北京市延庆区石窑村南地沟泥石流特征及发展趋势预测

本文以北京市延庆区石窑村南地沟泥石流为研究对象,通过野外调查与GIS统计分析,研究该流域降雨条件、地形地貌和沟道条件、物源条件等形成条件特征,针对流域内松散堆积物转换,开展了流域分区特征分析;通过14个因子分析,建立了该泥石流的发育阶段识别模型,对其发展趋势进行了预测;利用单沟泥石流堆积区公式开展了最大危险区预测研究,提出相应的防治措施建议。研究表明:石窑村南地沟泥石流内松散堆积物动储量达18.36×10~4 m~3,物源类型划分为冲洪积物源、残坡积物源、人工堆积物源和崩滑塌物源4种,其中残坡积所占比重最大。该泥石流属于暴雨-沟谷型-支沟群发型、中易发泥石流,泥石流发展阶段处于发育期,最大危险区面积为0.413 km~2,对沟口堆积区的石窑村及村民的生命财产安全造成威胁,建议采用局部物源平整与疏理排导渠相结合的综合治理措施。本文为该区地质灾害防治提供基础依据。     

高密度电阻率法和探地雷达在北京市延庆区泥石流灾害勘查中的应用

泥石流是北京地区最严重、最具破坏性的地质灾害类型,为了科学防治泥石流,本次采用高密度电阻率法和地质雷达相结合的方法,通过正反演计算和实测剖面的综合解释,基本查明了北京延庆区松散堆积物的厚度,其中井庄乡果树园村泥石流沟域范围内松散堆积物厚度较大,一般40~60 m,自下游向上逐渐变薄,并且浅部存在一层厚度为10~15 m的块石土堆积层;其余地段松散堆积物厚度一般8~10 m,并估算了研究区松散堆积物的方量。这两种方法的综合应用对松散堆积物的划分具有较好的效果,为科学防治泥石流提供了依据。     

龙达沟泥石流特征及其对工程影响的研究

西南某水电站坝址区龙达沟,历史上曾多次发生泥石流,从沟内松散物源分布、成分等特征,显示该沟属暴雨型稀性泥石流。通过对该泥石流,不同降水条件下一次冲出量预测,分析了泥石流对沟口拟建尾水洞出口等工程枢纽的影响程度。     

某泥石流发育特征及成因机制分析

某泥石流沟流域内东高西低,主沟长3.84km,流域面积约5km~2,总体表现为下游集水面积小,中上游集水面积相对较大,总体呈"树叶"状展布。现沟内松散固体物源较丰富,总量约300万m~3,大多处于稳定状态,初步分析,能为全沟泥石流提供的不稳定松散固体物质量约78万m~3。本文通过对该泥石流沟流域自然条件、泥石流沟谷分区特征、泥石流形成条件及机制分析进行了研究,为泥石流沟的防治提供依据。     

延庆地区水头村泥石流形成条件及发展趋势

水头村泥石流沟是延庆地区典型沟谷型泥石流沟之一,具易发性高、危险性大的特点,严重威胁下游水头村村民。本文以水头村泥石流沟为研究对象,通过精细调查与GIS统计分析,获取了该流域降雨、地形地貌、物质来源等信息,对泥石流流域分区特征和形成条件进行研究,综合14个识别因子,确定了该泥石流沟的发展阶段,并预测其发展趋势,通过单沟泥石流堆积区公式预测了该流域最大危险区,并提出了防治措施建议。研究表明：水头村泥石流沟内松散堆积物动储量达27.96万 m³,其中以残坡积和冲洪积为主要物源;该泥石流属于暴雨-沟谷型-支沟群发型泥石流沟,发展阶段处于形成期,最大危险区面积为0.737 km²,威胁沟口水头村住户21户59人和红水公路350 m。建议采用定期巡视+局部物源稳固+清理排导槽相结合的防治措施。研究成果可为该区泥石流灾害防治提供基础数据支撑和科学依据。     

喜德县波振沟泥石流形成条件及动力特征2

波振沟位于四川省凉山州喜德县境内孙水河左岸,属于川南红层地区典型沟谷型泥石流沟。通过工程地质调查与遥感影像解译,研究了该泥石流形成条件和机理,获取了泥石流动静力学参数。调查研究表明:(1)波振沟流域地貌正处于壮年期发育阶段;(2)泥石流容重1.64g/cm3,属于过渡(偏稀)性泥石流;(3)波振沟流域内还存在大量崩滑体及沟道松散堆积体,松散物源近4×105m3,在强降雨作用下容易启动泥石流,建议加强综合防治。该研究对砂泥岩互层地区泥石流形成机理的认识有一定帮助,对波振沟泥石流防治具有参考价值。     

汶川极震区锄头沟泥石流发育特征及启动机理

汶川地震过后大量的老泥石流被激活,随着潜伏期的过去,雨季来临,松散物源开始重新活跃。通过对锄头沟泥石流的实地调查及现场测量发现,该沟流域面积较大,支沟发育,支沟及主沟后缘比降大,主沟中下段宽缓,泥石流物源主要为崩塌物源,分布于流域中上部和支沟内,泥石流由中上部和支沟启动,汇聚于主沟内,并沿沟道下段堆积,并通过室内试验等手段,还原了泥石流发生时的激发雨量及物源分布特征。震后极震区泥石流的具有物源类型丰富、易发程度高、激发雨量偏小和支沟群发等特点,该沟泥石流还出现了堵溃型泥石流现象。     

