岷江上游溜砂坡发生机理与防治关键技术研究
文献类型：学位论文
| 作者 | 徐骏 |
| 学位类别 | 博士 |
| 答辩日期 | 2007 |
| 授予单位 | 中国科学院水利部成都山地灾害与环境研究所 |
| 授予地点 | 成都 |
| 导师 | 王成华 |
| 关键词 | 溜砂坡 休止角 PFC3D 干砂流 自组织临界性 元胞自动机 微型树根桩 桩板墙 |
| 学位专业 | 自然地理学 |
| 中文摘要 | 岷江上游气候干燥少雨，河谷两岸山坡陡峻，溜砂坡灾害时有发生，给行人及车辆安全带来较大威胁。作为山地灾害之一的溜砂坡，研究其形成机理及整治对策，对于国家的防灾减灾具有十分重要的意义。为此，对岷江上游溜砂坡分布较集中的茂汶段进行了多次野外调研，通过理论分析、数值模拟(基于离散元程序PFC3D)与室内试验相结合的方法，研究了溜砂坡灾害的形成及演化规律，并对溜砂坡灾害的防治关键技术进行了探讨，得出了一些成果和结论：（1）岷江上游溜砂坡的破坏主要是其表层松散堆积物的溜滑和滚动，根据堆积物的组成物质形状的不同可以将该地区溜砂坡划分为三类：粒状碎屑溜砂坡、片状碎屑溜砂坡和块状碎石溜砂坡。论述了溜砂坡的形成条件与诱发因素，并建立了岩石风化破坏产砂的时温效应模型，分析了风力搬运产砂机制，探讨了河沙沉积产砂过程，为溜砂坡砂源控制提供了一种理论依据。（2）天然休止角是溜砂坡研究的重要参数指标，对于研究砂坡的起动及稳定性有重要意义，论文提出了几种确定溜砂坡天然休止角的方法，并比较几种方法取较小值用于溜砂坡的防治设计。（3）分析了三类溜砂坡单个砂粒运动形式及起动条件以及干砂流的运动特征，并考虑加速度的影响，建立了相应的运动模型，并结合颗粒流模型来估算出溜砂坡坡面溜砂运动的最大流速, 为溜砂坡防治设计提供了重要依据。（4）对常规二维BTW元胞自动机模型进行改进，将其用于对溜砂坡进行数值模拟分析，具体包括两个方面：一是对岩石风化破坏的元胞自动机模拟，与以前的模型不同之处在于本模型中考虑了材料非均质性及各向异性的影响，并采用了8邻居模式，模拟方式更为合理；二是对扰动后砂坡演化的模拟，建立了不断加砂后砂坡演化的元胞自动机模型，并引入摩擦耗散能量指标用于考虑砂坡非均质性影响，同时考虑了砂坡的边界条件，使得模型能更好地符合实际情况。（5）利用高级非连续介质程序PFC3D模拟分析了溜砂坡的静力学特性及运动过程，有利于加深人们对溜砂坡形成与演化过程的认识，同时还得到了溜砂坡休止角及砂粒运动速度等参数，有了砂粒运动速度又能估算出砂粒对支挡结构的冲击力大小，考虑了冲击力影响下的砂坡推力使得设计更为安全。（6）结合挡砂工程，将干砂流体视为沿底面（根据砂坡天然休止角确定）滑动的三角体，分别采用朗肯土压力理论、极限平衡理论推导出溜砂坡砂坡水平推力的计算公式，指出极限平衡理论是一种更为通用和实用的计算方法，同时提出了考虑干砂流流动冲击力影响的计算方法，并介绍了利用PFC3D程序模拟分析砂坡与支挡结构相互作用过程，得到了模拟的最大砂坡水平推力，可作为溜砂坡防治工程设计的参考。（7）溜砂坡综合加固防护技术包括控制、封闭砂源区、稳定砂坡体和保护砂坡脚等。论文从稳定砂坡体、保护砂坡脚入手，详细论述了花管微型树根桩深部固砂技术及桩板墙加固防护技术，重点解决了施工中边开挖边溜沙的难题。 |
| 英文摘要 | Due to dry climate, lack of rain and steep slope on the both bank in the upper reaches of Minjiang River, sand-sliding slope hazards occur frequently. As a result, the safety of any passerby and vehicle is under threat. Sand-sliding slope is one of mountain hazards, and it is significant to National hazards preventing and decreasing to study on the formative mechanism and control key-technology of sand-sliding slopes. And thus, several field observations are performed at the area of Mao-Wen in the upper reaches of Minjiang River where mass sand-sliding slopes are distributed. The paper applies the method of the combination of experiment, numerical simulation(using a DEM program named PFC3D) and theory analysis to study on the law of sand-sliding slopes’ formation and evolvement and the control technology of sand-sliding slopes. The most important contents of this study are as follows:(1) The failure of sand-sliding slope in the upper reaches of Minjiang River is mainly the sliding and rolling of the loose accumulation on the surface. According to the composing matter’s different shape of the loose accumulation, the sand-sliding slopes in this area can be classified as three types: granular clast sand-sliding slope, flaky clast sand-sliding slope and block gravel sand-sliding slope. The formation conditions and some inducement have been discussed. In order to study the composing matter’s formation mechanism, a temperature-time-effect model has been built, and sand motion due to wind’s action has been analysed, and also the process of sands’ sediment in the river is discussed. And thus, a kind of theoretical foundation has been developed for the control of sand-sliding slope’s sand-providing areas.(2) The angle of repose is an important parameter of sand-sliding slope. It’s useful for studying on the startup and stabilization of sand-sliding slope. In order to determine the angle of repose of sand-sliding slope, some methods have been proposed. Based on the result comparison of those methods, the minimum angle of repose has been obtained for the sand-sliding slope’s control and design.