超孔隙水压诱发特大型近水平崩坡积层滑坡破坏研究

特大型近水平崩坡积层滑坡广泛发育于三峡库区重庆段万州城区及云阳地区。基于万州城区太白岩古滑坡以及云阳地区老药铺滑坡两个典型特大型近水平崩坡积层滑坡,分析了其结构特征及破坏特点;建立了强降雨作用下特大型近水平崩坡积层滑坡破坏的力学模型,解译了此类滑坡的破坏过程,并提出了滑带（面）超孔隙水压力是此类滑坡破坏的诱因。基于孔隙水压力与土体所处的应力状态的内在关系,推导了滑面处每个土条的孔隙水压力及水压力公式,并得出了考虑超孔隙水压力的滑坡稳定系数表达式。云阳地区老药铺滑坡算例表明,若将老药铺滑坡按zk5分为两个滑坡,两个滑坡的中心段是孔隙水压力值较高的区域;本文的孔隙水压力计算值略大于钻孔量测值,计算误差为5.8%～10%,原因在于滑面超孔隙水压力的消散;暴雨工况（含超孔隙水压力）下老药铺滑坡稳定系数为0.862,滑坡处于非稳定状态,并已发生破坏,验证了超孔隙水压力对滑坡体破坏的诱发作用;建议滑坡治理工程中应在按zk5分成的两个滑坡中间段打设排水孔,消除或降低滑面处的超孔隙水压力值,并结合滑坡周围及坡面的截排水工程以及封填裂隙治理老药铺滑坡。     

A loess landslide induced by excavation and rainfall

The initiation of loess landslides is a common engineering problem during the construction of the expressway or other engineering works in the Loess Plateau of China. The engineers and researchers should devote themselves to the prevention of the initiation of loess landslides. This study focused on a loess landslide which was induced during the construction of an expressway in Shanxi Province of China. The stabilities of the loess hillside slope before and after excavation were analyzed using limit equilibrium analysis method and the strength reduction finite element method, respectively. The analysis results indicated that the loess hillside slope, before excavation, was stable under both natural state and rainfall conditions. The collapse of the loess hillside slope, or the initiation of loess landslides, after having been excavated, was induced by excavation and rainfall. The integrated stabilization method including four parts was used to stabilize the loess landslide. The four parts were a reinforced concrete piles row, a rubble concrete retaining wall, alteration of slope geometry, and interception and drainage of water. The initiation of the loess landslide might be evitable if it was given enough attention before excavation; thus, the problem of loess landslides should be paid big attention during the survey and design of the engineering works, not only during the construction.     

Reinforced concrete shafts for the structural mitigation of large deep-seated landslides: an experience from the Macesnik and the Slano blato landslides (Slovenia)

During the last decade, several rainfall-induced deep-seated large landslides with volumes of the order of 1 million m³ were triggered in various locations in Slovenia (central Europe), each representing a serious threat to the nearby villages and traffic infrastructure and urging to be mitigated. The Macesnik landslide, triggered in 1989, and the Slano blato landslide, triggered in 2000, were the first two large landslides in Slovenia, where a combination of drainage and retaining works consisting of deep reinforced concrete (RC) shafts/wells was successfully used as a mitigation measure. This paper presents the field conditions and a brief history of the two landslides with emphasis on the design approach and method used for the stability analysis and the design of deep RC shafts/wells. In addition, the paper gives an insight into the problems associated with the execution of works and provides data about the behavior of the two landslides after drainage and retaining works were completed. The monitoring data show that the undertaken mitigation measures were efficient to improve the stability of both landslides and significantly reduce the risk.     

