泥石流容重的内涵诠释及其对灾害防治的启示

容重是描述泥石流性质的重要基础参数.本文基于泥石流运动过程的时空特征,厘定了最大容重、峰值容重和平均容重3个容重特征值.以蒋家沟1987年以来的泥石流观测数据为分析对象,分析了3个容重特征值在数值上的分布规律和影响因素.结果显示:①最大容重与峰值容重的关系式具有较好的相关性,最大容重与平均容重的关系式具有实际计算适宜性...     

崇礼县城张麻沟泥石流发育特征研究

通过对新疆崇礼县城张麻沟泥石流灾害的实地勘查,查明了张麻沟泥石流形成的地质环境条件、成因、类型、活动状况,并且对研究区泥石流的特征值进行了计算,计算结果表明:崇礼县张麻沟泥石流容重为1.594 t/m~3,为稀性泥石流,泥石流流速为2.73～3.90 m/s,泥石流峰值流量为2.506～16.512 m~3/s,固体物质一次冲出量为0.3041×10~4 m~3,泥石流规模为小型。研究结果为下一步泥石流灾害治理提供了可靠的科学依据。     

宁夏贺兰山区郑官沟水石流发育特征与形成机理研究

通过对宁夏贺兰山区郑官沟泥石流的现场勘查与室内试验,总结了泥石流形成的地质环境条件,分析了泥石流的产流汇流机理和地形条件,并在此基础上计算了泥石流的运动学、动力学特征值,并对其危险度进行了定量评价。结果表明,郑官沟泥石流的平均容重为1.73t/m~3,应属于水石流;泥石流启动的临界坡度为tanθ≥0.29,或=16°;泥石流流通区平均流速为4.08m/s;泥石流流量为98.14m~3/s;一次泥石流最大冲出量为2.38×10~4 m~3;郑官沟泥石流的危险度为0.397,属中危险度泥石流沟。     

青海省玉树当得隆沟泥石流发育特征及治理研究

在野外调查的基础上,通过分析地貌条件、地质构造等资料,结合室内泥石流特征值和动力学特征值的计算,对形成机理进行了探讨。结果表明:(1)当得隆沟泥石流类型属于稀性泥石流,容重15.8kN/m³,洪峰流量8.55 m3,洪峰流量8.55 m³/s,泥石流峰值流量29.75 m3/s,泥石流峰值流量29.75 m³/s,流速3.60 m/s;(2)通过泥石流动力学特征值计算,结合泥石流发展趋势及危险分区,确定"拦挡+排导"治理方案;(3)通过对当得隆泥石流沟问题研究,实现地质灾害防治与生态环境统筹;为该区同类泥石流防治工作提供参考借鉴。     

泥石流容重的时空变化特征及影响因素研究

为了探索泥石流容重在不同时空条件下的动态演化特征及其影响机制,基于蒋家沟1995年以来的泥石流观测数据和汶川震区2008年以来的调查资料,研究了典型泥石流灾害的水土耦合过程和容重动态变化的互馈作用,对比分析了常用的容重计算方法在汶川震区泥石流计算中的差异性,并从计算公式和灾害特征两方面探索误差产生的原因。结果表明:容重随泥石流孕灾条件的时空演化而动态变化;在时间尺度上,物源活动性与容重呈正相关,物源赋存状态从极度活跃演化至高度活跃时,容重将下降10.0%～27.8%;泥石流峰值流量与容重成幂函数关系,容重随着流量增大而增大,但具有明显的上限值;在空间尺度上,容重与沟床纵比降变化趋势一致,随着侵蚀作用而增大,淤积作用而减小;常用的6种泥石流容重计算方法在龙门山区的应用结果偏差幅度为10%～30%,仅使用某种计算方法确定容重参数将导致一定误差。文章最后利用物质组成计算容重的方法,基于冲淤总量和颗粒参数建立了不同沟道段泥石流容重经验计算公式,并在雍家沟泥石流进行应用,结果显示该方法针对具有完整序列观测资料的泥石流沟,具有较好的适用性。     