北京石窑村泥石流沟发育形成特征与动力学研究

以北京典型沟谷型泥石流沟——四海镇石窑村沟为研究对象,通过地表调查及资料统计,详细阐述了该泥石流的发育和形成特征,并重点分析了流域内物源补给条件.此外,根据该泥石流的动力学特征,预测评价了其最大危险区,并提出相应的防治建议.研究结果表明:该泥石流沟内物源动力学储量为36.39 × 104 m3,物源类型为沟道冲洪积物、...     

热河沟泥石流成因机制分析

受汶川地震的影响,西南地区地质灾害近来年频繁发生,尤其是泥石流灾害。在地震作用下,有更多的松散物源参与泥石流的运动,加大了泥石流的危害性和暴发频率。本文收集了热河沟的地质、气象和水文等资料,通过分析该沟的地形、物源和水源条件来分析泥石流的形成过程,结合现场调查取证来综合分析泥石流的形成机制,为泥石流的治理提供更为可靠的依据。分析表明,热河沟泥石流的成因机制为"暴雨-溃决"型。     

热河沟泥石流成因机制分析

受汶川地震的影响,西南地区地质灾害近来年频繁发生,尤其是泥石流灾害。在地震作用下,有更多的松散物源参与泥石流的运动,加大了泥石流的危害性和暴发频率。本文收集了热河沟的地质、气象和水文等资料,通过分析该沟的地形、物源和水源条件来分析泥石流的形成过程,结合现场调查取证来综合分析泥石流的形成机制,为泥石流的治理提供更为可靠的依据。分析表明,热河沟泥石流的成因机制为"暴雨-溃决"型。     

北京市延庆区秤勾湾沟泥石流特征及预警雨量研究

本文以北京市延庆区秤勾湾泥石流沟为研究对象,利用泥石流沟精细调查及历史资料,研究其降雨特征、流域特征、分区特征、物源特征,采用灰色系统关联度方法开展危险性评价研究,建立URCS-CN预警雨量模型,开展预警雨量阈值研究。研究结果显示:秤勾湾泥石流沟危险性评分为0.84分,危险等级为高危险,流域内红色预警过程雨量122 mm、橙色预警过程雨量109 mm、黄色预警过程雨量95 mm、蓝色预警过程雨量82 mm;秤勾湾沟泥石流累计流量与预警流量呈线性关系,前期的有效降雨与短时强降雨呈彼增我减的态势,在红色预警范围左侧为泥石流灾害的低频区,红色预警范围为泥石流灾害的高频区。研究成果为延庆地区该类泥石流单沟预警模型研究和灾害防治提供科学依据。     

Anatomy and behaviour of a post-eruptive rain lahar triggered by a typhoon on Mayon volcano,Philippines

Mayon Volcano in the Philippines, one the world's most active, is situated in a moist, tropical-maritime climate with frequent typhoons. A third of Mayon's eruptions generate destructive lahars (volcanic debris flows and hyperconcentrated streamflows). Lahars also occur during quiescent periods when monsoons and typhoons deliver rains of appropriate intensity and duration to the loose debris on the volcano slopes. Both eruption- and post-eruptive lahars occur most frequently during the typhoon-prone October–December season of the Northeast Monsoon. Post-eruptive lahars, the most poorly documented, are exemplified by a debris-flow event triggered by Saling, a typhoon of only moderate intensity, that occurred in Mabinit Channel on the southeast Mayon flank on October 17–18, 1985, one year after the last Mayon eruption. Detailed pre- and post-Saling surveys docment channel deepening of up to 4 m and maximum lateral erosion of 66 m. The debris flows left prominent, discontinuous multi-level terraces along the length of Mabinit Channel, either from pulsations due to temporary channel blockage, or as levee deposits. A significant volume of debris overtopped channel bends at 250–200 m elevations, coalescing to cover a 200,000 m² area of 4.5° slope with bouldery lateral deposits 1 m thick on the average. Channelized flows below this level plugged 0.5 km of the original channel and replaced it with a new conduit of comparable size. The Saling debris-flow deposits have a remarkably uniform sand-silt mode and less prominent, more variable modes in the pebble-boulder range. Shear strengths of the lateral flows ranged from 0.46×10⁴ to 2.32×10⁴ dn cm^?2; those of the channelized flows at the plug were significantly higher. Reconstructed flow velocity was 3.8 m sec^?1.     

