千将坪滑坡三维极限平衡分析

千将坪滑坡位于长江南岸支流青干河左岸,是三峡水库蓄水一个月后发生的水库新生型滑坡。通过千将坪滑坡恢复到原貌,采用三维极限平衡法对滑坡的整体稳定性和失稳下滑的触发因素进行了分析,探讨了水库蓄水和连续降雨对滑坡稳定性的影响。计算分析成果表明,水库蓄水后的浸泡软化作用使滑坡体稳定条件急剧恶化,蓄水和强降雨的联合作用最终导致千将坪滑坡产生大规模深层滑动。     

中等倾角岩层顺向坡滑坡发育特征及形成机制分析

中等倾角岩层顺向坡,受坡体结构和岩体物理力学性质控制,多存在变形、崩塌、滑坡等工程地质问题,常常会诱发大规模的地质灾害。该类斜坡潜在滑动面不直接出露地表,一般具有变形机制复杂、隐蔽性强和危害大的特点,是滑坡领域关注与研究的重点。拖担水库大坝左岸为一古滑坡,在水库扩建开挖过程中,诱发古滑坡体复活。在分析古滑坡工程地质条件的基础上,结合地质勘察和变形监测结果,研究了其变形特征及形成机制。研究结果表明:①左岸古滑坡具有岩层倾角“上陡下缓”、滑体底部存在反倾坡内的剪切破碎带、滑床岩体产生弧状弯曲的特点;②古滑坡体为一基岩顺层滑坡,滑动模式为“滑移（弯曲）—剪断”型,其变形破坏过程包括三个阶段:弯曲隆起阶段、滑移剪出阶段和扰动变形阶段;③该类斜坡变形破坏后,坡体易沿“上陡下缓”的椅型软弱层面发生二次滑动,滑坡控制关键是对下部变形区的保护。     

中等倾角岩层顺向坡滑坡发育特征及形成机制分析——以拖担水库左岸坝肩滑坡为例

中等倾角岩层顺向坡,受坡体结构和岩体物理力学性质控制,多存在变形、崩塌、滑坡等工程地质问题,常常会诱发大规模的地质灾害。该类斜坡潜在滑动面不直接出露地表,一般具有变形机制复杂、隐蔽性强和危害大的特点,是滑坡领域关注与研究的重点。拖担水库大坝左岸为一古滑坡,在水库扩建开挖过程中,诱发古滑坡体复活。在分析古滑坡工程地质条件的基础上,结合地质勘察和变形监测结果,研究了其变形特征及形成机制。研究结果表明:(1)左岸古滑坡具有岩层倾角"上陡下缓"、滑体底部存在反倾坡内的剪切破碎带、滑床岩体产生弧状弯曲的特点;(2)古滑坡体为一基岩顺层滑坡,滑动模式为"滑移(弯曲)—剪断"型,其变形破坏过程包括三个阶段:弯曲隆起阶段、滑移剪出阶段和扰动变形阶段;(3)该类斜坡变形破坏后,坡体易沿"上陡下缓"的椅型软弱层面发生二次滑动,滑坡控制关键是对下部变形区的保护。     

探地雷达在赵子秀山滑坡裂缝探测中的应用

滑坡裂缝是判定滑坡规模、分析滑坡形成机制、预测滑坡发展趋势、指导滑坡监测、治理的重要依据.分析了探地雷达技术进行滑坡裂缝特征调查的原理,确立了探地雷达进行滑坡裂缝调查的一般模式,并以四川华蓥市赵子秀山滑坡变形体的探地雷达探测为例,应用探地雷达技术获取了清晰反映裂缝位置、走向、深度的高质量图像.研究表明采用探地雷达进行滑坡裂缝探测是一种便捷有效的方法.     

湖北省清江隔河岩水库茅坪滑坡及白岩危岩体简介

茅坪滑坡茅坪滑坡位于湖北清江隔河岩水库库区近尾部左岸,下距隔河岩水库大坝66km,上距正在施工的水布垭坝址25km。它是目前库区规模最大、变形最严重的一处堆积层滑坡。因该滑坡有发生堵江的极大可能性而倍受有关方面关注。目前,该滑坡已被选作中科院知识创新工程重要方向支持项目“山体滑坡灾害防治中的关键力学问题研究(2002～2005)”的样板地段(封面照片)。该滑坡滑动面大致可追踪至泥盆系上统写经诗组(D3x)页岩夹泥灰岩岩层层面,因此也可以称此滑坡为“准基岩顺层滑坡”。由差异风化形成的倾向坡外的基岩顶面,成为此松散堆积层滑坡发…     