非匀质泥石流运动特征与峰值流量关系研究

对非匀质泥石流运动变化特征进行预测评价是泥石流防治工程规划和预警预报系统建设的重要内容,也是目前泥石流领域亟需完善的重点问题。通过对泥石流泥位和流速实测资料整理和分析,构建了非匀质泥石流运动特征值预测模型,该模型在前人成果的基础上,利用较少因子就能够判别研究区泥石流运动变化特征,并以陇南地区礼县下胡杨沟泥石流为例,通过FLO-2D流体模型对50年一遇(2%频率)和20年一遇(5%频率)降水条件下泥石流运动特征进行模拟。结果表明泥石流容重为1. 83 t ·m-3时,下胡杨沟20年一遇的泥石流运动特征值最小且差异性不大;当泥石流容重为1. 97 t ·m-3时,下胡杨沟50年一遇的泥石流运动特征值最大且差异性悬殊;当不同规模泥石流流量达到峰值时均产生较大的泥位深度。进一步将泥石流运动特征值模拟结果与实测断面相结合检验分析,并反推已发生泥石流事件的峰值流量,与实际情况都具有较好的一致性,表明采用本文预测模型计算的结果具有一定的可靠性,可为泥石流防灾减灾和泥石流监测预警示范区建设提供参考。     

四川省青川县红光集镇泥石流灾害特征及减灾对策

2006年8月28日四川省青川县红光集镇发生了泥石流灾害,造成了严重财产损失,并对红光集镇居民安全构成了威胁。本文根据现场调查,分析了泥石流形成条件、成灾过程,并计算了泥石流的容重、流量、冲出量等动力学参数。根据红光集镇泥石流的具体情况和当地经济、社会、生态建设的需要,以及被保护对象的重要性,提出了减灾对策。     

舟曲“8．8”三眼峪特大泥石流特征值分析

在对甘肃省舟曲县“8．8”特大泥石流调查的基础上,分析计算了三眼峪泥石流的静力学和动力学特征值。三眼峪泥石流重度介于2．O～2．15t／m^3之间,属于黏性泥石流;支沟大眼峪和小眼峪坡降大,谷底窄,泥石流流速比主沟流速大,最大流速达9．2m／s,流通区积蓄能量巨大;主沟最大流量位于大眼峪沟与小眼峪沟交汇处（峪门口）,流量达1830m^3／s,一次最大冲出量为152×10^4m^3,泥石流规模为特大型;三眼峪沟泥石流冲压力最大为小眼峪沟沟口断面处,冲击力为245kPa;实测泥石流堆积扇中石块最大粒径为11．2m,计算三眼峪沟泥石流中石块最大运动速度达15．06m／s。特征值分析结果可为舟曲泥石流灾后重建过程中工程设计提供重要依据。     

冰碛湖溃决泥石流流量计算方法

冰碛湖溃决泥石流是高山高寒地区一种常见的灾害类型,虽爆发频率低,但造成的危害极大,该类型的泥石流防治是区域开发建设中必须要面对的问题,而流量计算又是其核心问题之一。以西藏地区近100 a以来的冰碛湖溃决实例为基础,探讨了溃口深度的计算方法;以逐渐溃决模型和配方法为基础,分析了冰碛湖溃决泥石流的容重峰值流量与洪峰演进计算方法的适用性与流程;通过案例的对比研究,探讨了计算模型参数率定与误差来源。结果表明：瞬间溃决模型高估了冰碛湖溃决泥石流的峰值流量,泥石流的预测值偏保守;而逐渐溃决模型更接近于冰碛湖溃决的物理机制,在冰川U型谷内,可不考虑泥石流的堵塞作用,泥石流的峰值流量预测值与实测值较吻合;在冰川U型谷外或近沟口段则需考虑泥石流的堵塞作用。文中提出的计算模型作为冰碛湖溃决泥石流防治工程参数设计的依据是可行的。     

