四川省万源市花楼乡董家梁滑坡特征及成因机制研究

万源市花楼乡董家梁滑坡属于典型的四川盆地盆周山区红层地层滑坡.通过现场调绘、工程地质勘探等手段,揭示该滑坡为强大水压力起主导作用的滑动变形破坏.根据滑坡滑动后的空间形态及残留体特征,将滑坡划分为滑坡启动区(A区)、滑坡西侧推挤滑动区(B区)、滑坡东侧牵引滑动区(C区)三个部分.研究表明滑坡启动始于地下水活动强烈的中部区域(A区),水压力随雨量增加而急剧增长,该区岩体受水压力推挤沿层面及侧裂结构面发生剪切破坏,形成楔形体滑动,同时牵引B区和C区岩体产生推挤、拉张、牵引滑动破坏.     

地震坠落滑动型滑坡发育特点及典型实例分析

汶川地震诱发了大量的地震滑坡,其中坠落滑动型滑坡是一种普遍的地震滑坡类型,滑动特征独特,动力机制复杂。以彭州市九峰村滑坡为实例,介绍了滑坡发育的控制因素,滑坡运动及形成过程经历了后缘崩塌坠落启动、中下部整体启动滑移、滑后堆积等3个阶段。结合地震条件下斜坡岩土体的变形破坏机理,解释了地震坠落滑动型滑坡后壁上部为崩塌坠落裂面,斜坡中部坡体浅层滑动明显,滑坡滑动速度快、距离远,坡脚形成倒石堆危害大,次生灾害链持续时间长等特点。     

复合型滑坡推力计算方法研究

复合型滑坡是推移式和牵引式的组合,既有牵引式滑坡的特点又有推移式滑坡的性质,通过对复合型滑坡形成机理的研究,揭示了复合型滑坡具有前部牵引—后部加载—中部滑带剪断贯通—最终整体滑移失稳的变形破坏模式,对应地将复合型滑坡分为3个区前缘启动区(牵引作用)、中间主滑区、后缘启动区(加载作用)。针对不同区的破坏形式和受力特点,以及不同区之间的相互作用过程,建立了准确合理的地质力学计算模型,对不同区推力进行详细的计算推导。在推力计算过程中,复合型滑坡推力计算具有区段针对性,前缘启动区和后缘启动区需要考虑与中间主滑区之间的相互作用,而中间主滑区的稳定性是对整个滑坡起主导作用,在计算推力时,既要考虑前缘启动区阻滑段的缺失又要考虑后缘启动区的加载效应。以典型复合型滑坡为例,通过计算充分说明此推力计算方法的合理性,为复合型滑坡防治工程设计提供计算方法。     

降雨条件下水库滑坡变形特征及形成机制分析

河西水库滑坡位于云南省保山市昌宁县田园镇,其后缘存在明显的拉张裂缝和错坎,岸坡挡墙和截水沟开裂变形,严重威胁溢洪道和坝体安全。从滑坡基本形态特征、地质环境条件出发,结合工程地质勘察资料,分析了滑坡的变形特征和诱发因素,判断该滑坡为大型厚层牵引-推移式顺层滑坡。在不同降雨强度和库水位变化条件下,通过Geo-Studio数值软件模拟了坡体孔隙水压力和安全系数的变化,并对其稳定性进行分析评价。结果表明:持续降雨作用使库水位上升,软化坡体前缘土体强度,坡体内孔隙水压力增大,产生自然卸荷作用,致使下滑力增加,加剧了坡体变形破坏失稳。在库水位骤降过程中,库水反压作用弱化,先期坡体水分渗透作用产生动水压力,更容易导致此类滑坡的发生。滑坡区陡坡地形和下覆岩层顺向构造为滑坡的发育创造了有利条件,而持续降雨是造成滑坡的主要因素。采用削坡反压联合抗滑桩的方式是防治该滑坡的有效手段,研究结果可为水库日常运行管理及库区类似滑坡的分析、判断和及时防治提供理论参考依据。     

