急陡沟道泥石流起动特征模型试验研究——以汶川县福堂沟为例

急陡沟道泥石流是汶川震区发现的一类特殊泥石流,调查发现其具有物源量大、侵蚀强烈,冲出规模大等特点,是震区地质灾害治理的难点。本文以汶川县典型急陡沟道泥石流福堂沟为原型,分析了其发育条件和特征,并通过模型试验等手段,还原并分析了急陡沟道泥石流起动及形成的过程,以及相应的土体内部参数变化特征。试验显示在20°、25°、30°的坡度和480mL/s、410mL/s、360mL/s的径流量的试验条件下,泥石流分别以不同的方式起动(沟床侵蚀型、滑坡流态化起动型、消防管起动型),同时结合实验过程中土体内部孔隙水压力及体积含水率变化特征的研究,详细还原了相应的泥石流起动全过程。试验数据的分析结果显示,在不同的起动方式下,土体内部的数据变化表现出不同的特征:其中,不同试验条件下的泥石流起动孔隙水压力呈现出规律性差异,即水槽坡度、径流量越大,泥石流所需的起动力越小;此外,坡度越大,土体所需的饱水时间越长,而在相同坡度下,流速越大,预饱水时间越短;研究还发现,泥石流的爆发时间与沟床坡度呈反比,并且径流量越大,泥石流持续时间也越长。基于实验结果,通过相似理论计算得到的泥石流起动流速,与实际情况一致,表明本的...     

安宁河流域典型沟谷泥石流危险性评价

冕宁县安宁河流域为地质灾害密集分布区,安宁河断裂穿越于此,构造复杂,冷渍沟在上游左岸发育。在强降雨条件下,该沟就会暴发泥石流,堵塞安宁河流域和掩埋杀叶马村房屋和道路。冷渍沟泥石流具有流域面积小,主沟长度短,沟床纵比降大等特征,为了研究安宁河流域内泥石流的危险性,以冷渍沟为例,分析不同降雨周期下的泥石流暴发强度,模拟泥石流的运动过程并进行危险性评价。模拟的最大流速、最大堆积深度和降雨强度三者结合建立冷渍沟泥石流危险性评价模型。研究结果表明,冷渍沟泥石流危险范围内高危险区域占27%,主要集中在松散固体物质较多的沟道,中危险性区域和低危险区域各占56%和17%,该结论为危险范围内的居民和重点设施的风险管控提供参考。     

低频泥石流特征及防治 --以四川汶川县茶园沟为例

低频泥石流指30a以上发生1次的泥石流。尽管发生频率很低，但由于自身的特征及人们认识上的原因，其造l戒的人员伤亡和财产损失却居各类泥石流之首。对低频泥石流的研究在预防和减轻泥石流灾害方面有着重要意义。文章以2003年8月9日发生在四川汶川县茶园沟的泥石流为蒯，采用形态调查法和称重法等方法确定了流量、流速及重度。分析了其物质来源及形成的自然和人为原因，探讨了低频泥石流的特征。针对低频泥石流的低频性、破坏性和隐蔽性特点，同时考虑到低频泥石流沟的防治受保护对象的重要程度及资金投入等因素的限制，提出了进行泥石流危险性分区、搞好小流域水土深持、普及泥石流防灾减灾知识及加强监测和预警预报等措施，这对减轻低频泥石流区的灾害有一定的借鉴意义。     

Formation and characteristics of post-earthquake debris flow: a case study from Wenjia gully in Mianzhu, Sichuan, SW China

