IMHE OpenIR  > 山地灾害与地表过程重点实验室
鱼脊型泥石流水石分离结构的试验研究
Alternative Titlelaboratory test of a new water-sediment separation structure for debris flow defense
Language中文
谢涛
Thesis Advisor韦方强
2014
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Name博士
Degree Discipline自然地理学
Keyword泥石流 水石分离 泥石流防治 模型试验
Abstract泥石流是一种包含大量泥沙和石块的固液两相流体,通常其中的固相物质粒度分布比较广,且含有大量粗颗粒,甚至是巨砾。这些粗颗粒的存在大大增强了泥石流的破坏力,所以可以通过对粗颗粒进行调控,以减少泥石流中粗颗粒含量的方式降低泥石流破坏力,从而达到减灾目的。实现水石分离是对粗颗粒进行调控的基础,目前的泥石流减灾工程中具有水石分离功能的主要为各种透水型拦挡坝。然而,从这些结构的实际应用效果来看,均存在一个普遍问题,即由于结构设计局限性,致使其结构开口易被分离出的固体颗粒淤积和堵塞,从而导致结构的水石分离功能不能持续发挥。因此,为了解决这一问题,本文通过分析泥石流的运动规律和现有分离结构的特点,重点研究了利用粗颗粒自身重力使分离的粗颗粒自主离开结构体的分离方法,据此提出一种可持续并有分选地分离粗颗粒的鱼脊型水石分离结构。在此基础上,通过模型试验检验了结构的水石分离效果,确定了结构的适用范围;并通过模型试验和理论分析,对结构进行优化,确定了结构具有最佳运行效果时各个结构尺寸参数的选取方法以及结构的强度计算方法,从而得到实际应用中结构的设计方法。通过以上研究,得到了以下结论和研究成果: 1. 通过总结现有水石分离结构的特点和泥石流运动规律,得到了利用粗颗粒自身重力使分离的粗颗粒自主离开结构体的分离方法,据此提出了一种可持续并有分选地分离粗颗粒的鱼脊型水石分离结构,结构由引流坝、水石分离格栅、泄流槽以及停积场组成。引流坝用于引导泥石流顺利进入水石分离格栅,并为水石分离格栅的布置提供一定高度;水石分离格栅由脊梁、肋梁和支撑墩三部分组成,用于完成水石分离,使粒径大于格栅肋梁间距的固体颗粒被分离出来,并沿着格栅表面滑落到两侧停积场,而其余泥石流体透过格栅继续沿着沟道运动;停积场用于停放从格栅表面滑落下来的固体颗粒,泄流槽用于排泄透过格栅的泥石流。 2. 通过在室内开展模型试验,得到鱼脊型水石分离结构具有良好的水石分离能力,可以将其应用于泥石流减灾实践中。试验中,80%以上粒径大于设计分离粒径的固体颗粒被分离出来,而仅30%左右粒径小于设计分离粒径的固体颗粒被分离出来,同时几乎所有被分离出来的固体颗粒均滑落到两侧停积场,格栅开口不会被分离的固体颗粒堵塞,说明该结构的水石分离效果显著,能有分选并持续的将泥石流中的粗颗粒分离出来,可解决现有分离结构水石分离功能不能持续发挥的问题,对泥石流减灾实践具有重要意义。 3. 通过在室内开展模型试验,得到鱼脊型水石分离结构适用于容重γc < 1.9t/m3的泥石流,从而确定了实际应用中结构的适用范围。试验中,当泥石流容重γc ≥ 1.9t/m3后,被结构分离到停积场的小于设计分离粒径的固体颗粒明显增多,而且调节泥石流容重的能力也显著降低。因此,从有分选地分离粗颗粒的角度考虑,鱼脊型水石分离结构的最佳适用范围为容重γc < 1.9t/m3的泥石流,超过此范围后,其功能的发挥将显著降低。同时,由于泥石流容重γc ≥ 1.9t/m3后,大量粗细颗粒一起被分离到停积场,所以从减小泥石流规模而言,结构仍能起到一定作用。 4. 通过模型试验,并结合理论分析,确定了对粗颗粒具有最佳分离效应时鱼脊型水石分离结构中各个结构参数的选取方法,从而得到了实际应用中鱼脊型水石分离结构的设计方法。 5. 通过理论分析,确定了鱼脊型水石分离结构中水石分离格栅承受的荷载种类及其计算方法,并通过简化结构计算模型,依据强度条件得到了水石分离格栅的强度计算方法,从而为实际应用中选取水石分离格栅所用的钢材型号和截面尺寸提供了计算方法。
Other AbstractCoarse particle in debris flow is an important reason why debris flow have huge destructive power, thus, regulating the coarse particles is an important way to reduce debris flow disaster through adjusting and controlling the energy in debris flow movement process. Completing water-sediment separation for debris flow by some structural measures, such as open dam, is precondition of regulating the coarse particle. However, the existing open dams often lose their water–sediment separation function over time and/or during a debris flow event because of blockage by separated sediment. To resolve this problem, this paper developed a new method for separating coarse particles. The new method can keep the function of the separation structure in debris flow processes by making the separated coarse particles automatically leave the separation structure under the action of gravity. Based on this method, a new water-sediment separation structure which can continuously maintains its water-sediment separation function has been designed. For this new structure, a serial of laboratory experiments have been developed to test its effectiveness and application scope. Combining the theoretical analysis, the structural dimensions also have been determined. Based on these researches, some conclusions and achievements are as follows: 1. By analyzing the feature of the existing water-sediment separation structure and debris flow movement, a new method can keep the function of the separation structure in debris flow processes by making the separated coarse particles automatically leave the separation structure under the action of gravity has been established. Based on this method, a new water-sediment separation structure which can continuously maintains its water-sediment separation function has been designed. This new structure incorporates a draining dyke, a water-sediment separation grid, an outflow channel, and deposit fields. The draining dyke is designed to provide a height difference to direct debris flows to the water–sediment separation grids. The sloping grids direct the separated sediment to the deposit field under the action of gravity. The remaining part of the debris flow will pass through the grids and along the outflow channel to the debris-flow channel or gully. 2. By a series of model experiments, the structure’s water-sediment separation function has been tested. The experiments results show that the water–sediment separation function was maintained. More than 80% of the sediment larger than the design sediment was separated, and most of it left the structure automatically with the water-sediment separation functioning throughout the debris flow process. 3. By a series of model experiments, the structure’s application scope has been determined. The experiments results show that more than 95% of the sediment larger than design sediment is separated under all bulk densities, however, after the bulk densities is larger than 1.9t/m3, separation ratio of the sediment smaller than design sediment is significantly increased, and the bulk density has little change before and after separation. Comparing experimental results with effectiveness of the structure, the structure is mainly used to control debris flow which bulk density is smaller than 1.9t/m3. 4. Combining a series of model experiments with theoretical analysis, the structural dimensions have been determined for the optimum water-sediment separation efficiency (Table I-1), therefore, the structural design method in practical application was determined. 5. By theoretical analysis, the load type and its calculation method of water-sediment separation grid were determined, and by simplifying the structure calculation model, based on the strength conditions, the strength calculation method of the grid was determined, which can be used to choose steel model and section size of the grid in practical application.
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/7860
Collection山地灾害与地表过程重点实验室
Recommended Citation
GB/T 7714
谢涛. 鱼脊型泥石流水石分离结构的试验研究[D]. 北京. 中国科学院研究生院,2014.
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