【摘要】 复杂深厚覆盖层的存在,使得从底部基岩输入的地震波在向上传播至结构-地基系统建基面时,地震动特性发生明显改变,进而显著影响其上修建结构的地震反应特性。本文针对峡谷区土石坝复杂深厚覆盖层场地条件,建立能够考虑覆盖层结构性沿竖直和水平方向都变化的场地地震反应分析模型,采用基于有效应力法的有限元分析方法,研究覆盖层结构特性对其地震动特性的影响规律。研究表明:河谷基岩地形条件、覆盖层的厚度、水平向上土层结构性变化、软弱层的存在以及场地上新建土石坝结构等,均会对覆盖层的地震动特性产生明显影响;覆盖层结构性对其地震动特性的影响规律相对复杂,覆盖层不仅使得地震动幅值显著变化,也使得输入地震动的频谱特性发生明显改变。更多还原

【Abstract】 Dynamic response characteristics of the structures constructed on a deep overburden layer are affected obviously by the seismic motion characteristics of soil layer, because the characteristics of seismic motion transmitted from the bedrock under this deep layer are varied greatly by the deep overburden layer. This paper develops the analysis models of ground seismic response considering the horizontal and vertical structural characteristics of the deep overburden layer, and studies the influences of these structural characteristics on the seismic motion of soil layer using a finite element method based on effective stress analysis. The results show that the seismic motion characteristics of deep overburden layer are affected greatly by topographic condition of bedrock, thickness of soil layer, variations of structural characteristics in horizontal direction, existence of soft layer, and new structures constructed on ground. The structural characteristics of soil layer has a relatively complicated influence on the seismic motions of soil layer, it not just significantly affect the amplitude of seismic motion input from bedrock, but also apparently vary the frequency spectrum characteristics of the seismic motion.更多还原