Quantitative evaluation method for seismic control effects due to the sidewall of embedded foundation

本研究开发了一种新的频域三维动力相互作用分析方法，该方法可以处理任意形状的埋置地基和粘弹性多层地基，使用32位高质量工作站。在薄层土模型中，用间接边界积分方程法分析了土体的外域。采用轴对称等参元对含有不规则软土的内域进行离散。将虚位移原理应用于外域的刚度方程，得到了总域的组合方程。刚性回填土以较短的自振周期降低了上部结构的最大反应。为了研究侧墙对埋入结构在真实地震作用下的实际反应的影响，利用加速度地震仪和土压力计对一座钢筋混凝土塔楼进行了观测，并将其反应谱与理论计算结果在频率范围内进行了比较，得到了反映侧墙土压力有效程度的参数。

The present research developed a new analytical method for the three dimensional dynamic interacion in the frequency domain which can deal with arbitrary shapes of embedded foundation and visco-elastic multi-layered soil by using a 32bit high quality WORK STATION.The summary of the method is as follows. The outer domain of a soil is analyzed by indirect boundary integral equation method in the thin layered soil model. The inner domain which contains an irregular soft soil is discretized using the axi-symmetric isoparametric finite elements. Combining equations for the total domain are obtained by applying the principle of virtual displacements to the stiffness equation of the outer domain.The results obtained by numerical analyses are as follows. The rigidly backfilled soil reduces the maximum response of the superstrucure with the relatively short natural period. Convesely the softly backfilled soil is usefull for the structure with the relatively long natural period.To investigate the effects of the sidewall on the actual responses of the embedded structure to real earthquake, we obtained the observed data of a reinforced concrete tower with acceleration seismographes and soil pressure guages, and globally evaluated the effects of the sidewalls by comparison of the response spectra of the tower with the theoretical results in the frequency range obtained by using a parameter representing the effective degree of soil pressure along the sidewall.