During the three flood seasons following the Wenchuan earthquake in 2008, two catastrophic groups of debris flow events occurred in the earthquake-affected area: the 2008-9-24 debris flow events, which had a serious impact on rebuilding; and the 2010-8-13/14 debris flow events, which destroyed much of the progress made in rebuilding. The Wenjia gully is a typical post-earthquake debris flow gully and at least five debris flows have occurred there. As far as the 2010-8-13 debris flow is concerned, the deposits of the Wenjia gully debris flow reached a volume of 3.1 × 10⁶ m³ in volume and hundreds of newly built houses were buried. This study took the Wenjia gully debris flow as an example and discussed the formation and characteristics of post-earthquake debris flow on the basis of field investigations and a remote sensing interpretation. The conclusions drawn from the investigation and analysis were as follows: (1) Post-earthquake debris flows were a joint result of both the earthquake and heavy rainfall. (2) Gully incision and loose material provision are key processes in the initiation and occurrence of debris flows and a cycle can be presented as the following process: runoff—erosion—collapse—engulfment—debris flow—further erosion—further collapse—further engulfment—debris flow enlargement. (3) The amount of rainfall that triggered debris flows from the Wenjia gully was significantly less than the average daily rainfall, while the intraday rainfall threshold decreased by at least 23.3%. (4) The occurrence mechanism of Wenjia gully debris flow was an erosion type and there was a positive relationship between debris flow magnitude and rainfall, which fitted an exponential model. (5) There were five representative characteristics of Wenjia gully debris flow: the long duration of the occurring process; the long distance of deposition chain conversion during the process of damage; magnification in the scale of debris flow; and the high frequency of debris flow events.     

四川省冕宁县华岩子沟火后泥石流成灾机理

以四川省冕宁县腊窝乡华岩子沟2019年7月发生的火后泥石流为典型案例,通过对火烧迹地现场地质勘察、降雨模拟试验研究了与火后泥石流形成相关的地形地貌、火行为分布、松散物源规模、产流产沙特征以及相应的灰烬层、斥水性、渗透性等相关试验。结果表明:（1）火烧迹地的斥水性强度越强,径流产流量越大;（2）严重火烧区的产沙量明显高于中度和轻度火烧区;（3）火烧迹地的斥水性与火烈度大致呈正相关,而渗透性恰好与之相反。研究揭示了火后泥石流的演变过程,为火后泥石流的防治和预警提供了理论依据。     

沟谷型泥石流地质灾害调查评价方法研究——以皖南小容泥石流地质灾害调查为例

在总结皖南地区泥石流主要特征的基础上,重新梳理了沟谷型泥石流调查评价过程中的调查要素和评价因子,提出了沟谷型泥石流调查评价工作方法:对沟谷进行泥石流初步评价,以可搬运物源量和可淤积容量比值系数作为初步评判标准;以沟谷泥石流集水盆地形态特征、可搬运物源属性分布及储量、堆积区地形等特征作为主要调查内容,对易发性评价因子赋予分值.在此基础上,以皖南小容泥石流地质灾害调查为例,探讨更直观、更科学、更切合实际的沟谷型泥石流地质灾害调查评价工作方法.     

泥石流防治工程损毁度评价

泥石流岩土防治工程被广泛应用于泥石流灾害的治理,而工程的损毁程度会对工程的功能性产生一定的影响,并影响效益的持续发挥。文章以汶川为研究区域,选取18条泥石流沟的岩土防治工程作为研究对象,结合现场考察,对防治工程的损毁程度进行评价。评价指标体系总体上分为拦挡工程因子和排导工程因子2项,细化二级评价指标包括坝基损毁度、坝肩损毁度、坝体损毁度、基础冲刷度、结构冲击度、斜坡推力度等6项。运用模糊综合评价方法构建判断矩阵和隶属度函数,将损毁度等级划分为优、良、中、差四个等级。评价结果显示,除板子沟和登溪沟的防治工程损毁等级为差和中以外,其余泥石流沟内防治工程损毁等级均为良或优,且评价结果与现场考察一致。     

汶川震区龙门山镇高架子沟“8·18”泥石流灾害机理与特征

2012年8月18日四川省彭州市龙门山镇地区遭受50年一遇的暴雨,引发大规模群发性泥石流灾害,其中以高架子沟最为突出,导致银厂沟内居民生活和交通严重受损。本文据现场调查和航空影像解译,分析高架子沟流域、物源特征的基础上讨论该次泥石流的演化过程、启动方式及灾害机理。结果表明：高架子沟在震前是一条非泥石流沟,震后流域内物源丰富,泥石流形成及演化过程为：地震-滑坡、崩塌-降雨-泥石流,其成灾启动过程包括启动阶段、加速阶段、下切拉槽阶段、堆积四个阶段,启动模式为沟床启动型。该泥石流形成过程中,＂消防水管效应＂使沟道水流快速集中,并强烈冲刷沟床中的松散堆积体,导致沟床固体物质移动形成大规模的泥石流灾害。     

