金沙江上游特米古滑坡堰塞湖形成与溃决时间讨论

开展古滑坡堰塞湖形成演化过程研究,可以揭示古灾害地质环境效应,重建区域构造历史活动序列和古气候演变特征。特米古滑坡发育于金沙江上游巴塘段,滑坡堆积地貌和堰塞湖相沉积物保存较好,是研究区内古地质环境的良好载体。在遥感解译、无人机测绘、现场调查和地质测年的基础上,结合前人研究成果,分析探讨了特米古滑坡发育特征、堰塞湖形成时间与溃决演化过程。结果表明,特米古滑坡是特大型岩质历史堵江滑坡,滑坡堰塞湖实际形成时间应该远早于2.15 ka BP,历史上曾发生过多次溃决,完全溃决时间大约为1.08 ka BP,堰塞湖稳定保存时间大于1.07 ka。金沙江巴塘段大型堵江滑坡群并非由单次地质事件形成,而是由金沙江断裂带多次强烈地震诱发。     

金沙江上游特米古滑坡堰塞湖形成与溃决时间讨论

开展古滑坡堰塞湖形成演化过程研究,可以揭示古灾害地质环境效应,重建区域构造历史活动序列和古气候演变特征.特米古滑坡发育于金沙江上游巴塘段,滑坡堆积地貌和堰塞湖相沉积物保存较好,是研究区内古地质环境的良好载体.在遥感解译、无人机测绘、现场调查和地质测年的基础上,结合前人研究成果,分析探讨了特米古滑坡发育特征、堰塞湖形成时...     

金沙江上游特米古滑坡堰塞湖成因与演化

金沙江上游巴塘—中咱河段位于青藏高原东南缘,该河段两岸岸坡发育众多的大型古滑坡,且部分古滑坡曾堵塞金沙江形成了堰塞湖,特米大型古滑坡堰塞湖是其中之一。关于特米古滑坡堰塞湖的形成与演化过程目前尚未见有过详细的报道。本文在野外调查的基础上,结合遥感影像解译和年代学测试,对特米古滑坡堰塞湖的地貌和沉积特征进行了详细研究,并对其形成与演化过程进行了分析。研究结果表明,特米古滑坡堰塞湖很可能是由该地区的古地震活动触发大型滑坡并堵塞金沙江形成的,最大湖面面积约为1.42×10⁷ m²,库容蓄水量约为1.46×10⁹ m³。该古堰塞湖的形成时间约为1.8 ka BP,其溃决消亡的时间约为1.4 ka BP,溃决洪峰流量约为55 858 m³/s,该滑坡堰塞湖持续稳定了约400年的时间。     

基于HEC-RAS及GIS的川西叠溪古滑坡堰塞湖溃决洪水重建

青藏高原东南缘岷江上游地区地质环境条件十分复杂,滑坡堵江灾害及堰塞湖溃决事件频发,重建其灾害演化过程对于地区性防灾减灾和风险控制具有重要指导意义。以川西岷江上游叠溪古滑坡堰塞湖为研究对象,首先利用高精度DEM和ArcGIS软件重建了叠溪古堰塞湖的原始规模,其原始最大湖水面积为1.1×10⁷ m²,相应的湖容量为2.9×10⁹ m³;然后采用经验公式法和HEC-RAS一维水力学模型重建叠溪古堰塞湖溃决洪水的水力学特征。计算结果表明,HEC-RAS模拟的最大溃决洪水洪峰流量为73 060 m³/s,与经验公式法计算结果(74 500~76 800 m³/s,平均值76 000 m³/s)非常接近,误差小于5%。对应的最大洪水深度和流速分别为70.1 m和16.78 m/s,模拟河段的洪水淹没范围约为6.08 km²。综合误差分析推测的溃决洪峰流量误差范围为69 000~81 000 m³/s。叠溪古滑坡堰塞湖溃决洪水在世界范围内是十分罕见的,其最直接的影响是在下游数公里范围的河谷内形成大量带状或台阶状的溃坝堆积体和巨砾石堆积“阶地”,且这种影响仍延续至今,这与前人关于高能洪水水文特征和沉积特征的研究认识高度一致,证明本研究成果是非常可靠的。此外,本研究还表明,HEC-RAS一维水力模型可用于高山峡谷地区古滑坡堰塞湖溃决洪水重建研究,可为青藏高原东南缘岷江上游古环境重建和地貌演化提供参考。     

