Scattering Of SH-wave By Shallow Buried Debonded Inclusions Under A Subsurface Layer

The seismic design of structure and its safety evaluation is a super important problem for engineering designer to concern about.Interface delamination between the structure and the media is a behavior which common occurred and then impacted the overall failure.Exist of debonding zone is just the direct cause of disastrous damage.And,estimating the influence of the dynamic stress concentration and ground motion by covered layer is an important subject in earthquake engineering.In the past research,relatively few man analyzed the scattering of elastic waves by debonded inclusions in half space.The main problem in this paper is to solve the dynamic response of steady SH-wave scattering by partially debonded cylindrical inclusions in a layered half space.Three calculation models of single debonded inclusion,debonded inclusions and non-debonded inclusions,debonded inclusions and cavities are established in solving process.First,through large-arc assumption method,we transform the straight boundary into a new curved-surface boundary in half space,with the theory of Helmholtz,the general solution of the Biot’s wave function is attained.Utilizing the multi-polar coordinate shift technology,we set up the scattering wave’s displacement field of inclusions and cavities expressed by Hankel function and standing wave’s displacement field expressed by Bessel function in inclusions.Then,with the aids of complex function method,wave functions expansion method and the boundary being satisfied,the problem is just to solve the infinite linear algebraic equations with unknown coefficients and the numerical solution by truncating equations.Finally,variations of dynamic stress concentrations around the debonded inclusions under the condition of different media parameters combination were discussed in numerical examples.The results show that:the shallow structural defects is often amplified dynamic stress concentration,dynamic stress concentration can also be weakened under certain conditions;variation of stiffness and thickness of the covering layer have great influence on the scattering of SH-waves and can significantly change the distribution of dynamic stress concentrations around shallow debonded inclusions;Dynamic stress concentration factor of debonding edge changes dramatically because of the existence of debonded inclusions,debonding edge(start point and end point)will appear strong phenomenon of stress concentration,stress increases greatly compared with non-debonded inclusions under the same conditions,so the debonding edge should be the weakest place of the debonding structures.