台风暴雨型泥石流单沟危险度研究

台风暴雨型泥石流分布广泛并常造成重大灾害,有必要对其危险度进行研究。选取温州山区的14处典型台风暴雨型泥石流为研究对象,构建了基于组合因子的单沟泥石流危险度评价模型。选取泥石流规模（M）、泥石流频率（F）、冲沟纵比降（J）、形成区完整系数（C）、台风降雨综合值（E）和地质综合因子（G）来表征泥石流危险程度,并基于信息熵理论获得各组合因子权重值。针对研究区均为低频泥石流的特点,引入麦尔登比率（R值）以间接确定基于不同R值范围的泥石流爆发频率（F）。将评价模型应用于所选的典型沟谷,得到各沟谷泥石流危险度,评价结果符合研究区泥石流沟谷为中、小型低频泥石流的实际情况,并且评价为危险度高的沟谷具备区域上最易形成泥石流的地质地貌条件。     

A coupled SPH-DEM-FEM model for fluid-particle-structure interaction and a case study of Wenjia gully debris flow impact estimation

Landslides - Debris flows are rapid gravity-driven unsteady flows of highly concentrated mixtures of water and solid particle material, destroying numerous mountain building structures and traffic...     

四川壤塘县石吾陇沟泥石流启动条件与堵河程度分析

阿坝州壤塘县宗科乡石吾陇沟于2014年历经20年一遇强降雨,暴发了较大规模泥石流,泥石流峰值流量35.38m^3/s,冲出约6000m^3固体物堆积于沟口,造成沟口宗科河堵塞约三分之二。本文在对石吾陇沟的发育特征进行分析和对运动特征参数进行计算的基础上,对吾陇沟在不同频率泥石流规模下的堵河特征进行研究。首先利用已有经验公式对石吾陇沟在不同频率下堵河程度进行判断,其次结合流体动力学软件CFX对石吾陇沟堵河情况进行模拟分析。经验公式和数值模拟结果均表明,20年一遇泥石流会造成主河严重堵塞,与2014年实际情况基本一致;50年一遇泥石流会造成主河堵断。此研究结果可为石吾陇沟泥石流治理提供依据。     

基于增量加载法的泥石流拦挡坝抗冲击力数值模拟

为提高泥石流重力式拦挡坝的设计安全和避免资金投入过大而造成浪费,选择合理的泥石流冲击力作为设计依据尤为重要。文章结合舟曲县三眼峪沟灾后重建防治工程相关数据,利用有限元软件ABAQUS进行计算分析,采用增量加载的数值计算方法,分别求得2种工况下重力式拦挡坝的抗冲击力。根据三眼峪沟治理工程运行至今的反馈情况,证明在泥石流治理工程设计中,冲击力选择工况1和2的平均值较合理,同时说明该方法与经验公式结合使用,其结果更加精确可靠,在泥石流工程设计和研究中具有良好的应用前景。     

