Scattering Of ElasticWaves By Underground Group Cavities

Scattering and diffraction of earthquake waves by the underground groupcavities can affect the ground motion near the group cavities and the dynamic stressconcentrationfactor,andfurtheraffectthebuildings abovetheground.Therefore,itisimportanttosolvetheproblembothintheoryandinengineeringapplication.In this paper, an indirect boundary integral equation method will be used tostudy the scattering of plane waves by underground group cavities in half-space. Thetotal wave field is superposed byfree field and scattered field. Based on the theoryofsimple layer potential, scattered wave field is constructed by distributed line sourceson the virtual source plane. The density of the virtual wave source can be gained bysolving the equations which are derived by boundary conditions. Finally, the wholewavefieldcanbeachieved.Theaccuracyofthenumericalresultischecked upbytheanalyticsolutionandresidualerrorsofboundaryconditionswiththeincreaseofthetruncationorder.Atthesametime,theeffectsofsomefactorssuchasthefrequencyoftheincident waves,theangle of the incident waves and the distance between the group cavities on thedynamic stress concentration factor on the wall of the cavities and also the groundmotion are illustrated. By the analytic solution of the scattering with undergroundgroup cavities subjected to plane P, SV and Rayleigh waves, we can analyse theeffects of the ground motion and the dynamic stress concentration factor due to theunderground group cavities. It is useful for further studding the scattering of plane P,SV and Rayleigh waves by underground group cavities in half-space. The numericalresult shows that there are significant amplified effects on ground motion anddynamic stress concentrationfactorduetothe existingofunderground groupcavities.The analysis result of the thesis provides foundations for the anti-seismic design ofundergroundgroupcavitiesandtheevaluationofareasanti-seismiclevels.