This paper reports a series solution of wave functions for two-dimensional scattering and diffraction of plane SH waves induced by a symmetrical V-shaped canyon with different shape ratios. A half-space with a symmetr...This paper reports a series solution of wave functions for two-dimensional scattering and diffraction of plane SH waves induced by a symmetrical V-shaped canyon with different shape ratios. A half-space with a symmetrical V-shaped canyon is divided into two sub-regions by using a circular-arc auxiliary boundary. The two sub-regions are represented by global and local cylindrical coordinate systems, respectively. In each coordinate system, the wave field satisfying the Helmholtz equation is represented by the separation of variables method, in terms of the series of both Bessel functions and Hankel functions with unknown complex coefficients. Then, the two wave fields are described in the local coordinate system using the Graf addition theorem. Finally, the unknown coefficients are sought by satisfying the continuity conditions of the auxiliary boundary. To consider the phase characteristics of the wave scattering, a parametric analysis is carried out in the time domain by assuming an incident signal of the Ricker type. Surface and subsurface transient responses demonstrate the characteristics and mechanisms of wave propagating and scattering.展开更多
基于1137个钻孔资料的场地模型及相应的土层地震反应分析计算结果,从场地地震动峰值加速度和特征周期两方面讨论分析了中国《建筑抗震设计规范:GB50011—2016》和美国规范IBC(International Building Code)中的场地分类方法。依据场地...基于1137个钻孔资料的场地模型及相应的土层地震反应分析计算结果,从场地地震动峰值加速度和特征周期两方面讨论分析了中国《建筑抗震设计规范:GB50011—2016》和美国规范IBC(International Building Code)中的场地分类方法。依据场地效应一致性分析得出:在中硬土场地上,美国的C类场地的离散性最小;在中软土场地上,中国的Ⅲ类场地表现出一定的弱势性;在软弱土场地上,中国的Ⅳ类场地优势性明显。总体上中国的双指标分类方法体现了一定的优势性。因此,提出了新的场地分类方法,方法中按照覆盖层厚度和30 m两者较小值的土层计算等效剪切波速,并将目前的Ⅱ类场地划分为Ⅱ1和Ⅱ2,将Ⅲ类场地中覆盖层厚度大于50 m且等效剪切波速小于等于170 m/s的场地归类到Ⅳ类场地,500 m/s以下的等效剪切波速分界线提高20 m/s。研究为建立更合理的场地分类方法提供新的解决方案。展开更多
基金National Natural Science Foundation of China Under Grant No.51278382
文摘This paper reports a series solution of wave functions for two-dimensional scattering and diffraction of plane SH waves induced by a symmetrical V-shaped canyon with different shape ratios. A half-space with a symmetrical V-shaped canyon is divided into two sub-regions by using a circular-arc auxiliary boundary. The two sub-regions are represented by global and local cylindrical coordinate systems, respectively. In each coordinate system, the wave field satisfying the Helmholtz equation is represented by the separation of variables method, in terms of the series of both Bessel functions and Hankel functions with unknown complex coefficients. Then, the two wave fields are described in the local coordinate system using the Graf addition theorem. Finally, the unknown coefficients are sought by satisfying the continuity conditions of the auxiliary boundary. To consider the phase characteristics of the wave scattering, a parametric analysis is carried out in the time domain by assuming an incident signal of the Ricker type. Surface and subsurface transient responses demonstrate the characteristics and mechanisms of wave propagating and scattering.