西藏洛隆县巴曲冰湖溃决型泥石流演进过程模拟研究

巴曲冰湖溃决型泥石流紧邻川藏铁路某车站,可能对其建设及运营产生威胁。首先基于现场调查和遥感解译查明了巴曲泥石流的基本特征,采用规范公式计算了巴曲暴雨泥石流的动力学参数。然后采用无量纲堵塞指数（DBI）评价了巴曲沟内7个主要冰湖堰塞坝的稳定性。评价结果表明:巴曲1#冰湖堰塞坝的DBI值处于非稳定区,3#、4#和6#堰塞坝的DBI值处于非稳定区与稳定区之间,存在发生冰湖溃决的风险。最后,采用快速物质运动模拟软件（RAMMS）单相流数值方法,模拟分析了巴曲沟在4个极端场景下的冰湖溃决演进过程。模拟结果显示:巴曲冰湖溃决后的演进过程分为开始-汇流-冲出-停积四个阶段,共历时约4.5 h。在1#—4#及6#冰湖堰塞体全部溃决工况下,冰湖溃决泥石流在沟口的最大流速为5.92 m/s,最大深度为4.35 m,最大流量为1 954.42 m3/s,为暴雨型泥石流的5.1倍。除此之外,4个场景下冰湖溃决洪水的影响范围都经过拟建车站,泥石流最大深度分别为1.91,3.36,1.53,4.35 m。因此在车站设计时需采取排导槽或导流堤等工程措施进行防护治理。上述研究结果可为川藏铁路选线及青藏高原东部地区的冰湖溃决型泥石流防治提供参考。     

Hazard assessment of debris flows in the Wenchuan earthquake-stricken area,South West China

The Longxi river basin with the city of Dujiangyan, in the Sichuan province of South West China, belongs to the seismic area of the May 12, 2008 Wenchuan earthquake. Lots of loose co-seismic materials were present on the slopes, which in later years served as source material for rainfall-induced debris flows. A total of 12 debris flows, were triggered by heavy rainfall on August 13, 2010 in the study area. The FLO-2D numerical analysis software was adopted to simulate debris flows intensity, including movement velocities and maximum flow depths. A comparison of the measured fan spreading with the simulation results, the evaluation parameter Ω was used to verify accuracy of simulation, the results show Ω values ranging between 1.37 and 1.65 indicating relative good simulation results. This study also estimated the flood hydrograph for various recurrence intervals (20, 100, and 200 years, respectively) to perform scenario simulations of debris flows, and followed Swiss and Austrian standards to establish a debris flow hazard classification model on the basis of a combination of the debris flow intensity and the recurrence period. This study distinguishes three hazard classes: low, medium, and high. This proposed approach generated a debris flow hazard distribution map that could be used for disaster prevention in the Wenchuan earthquake-stricken area, South West China.     

北京市密云区典型泥石流侵蚀过程分析

泥石流运动过程伴随着剧烈的侵蚀,导致其洪峰流量增加、规模增大、破坏性增强。本文通过对2016年8月12日北京市密云区龙潭沟景区曹庄子沟泥石流为例,通过野外调查和地形扫描分析了该场泥石流的动力侵蚀过程。结果表明:激发该场泥石流的降雨重现期达到20年一遇,为典型短历时、高强度降雨;泥石流体中缺乏粘性颗粒,主要以砂粒为主,但容重达到粘性泥石流标准,为典型高容重、低粘度泥石流体。泥石流侵蚀作用一开始并不剧烈,但随着泥石流运动,这种侵蚀作用增强,导致沟道侵蚀深度增加;沟道中弯道处和地形急变段受到泥石流侵蚀作用最为剧烈,尤其是地形急变段对泥石流的侵蚀作用具有加强效应;侵蚀率与流速同步变化,并且与泥石流体所产生的剪切力呈正相关关系。林木能够降低泥石流流速,消耗泥石流动能,进而减小泥石流破坏性。由于天然条件下的泥石流侵蚀过程研究较少,本文中侵蚀率与地形变化的关系以及泥石流体剪切力的正相关关系为泥石流防治规划设计和该类泥石流的预测预报提供了案例和思路。     

Study of kinematic characteristics of a rock avalanche and subsequent erosion process due to a debris flow in Wenjia gully,Sichuan, China

Natural Hazards - This paper aims to systematically study kinematic characteristics of Wenjiagou rock avalanche triggered by the M8.0 2008 Wenchuan earthquake and one of subsequent debris flows...     

