地震波倾斜入射下岩质边坡动力响应特征及破坏失稳机理研究

For near-fault earthquakes, the influence of incident angle on the earthquake-induced landslides cannot be ignored. However, most of the current researches on earthquake-induced landslides assume that the earthquake waves are vertical incidence, it is unreasonable for the near-fault earthquakes. To address this problem, based on the propagation characteristics of the seismic waves and the mechanical mechanisms of the viscous artificial boundary, an input method for oblique incidence in the numerical simulation is developed in this project. A study area is selected and the calculation method for earthquake wave incident angle is determined. The incident angle is regarded as a variable, the dynamic response of the rock slope is studied in this project. According to the 3D representation in the time-frequency-amplitude associated domain of the seismic energy carried by earthquake waves, the energy distribution and propagation characteristics in the rock slope mass are studied. The failure mechanism of the rock slope under the oblique incident seismic waves is also studied, and finally a sliding displacement experience model for the earthquake-induced landslides is developed in this project. The research of this project aims to improve the cognitive level of the mechanism of earthquake-induced landslides, provide theoretical basis for the prevention and control of earthquake-induced landslides, and provide technical reference for improving the earthquake disaster reduction system in China.

对于近源地震而言，地震波倾斜入射角度对地震滑坡的影响不容忽视，但现有地震滑坡研究中多假定地震波为垂直入射，这对于近源地震是不合理的。本项目基于地震波传播特性及粘性人工边界的力学机制，研究建立地震波倾斜入射在数值分析中的实现方法。在此基础上，选取研究区域，确定典型地震滑坡，建立数值分析计算模型。采用三维时-频-幅联合域分析方法，以地震波倾斜入射角度作为研究变量，对地震波倾斜入射下岩质边坡的动力响应特征进行研究。基于地震波能量的三维时频域表征方法，研究地震波倾斜入射下岩质边坡内部的地震波能量分布及传播特征。研究地震波倾斜入射下岩质边坡的破坏失稳机理，并最终建立考虑地震波倾斜入射角度的地震滑坡滑动位移经验模型。本项目研究旨在提升地震滑坡诱发机理的认知水平，以期为今后地震滑坡灾害的防治提供理论依据，为健全我国的防震减灾体系提供技术参考。

摘要：通常在岩质边坡地震响应研究中，均假定地震波为垂直向上一致激励。这一假定对于远源地震是合理的。远源地震中，地震波经过地层的连续折射，可以近似认为地震波到达地表附近时为垂直向上传播。但在近源地震中，因地震波折射路径较短，地震波将以一定的倾斜角度到达地表附近。所以，研究岩质边坡对斜入射地震波的动力响应成为急需解决的问题。本文利用3DEC离散元分析软件，通过建立三维模型，在不同入射条件下，利用El Centro地震波激发三种坡度的边坡，坡角分别为30°、45°和60°。记录面坡与背坡的10个监测点，分析了SV波不同角度斜入射下面坡与背坡的加速度响应与位移响应。计算了坡面各点的峰值加速度，不同监测点之间、对应监测点之间进行对比分析，验证了“背坡效应”，找到了“最损伤角”。结果表明，入射角度和边坡坡角显著地影响了边坡的动力响应。最后，针对坡面滑动失稳进行了分析，分析了地震滑坡的不同类型与成因，判断出在地震波倾斜入射时滑坡失稳的类型与特点。