基于综合物探的黄土滑坡优势通道探测

黄土区域优势通道的发育,改变了降雨及灌溉水的径流和入渗过程,降低了土体强度,造成斜坡失稳易发崩塌、滑坡等地质灾害。针对黑方台DH2~#滑坡体及后缘,总结了优势通道的物性特征,选用优势通道非侵入式研究方法,开展了基于地球物理方法的优势通道精细化探测方法有效性研究。该研究在人为浇水漫灌干预的基础上,采用小点距的高密度电法(0.20 m)和探地雷达(0.02m)初步查明了微型裂隙(宽度为0.2~0.5cm)、滑坡后缘裂缝及滑动面等优势通道的发育展布特征,实现了黄土微小裂隙等优势通道精细刻画,证明了精细物探应用的有效性。同时,论述了在灌溉水入渗和冲蚀、黄土蠕动及滑动等综合作用下,微型裂隙逐渐发育为裂缝,进而形成滑动面的转化关系,为黄土优势入渗及滑坡研究提供研究基础。该技术在黄土地区的地裂缝、微型断裂探测等城市地质问题中具有较大的应用前景。     

三峡库区千将坪滑坡地质力学模型研究

三峡水库初次蓄水不久,千将坪即发生了特大型滑坡。通过对千将坪滑坡滑动区与影响区的勘察试验及对比研究,查明了千将坪滑坡的物质组成、结构及滑坡边界条件,分析了滑坡影响因素及其机制,建立了千将坪滑坡的地质力学模型。分析表明,千将坪滑坡为三峡水库水位上升与降雨联合诱发的水库新生型深层岩质滑坡,水库蓄水起主要和关键作用。     

清江隔河岩水库蓄水后茅坪滑坡的变形机理及其发展趋势研究

茅坪滑坡位于清江隔河岩水库左岸,下距隔河岩坝址66Km,是隔河岩水库中最大的一个基岩古滑坡,体积约2350104m3。自1993年4月10日水库下闸蓄水以来,该滑坡发生了持续的缓慢变形,至目前为止,最大位移达2100mm,且仍在变形过程中。     

探地雷达在淡水区浅水域的探测试验

通过堤防护岸水域抛石探测、水下砼格及碎石层探测、江边堆场滑坡水域探测三个案例,说明探地雷达在淡水区浅水域探测效果。重点分析了探测对象所处环境的电导率、介电常数和探测所采用天线频率对探测效果的影响。探地雷达填补了浅水域工程勘察空白,研究成果对非水域探地雷达探测与检测具有借鉴意义。     

三峡库区千将坪滑坡高速滑动机制研究

2003年7月13日,三峡水库初期蓄水至135 m高程30 d之际,在三峡库区秭归县发生了三峡库区的第一个水库滑坡,滑坡方量达1 500万m3,最大滑速达16 m/s,最高涌浪达24.5 m。滑坡造成10人死亡,14人失踪,摧毁129间民房以及4个工厂,致1 200人无家可归。千将坪滑坡发生后,为了预测三峡库区及世界其它水库工程可能发生的同类高速滑坡,持续数年研究千将坪滑坡的高速滑动机制,通过理论分析及数值模拟,探索了千将坪滑坡的高速滑动机制,认为千将坪滑坡具有孕育高速滑坡的典型结构特征,滑坡滑带的峰残强降差是滑坡高速启动的根本原因,高陡边坡蕴藏的高势能及滑带液化是滑坡加速高速滑动的主要原因。     

一种基于强度折减法的次级滑动面分析方法研究

传统强度折减法通常对整个边坡区域进行折减,因而只能得到最小安全系数及对应的最危险临界滑动面。但在工程实践中,边坡的治理范围不能局限于最危险滑动面所包围的区域,不满足规范要求的次级滑动面范围内的坡体亦应得到治理。为了克服传统强度折减法在搜索次级滑动面方面的缺陷,提出了一种新的强度折减法。一般而言,边坡的屈服区域主要集中在滑动面两侧附近,形成一个沿滑动面分布的剪切破坏带,因此,在用强度折减法进行边坡稳定性分析时,只需对剪切破坏带范围内的局部坡体进行折减,则可得到该滑动面的安全系数和滑动面。基于以上认识,假设剪切破坏带沿对数螺旋曲线分布,不断调整对数螺旋曲线的形状以得到不同范围的剪切破坏带,对各种不同的剪切破坏带范围内的坡体进行局部折减计算,即可得到不同的安全系数及对应的滑动面。通过两个边坡算例（单台阶、双台阶）验证了该方法的可行性,并最后讨论了剪切破坏带的宽度对结果的影响。两个算例的计算结果表明,该方法不仅可以得到最危险临界滑动面,亦可得到任意安全系数对应的滑动面。     

