STUDY ON SEISMIC GROUND MOTION OF BEDROCK-SATURATED SOIL-UNSATURATED SOIL SITE WITH P-WAVE INCIDENT UNDER THERMAL EFFECT

Based on the theory of elastic wave propagation under thermal effect, the problem of seismic ground motion under the site is studied by establishing the model of P wave incident bedrock-saturated soil-unsaturated soil site. Based on the Helmholtz decomposition principle, combined with the boundary conditions, the wave field in the site under the thermal effect is analyzed, and the analytical solution of the seismic ground motion of the plane P wave incident bedrock-saturated soil-unsaturated soil site is obtained. Through numerical simulation, the influence of physical and mechanical parameters such as thermal conductivity, saturation and groundwater level on the seismic ground motion of the site is analyzed. The results show that when considering the thermal effect and isothermal conditions, the site displacement amplification coefficient shows a significant difference. In particular, the displacement amplification factor under isothermal conditions is generally greater than the value when the thermal effect is considered; the change trend of the horizontal displacement amplification coefficient is positively correlated with the increase of the thermal expansion coefficient and the phase delay time of the heat flux. At the same time, when the medium temperature and saturation increase, the horizontal displacement amplification coefficient shows a downward trend; For the vertical displacement amplification factor, its change pattern is positively correlated with the increase of heat flux phase delay time, medium temperature and saturation. However, when the thermal expansion coefficient increases, the vertical displacement amplification coefficient shows a decreasing trend. In addition, the increase of the thermal conductivity has no significant effect on the displacement amplification factor of the free site, indicating that the thermal conductivity has little effect on the change of the displacement amplification factor of the site. When considering the influence of groundwater level, the horizontal and vertical displacement amplification coefficients gradually increase with the increase of groundwater level under thermal effect. On the contrary, the displacement amplification coefficient decreases under isothermal conditions.