昆明市东川城区泥石流危险度评价

泥石流是昆明东川城区最主要的地质灾害之一,严重阻碍了城市的社会经济发展。开展东川城区泥石流危险度评价对城市安全与稳定有着重要的意义。文章从地貌学侵蚀旋回理论出发,运用斯特拉勒面积-高程分析法对东川城区后山的3条泥石流沟的危险度进行评价研究。结果表明,深沟和石羊沟的斯特拉勒面积-高程值分别为0.580和0.520,泥石流沟谷正由发育的中年末期向老年期演化,泥石流危险度较低;尼拉姑沟的斯特拉勒面积-高程值为0.452,处于沟谷发育的旺盛时期,泥石流危险度较高,计算结果与当地实际情况有较好的一致性。     

Physically based dynamic run-out modelling for quantitative debris flow risk assessment: a case study in Tresenda,northern Italy

Quantitative landslide risk assessment requires information about the temporal, spatial and intensity probability of hazardous processes both regarding their initiation as well as their run-out. This is followed by an estimation of the physical consequences inflicted by the hazard, preferentially quantified in monetary values. For that purpose, deterministic hazard modelling has to be coupled with information about the value of the elements at risk and their vulnerability. Dynamic run-out models for debris flows are able to determine physical outputs (extension, depths, velocities, impact pressures) and to determine the zones where the elements at risk can suffer an impact. These results can then be applied for vulnerability and risk calculations. Debris flow risk has been assessed in the area of Tresenda in the Valtellina Valley (Lombardy Region, northern Italy). Three quantitative hazard scenarios for different return periods were prepared using available rainfall and geotechnical data. The numerical model FLO-2D was applied for the simulation of the debris flow propagation. The modelled hazard scenarios were consequently overlaid with the elements at risk, represented as building footprints. The expected physical damage to the buildings was estimated using vulnerability functions based on flow depth and impact pressure. A qualitative correlation between physical vulnerability and human losses was also proposed. To assess the uncertainties inherent in the analysis, six risk curves were obtained based on the maximum, average and minimum values and direct economic losses to the buildings were estimated, in the range of 0.25–7.7 million €, depending on the hazard scenario and vulnerability curve used.     

Rainfall thresholds for debris flow initiation in the Wenchuan earthquake-stricken area,southwestern China

The Wenchuan earthquake-stricken area is frequently hit by heavy rainfall, which often triggers sediment-related disasters, such as shallow landslides, debris flows, and related natural events, sometimes causing tremendous damage to lives, property, infrastructure, and environment. The assessment of the rainfall thresholds for debris flow occurrence is very important in order to improve forecasting and for risk management. In the context of the Wenchuan earthquake-stricken area, however, the rainfall thresholds for triggering debris flows are not well understood. With the aim of defining the critical rainfall thresholds for this area, a detailed analysis of the main rainstorm events was carried out. This paper presents 11 rainfall events that induced debris flows which occurred between 2008 and 2012 after the Wenchuan earthquake. The rainfall thresholds were defined in terms of mean rainfall intensity I, rainfall duration D, and normalized using the mean annual precipitation (MAP). An ID threshold and a normalized I _MAP D threshold graph could be set up for the Wenchuan earthquake-stricken area which forms the lower boundary of the domain with debris flow-triggering rainfall events. The rainfall threshold curves obtained for the study area were compared with the local, regional, and global curves proposed by various authors. The results suggest that debris flow initiation in the study area almost requires a higher amount of rainfall and greater intensity than elsewhere. The comparison of rainfall intensity prior to and after the earthquake clearly indicates that the critical rainfall intensity necessary to trigger debris flows decreased after the earthquake. Rainfall thresholds presented in this paper are generalized, so that they can be used in debris flow warning systems in areas with the same geology as the Wenchuan earthquake-stricken area.     

弯道超高法在泥石流流速计算中的应用——以四川省汶川县G317国道磨子沟泥石流为例

选取四川省汶川至马尔康公路线的磨子沟作为试验对象,采用弯道超高法推算其泥石流流速。进而可以计算出该次泥石流的平均流量,为公路的改建工程提供设计依据。经过实地调查,用此方法计算磨子沟2005年8月17日暴发的泥石流流速为4.4m/s。同其他流速方法计算的结果相比较,前者值偏大,且偏向于工程安全值。弯道超高法可以解决泥石流观测的局限性和泥石流发生的不可重复性。此方法简便易行,对泥石流防治工程具有一定的实用价值。