降雨强度对松散堆积土斜坡破坏的模型试验研究

通过在室内构建泥石流源区松散堆积土体斜坡模型,采用三种不同降雨强度对其稳定性进行研究。得出了不同降雨强度下斜坡土体流失规律与斜坡的失稳方式。结果表明：在低雨强（26mm/h）作用下,松散斜坡的土体流失量最少,并以坡面侵蚀为主;在中、高雨强（51mm/h,68mm/h）作用下,首先表现为坡面侵蚀和沟道侵蚀,进而是大规模土体流滑破坏,在土体累积流失量与时间曲线上有突变点;在高雨强作用下,形成了阵性泥石流。     

Hydraulic mechanism and time-dependent characteristics of loose gully deposits failure induced by rainfall

Failure of loose gully deposits under the effect of rainfall contributes to the potential risk of debris flow.In the past decades,researches on hydraulic mechanism and time-dependent characteristics of loose deposits failure are frequently reported,however adequate measures for reducing debris flow are not available practically.In this context,a time-dependent model was established to determine the changes of water table of loose deposits using hydraulic and topographic theories.In addition,the variation in water table with elapsed time was analyzed.The formulas for calculating hydrodynamic and hydrostatic pressures on each strip and block unit of deposit were proposed,and the slope stability and failure risk of the loose deposits were assessed based on the time-dependent hydraulic characteristics of established model.Finally,the failure mechanism of deposits based on infinite slope theory was illustrated,with an example,to calculate sliding force,anti-sliding force and residual sliding force applied to each slice.The results indicate that failure of gully deposits under the effect of rainfall is the result of continuously increasing hydraulic pressure and water table.The time-dependent characteristics of loose deposit failure are determined by the factors of hydraulic properties,drainage area of interest,rainfall pattern,rainfall duration and intensity.     

云南本屋宅箐泥石流沟特征及危险性评价

文章以云龙县宝丰乡福利村本屋宅箐泥石流沟为研究对象,在现场实地调查的基础上,阐述泥石流沟特征、类型、成因、发展趋势,并对该泥石流沟的危险性进行了评价。该泥石流的形成受地质、地形、气象水文及人类活动等综合因素的影响,前期降雨使固体物质分散汇入沟床积累,属于崩塌+滑坡型、沟谷泥石型、中型、高频、发展期稀性泥石流。目前,福利村本屋宅箐流域固体物源丰富,降雨集中,水源充沛,溯源侵蚀作用强烈,物源区滑坡、沟岸坍塌发育,谷坡稳定性差,泥石流的发展有增强趋势。本次采用成都山地所刘希林于1996年提出的单沟泥石流危险度评价方法对该泥石流沟的危险性进行评价,单沟泥石流危险度H单=0604,按照分级标准,福利村本屋宅箐泥石流沟属高度危险泥石流沟。     

Debris flow hazard assessment by combining numerical simulation and land utilization

Debris flow has caused serious human casualties and economic losses in the main earthquake-hit areas affected by the Wenchuan earthquake. As one of the important and effective means of non-engineering disaster mitigation, debris flow hazard assessment is a key issue for the sustainable economic and social development of earthquake-hit areas. This article illustrates a new method to quantify the debris flow hazard by combining debris flow simulated results with different land utilization within the influence area. The Guo Juanyan gully in Dujiangyan city, Sichuan province, China, located in the meizoseismal area of the Wenchuan earthquake, was selected as the study area. The rainfall characteristics, including the rainfall pattern and the 10-min, 1-h, and 24-h critical rainfalls, were fully explored first. Then, the numerical simulation method was applied as a modeling tool to simulate debris flow influence area and final buried depth under rainfall with different return periods. The simulated results under a 100-year return period rainfall were validated based on field measurements. Finally, the debris flow hazard maps under different return periods were overlapped by combining the simulated results and the types of land utilization. The proposed method can enhance the accuracy of debris flow hazard assessment and can be widely used for debris flow mitigation, which has important application value.     

Geotechnical characteristics of soils susceptible to severe gullying in eastern Nigeria

The geotechnical characteristics of soils that are susceptible to severe gullying in the rain forest zone of Nigeria were studied. The soils are predominantly sands whose fines (silt/clay) contents are very negligible. The sands are loose (dry density 1.42–1.73 g/cm³) and highly permeable (permeability 9.43×10³?3.4×10²cm/s) with permeability increasing with depth. Porosities and void ratios are also high (41.6–50.3% and 0.71–1.01 respectively), while cohesion is small to zero (0–85 kN/m²). It is thought that although these conditions favour less runoff and high infiltration, they lead to high internal flow velocities and seepage pressures, and ultimately high internal erosion. It is concluded that once a gully is initiated, the soil properties become responsible for rapid propagation. Non response of the gullies studied to afforestation control measures is thought to result from these soil properties.     

北京碰河寺沟泥石流成因及综合防治对策

北京地区泥石流主要分布在密云区北部、怀柔区中部、延庆区东部及房山、门头沟区西部地区。北山泥石流受区域构造和山势走向所控制,总体呈北东向展布,其无论爆发频率、活动规模及发育密度均为北京山区之首位。研究区位于密云区东北部,为北山地区的一条老泥石流沟,曾在1976年发生过泥石流活动,支沟沟口处赵洪全一家房屋被冲毁,其它损失情况不详。2011年7月24日,碰河寺沟主沟发生特大山洪,将进村道路冲毁、毁坏房屋数十间、冲毁良田、果木上百株,造成造成巨大的经济损失,进行治理已是迫在眉睫。