Dynamic Stress Path under Obliquely Incident P- and SV-Waves

This study derives the expression of dynamic stress components of the soil element in the semi-infinite elastic space under obliquely incident P- and SV-waves, and obtained the corresponding dynamic stress path. The effects of some factors including the incidence angle, Poisson’s ratio, frequency, wave velocity, phase difference, and soil depth on the dynamic stress path are analyzed. It is found that the dynamic stress path in the (σy − σx)/2 − τxy plane is an oblique ellipse, and the above factors have significant effects on that. The maximum dynamic stress level for Poisson’s ratio of 0.3 is about twice that for 0.48. The maximum dynamic stress level for 2.5 Hz is about six times that for 1 Hz. In general, the maximum dynamic stress level is about 40 kPa, no matter how the wave velocity changes. Compared with other phase difference, the dynamic stress level for the phase difference of 60° is largest with a value of 43 kPa. The dynamic stress level becomes greater as the soil depth increases, and the maximum value at 30 m depth is about 40 kPa. The variation trend of the three characteristic parameters with the incident angle exhibits the double-peak or triple-peak curves for different influencing factors. The research findings can provide some guidance for the site seismic dynamic response analysis and structural seismic design.