斜坡临滑形变能释放与滑体起程速度关系的探讨

斜坡内聚集的巨大剪切形变能在临滑时释放,坡体能量释放率具有力的量纲,在坡体能量释放率幅值大于锁固段潜滑带抗剪强度幅值的情况下,坡体临滑释放的形变能将大于潜滑带岩体破裂需要的能量,所大于的部份将转变成滑体动能,滑动为剧动式滑坡;反之,则为缓动式滑坡。剧动式滑坡横截面上的弹冲速度与该点切应力的大小成正比。潜滑面附近坡体介质的切应力和切应变能密度最大,滑动时获得的弹冲速度也最大。导得蕴涵丰富信息量的斜坡弹性势能变化率曲线及其表达式,通过解析及Matlab图解形式对坡体的形变能聚集、临滑形变能释放量及其与滑体启动速度、启动方式进行了阐述。     

Debris slide hazards in the Adirondack Province of New York state

More than 400 debris slide scars have been identified in the Adirondack Province through aerial photographic interpretation. Debris slides are concentrated in the high relief, east-central portion of the province, although some isolated scars occur in the north and southwest. Intense rainfall, relief, slope angle, slope form, and slope exposure are recognized as factors in Adirondack slide formation and distribution. Vegetational, pedological, and geological characteristics also influence slope stability conditions, but complexities in after-the-fact analyses obscure their exact function in slide activity. On the basis of slope angle and slope form, more than 600 major valley systems which exhibit slide potential were identified in the Adirondacks. Approximately 25 percent of these sites of potential slides are on private land. The prospect for higher land-use in these areas warrants serious consideration of the hazards of debris slides. Debris slides cannot be prevented, or even accurately predicted, but certain measures may possibly be taken to avert extensive economic damage or loss of life.     

基于贝叶斯-粒子群算法的溜砂坡稳定性评价

溜砂坡具有突发、不易预测,且产生危害大的特点。文章对拉萨市周边实地调研测量收集数据,采集了12组具有代表性的溜砂坡灾害点数据集合,运用贝叶斯网络与粒子群算法相结合,并利用算法更新公式弥补单一算法的不足,引入信息熵分析了降雨量、坡度、坡高和植被覆盖率在算法中的权重,以及各因素对溜砂坡稳定性的影响,并对溜砂坡的稳定性进行了等级划分,实验证明该方法有效,对溜砂坡稳定性评价具有一定参考价值。     

滑坡治理中的抗滑桩设计

抗滑桩因其抗滑能力强,适用条件广泛,对滑坡的根治性能好等突出优点而被广泛地应用于滑坡治理中。但由于以往“表格”计算方式的限制,在其设计应用中存在一些不尽如人意的地方。对滑坡治理中抗滑桩的应用、桩身形变、内力、钢筋混凝土桩的结构设计进行分析,给出了不同地基系数条件下的桩内力表达式、不同位移及转角边界条件下桩身变形,以及钢筋混凝土桩的结构形式。编制了从滑坡推力计算至桩结构设计的全套应用程序,从而使抗滑桩的分析快捷、准确、实用性更强。     

构造控制型天然气水合物矿藏及其特征

构造环境是天然气水合物富集成藏的重要控制因素,增生楔、断裂体系、褶皱、(泥)底辟、滑塌等特殊构造体是影响天然气水合物成藏的主要地质载体。通过对这些特殊构造体与天然气水合物成藏关系的研究,结合流体活动对水合物形成的影响,总结出陆缘地区有增生楔型、盆缘斜坡型、埋藏背斜型、断褶型、滑塌型及底辟型等六类构造控制型水合物矿藏。南海位于欧亚板块、太平洋板块及印澳板块的交汇处,早期为活动陆缘,晚期演化为被动陆缘,其构造活动具有早期张裂、后期挤压的特点,这既不同于被动陆缘,也有别于活动陆缘,可视为“复合型”大陆边缘,兼具了“被动陆缘沉积速率高、活动陆缘构造活跃”的优点,从而形成了“增生楔型、断褶型、底辟型、滑塌型、盆缘斜坡型”等多种构造控制型水合物矿藏,是“复合型”大陆边缘水合物成藏地质模式的典型代表。     