Spatial distribution analysis and susceptibility mapping of landslides triggered before and after Mw7.8 Gorkha earthquake along Upper Bhote Koshi,Nepal

The 2015 Mw7.8 Gorkha earthquake triggered thousands of landslides of various types scattered over a large area. In the current study, we utilized pre- and post-earthquake high-resolution satellite imagery to compile two landslide inventories before and after earthquake and prepared three landslide susceptibility maps within 404 km² area using frequency ratio (FR) model. From the study, we could map about 519 landslides including 178 pre-earthquake slides and 341 coseismic slides were identified. This study investigated the relationship between landslide occurrence and landslide causative factors, i.e., slope, aspect, altitude, plan curvature, lithology, land use, distance from streams, distance from road, distance from faults, and peak ground acceleration. The analysis showed that the majority of landslides both pre-earthquake and coseismic occurred at slope >30°, preferably in S, SE, and SW directions and within altitude ranging from 1000 to 1500 m and 1500 to 3500 m. Scatter plots between number of landslides per km^?2 (LN) and percentage of landslide area (LA) and causative factors indicate that slope is the most influencing factor followed by lithology and PGA for the landslide formation. Higher landslide susceptibility before earthquake is observed along the road and rivers, whereas landslides after earthquake are triggered at steeper slopes and at higher altitudes. Combined susceptibility map indicates the effect of topography, geology, and land cover in the triggering of landslides in the entire basin. The resultant landslide susceptibility maps are verified through AUC showing success rates of 78, 81, and 77%, respectively. These susceptibility maps are helpful for engineers and planners for future development work in the landslide prone area.     

万(州)-梁(平)高速公路K34～K59段滑坡成因分析

万(州)-梁(平)高速公路K34-K59段滑坡十分发育，是重庆境内滑坡灾害最为严重的一段。该区地质条件复杂，岩体中缓倾角结构面、软化夹层发育，在外界因素触发下，即可形成岩层向临空面松弛滑移的依附面。1999年12月-2003年9月，该路段发生滑坡灾害23处，增加工程投资2亿多元，对高速公路的建设造成很大的危害和威胁，并拖延了工期，给国民经济建设带来严重的影响和损失。文章依据工程地质勘察结果，从该滑坡的地质环境及变形特征分析，对其形成机制做了深入研究，为今后类似滑坡的防治提供参考。近年来，在高等级公路的建设中，线形要求严格，在山区及丘陵地区往往需要采用开挖方式通过，由于建设中的不合理工程活动，新滑坡的产生以及老滑坡的复活可能性大增。致使滑坡灾害日趋严重。通过对影响岩质路堑边坡稳定性因素分析，说明了这些影响因素与边坡稳定性的关系。文章认为特殊的地质构造及易滑地层的广泛分布，是滑坡大量出现的地质基础。大量降雨入渗，不合理的人为工程是滑坡的诱发因素。各种情况表明，在今后一定时期内，人类活动可能成为滑坡的主要影响因素。     

A review of conventional techniques for subsurface characterization of landslides

Naturally occurring landslides can be difficult to characterize and often exhibit anomalies in controlling geometry and consistency. The characterization of landslides in engineering geology practice is usually based on program of subsurface exploration; focused on identifying subsurface materials, structure and stratigraphy, hydrologic conditions, and appropriate strength parameters. On native slopes bereft of anthropogenic modification (excavation), geomorphic evidence of previous movement and its relative depth and scale are often discernible to the experienced eye. This paper seeks to describe the various techniques that have been successfully employed in site-specific subsurface investigations of prehistoric landslides. These include considerations of limiting geometry (for planning subsurface exploration and sampling), overcoming problems with site access, exploratory trenches, small diameter borings, downhole logging of large diameter borings, and geophysical techniques. These procedures can be combined to develop more realistic cross sections along the vector of maximum landslide movement, so the displaced mass can be realistically analyzed. The respective advantages and disadvantages of these techniques are discussed, with baseline references on subsurface exploration.     