(3) Mechanical analysis has been done for the motion character of the single sand and the sand flow. With the acceleration concerned, dynamics and resistance equation of sand flow has been deduced. In combination with the particle fllow model, the maximum velocity of the sand slope’s surface has been estimated.(4) With improved BTW model, some numerical simulation has been carried on for studying the sand-sliding slope. The simulation includes two aspects: rock cracking and sand slope evolvement. In the improved cellular automata model, an eight neighbor model, boundary condition, material’s heterogeneity and anisotropy has been adopted. As a result, the model is more proper for the sand-sliding slope’s simulation.(5) Advanced DEM Program PFC3D has been used to simulate the accumulation process, statics characteristic and motion process of three types of sand-sliding slopes. Thus a lively movie is shown in front of us which is playing the whole accumulation or motion process of sand-sliding slope. And it’s benefit for us to further understand the sand-sliding slope’s formation and evolvement process. At the same time, with the PFC3D, some useful parameters(such as the angle of repose, granula velocity and etc.) has been gained. Having the granula velocity parameter, the impact pressure which dry sand flow imposes on the retaining structures can be deduced. And in combination with the calculation expression of lateral soil pressure acting on the retaining structures by sand slope single, proper lateral soil pressure value under the condition of motion state is acquired, which is of benefit to much safer sand-sliding slope design. (6) In combination with the sand retaining structures, the dry sand mass is treated as a triangular body which may slide alone its bottom, i.e., the natural repose surface of the sand slope. And then, Rankine’s earth pressure theory, limit equilibrium theory and have been respectively adopted to calculate the lateral soil pressure acting on the retaining structures by sand slope. And the limit equilibrium theory has been regarded as more universal and practical one for the sand-sliding slope’s design. The impact of sand flow against retaining structure has been studied, too. In order to simulate the interaction between sand-sliding slope and retaining structure, PFC3D has been used, and then the maximum lateral force acting on the structure has been obtained which may be a useful reference for sand-sliding slope’s design. (7) There are generally three ways to stabilize or protect sand-sliding slopes: controlling and blocking the sand source, stabilizing the slope and protecting the slope toe. In this paper, the techniques of sand-slope consolidation by perforated pipe micro-root pile and sheet pile wall are introduced. The problem that the sand slides as the cut of slope toe has been solved. |
| 学科主题 | 灾害学 |
| 语种 | 中文 |
| 公开日期 | 2010-10-20 |
| 分类号 | P64;X43 |
| 源URL | [http://ir.imde.ac.cn/handle/131551/2248]  |
| 专题 | 成都山地灾害与环境研究所_成都山地所知识仓储（2009年以前） |
| 推荐引用方式 GB/T 7714 | 徐骏. 岷江上游溜砂坡发生机理与防治关键技术研究[D]. 成都. 中国科学院水利部成都山地灾害与环境研究所. 2007. |
入库方式： OAI收割
来源：成都山地灾害与环境研究所
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