相较于目前地震危险性分析方法广泛采用的经验地震动模型，基于物理机制的地震动数值模拟方法可以全面考虑震源破裂过程、传播路径、以及局部场地的影响，因此在地震工程领域具有广阔的应用前景。本文首先对震源模型、区域波速结构构建方法、宽频带震源反演方法进行了研究，然后在此基础上发展了基于宽频带地震动数值模拟的重大高坝工程场地地震危险性分析方法。主要工作总结如下：（1）为了模拟断层破裂过程细节并生成合理的宽频带地震动，在震源中引入“层”的概念，提出了多层震源模型。多层震源模型由多个具有相同破裂过程的层组成，通过不同尺度的子源叠加描述破裂过程的时空非均匀性并生成宽频带地震动。将总地震矩以适当比例分配到不同层，使生成的宽频带地震动的频谱符合ω-2模型。通过对1994年Northridge地震和情景地震的模拟，验证了多层震源模型的可靠性。（2）针对目前绝大部分地区都缺乏精确波速结构的问题，提出了一种考虑局部场地波速信息的区域波速结构构建方法。系统研究了局部场地波速信息分别与三维区域波速结构和不同的一维区域波速结构融合用于地震动数值模拟的可行性，以及局部场地波速结构调整范围对模拟结果的影响。对1994年Northridge地震的模拟表明，提出的方法可以显著改善宽频带地震动模拟结果。（3）为了揭示与宽频带地震动相关的破裂过程细节，提出了一种宽频带断层破裂过程反演方法。首先通过应用多层震源模型中子源参数的自相似性，对震源模型的变量空间降维。然后采用确定性数值模拟方法计算考虑真实场地模型的格林函数。最后基于多层震源模型和精确的格林函数，采用多目标优化算法反演断层破裂过程。对1992年Landers地震破裂过程的反演表明，提出的方法可以还原与宽频带地震动相关的复杂破裂过程。（4）基于本文发展的宽频带地震动数值模拟方法，建立了一套重大工程场地地震危险性分析方法。首先基于多层震源模型，采用蒙特卡洛方法生成目标场地可能遭遇的情景地震库。然后根据预先计算的潜在震源区域的应变格林张量得到所有可能情景地震在场址的宽频带地震动，用于场址地震危险性分析。该方法采用确定性数值模拟得到工程场址地震危险性曲线，同时能够给出不同地震危险性水平对应的情景地震及其在场址的宽频带地震动，为重大工程场地地震危险性分析提供了新的技术路线。

Compared with the empirical ground-motion models that have been widely used in the current seismic hazard analysis methods, the physical-based ground-motion simulation methods can comprehensively consider the source mechanism, the propagation path, and the effect of local conditions, and thus have vast application prospect in the field of earthquake engineering. To achieve broadband ground motion simulation, the source model, the velocity structure construction method, and the broadband source inversion method are firstly studied in this thesis. Based on the proposed broadband ground-motion simulation method, a novel seismic hazard analysis method for the engineering sites of high dams is further proposed. Here is the summarization of the main achievements:(1) To simulate the complex rupture process and generate broadband ground motions, a multidimension source model is proposed by introducing the concept of “layer”. The multidimension source model is composed of several layers with the same rupture process. The spatiotemporal nonuniformity of the rupture process is described by the superimposed subsources with multi-scales. By assigning the seismic moment to these layers in appropriate proportions, realistic broadband ground motions with the ω-2 spectral falloff can be generated. The multidimension source model is verified by simulating the 1994 Northridge earthquake and a scenario earthquake. (2) Considering that most regions lack accurate 3D velocity structures, a regional velocity structure construction method considering local geophysical information is proposed. The feasibility of coupling local velocity information with 3D velocity structures and different 1D velocity structures for ground motion simulations, as well as the effect of the modification area of local velocity structures on simulation results, are systematically investigated. The simulation of the 1994 Northridge earthquake indicates that the proposed method can improve the generated broadband ground motions greatly.(3) To reveal the details of the rupture process associated with broadband ground motions, a broadband source inversion method is proposed to invert the rupture process of earthquakes. By applying the self-similarity feature of the subsource parameters in the multidimension source model, the dimension of variant space of the source model is firstly lowered. The deterministic numerical simulation method is then used to calculate the Green's functions considering realistic Earth models. Finally, based on the multidimension source model and the accurate Green's functions, a many-objective optimization algorithm is used to invert the final rupture process. The source inversion for the 1992 Landers earthquake shows that the proposed method can indeed reveal the complex rupture process associated with broadband ground motions.(4) Based on the developed broadband ground-motion simulation methods, a seismic hazard analysis method for major projects is proposed. Based on the multidimension source model, the Monte Carlo method is used to generate the scenario earthquakes that may attack the engineering sites. Based on the pre-calculated strain Green's tensor in the potential source area, broadband ground motions of all considered scenario earthquakes at the target site are obtained directly and used in the seismic hazard analysis of the target site. The proposed seismic hazard analysis method uses deterministic numerical simulation to give the seismic hazard curves of the target site. Moreover, scenario earthquakes and their broadband ground motions at the target site for different seismic hazard levels can be given simultaneously. The proposed seismic hazard analysis method provides a new technical route for the seismic hazard analysis of major engineering sites.