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IMECH-IR  > 流固耦合系统力学重点实验室(2012-)  > 学位论文
Title:
滑坡涌浪产生过程及近场特征的数值研究
Alternative Title: Numerical Study on Generation Processes and Near-Field Characteristics of Landslide Induced Impulse Waves
Author: 石传奇
Abstract:

滑坡失稳进入水库将会引起巨大的涌浪,严重危害到库区内航行船只和沿岸居民的安全,甚至会对水库大坝产生威胁。本文针对滑坡涌浪的产生过程和近场特征这一关键问题,以滑坡体与水体的相互作用为切入点,深入开展了基于流固耦合的滑坡涌浪数值模型研究,进一步重点分析了涌浪产生的力学机制、首浪波形和三维特征,以及复杂边界对涌浪近场特征的影响等。取得的主要成果包括:

1.将滑坡体简化为刚体,应用N-S方程改进以往用浅水方程描述复杂流体运动的缺陷, 采用基于拉格朗日描述的光滑粒子流体动力学(SPH)方法,建立了块状刚体滑坡涌浪的三维流固耦合数值模型,能够合理模拟滑坡体与水体相互作用诱导涌浪的全过程,并得到了典型实验结果的良好验证。将模型应用于荒田滑坡涌浪实际问题,很好地再现了荒田滑坡涌浪的产生和演化过程, 给出了荒田滑坡涌浪主要特征和爬升过程的定量结果。并对涌浪在深V河道里的近场特征进行了分析。

2. 针对滑坡体大多为可变形岩土体的特点,通过引入土体弹塑性本构关系,合理描述土体的大变形及破坏过程,将土体的变形破坏过程和水体运动过程统一起来,建立了基于SPH方法的可变形滑坡涌浪的三维水土耦合数值模型,首次实现了对复杂可变形滑坡诱导涌浪的水土耦合数值模拟,揭示了滑坡涌浪产生的内在力学机制。通过数值模拟以及与非牛顿流体模型的对比分析,显示了模型更好的物理意义和模拟精度,并发现土体剪胀角对模型计算具有不可忽略的影响。

3. 运用建立的刚体滑坡涌浪模型,对滑坡涌浪的首浪特征进行了细致的数值模拟研究。细致分析了不同条件下产生涌浪的首浪类型和特征,给出了首浪的波浪参数(波速、波高、波长等)与滑坡体入水Froude数和滑坡体相对厚度的关系;进一步细致讨论了滑坡产生涌浪过程中的能量转化机制,以及与非线性的相关性,发现水体获得的最高能量与非线性参量Ursell数有着较高的相关性,给出了产生不同首浪波形的临界判断条件。

4. 利用可变形体滑坡涌浪水土耦合模型,深入研究了河道型水库中,由于边界受限,滑坡涌浪的产生、演化过程及其独特近场三维特征。重点研究了首浪向对岸的传播和爬升过程,根据涌浪是否出现衰减过程,将河道分为相对宽河道和相对窄河道,得到了相对窄河道中首浪高度在上下游传播的衰减函数;发现河道型水库的滑坡涌浪受边界条件约束,一般难以充分发展,能够向上下游传播的涌浪高度一般明显小于滑坡体冲击产生的首浪高度,为合理预测涌浪的传播提供了重要的科学依据。

English Abstract:

Landslides may generate large impulse waves in lakes or reservoirs, which have a high potential to cause direct damage to the reservoir buildings and residents, and even result in the loss of life. The accurate estimation of the landslide-induced wave hazard is still an open problem because of its complexity. Suitable fluid-solid coupling models are developed here to simulate the interaction between the landslide and water. Focus on the the generation process and near-field characteristics of landslide induced impulse waves, we have discussed the generation mechanism of impulse waves, wave type and three dimensional charateristics of the leading wave, and the effect of complex boundary condition on the near-field charateristics. The main contents of this dissertation are as following:

1. A 3D solid-fluid coupling model is developed to simulate the impulse waves generated by a rigid body. Based on the smoothed particle hydrodynamics (SPH) framework, this model, using Navier-Stokes equations, can be much better than shallow water equations when simulating the complex flow field. Two typical experiments are used to validate this model and a good agreement about the whole generation process is observed. Then the model is used to study the initial wave in Huangtian landslide event. The complete three-dimensional evolution of the initial wave is obtained and its quantitative results, including the runup process, are obtained. The near field characteristics of impulse waves generated in a deep-V channel is also studied.

2. A newly-developed 3D soil–water coupling SPH model is developed to simulate the generation of a landslide-induced impulse wave. To simulate the large deformation and failure flow of the landslide, an elasto–plastic constitutive model is included. It’s the first time to realize the soil-water coupling simulation about the impulse waves generated by a complex deformable landslide, helpling to obtain the generation mechanism of the impulse waves. Comparison with non-Newtonian fluid model shows the better physical principles and simulated precision of our model. Also the influence of the dilatancy angle of soil is found to be non-negligible.

3. Using the solid-fluid coupling SPH model, the charateristics of the leading wave is studied carefully. The wave type of the leading wave and its charateristics (wave height, wave velocity, wavelength et al.) is analyzed on different initial conditions including different impact Froude number and relative slide thickness. Energy transfer process is also studied and the high relativity between the crest value of mechanical water energy and nonlinearity parameter Ursell number is obtained. Then the criteria of wave type classification based on different parameters are studied.

4. Using the soil-water coupling SPH model, we have simulated the whole process where landslides rush in to a 3D fjord river channel. Because of the limited boundary of the channel, the generation and evolution processes have special 3D near-field characteristics. Focusing on the process of propagation to the opposite shore and later runup, the channel is separated into relative wide and relative narrow based on the existence of decline stage. The amplitude decline function of the leading wave propagating along the relative narrow channel is also obtained. Analysis of detailed near field wave characteristics shows that the formation and magnitude of the initial wave are strongly constrained by topography in the fjord channel. The different amplitude between the near field waves which propagate along the river and the namely initial wave is analyzed, which is helpful for accurately predicting the leading wave.

Degree Level: 博士
Issued Date: 2018-05-25
Degree Grantor: 中国科学院大学
Place of Degree Grantor: 北京
Supervisor: 刘青泉
Keyword: 滑坡涌浪,近场特征,水土耦合,光滑粒子动力学方法,数值模拟
Major: 流体力学
Language: 中文
Other responsible: 中国科学院力学研究所
Content Type: 学位论文
URI: http://dspace.imech.ac.cn/handle/311007/77517
Appears in Collections:流固耦合系统力学重点实验室(2012-)_学位论文

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Recommended Citation:
石传奇. 滑坡涌浪产生过程及近场特征的数值研究[D]. 北京. 中国科学院大学. 2018-05-25.
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