关键词: 深厚覆盖层, 土石混合体, 高填方人工半岛, 地震反应, 永久变形

Abstract: In high seismic intensity reservoir areas, the seismic performance of high filled artificial peninsula with soil-rock mixtures on deep overburden is a key issue that needs to be considered in engineering design and construction. The seismic response of such structures is complex, not only affected by seismic waves, but also by the interaction between the overburden and the filling body. This paper takes the construction project of the Xiangbiling residential settlement in the Baihetan hydropower station reservoir area as the research background. Based on the geotechnical investigation results of the engineering site and structure design documents, a three-dimensional finite element refined model of the artificial peninsula-foundation-upper structure system is conducted using the finite element software MIDAS GTS/NX. According to field and laboratory test data, the physical and mechanical properties and constitutive model parameters of various geotechnical materials and filling materials are determined. Based on the seismic safety evaluation results of the site, the trigonometric series method is used to synthesize the artificial seismic waves with a 50 years exceedance probability of 10% for the engineering site. Through elastic-plastic dynamic time history analysis, the dynamic interaction mechanism, seismic response, and permanent deformation characteristics of the artificial peninsula-foundation-upper structure system are studied. The research results indicate that under the action of fortification earthquakes, the peak acceleration distributions along the transvers, longitudinal, and vertical directions at the central axis of the artificial peninsula generally shows a trend of first decreasing and then increasing with elevation, and their maximum acceleration amplification coefficients are 1.43, 1.81 and 1.67, respectively; The peak relative displacement along the transvers, longitudinal, and vertical directions at the central axes of the artificial peninsula reveals a non-linear increasing relationship with elevation, and the displacement in the transvers direction exhibits a clear whiplash effect; The maximum permanent deformation of the top platform along the transvers and longitudinal directions are 12.2 and 1.7 cm, respectively, which are much smaller than the limit given in the specifications; The maximum settlement of the top platform is 7.6 cm, and the corresponding seismic settlement rate is 0.25%, which is much smaller than the limit given in the specifications.

Key words: deep overburden, soil-rock mixture, high filled artificial peninsula, seismic response, permanent deformation