青海尖扎盆地寺门村滑坡发育特征及成因分析

滑坡形成演化及复活一直是滑坡防灾减灾领域研究的热点问题。本文在对黄河上游尖扎盆地地质环境背景分析和滑坡体野外调查、遥感解译、实验测试的基础上,分析研究了盆地内寺门村滑坡的变形过程、滑带土和堆积体特征,还原了滑坡的演化过程,厘定了滑坡复活因素,提出了黄河上游滑坡堆积体开发利用对策建议,认为（1）该滑坡是2005年之前发生的老滑坡因河流侧蚀和2018年春季人工灌溉引发的复活性滑坡;（2）滑坡体综合治理应与土地整治相结合且应选择合适的灌溉方式。研究结果对于青藏高原东北缘黄河上游地区的滑坡防灾减灾及滑坡体开发利用具有重要意义。     

滑坡堰塞湖溃决风险与过程研究进展

滑坡堰塞湖是山区常见的一种自然灾害, 对其溃决风险与过程的科学认知和合理评估是应急处置的关键。外荷载作用下滑坡堰塞体的力学响应、滑坡堰塞湖渐进破坏机理与溃决洪水预测理论是滑坡堰塞湖风险评估研究领域的关键科学问题。本文围绕滑坡堰塞湖形成后的溃决风险与过程展开综述, 从定性和定量的角度分别对堰塞湖危险性评价方法进行分析总结, 从小尺度、大尺度和超重力场试验技术的角度总结了堰塞湖的溃决机理、溃决过程及其影响因素, 从数学方法的角度对堰塞湖溃决洪水预测中经验公式法、简化和精细化数值模拟方法的进展进行总结评价。然而, 国内外关于滑坡堰塞湖风险评估领域的研究仍处于起步阶段, 空-天-地一体化监测技术、堰塞湖危险性评价中的不确定性问题、堰塞体材料冲蚀特性与溃决机理、堰塞湖溃决洪水精细化模拟等将是未来的重点研究方向。本综述可为堰塞湖防灾减灾和流域水工程风险管理提供有价值的参考。     

黄河上游德恒隆-锁子滑坡堵塞黄河事件

黄河上游龙羊峡刘家峡河段两岸岸坡形成了众多残留体积超过10⁸ m³的古巨型滑坡,最大体积近30×10⁸ m³,且大部分堵塞过黄河。但部分巨型滑坡至今未有学者进行科学研究,其中包括德恒隆滑坡和锁子滑坡。结合区域地质环境条件,通过对德恒隆-锁子两个巨型滑坡基本特征和滑坡堵塞黄河的野外7个地质现象进行分析,并对德恒隆-锁子滑坡形成机制进行初步探讨,认为德恒隆-锁子滑坡为地震型滑坡,且形成原因与青藏高原8万 a的构造期有密切关系。通过分析黄河沿岸堰塞湖湖相沉积,认为堰塞湖形成时间为8万 a左右,这与德恒隆-锁子滑坡的形成年代一致。因此德恒隆-锁子滑坡在地震作用下触发并堵塞黄河。     

岷江叠溪古堰塞湖的研究意义

近年来,在岷江上游及其支流杂谷脑河中发现了多处滑坡古堰塞湖沉积物,并受到广泛关注,但也有不少学者质疑是否是堰塞湖相沉积物.2008年5月12日四川汶川地震引发了几十个规模较大的滑坡堰塞湖,叠溪古堰塞湖展示的重大地质历史事件再次引起学术界广泛的关注.本文根据最新调查、勘查和测试资料对古堰塞湖的形成与消亡过程做了进一步查证...     

