimensional numerical model of the high-speed railway pile-supported reinforced embankment was established based on the FLAC3 D software,and the laws obtained from the shaking table test were supplemented by numerical calculation.In addition,the dynamic responses of indexes such as effective stress,internal force of pile body and excess pore pressure ratio of embankment structure under earthquake are compared and analyzed,and the element failure state and liquefaction state of foundation soil under earthquake excitation are discussed.(3)A series of numerical models of pile-supported reinforced embankment under different parameters are established.By numerical calculation,the influence of the ground motion duration,frequency,length of pile body,cross-section size of pile,pile spacing,elastic modulus of geogrid,reinforcement spacing and pile spacing on the acceleration response,slope displacement response,pile internal force response,foundation liquefaction state response and other laws are explored.(4)On the basis of considering the shear strength of the pile body and the tensile strength of the geogrid,the calculation formula of the safety factor of the pile-supported reinforced embankment under earthquake action is deduced based on the limit equilibrium method.On this basis,the influence of various factors on the safety factor of the embankment slope is analyzed,and measures to increase the seismic stability of the embankment are proposed,and suggestions for the seismic design of the structure are put forward.Figure 155,Table 32,Reference 131...