Effect of Canyons and Their Interaction on Ground Response to Vertically Traveling SH Waves

Document Type : Geotechnical Earthquake Engineering


Shiraz University


In this paper the dynamic response of the ground surface subjected to vertically traveling two dimensional harmonic SH waves in the presence of a single or two canyons is investigated using boundary element method. The models consist of one and two semicircular canyons cut from a homogeneous, linear and viscoelastic half space. The total response is computed by summing up the responses of free field and scattered waves. The former is calculated from the closed form solution of propagated waves in the half space and the latter from the boundary element method. For this, surface irregularities are discretized by linear elements and influence coefficient matrices are obtained by using harmonic fundamental solutions. To validate the technique, the response of a single canyon and its nearby ground surface due to harmonic SH waves with different frequencies is determined and compared with the existing closed form solution. Then, the response of double canyon is determined by the same procedure. Results of analyses indicate that the distance between canyons is a key parameter that affects the surface displacement amplitude of both canyons. It is demonstrated that when this distance is increased, the response of both canyons approach to that of a single one. Furthermore, it is shown that the interaction is also very much dependent on the frequency of the incident wave.