金沙江上游雪隆囊古滑坡堰塞湖溃坝堆积体的发现及其环境与灾害意义

西藏芒康县金沙江上游雪隆囊河谷史前时期(全新世晚期)发生了一次明显的堰塞事件,形成了一个湖水体积约3.1×108 m3的大型堰塞湖。该堰塞湖形成后期发生溃决并引发异常大洪水,这一溃决事件发生在大约1 117 A.D.。地震诱发山体滑坡可能是金沙江发生堰塞的直接原因。在雪隆囊古堰塞坝体的下游一侧到其下游3.5 km的范围内,发现大量由砾石、砂和少量黏土组成的混杂堆积体,判定其为滑坡堰塞湖的溃坝堆积,是滑坡坝体及上游河床物质在坝体溃决后快速堆积形成。整套溃坝堆积体具有支撑-叠置构造、叠瓦构造和杂基构造等沉积特征,还具有一种特殊的沉积构造:即在垂向剖面上发育粗砾石层与细砂砾层的韵律互层,但剖面中缺少砾或砂的透镜体。这种沉积构造("互层构造")是溃坝堆积相区别于冲-洪积相、泥石流相等的一种重要判别标志。采用水力学模型反演确定雪隆囊古滑坡堰塞湖溃决洪水的平均流速为7.48 m/s,最大洪峰流量为10 786 m3/s。雪隆囊溃坝堆积体沉积特征及其环境的研究,不但有助于揭示古洪水事件发生的过程和机制,同时对于认识金沙江上游地区的环境演变也具有重要意义。     

黄河上游松坝峡特大型滑坡堰塞湖及地貌效应研究

青藏高原贵德盆地东部的松坝峡峡谷区分布有多处特大型和巨型岩质古滑坡,其滑动后曾堵塞黄河干流形成巨大堰塞湖。文章在野外调查、样品测试和高分影像解译的基础上,分析了松坝峡特大型和巨型滑坡的空间特征、滑坡堰塞湖地貌形态及湖泊溃决后的环境效应,主要取得了以下认识:(1)贵德盆地东部晚更新世以来至少发育了7处特大型-巨型古滑坡,其中松坝峡左岸和右岸滑坡发生后堵塞黄河形成面积达150 km~2的古滑坡堰塞湖;(2)该堰塞湖湖相纹泥层厚约14 m,湖相层底部和顶部14C年代分别为4 030+/-30 BP和1 090+/-30 BP,指示堰塞湖持续了约3 000 a;(3)贵德盆地东部晚更新世以来地貌演化时间顺序:松坝峡左右岸滑坡发生→堰塞湖形成→古洪积扇发育→堰塞湖溃决→革匝滑坡发生→古河道摆动和近百年泥石流扇发育。     

Dynamic process analysis for the formation of Yangjiagou landslide-dammed lake triggered by the Wenchuan earthquake, China

The damming of rivers by landslides resulting in the formation of a lake was one of the typical secondary geological hazards triggered by the Wenchuan earthquake which occurred on May 12, 2008. Some landslide-dammed lakes were at a high risk of causing further damage since the rainstorm season was expected soon after the earthquake. Understanding the dynamic processes in the formation of landslide-dammed lakes is helpful in planning the mitigation measures. The Yangjiagou landslide-dammed lake was selected as a case study to investigate the typical processes of dam formation. The dynamic simulation of the formation of the Yangjiagou landslide-dammed lake was divided into two steps: the landslide step and the overflow/overtopping step. Two-dimensional discrete element method (DEM) was adopted to investigate the mechanics of the Yangjiagou landslide. The landslide process was found to be controlled by the bond strength and residual friction coefficient of the DEM models. Computational results show that the formation of the landslide dam took approximately 35 s. The maximum velocity of a typical particle was approximately 26.8 m/s. The shallow-water equation and finite difference method were used to analyze the hydrodynamic mechanisms of the overflow process of the landslide-dammed lake. Computational results show that overflow would have occurred 15.1 h after the river was blocked, and overtopping failure occurs for the landslide dam in the rainstorm season when the water flow is large enough, causing a major disaster.     

岷江上游河流阶地发育特征及与古滑坡关系初步分析

河流阶地形成演化及其对滑坡的控制是近年来古滑坡研究的热点问题。笔者在对岷江上游河流阶地和古滑坡实地调查测试的基础上,对岷江上游河流阶地的级序、拔河高度、成因类型等进行了分析,绘制了阶地高程位相图和年龄位相图,并结合阶地和古滑坡年代,讨论了阶地与古滑坡的发育关系等。主要取得了以下认识:1)岷江上游的河流阶地具有分段性,成因主要为气候多期次波动与构造活动共同作用,古滑坡及堰塞湖是影响高山峡谷区河流阶地发育的重要因素;2)叠溪-茂县段在20~30 ka B.P.发生了多处大型古滑坡,其中20 ka B.P.的古滑坡可能主要是气候波动引发,30 ka B.P.发生的古滑坡可能主要受控于构造活动(地震);3)岷江上游大量分布的古滑坡堆积体与阶地发育的叠置关系有待进一步理清,开展该地区的河流阶地级序研究要充分考虑古滑坡和堰塞湖的影响.     

