Based on the spherical cavity expansion theory in the elastic half space, the ground surface movement characteristics of shallowly buried explosions are analyzed. The results show that the induced seismic wave is a longitudinal wave in the near zone and a Rayleigh wave in the far zone. The maximum displacement (velocity) of the longitudinal wave and the Rayleigh wave are inversely proportional to the scaled distance, and can be described by exponential function with exponents equal to 1.4 and 0.5, respectively. The vibration frequencies of the waves have almost no change. The vibration frequency of the longitudinal wave approximates the natural vibration frequency of the cavity in the broken area, and the vibration frequency of the Rayleigh wave is about half that of the longitudinal wave. On the same reduced buried depth and reduced distance, the particle displacement is directly proportional to the product of the boundary loading and cavity radius, and is inversely proportional to the transversal wave velocity. Meanwhile, the particle velocity is directly proportional to the boundary loading and inversely proportional to the wave velocity ratio. In the far zone, the buried depth of the explosive only has a slight effect on the longitudinal wave, but has a larger effect on the Rayleigh wave.

Ground surface response induced by shallow buried explosions

The theory of Hankel transforms is used to obtain the displacement field forSH waves generated by time harmonic, buried, torsional sources in semi-infinite heterogenous media in which material properties are functions of the depth coordinate. An application to a heterogeneous medium with exponentially varying properties has been discussed. Surface displacements from a surface source have been evaluated at large distances from the source. The results have been compared with those for the homogeneous medium.

SH waves from torsional sources in semi-infinite heterogeneous media

A S.H. point source in heterogeneous elastic medium where the modulus of rigidity and density vary exponentially with depth has been considered. The form of disturbance due to such a point source in a semi-infinite medium has been obtained in integral form. The integrals are evaluated by contour integration.

Tapan Kumar De

Papers

On S. H. point source in heterogeneous medium