关于反应位移法中地层变形模式的讨论

Discussion on the Ground Deformation Mode in Response Displacement Method

反应位移法中地层位移的计算方法主要有两种:等效线性化方法和速度反应谱方法。采用基于等效线性化方法的SHAKE91程序,探讨不同地震动水平下考虑不同场地条件的地层变形模式;以SHAKE91的计算结果为基准,对比分析速度反应谱方法计算结果的差异性,从而评价其适用性。结果表明,当地层均匀且剪切波速基本一致时,地层变形模式为标准的正弦曲线形状,速度反应谱方法的适用性较好;而当地层剪切波速的差异性较大时,地层变形模式不再符合正弦曲线形状,此时速度反应谱方法的适用性较差,将不再适用于地下结构抗震设计。

Abstract In Response displacement method, two methods are widely used to obtain the ground deformation： the equivalent linear method and the velocity response spectrum method. In order to investigate the ground deformation mode under seismic loading, the program, SHAKE91 code based on the equivalent linear method was employed to obtain the ground deformation under the scenarios of different ground conditions and various earthquake intensities. The results of SHAKE91 are regarded as the benchmark. For the propose of adaptability validation, results obtained from the velocity response spectrum method were compared with the resuhs from the benchmark. Results show that the ground deformtion mode is expressed in the shape of a standard sine curve, when the soil layer is uniform and the shear wave velocity is constant, and in that case the velocity response spectrum method is validated ; inversely, when the soil consists of layers with significantly different shear wave velocities,the ground defomlation mode becomes irregular, and the velocity response spectrum method is no longer validated and could not be applied in seismic design of underground structures.