Bearing Capacity of pile against Rocking of Tall Buildings under Earthquake Motions

首先，我们考虑结构在强震地面运动的反应，并估计重复荷载的基础桩的属性。采用模型桩和砂土模型地基进行了模型试验。为了控制小拔出，对夹具进行了巧妙的改进。试验中采用了两种直径进行有效测量。当重复加载次数小于5次时，表面摩擦阻力随重复加载次数的增加而减小。当重复加载次数超过5次时，桩侧摩阻力比未拔出时减小约40%。在试验中，剪切力的比例是稳定的。这说明侧摩阻力与侧土压力有关。1995年1月17日发生科比地震后，人们注意到了地震的加载速度.在这个项目中，没有估计速度的影响。速度的影响应通过其他方法来研究。

First of all, we considered structural response at the strong earthquake ground motions, and estimated properties of repeated load for footing piles. Then, model tests were carried out, using model pile and model ground of sand. For the control of small pull-out, jig was ingeniously improved. Two kinds of diameters were used in the tests for effective measurement. Skin friction resistance decreased by the number of times of repeated loading when the number was less then five times. The skin friction resistance was about 40% smaller than the case of no pulling-out when the number of repeated loading was more than five times. In the tests, the ratio of shear forces were stable. This means that skin friction resistance was related with lateral soil pressure. After Kobe earthquake, occures on January 17,1995, velocity of loading has been noted. On this project, the effect of velocity was not estimated. The effect of velocity should be investigated by the other ways.