Ancient landslide-dam events in the Jishi Gorge,upper Yellow River valley,China

Some scholars have argued that the formation and outburst of an ancient dammed lake in the Jishi Gorge at ca. 3700 cal yr BP resulted in the destruction of Lajia, the site of a famous prehistoric disaster in the Guanting Basin, upper Yellow River valley, China. However, the cause of the dammed lake and the exact age of the dam breaching are still debated. We investigated ancient landslides and evidence for the dammed lake in the Jishi Gorge, including dating of soil from the shear zone of an ancient landslide, sediments of the ancient dammed lake, and loess above lacustrine sediments using radiocarbon and optically stimulated luminescence (OSL) dating methods. Six radiocarbon dates and two OSL dates suggested that the ancient landslides and dammed lake events in the Jishi Gorge probably occurred around 8100 cal yr BP, and the ancient dammed lake was breached between 6780 cal yr BP and 5750 cal yr BP. Hence, the outburst of the ancient dammed lake in the Jishi Gorge was unrelated to the ruin of the Lajia site, but likely resulted in flood disasters in the Guanting Basin around 6500 cal yr BP.     

黄河上游康杨滑坡堆积体特征及形成机理分析

滑坡堆积体特征及其成因机理是进一步研究滑坡防治及开发利用的基础与前提。位于青藏高原东北缘的黄河上游群科—尖扎盆地内的康杨滑坡属于典型的巨型古滑坡,其堆积体特征及形成机制在该地区具有典型性和代表性,具有较高的学术研究价值。结合工程地质钻孔资料,通过详细的野外调查、粒度分析等方法对康杨滑坡形态特征、形成年代、滑坡体粒度特征及其成因机理进行了研究,主要认识如下:（1）康杨滑坡为晚更新世晚期发生的泥岩滑坡,体积约为12.59×108?m3,为一典型巨型古滑坡,后壁高耸直立;（2）滑坡前缘曾滑移至黄河北岸,堆积体可能堵塞黄河,后被黄河从中部侵蚀切穿,目前在黄河北岸仍存留有古滑坡堆积体;（3）高原抬升和黄河下蚀等作用可能是滑坡发生的背景条件,降水入渗形成软弱滑带和黄河侧蚀作用可能是触发康杨滑坡的主要因素。     

Formation process of a large paleolandslide-dammed lake at Xuelongnang in the upper Jinsha River,SE Tibetan Plateau: constraints from OSL and <Superscript>14</Superscript>C dating

A large number of the landslide dams located on the major rivers at the southeastern margin of the Tibetan Plateau have been previously identified through remote sensing analysis and field investigations. The Xuelongnang paleolake was one of the lakes formed by these landslide dams in the upper Jinsha River, where the association of a relict landslide dam, lacustrine sediment, and outburst sediment is well preserved. This preservation provides an opportunity to better understand the formation, evolution, and longevity of a large landslide-dammed lake in the upper Jinsha River. It was inferred that the Xuelongnang dammed lake may have been formed by an earthquake-induced paleoavalanche. The surface area of the lake at its peak was estimated at 7.0?×?10⁶ m², and the corresponding volume was approximately 3.1?×?10⁸ m³. Two outburst flood events were determined to have occurred during the life span of the lake. Based on the 18 ages obtained from optically stimulated luminescence (OSL) and carbon-14 (¹⁴C) dating combined with stratigraphic sequences observed in the field, the paleolandslide-dammed lake was formed at approximately 2.1 ka and subsequently breached locally. The dammed lake was sustained for a period of some 900 years based on the chronological constraining. This study confirms that a major landslide-dammed lake can be sustained for at least hundreds of years and breached by several dam breaks in multiple periods, which contributed to the preservation of the knickpoints at millennial scale along the major rivers in the study area.