| 题名 | 地震和干旱对泥石流发育的影响模式及机理研究 |
| 作者 | 卢阳 |
| 学位类别 | 博士 |
| 答辩日期 | 2013 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 陈宁生 |
| 关键词 | 泥石流 侵蚀 地震 干旱 形成机理 自然灾害 |
| 其他题名 | Study for the effect mode and mechanism of Earthquakes & droughts on debris flows |
| 学位专业 | 岩土工程 |
| 中文摘要 | 地震和干旱是控制和影响泥石流发育的两个重要因素。在地震、干旱与灾害性泥石流时空关系的现有研究基础上，依据地震活动和干旱事件与泥石流灾害发生时间的关系紧密程度，定量统计分析了地震活动和干旱事件与大型泥石流灾害之间的时空耦合关系；在此基础上，一方面，结合现有的研究成果和生产实践，分析了地震和干旱对泥石流形成条件的影响；另一方面，通过野外人工降雨试验，结合室内土体细观结构CT试验，从宏细观角度，分析了地震和干旱后松散土体起动形成泥石流的表面过程和力学机理。最后，基于以上的研究成果，提出了一种基于地震和干旱监测的泥石流发育区灾害早期预测方法。本文主要取得了以下成果： 1、就中国泥石流而言，地震活动和干旱事件对泥石流灾害的影响作用受地域和气候的控制。对于地震活动越活跃的山区（如地震带），地震对灾害性泥石流的影响作用越强；干旱事件对半湿润区的灾害性泥石流具有显著的促进作用，而随着年降雨量极大增加至湿润区或减少至半干旱-干旱区，干旱事件对灾害性泥石流的影响作用减小。 2、地震活动对泥石流灾害发育的影响明显，地震通常会在极短的时间内既改变沟谷流域的地形地貌，又为泥石流形成提供了丰富的松散固体物质，还可为泥石流提供间接水源；同样，干旱对泥石流灾害的发育起到重要的作用，干旱会从地形地貌、松散固体物质及水源等三个方面影响泥石流的形成条件。这些改变和影响往往构成有利于泥石流形成的条件组合。但归根结底，松散固体物质的增加是地震、干旱与泥石流链生关系最重要的纽带。 3、地震、干旱会造成土体内部孔隙率增加，土颗粒之间的粘结强度降低，形成松散结构。在后期强降雨作用下，这种结构松散、空隙率大（渗透系数大）、强度低的土体很容易发生细颗粒运移和不均匀湿陷等结构破坏和调整而形成泥石流。泥石流形成条件和形成过程的复杂性导致其形成机理错综复杂，但归纳起来，疏松土体的“剪缩”机制是地震和干旱后松散土体易于破坏形成泥石流的重要内因。 4、以地震、干旱对泥石流影响模式及机理为基础，提出了一种基于地震和干旱监测的泥石流灾害早期预测方法，并运用实际案例对该方法进行了检验。检验结果表明，本泥石流早期预测技术能够对泥石流灾害易发程度进行预测，且预测结果较为准确。 |
| 英文摘要 | Earthquake and drought are the two important factors that control and influence debris flows. Based on the quantitative analysis on relationship in time between large-scale debris flows, earthquake activities and drought events, the coupling relationship between debris flows, seismic activities and droughts are explored. Then on the one hand, the study for the effect mode and mechanism of earthquake on debris flow are conducted by analyzing the existing research results and field practices; On the other hand, since the studies for the effect of drought on debris flow are relatively few, through the field experiment of artificial rainfall combined with the experimental simulations on soil surface cracking and the meso-structure changing test of dry-wet soil by CT machine, from the macroscopic and microscopic view, the surface processes and mechanical mechanisms of the dry soil starting and changing into debris flow are studied. Finally, a method is proposed for predicting the debris flows in debris flow high-distribution areas based on early earthquake and drought monitoring. In this paper, the following results are obtained: 1. For the debris flows in China, the effect of seismic activities and drought events on debris flows are controlled by the location and climate. For the mountain areas with more seismic activities (such as the seismic belts), the promotion effect of earthquake on debris flow is stronger. Drought events have stronger promotion effect on the debris flows in semi- humid mountain areas, while in humid areas with bigger annual precipitation and in semi-arid areas and arid areas with smaller annual precipitation, the drought effect is smaller. 2. Earthquake plays an important role on the development of debris flows. Within a very short time, great earthquake not only changes the topography of the valley basin, and also provides lots of loose solid materials & water, which often makes a good combination of conditions for the formation of debris flows; For the different and complex formation conditions and formation process after earthquake, the formation mechanism of debris flow is complex. But in total, the mechanism of its formation can be divided into two basic types: the soil-mechanical one and the hydraulic-mechanical one with that after earthquake, the formation mechanism and the combination mode becomes more richer and more complex. In addition, the large number of increased loose solid materials is the most important link between earthquake and debris flow and the dilating mechanism of loose soil is the important internal mechanism for soil mass easy changing into debris flow. 3. Drought also plays an important role in the development of the debris flow, which change the formation condition of debris flow by affecting topography, loose solid materials and water. For the effect on soil, on the one hand, drought can cause the soil surface cracking along the part where the fine particles are enriched; On the other hand, drought can increase the internal porosity, decrease the bonding strength between the soil particles, and form the loose structure for soil. Under the later intensive rainfall, the soil with loose structure, high porosity (with big permeability coefficient) and low strength is prone for the migration of fine particles and uneven collapse of soil whose structure damage and adjustment then trigger the formation of debris flow. In addition, the pore water pressure plays an extremely important role in the formation process for the geotechnical class debris flow; in the process that soil liquefied into debris flow, the values of water content and pore pressure in soil do not reach their maximum value. 4. Based on the impact mode and mechanism of earthquake and drought on debris flow, an early dynamic prediction method for debris flow by monitoring earthquake and drought is obtained, and the method is used on some cases. The test results show that the prediction method can dynamically forecast the debris flow hazards and can get accurate forecasting results. |
| 语种 | 中文 |
| 公开日期 | 2014-07-26 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.imde.ac.cn/handle/131551/7060]  |
| 专题 | 成都山地灾害与环境研究所_山地灾害与地表过程重点实验室 |
| 推荐引用方式 GB/T 7714 | 卢阳. 地震和干旱对泥石流发育的影响模式及机理研究[D]. 北京. 中国科学院研究生院. 2013. |
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