金沙江永善—水富段滑坡分布规律及其形成模式

为了评估金沙江向家坝水库(永善—水富)蓄水后岸坡稳定性,同时为水库运营期地质灾害监测预警提供参考资料,以地质图、地形图、正射航空影像和SPOT-5商用卫星影像为基础资料,利用GIS平台,结合蓄水前现场调查和遥感解译方法建立滑坡数据库,利用统计学方法分析滑坡空间分布与岸坡结构、地层的关系,最后归纳了滑坡的四种形成模式。获得以下结果:(1)滑坡主要发育于新市镇以下侏罗系地层,新市镇以上滑坡分布受猰子坝断层控制;(2)缓倾外顺向层状岸坡(Ⅲ1)滑坡数量分布密度最大,斜向层状岸坡(Ⅴ)滑坡数量分布密度最小;(3)侏罗系自流井组(J2z)的滑坡点密度最大,二叠系乐平组(P2l)的滑坡面密度最大;(4)库区已有滑坡形成模式可归纳为四种:(1)倾坡外层状岩体岸坡(Ⅲ2)的切层滑动;(2)缓倾坡外层状岩体岸坡(Ⅲ1)的顺层滑动;(3)缓倾坡内层状岩体岸坡(Ⅳ1)的弧形滑动;(4)崩坡积、冲积松散层顺下伏基覆界面滑动。在向家坝水库蓄水期及运营期,应重点监测新市镇以下岸坡,尤其是缓倾外顺向层状岸坡(Ⅲ1)。     

贵州省开阳县田坝寨滑坡形成机理研究

2016年5月23日,贵州省开阳县龙岗镇大石板村鱼鳅坡组田坝寨突发滑坡灾害,造成2人死亡、5间房屋和10余亩耕地损毁,直接经济损失90万元。在进行详细地质调查的基础上,对田坝寨滑坡的基本特征进行了分析,并结合PFC~(2D)数值模拟,对滑坡成因机制进行了研究。结果表明:降雨为田坝寨滑坡的直接诱发因素,斜坡变形破坏模式为上部的土体沿基岩面先出现变形,对下部滑体产生推挤作用,直至坡脚产生剪切破坏,并向上牵引发展,导致整体滑动。田坝寨滑坡形成机制的研究对于贵州地区类似滑坡分析及识别具有重要的参考价值。     

万州孙家荆竹屋基滑坡滑动模型研究

荆竹屋基滑坡的滑动过程存在多种解体模式,为了研究该类顺层岩质滑坡的滑动模型,在对滑坡后滑体结构和地面破裂现象系统调查的基础上,根据解体特征对滑坡进行了分区,并通过建立的滑坡作用强度评价模型,探讨了滑坡滑距、运动解体模式和建筑物易损性等问题。研究结果表明①前缘采石场的切坡使潜在不稳定的斜坡临空,抗滑力降低,诱发了中部浅层顺层软弱页岩层及后部风化接触带的整体滑动;②主滑体滑移距离约29.5 m,主滑方向为5°,滑体厚度约15 m;③受滑体风化层厚度变化和前地形条件限制,在整体滑动后分区解体现象明显。滑体上各区对建筑物易损性的作用强度从大到小依次为前缘堆积区(Ⅵ)>后缘拉槽破坏区(Ⅱ)>中部推覆区(Ⅳ)和破碎区(Ⅶ)>局部分块滑移区(Ⅴ)>中部逆冲区(Ⅳ)>顺层整体滑移区(Ⅲ₁、Ⅲ₂)>后缘拉裂影响区(Ⅰ)。研究绘制出的滑坡解体破碎分区图,对分析滑坡风险分布规律具有参考价值。     

库岸滑坡稳定性物理模拟研究

库水位升降与降雨是库岸滑坡发生的主要诱因。以三峡库区塘角村2号滑坡为例,在室内建立了滑坡地质力学模型。试验结果表明:水库水位升降对滑坡前缘涉水部分影响较大,对中部和后缘影响较小;降雨对滑坡前缘、中部、后缘影响相对显著,主要表现在土压力及孔隙水压力与降雨过程呈现同步并略滞后于降雨的特征;降雨及库水位变化联合作用下,前缘变形破坏最大,前缘部分的变形破坏牵引中部发生变形。     

蓄水条件下库岸滑坡形成机制研究

以九甸峡库区燕子坪滑坡为例,采用GPS对滑坡外部进行变形监测的方法确定滑坡的变形特征。结合库水位变化及降雨等影响因素,定量研究蓄水条件下库岸滑坡的水力触发因素及形成机制,并采用极限平衡法对分析规律进行验证。结果表明:(1)库岸滑坡的变形破坏是一个蠕变破坏过程,主要因素是较大蓄水速率的加剧条件下短时间发生的,次要因素是强降雨;(2)燕子坪滑坡主要是由于库水位上升和开挖公路的共同作用导致了滑坡体中部及前缘牵引后部滑坡体滑动。     

