滑坡涌浪的产生过程及近场特征研究

Huge impulse waves are usually induced in slope failure accidents occurring in reservoirs, which are commonly addressed as landslide induced impulse waves. Landslide induced impulse waves often cause serious disaster as the huge wave. Effective estimation and prediction of occurrence and characteristics of the impulse waves are of great scientific significance and engineering value. Focusing on the generating process of the landslide induced impulse waves, great attention would be paid on the mechanism and near-field characteristics of the initial stage in the impulse waves generating processes in this proposal. As the coupling of landslide body and reservoir water in the impact process are regarded as the key to this problem, developing accurate experimental and valid numerical methods which could deal with this coupling problem is crucial. The smoothed particle hydrodynamics(SPH) method, a Lagrange description based method, is employed in numerical simulation to describe the motion and deformation of water(newtonian fluid) and landslide body which include soil(modeled as elastic-plastic continuum) and rock blocks(modeled as discreted rigid blocks) simultaneously and directly, especially the interaction between them explicitly. On the other hand, several meticulous laboratory scale experiments focusing on the measurement of interaction intensity and impulse wave characteristics are also designed. Experimental data will be used to validate the numerical model and discuss the connection between interaction intensity and the wave features. Thus, the generation process of the impulse waves could be studied detailedly and reasonably both from numerical and experimental methods, where novel knowledge could be obtained in this study. Based on series of numerical and laboratory experiments, the mechanism in the interaction of landslide body and water will be analyzed, the modification on landslide velocity after impacting water could be generalized, and the three-dimensional characteristics and patterns of the initial impulse waves will be studied. With the study on the generation mechanism and characteristics of the impulse waves, an effective simulation method dealing with complex landslide induced wave problems will be developed, and a simplified estimate equation for engineering using will be generalized too. A demonstration of the numerical simulation study on practical landslide induced impulse wave problems in the Three Gorges areas will be carried out at last. And an effective and practical method for prediction of initial impulse wave in reservoir landslide problems could be expected.

地质体滑坡失稳入水往往引起巨大的涌浪，造成严重灾害，合理分析预测涌浪的产生和特征，具有重要科学意义和应用价值。本项目针对滑坡体失稳入水产生的涌浪问题开展研究，重点关注滑坡入水涌浪产生的力学机制和初期（近区）特征这一关键问题。以水体与滑坡体的相互作用及其产生的涌浪首浪的三维特征为切入点，采用基于Lagrange描述的光滑粒子动力学（SPH）方法，建立复杂滑坡涌浪产生过程的数值模型，实现滑坡体与流体及其相互作用的流固土全耦合模拟。同时辅以针对性的机理性实验，对涌浪的产生过程进行细致地数值模拟和模型实验研究，分析滑坡体与水体的强耦合作用机制，讨论滑坡体入水后的滑动速度修正，揭示涌浪首浪的产生机制和特征，得到首浪特征的变化规律，最终建立模拟复杂滑坡涌浪产生过程的有效手段和首浪特征参数的估算公式，并开展初步应用，为水库滑坡涌浪预报提供有效分析方法。

滑坡失稳入水往往引起巨大的涌浪，并造成严重灾害。由于滑坡涌浪产生过程中的复杂水土耦合作用，对滑坡涌浪的精确模拟和预测，以及对涌浪特征的认识是个一直被关注而尚未解决好的重要科学问题。本项目针对这一问题，系统地研究了滑坡涌浪产生的水土耦合力学机制、数值模拟方法和涌浪的近场特征，取得如下重要进展：(1) 针对滑坡体在失稳滑动过程往往产生大变形和破坏的特点，将土体看作弹塑性体，基于二维本构关系，构建了基于Drucker–Prager模型的土体三维弹塑性本构关系，首次建立了基于SPH方法的滑坡体失稳产生大变形与破坏的三维数值模型，得到了实验资料的良好验证，实现了滑坡体大变形及破坏过程的三维数值模拟。（2）针对涌浪产生过程中的典型水土耦合特点，采用基于拉格朗日观点的光滑粒子动力学（SPH）方法的优点，将土体的变形、破坏过程和水体的运动过程统一起来，建立了基于N-S方程和SPH方法的三维滑坡涌浪水土耦合数值模型，能够合理模拟滑坡体的复杂变形破坏及其与水体的相互作用过程，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。（3）运用建立的三维滑坡涌浪水土耦合模型，对滑坡涌浪的首浪和近场特征进行了细致的数值实验研究。细致分析了不同条件下产生的涌浪类型和特征，揭示了涌浪产生过程中的水土耦合机制，以及复杂边界对涌浪的影响机制，给出了首浪的波形、波速、波高、波长等变化规律。并从非线性特征出发，揭示了首浪波形与表征波非线性特征参数Ursell数的关系，给出了产生不同首浪波形的临界判断条件。（4）建立了基于S-V方程的浅水涌浪传播模型，与涌浪产生模型有机结合，发展了可以统一模拟滑坡涌浪产生及传播过程的组合数值模拟方法，实现了对滑坡涌浪产生、传播和致灾全过程的合理模拟。应用于拟建的如美水库滑坡涌浪实际问题，得到了滑坡诱导涌浪的特征和演化过程，为大坝工程设计提供了科学依据。