河南省商城县琉璃河泥石流地质特征和动力学参数分析

琉璃河泥石流位于河南省商城县东部的苏仙石乡,是一条典型的沟谷泥石流。本文在分析琉璃河泥石流沟流域和泥石流基本特征的基础上,对形成泥石流的地形、水源、物源等基本条件进行了论述,并基于动力学原理,详细计算了泥石流的密度、流速、流量、冲出量等动力学参数。结果表明,琉璃河泥石流的流体密度为1.47 t/m3,泥石流峰值流量为29.3 m3/s,泥石流流速为4.94 m/s,大块石的运动速度为4.0 m/s,泥石流整体冲击压力4.86 Pa,泥石流的最大冲起高度1.24 m,爬高1.99 m。动力学参数计算结果较为可靠,可指导泥石流防治工程设计工作。     

Initiation process of debris flows on different slopes due to surface flow and trigger-specific strategies for mitigating post-earthquake in old Beichuan County, China

The 12 May 2008 Wenchuan earthquake (Ms 8.0) in China, produced an estimated volume of 28 × 10⁸ m³ loosened material, which led to debris flows after the earthquake. Debris flows are the dominant mountain hazards, and serious threat to lives, properties, buildings, traffic, and post-earthquake reconstruction in the earthquake-hit areas. It is very important to understand the debris flow initiation processes and characteristics, for designing debris flow mitigation. The main objective of this article is to examine the different debris flow initiation processes in order to identify suitable mitigation strategies. Three types of debris flow initiation processes were identified (designated as Types A, B, and C) by field survey and experiments. In “A” type initiation, the debris flow forms as a result of dam failure in the process of rill erosion, slope failure, landslide dam, or dam failure. This type of debris flow occurs at the slope of 10 ± 2°, with a high bulk density, and several surges following dam failure. “B” type initiation is the result of a gradual increase in headward down cutting, bank and lateral erosion, and then large amount of loose material interfusion into water flow, which increases the bulk density, and forms the debris flow. This type of debris flow occurs mainly on slopes of 15 ± 3° without surges. “C” type debris flow results from slope failures by surface flow, infiltration, loose material crack, slope failure, and fluidization. This type of debris flow occurs mainly on slopes of 21 ± 4°, and has several surges of debris flow following slope failure, and a high bulk density. To minimize the hazards from debris flows in areas affected by the Wenchuan earthquake, the erosion control measures, such as the construction of grid dams, slope failure control measures, the construction of storage sediment dams, and the drainage measures, such as construction of drainage ditches are proposed. Based on our results, it is recommend that the control measures should be chosen based on the debris flow initiation type, which affects the peak discharge, bulk density and the discharge process. The mitigation strategies discussed in this paper are based on experimental simulations of the debris flows in the Weijia, Huashiban, and Xijia gullies of old Beichuan city. The results are useful for post-disaster reconstruction and recovery, as well as for preventing similar geohazards in the future.     

岔沟泥石流运动特征及诱发因素分析

文章阐述泥石流流体重度、泥石流流速和泥石流洪峰流量等运动特征之间的相互关系,并分析降雨量作为诱发因素与这些运动特征的关系。为泥石流地区类似工程防灾减灾提供基础资料。     

滑坡碎屑堆积体形成泥石流的实验

地震或强降雨诱发滑坡,滑坡体碰撞解体形成碎屑物质堆积在沟道内,在后期降雨作用下形成泥石流,这是泥石流形成的一种方式,可称为滑坡碎屑堆积体泥石流。笔者分析了影响碎屑堆积体泥石流起动的特征参数,通过实验研究了碎屑堆积体泥石流形成的过程,分析了堆积体表面坡度、黏粒质量分数、中值粒径（d₅₀）以及不均匀系数（Cu）对泥石流形成的影响。结果表明：碎屑堆积体表面坡度对形成泥石流所需单宽流量无明显影响;黏粒质量分数在不大于5%时仅影响碎屑堆积体侵蚀,对碎屑堆积体揭底所需单宽流量无明显影响;影响碎屑堆积体形成泥石流所需单宽流量的因素主要为中值粒径和不均匀系数--随堆积体中值粒径、不均匀系数的增大而增大。通过实验数据拟合得出了中值粒径和不均匀系数与泥石流形成和揭底所需单宽流量的公式;由于公式中只考虑了影响碎屑堆积体形成泥石流的两个主要因素（d₅₀和Cu）,因此对比水文计算结果偏小,但整体趋势基本一致。在实际应用到这类泥石流沟时,可通过修正进行预测。     

