Study On Seismic Dynamic Response Of Expressway Bridge-Tunnel Lap Of Weak Surrounding Rock

As an important traffic building,the tunnel is widely used in mountain road engineering.For terrain,geological and environmental factors that may obstruct the traffic,projects like expressway tunnels and bridges connected are increasing quickly.Bridge and tunnel connected section under the condition of the weak surrounding rock is the most easily part that can be damaged in strong earthquake because they are usually in the shallow-buried sections.It is known that the key part of tunnel portal could be damaged or destroyed if the tunnel locates in poor geological condition or affected by weather broken surrounding rock.Therefore,it is a precondition and a vital content to do the systematic and intensive research on the rule of seismic dynamic responses in order to study the characteristics of bridge and tunnel connected section suffering earthquake and seismic measures.Basing on the project-"Research on Seismic Dynamic Response of Bridge and Tunnel Lap Structures Based on Damage Accumulation Effect"(No.:51408617)launched by the National Natural Science Foundation of China,this thesis carries out a large-scale shaking table model test on the seismic dynamic responses of the expressway connected bridge under the condition of the weak surrounding rock and the corresponding numerical simulation analysis.The results are analyzed comparing with the results of the shaking table.The main contents of this thesis include:(1)Basing on the similarity theory,the similarity constants of the main physical quantities,the similarity materials of the model and the arrangement of the measuring points are determined and the experimental loading scheme is established.Then,the two kinds of seismic waves of Wenchuan wave and EI-Centrol wave are taken as the main input wave in the shaking table test study on the weak surrounding rocks tunnel with 1:50.(2)The results of seismic dynamic response of expressway bridge and tunnel section under weak surrounding rocks are analyzed according to the data of partial shaking table model test,showing that the seismic dynamic response characteristics and change rules of acceleration,dynamic displacement and surrounding rocks pressure of connected bridge and tunnel under different vibration intensity and loading method.The variation rule of the acceleration magnification coefficient in the three directions of the lining X,Y and Z are analyzed by changing the acceleration magnification coefficient and the differences.Meanwhile,the influence of the incident direction of the different seismic waves on the bridge section is discussed.The results show that the transverse seismic Structural impact is relatively larger.(3)Based on the three-dimensional bridge-tunnel lap model,the Wenchuan wave(X single direction,Y direction direction)of different direction is taken as an example,and ANSYS is used to analyze the dynamic response of the bridge.Finite element software is used to simulate the dynamic response of the tunnel hole.The numerical simulation results are compared with the model test results.The results show that the two values are close to each other and the main changes are consistent,which prove the results is reasonably.In addition,the internal force characteristics of the measuring points with different distances from the tunnel under the earthquake force are analyzed basing on the numerical model.The results show that the horizontal displacement response of the lining is related to the distance from the hole.