牵引式滑坡降雨预警判据的模型试验研究

以河南省灵宝市麦尖窝滑坡作为试验对象,进行室内人工降雨模型试验,研究降雨作用下牵引式滑坡的变形破坏规律,并提出适用于研究区的降雨预警判据。采用含水率传感器、坡面示踪点和数码相机等仪器设备对关键部位含水率、坡面变形和裂缝发育情况进行监测、记录。试验表明在强降雨作用下,边坡表现为自下而上的渐进式牵引变形破坏。通过分析模型各关键部位的变形破坏特征和含水率监测数据,确定牵引式滑坡变形破坏过程中的关键时间节点,并将整个过程划分为变形启动、变形加速和整体破坏3个阶段。基于以上变形破坏模式,提出以滑坡坡脚、坡肩表面出现贯通裂缝时的持续累计雨量E₁(75 mm)、E₂(180 mm)分别作为麦尖窝滑坡的橙色、红色降雨预警判据。     

长江中游四大家鱼发江生态水文因子分析及生态水文目标确定

基于长江中游四大家鱼发江量历次调查数据,采用宜昌站作为长江中游水文情势变化分析的控制站,基于其1900~2004年共105年的日径流资料,采用每年5~6月涨水过程数、总涨水日数、平均每次涨水过程日数等3项生态水文指标,分析了四大家鱼发江量与3项生态水文因子的变化关系,认为产卵场所处江段每年5~6月的总涨水日数是决定家鱼苗发江量多寡的一个重要环境因子。根据IHA方法,对宜昌站105年来的生态水文指标分析表明,长江宜昌站生态水文过程的改变并不明显,5~6月总涨水日数变化趋势不显著,显示长江中游影响四大家鱼苗发江量的生态流量过程改变不明显,与前人得出的葛洲坝枢纽修建后四大家鱼的产卵条件和卵苗江汛规律没有变化这一认识一致。但是,随着三峡水库的运行,下游河道的生态环境流量过程会有较大改变,本文建议三峡水库的调控以保障长江中游每年5~6月的总涨水日数维持在22.1±7.2范围内为生态水文目标,即可从生态环境流量过程方面补偿水利工程对中游四大家鱼鱼苗发江量的影响。     

Seminar on Water and Energy,Stockholm, Sweden,August 21, 2005

Abstract

In Europe the implementation of the Water Framework Directive (WFD) will have major implications for water resources management. Part of the Directive requires Member States to implement a comprehensive system of controls (licences) on the allocation and abstraction (withdrawal) of surface and groundwater resources. This paper describes the development of a procedure to help assess and set abstraction licences for agricultural irrigation. The methodology is described with reference to Scotland, a country with limited abstraction control previously and where irrigation is supplemental to rainfall. The methodology combines spatial climatic information using a Geographical Information System (GIS) with data derived from a water balance computer model. The procedure enables the volumetric irrigation demand in a ‘design’ dry year for a given site to be estimated, taking into account local variations in climate, soil type, land use and irrigation practices. The approach provides a scientifically robust framework to allow the regulatory authority to assess the ‘reasonable’ water requirements of individual irrigators and hence develop allocations to satisfy the range of competing demands (e.g. agriculture, industry, and environment) on water resources. The methodology is applicable in other temperate countries where water abstraction controls are required and where appropriate datasets are available. The application of the procedure and its methodological limitations are described.     

Stakeholder-driven,enquiry-driven,or stakeholder-relevant,enquiry-driven science?

There is currently debate within the international hydrological community on whether hydrological science should give priority to providing measurements, knowledge, and understanding pre-determined as being needed by stakeholders, or priority to more basic enquiry-driven science that will stimulate the continued health and growth of hydrology as an important Earth science discipline. Two recent major international initiatives in hydrology reflect these two perspectives. One, the Hydrology for the Environment, Life, and Policy (HELP) program, is primarily fostered by UNESCO-IHP and is focused on stimulating the stakeholder-driven hydrological science required in specific catchments that have become members of a global network. The second, the decade on Prediction in Ungauged Basins (PUB), which is appropriately managed by IAHS, is primarily driven by scientific enquiry and is focused on creating new scientific methods and understanding, albeit with practical application ultimately in mind. This paper summarizes the nature, origins, growth, and progress of these two international programs but also describes the subtly different approach that has been adopted by the U.S. National Science Foundation's (NSF's) Center for Sustainability of semi-Arid Hydrology and Riparian Areas (SAHRA). NSF is a federal agency whose primary goal is to ‘enable the future’ by stimulating novel science. Because SAHRA is a federally-funded entity supported by an agency with this goal, the Center clearly cannot operate in stakeholder-driven, response mode in competition with the already effective private U.S. consultancy industry. Nonetheless, SAHRA's mission is to create knowledge and build understanding that will enhance the prospects of sustainable water management in semi-arid regions, especially the southwestern U.S. To resolve this apparent conflict, SAHRA looks ahead to future stakeholder needs and builds its research agenda around selected critical stakeholder-relevant questions that require substantial and sustained investment in basic, multidisciplinary, enquiry-driven science. This paper describes SAHRA's approach and reports on associated research and outreach activities.     

