Stoneley wave propagation at the solid–solid interface of micropolar rocks

The propagation of Stoneley waves has been investigated at the unbonded interface of two micropolar types of rocks. On solving the governing equation, we observe the propagation of basic body waves for micropolar solid rock. We construct impedance boundary conditions for the unbonded solid–solid interface of micropolar type. Using the boundary conditions considered, the secular equations of Stoneley waves are derived and solved numerically. Two significant modes of waves are obtained to propagate simultaneously at the considered interface. The phase speeds and attenuation coefficients for the two modes are depicted graphically based on different types of micropolar rock. The Stoneley wave speed is found to depend on the micropolar couple modulus and the boundary impedance values of the two solid materials. The phase speed of the second mode mostly decreases with increasing micropolar couple modulus. Certain propagation properties we obtained may be useful for the detection of mineral embedded inside the solid rocks and the Earth’s crust.