A new total volume model of debris flows with intermittent surges: based on the observations at Jiangjia Valley,southwest China

Debris flow with intermittent surges is a major natural hazard. Accurate estimation of the total volume of debris flow is a challenge for academic researchers and engineering practitioners. This paper has proposed a new model for the total volume estimation based on 15 years of observations in Jiangjia Valley, China, from 1987 to 2004. The model uses two input variables: debris flow moving time and average surge peak discharge. The Weibull distribution formula is adopted to describe the relationship between the debris flow surge peak discharge and its relative frequency. By integrating the Weibull function and two-point curve fitting, the relationship between the maximum discharge and average surge peak discharge can be established. The total debris flow volume is linked with the debris flow moving time and the average peak discharge. With statistical regression, the debris flow moving time is derived from the debris flow total time. The proposed model has fitted very well with the validation data and outperformed the existing models. This study has provided a new and more accurate way for estimating the total volume of debris flows with intermittent surges in engineering practice.     

开口柔性防护网调控泥石流性能试验研究

柔性防护网是防治泥石流灾害的重要工程措施之一,现有防治结构以闭口防护网形式为主,易发生堵塞且调控能力欠佳。为此,提出一种开口柔性防护网结构,并基于理论分析、物理模型试验开展了开口柔性防护网对泥石流的调控性能研究,推导泥石流速度衰减率、爬升高度和柔性防护网拦挡率的理论公式。结果表明：与闭口柔性防护网结构相比,该结构起到了良好的自清洁作用,且可有效调控泥石流速度峰值;所推导的无量纲理论公式计算结果与物理试验结果具有较好的一致性;速度衰减率、爬升高度和拦挡率主要由相对开口高度、无量纲流深、泥石流相对密度和弗罗德数控制;速度衰减率和拦挡率与相对开口高度呈负相关,与泥石流相对密度呈正相关,爬升高度与相对开口高度、相对密度均呈负相关。上述研究可为开口柔性防护网在泥石流防治工程中的应用提供理论及技术支持。     

泥石流阵流序列的整体性

泥石流往往以阵流群的形式出现,不同阵流参数具有统一的统计分布,意味着阵流序列隐含着深层的系统信息。文中根据蒋家沟泥石流观测数据,揭示阵流序列的自相关性和时空变化特征,进而确立其整体性。Hurst指数是刻画序列相关性的指标。阵流的流量、速度和时间间歇序列的Hurst指数值均大于05,从而证明序列具有长程相关性;另一方面,将阵流作为其运动参数(如流速、流量、间歇时间)组所确定的点,则一个泥石流事件为参数空间的一个点集,且集中在一个狭小区域,直观表现了阵流在时空的聚集特征,这是序列整体性的又一特征。阵流序列的这些基本特征,意味着不同泥石流事件背后隐藏着同一个动力学机制,即泥石流作为流域行为(而不是流体运动)的系统动力学。     

Mapping debris flow susceptibility using analytical network process in Kodaikkanal Hills,Tamil Nadu (India)

Rapid debris flows, a mixture of unconsolidated sediments and water travelling at speeds > 10 m/s are the most destructive water related mass movements that affect hill and mountain regions. The predisposing factors setting the stage for the event are the availability of materials, type of materials, stream power, slope gradient, aspect and curvature, lithology, land use and land cover, lineament density, and drainage. Rainfall is the most common triggering factor that causes debris flow in the Palar subwatershed and seismicity is not considered as it is a stable continental region and moderate seismic zone. Also, there are no records of major seismic activities in the past. In this study, one of the less explored heuristic methods known as the analytical network process (ANP) is used to map the spatial propensity of debris flow. This method is based on top-down decision model and is a multi-criteria, decision-making tool that translates subjective assessment of relative importance to weights or scores and is implemented in the Palar subwatershed which is part of the Western Ghats in southern India. The results suggest that the factors influencing debris flow susceptibility in this region are the availability of material on the slope, peak flow, gradient of the slope, land use and land cover, and proximity to streams. Among all, peak discharge is identified as the chief factor causing debris flow. The use of micro-scale watersheds demonstrated in this study to develop the susceptibility map can be very effective for local level planning and land management.