Ultrasonic Simulation Of Seismic Waveincident Direction Impacting On The Seismic Response Of Slope

Earthquake disaster is one of the serious natural disasters which will cause serious economic losses and casualties.Landslide is one of the major secondary disasters of earthquakes.In order to prevention seismic landslide hazard,it's necessary to study slope seismic response.The accuracy of slope seismic response numerical simulation depends on the rationality of the numerical models and dynamic constitutive relationship while it's also essential to verify the results of slope seismic response test.The current slope seismic physical simulation studies on dynamic response by vibration table cannot meet the physical model similarity requirement,and failed to achieve seismic wave excitation under different incident orientation.For the development of a system that meets the need of wave similarity and contribute to the study of physical simulation about the relationship between slope and seismic wave excitation with different incident orientation,the study focus on the exploration of the ultrasonic physical modeling method of slope seismic response.To overcome the deficiency that the size of model used in the vibration table simulation test is inconsistent with the actual ones,we first designed three two-dimension ultrasound physical experiment models considering three species typical slope,flat,and convex,and concave,based on the ratio of similitude;then,to determine a reasonable grid density through laying out observation points and inspired points locating on bottom of model;after that,to achieve the excitation inducing by the incident that plane wave P and SV wave acting on the slope,we took the method of exciting point by point at the bottom of slope according to the Huygens'principle and the direction characteristics of transmitting transducers;and then to collect and record the time course of plane wave P and SV vibration acting on each observation point taking the vibration characteristics of wave field inducing by plane wave and the directional characteristic of receiving transducers into accounts.In addition,according to the Huygens'principle,to analyze the method of the synthesis of excitation inducing by the oblique incident of plane wave by point excitation from the bottom of the model,we used the vibration data generated by different exciting way to compose the time course of wave field vibration of slope model inducing by different incident angles of different plane wave and we got corresponding wave field intensity distribution.Finally,to verify the similarity between the ultrasonic physical simulated results and the numerical simulation results by comparing their wave field intensity distribution under the same conditions.The results show that it is reasonable to use the ultrasonic physical model to simulate the seismic response characteristics of seismic slope and it can achieve seismic wave excitation under different incident orientation;Concave and convex slope have divergence and convergence effect on the seismic waves propagating in the slopes among which a concave slope will weaken the seismic vibration response while a convex slope will play a role of reinforcement.Under the excitation of plane waves SV or P waves,the rhythms of the wave field intensity distributions are quite obvious no matter in the flat,convex or concave slopes.The results also show that under the excitation of plane wave P,the rhythms of the wave field intensity distributions along the height of the flat slopes are related to the wavelength of wave P to a certain extent.The relationship of the distance between strong vibrations?L₁?and wavelength???is L₁=?/15;The relationship of the distance between strong vibrations along the height direction?L₂?and wavelength???is L₂=?/10.The relationship of the distance between strong vibrations of different types of slopes is as follow:convex slope>flat slope>concave slope.This study develops a systematic method of studying seismic response of slope by ultrasonic physical simulation through analyzing seismic response characteristics of slopes with different incident orientation and provides the research of seismic response of slope a physical simulated method which meets the requirement of similarity.