Growth,Reproduction, Mortality,Distribution, and Biomass of Freshwater Drum in Lake Erie

Predominant age-groups in the Lake Erie freshwater drum Aplodinotus grunniens population were 3, 4, and 5 as determined from gill net, trap net, bottom trawl, and midwater trawl samples. Age and growth calculations indicated that females grew faster than males. However, the length-weight relation did not differ between sexes and was described by the equation: log W = ?5.4383 + 3.1987 log L. Some males became sexually mature at age 2 and all were mature by age 6. Females matured 1 year later than males. Three sizes of eggs were present in ovaries; the average total number was 127,000 per female for 20 females over a length range of 270 to 478 mm. Seasonal analysis of the ovary-body weight ratio indicated that spawning extended from June to August. A total annual mortality rate of 49% for drum aged 4 through 11 was derived from catch-curve analysis. Freshwater drum were widely distributed throughout Lake Erie in 1977–1979, the greatest concentration being in the western basin. They moved into warm, shallow water (less than 10 m deep) during summer, and returned to deeper water in late fall. Summer biomass estimates for the western basin, based on systematic surveys with bottom trawls, were 9,545 t in 1977 and 2,333 t in 1978.     

水-能源-粮食纽带关系定量研究方法综述

在总结水-能源-粮食纽带关系研究中, 使用频率较高或潜力较大的 8 种水-能源-粮食纽带关系定量研究方法为: 水-能源-粮食纽带关系工具 2.0( WEF Nexus Tool 2.0) ; 生命周期评价( LCA) ; 可计算的一般均衡模型( CGE) ; 系统动力学模型( SD) ; 气候、土地、能源与水资源策略( CLEWS) ; 基于社会生态系统代谢的多尺度综合评价( MuSIASEM ) ; 市场配置/ 市场配置系统集成模型( MARKAL/ TIMES) 和水资源评价规划模型-长期能源替代规划系统 ( WEAP2LEAP) 。通过总结各研究方法的产生、发展及特性, 并引用案例讨论其适用范围, 分析其优缺点和在使用 时需要注意的问题。在此基础上, 对未来水2能源2粮食纽带关系定量研究方法的发展趋势进行讨论, 认为伴随可持 续发展问题关注度的上升与水-能源-粮食纽带关系内在机理的挖掘, 未来的水-能源-粮食纽带关系定量研究方法将 更加注重量化的精确性和数据的互通以及跨学科研究和多方法的耦合。本文可为水-能源-粮食纽带关系定量研究方法的选择和更新优化提供参考。     

Survival,Growth, and Movement of Subadult Humpback Chub,Gila Cypha,in the Little Colorado River,Arizona

Ecologists estimate vital rates, such as growth and survival, to better understand population dynamics and identify sensitive life history parameters for species or populations of concern. Here, we assess spatiotemporal variation in growth, movement, density, and survival of subadult humpback chub living in the Little Colorado River, Grand Canyon, AZ from 2001–2002 and 2009–2013. We divided the Little Colorado River into three reaches and used a multistate mark‐recapture model to determine rates of movement and differences in survival and density between sites for different cohorts. Additionally, site‐specific and year‐specific effects on growth were evaluated using a linear model. Results indicate that summer growth was higher for upstream sites compared with downstream sites. In contrast, there was not a consistent spatial pattern across years in winter growth; however, river‐wide winter growth was negatively related to the duration of floods from 1 October to 15 May. Apparent survival was estimated to be lower at the most downstream site compared with the upstream sites; however, this could be because in part of increased emigration into the Colorado River at downstream sites. Furthermore, the 2010 cohort (i.e. fish that are age 1 in 2010) exhibited high apparent survival relative to other years. Movement between reaches varied with year, and some years exhibited preferential upstream displacement. Improving understanding of spatiotemporal effects on age 1 humpback chub survival can help inform current management efforts to translocate humpback chub into new locations and give us a better understanding of the factors that may limit this tributary's carrying capacity for humpback chub. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.