平顶形边坡开挖剪滑段确定及对坡体稳定性的影响

对公路的平顶形边坡开挖进行了受力分析,提出了确定坡脚剪滑段的方法,指出在剪滑段范围内岩土体的抗剪强度降低,从而导致坡体稳定性下降。实例表明,在考虑剪滑段力学性质差异的情况下,通过极限平衡法搜索的最危险滑动面退化为次危险滑动面,且坡面分阶对坡脚应力集中的消散作用。     

Characteristics and remediation of a landslide complex triggered by the 2008 Wenchuan, China earthquake-case from Yingxiu near the earthquake epicenter

During the 2008 Wenchuan earthquake, the river valley from Yingxiu to Wenchuan experienced numerous landslides and became a prominent area of landslide complexes. The present large landslide complex near the earthquake epicenter consisted of Laohuzui slide 1, Laohuzui slide 2 and Douyaping slide. The scale, geology, morphology, sliding process, and failure mechanism of the landslide complex are analyzed by means of field investigation, aerial photograph and stereographic projection technique. Characteristics of these three slides including seismic response of slope, landslide debris, damage and potential failure are discussed: the convex slope and the upslope of fractured granitic rock at high altitude are highly prone to landsliding under earthquake; the high source altitude and long travel path determine grain sizes and the deposit angle of the slide debris; the landslide complex completely buries the G213 roadway and dams up the Minjiang River in these sections; after the earthquake, rainfall, aftershocks and river erosion may retrigger new failures, such as retrogressive slide of weathered fractured rock, colluvial landslide, debris flow, embankment failure and rockfall. The following are presented as suggested remedial measures to protect the roadway and stabilize the slope: the removing and trenching, protective concrete/rock blocks against erosion, retaining structure, rockfall stopping wall, rockfall restraining net, rock bolt, and the planting of vegetation.     

Mechanism of activation of the Lanta Khola landslide in Sikkim Himalayas

The Lanta Khola is a major landslide on the North Sikkim Highway in the Indian state of Sikkim. The abnormally low width-to-length ratio and slope instability in spite of the gentle surface slope (24°) make this slide unique. Geological, geophysical, and geotechnical studies reveal that a major Himalayan discontinuity daylights within the slide. At the contact, the schist is weathered to fine sand and silt with lower shear strength and permeability. The overlying gneiss is less weathered and exposed at the contact. Surface runoff enters the contact zone through crevices in the overlying gneiss, and debris material is extruded laterally from within this zone rendering instability, with blocks collapsing and eventually rolling down the slope after cloud bursts. Numerical modeling of the slide confirms this mechanism of instability. Diversion of runoff, plugging of crevices, and construction of pipe piles and horizontal drains are suggested as remedial measures.     

Experimental study on impulse waves generated by a viscoplastic material at laboratory scale

This experimental study provides insight into impulse waves generated by a viscoplastic material. The viscoplastic material chosen is a stable polymeric gel called Carbopol Ultrez 10, which is approximately modeled as Herschel–Bulkley model. As observed from high-speed cameras, the viscoplastic material such as Carbopol moves as a long and thin train of material along the slope, and only a fraction of the sliding mass is engaged in generating the leading wave. Therefore, our primary objective is to study how much of the initial slide mass is able to contribute to the leading wave formation. For the sake of distinguishing the actual slide mass acting on the leading wave formation with the initial mass, we define the submarine slide mass when the leading wave reaches its maximum wave height as “effective mass”. In this work, we held the still water depth and slope angle constant, and varied the initial slide mass and slope length. Then, we measured the slide velocity, slide thickness, and slide mass at impact, as well as the wave amplitude and wave height. The results indicate that the effective mass is dependent on both the initial slide mass and the slope length. The ratio of the effective mass to the initial slide mass is less than 20% in our experimental range, and the ratio increases with larger initial mass. In addition, we also examined our experimental data with previous empirical equations developed from granular slides. By considering the effective mass instead of the initial slide mass, the prediction of impulse waves generated by viscoplastic material is significantly improved.