地震波入射方向对边坡地震响应影响的超声模拟研究

Slope stability owing to earthquake actions is a hard problem involving a series of different scientific fields, and is also a hot research point in engineering gelology and engineering seismology. As a foundation for the analysis of slope dynamic stabilities, slope response to earthquakes has been widely concerned. At presedent, approaches to the study of slope responses to earthquakes mainly include in-situ mornitoring of seismic ground motion, physical moddeling by vibration table and numerical simulation by cumputer. Because of the limitation on the stimulating frequency of vibration stables, the physical similarities of the moddeling of "high slope" responses to earthquakes can hardly be satisfied. In addition, attentions put on slope responses to seismic waves with different incident directions are very little. In consideration of these two problems in the study of slope response to earthquakes, a proposal of research on slope responses to seismic waves with different incident directions is put forward: overcome the frequency obstacle of vibration stables to the moddeling of "high slope" responses to earthquakes by the high frequency advantage of ultrasonic moddeling; confirm the methodological value of ultrasonic moddeling approch to the study of slope responses to earthquakes by means of ulatrasonic moddeling expriments and numerical simulations by computer; reveal the characteristics of dynamic responses of typical shaped slopes with uniform media to seismic waves with different incident directions, so as to lay a foundation to probability analysis of slope damages by earthquakes. The main researchs in this project include: (1) the variation in dynamic responses of slopes to the stimulation of weak to strong seismic waves; (2) ultrasonic modeling method for slope response to seismic waves with different incident directions; (3) wave field characteristics in a typical shaped slope with a uniform medium stimulated by seismic waves with arbitrary incident directions. The key scientific problems to be resolved are as follows: (1) significance and value of ultrasonic modeling for slope respones to earthquakes; (2) key techniques for simulating the incidence of a plane wave by ultrasonic point source; (3) time and space relationship between the vibration mode and the wave field of slope resoponse to earthquake. The study of this project will be divided into two parts: approach exploration and stimulaiton of slope response to earthquake. The first part, approach exploration, will work on a simple slope to test stimulating method with ultrasonic point source and to confirm the value of the ultrasonic modeling approach; and the second one will carry out contrastive research between ultrasonic modeling and numerical simulation so as to reveal the charachteristics of slope dynamic response to seismic waves with different incident waves.

地震作用下的边坡稳定性是一个涉及多学科交叉的难题，是当前岩土工程和地震工程学研究的热点之一。边坡地震动力响应研究是边坡动力稳定性分析的基础，已经受到了普遍关注。当前对边坡地震动力响应研究的方法主要有现场地震动监测、振动台模拟实验和计算机数值模拟。由于振动台激振频率的限制，"高边坡"地震动力响应的振动台模拟很难满足物理相似性要求。另外，当前对斜入射地震波激励作用下边坡地震动力响应的研究十分有限。针对边坡地震动力响应研究中的这两个问题，本项目提出了地震波入射方向对边坡地震响应影响的超声模拟研究的目标：利用超声地震模型试验方法的高频优势突破振动台模拟的频率障碍；采用超声地震模拟和计算机数值模拟相结合的方法，确认超声波地震模拟方法对边坡地震动力响应的研究价值；揭示典型均质边坡对不同方向入射的地震波激励的动力响应特征，从而为边坡地震破坏方式的概率分析奠定基础。

边坡地震稳定性是涉及多学科交叉的难题，边坡地震响应是边坡地震稳定性分析的基础，已受到普遍关注。目前，边坡地震响应研究的方法主要有现场地震动监测、振动台物理模拟和计算机数值模拟。由于振动台激振频率和激振方式的限制，振动台模拟很难满足“高边坡”地震响应的物理相似性要求，也无法实现地震波斜入射激振。针对边坡地震响应物理模拟技术面临的这两个问题，本项目提出了地震波入射方向对边坡地震响应影响超声模拟的研究目标：利用超声波的高频优势突破振动台模拟的频率障碍，实现点源激振模拟平面波任一方向入射激振；利用超声模拟和数值模拟相互验证，确认超声模拟方法对边坡地震响应研究的价值；揭示边坡地震响应和破坏方式的多少样性，为边坡地震破坏概率分析提供依据。.项目研究取得的研究成果包括：确定了高边坡地震响应超声模拟物理相似性条件和边坡模型建造方法；证明了弱震与强震激励边坡地震响应波场振型的一致性，确认了超声模拟对边坡地震响应研究的意义和价值；形成了点源激振模拟任一方向入射平面波激振边坡地震响应的成套技术；通过模拟实验，揭示了平、凸、凹三种形态坡面边坡对斜入射体波激振响应的波场特征，与同条件的边坡地震响应数值模拟对比，验证了边坡地震响应超声模拟方法的有效性。迄今为止，已发表英文SCI论文1篇，因专利申请优先原则，成果发表相对滞后；申请发明专利3项，其中申请美国专利1项；培养毕业博士生1名、硕士生14名。.项目研究形成的一套边坡地震响应超声模拟方法，既能满足物理相似性要求，又可实现任一方向入射平面波激振，填补了高边坡地震响应物理模拟方法空白，对克服天然地震边坡地震响应观测时机难以把控、数值模拟结果物理验证手段缺乏，具有不可替代的作用。应用这套方法研究不同方向入射平面波激振边坡地震响应，了解边坡地震动力响应振型和破坏方式的多样性，对于边坡地震稳定性评价和地震地质灾害评估具有重要意义。