坡脚型与偏转型地震滑坡运动距离及地形因素作用

运动距离作为滑坡防灾减灾的主要评价指标之一,不仅受到滑坡体积和落差的控制,还与滑坡的下垫面场地的地形作用相关。通过分析坡脚型和偏转型两类典型的地震滑坡运动特征,研究了滑坡体积V、落差 、坡度差 和偏转角度 对最大垂直运动距离H、水平运动距离L以及坡脚以下或偏转后的水平运动距离 的作用。由于偏转型滑坡受偏转前、后坡度和偏转角度对运动距离的共同影响,导致 指标小于坡脚型滑坡,而两类滑坡的 的均值较为一致,表明地形因素对不同类型滑坡的水平运动参数的作用具有一致性特征。分别建立了体积、落差与地形参数的坡脚型和偏转型滑坡运动距离拟合方程。拟合方程的参数指标表明：体积对H的作用指数较小,体现了高位滑坡的运动特征; 对 的影响指数较小;坡脚型滑坡的坡度 对运动距离的影响指数都较为显著,偏转角度 对偏转型滑坡的 的影响较为显著。研究结果为滑坡运动距离的预测和地形因素控制提供了参考,并且对于坡脚型和偏转型滑坡运动距离的模拟和机制研究而言,不应忽略坡脚坡度差和偏转角度的作用。     

Lessons Learned from the Landslides in Shengli East Open-Pit Mine and North Open-Pit Mine in Xilinhot City,Inner Mongolia Province,China

The locations of the 2013 eastern ShengLi open pit mine landslide and the 2010 northern ShengLi open pit mine landslide were both in the XilinHot city of Inner Mongolia province, in areas with similar geographical, regional geological, geomorphic conditions and excavation depth. There are so many similar characteristics, such as landslides triggered by the rain storms, landslides occurred many times, landslides with long time deformation, but there are also some differences between the two landslides, such as the scale and failure mode. Field investigations showed that the two landslides were both occurred several days after the rain storms, the eastern ShengLi open pit mine landslide body with the volume of 85 million m³ has been in persistent deformation with an observed maximum horizontal displacement of 58 m in August 2013, Furthermore the implemented check dams at east open pit mine had not formed an efficacious blocking system to resist the flow because of incorrect judgment regarding the landslide style. The northern ShengLi open pit mine landslide body with 0.5–1 million m³ occurred several times after each rain storm. In the whole, the time of persistent deformation about the eastern ShengLi open pit mine was much longer than that of the northern ShengLi open pit mine because of the difference of the filling material of fault and space combination between the faults and the slope. Field investigation, physical model experiments, real-time displacement monitoring and numerical simulation were implemented to investigate the characteristics, mechanism, and retaining measures of the two landslides. The insights gleaned herein may be valuable for the understanding of the mechanisms of landslides and improving preventative measures against these types of events in north China in the future.     

Topographical features of rainfall-triggered landslides in Mon State,Myanmar, August 2019: spatial distribution heterogeneity and uncommon large relative heights

Continuous 5-day (August 4–9, 2019) torrential rainfall in the monsoon season triggered more than 90 landslides on northwest-southeast extended mountain range of Mon State, Myanmar. In this study, remote sensing images, DEM, and limited fieldworks were used to create the landslide inventory. The topography features of these landslides are analyzed via ArcGIS. The largest one occurred on 9 August 2019 and caused 75 deaths and 27 buildings were damaged. This landslide occurred on gentle topography (slope angle, 23°) with long run-out, in which the angle of reach was relatively low (10°). The volume was 111,878 m³ was mainly composed of weathered granite and red soil and the sliding depth was approximately 7.5 m. Topographic characteristics including the relative slope height, angle of reach, and slope angle of source area of 35 landslides with areas?>?4000 m² were analyzed. The spatial distribution characteristics and topographic features of the 35 landslides below are distinguished: (1) the concentration of most of landslides on southwest-facing slopes showing the heterogeneous spatial distribution of landslide; (2) an uncommon landslide distribution in which more than half of landslide originates from upper slope; (3) the range of the angle of the source area (17°–38°) compatible with the internal friction angle of soils in tropical regions (17°–33°); and (4) the tangent of the angle of reach is generally smaller than 0.5 (angle of reach?<?27°) shows a relative high mobility and the relation between landslide mobility and the slope angle of the landslide source area is similar to the one of earthquake-triggered landslides, even though the triggering mechanism, landslide type, and landslide volume are dramatically different.

     

滑坡预警判据初步研究--以三峡库区为例

在三峡库区典型地段滑坡灾害调查评价和统计分析的基础上,结合典型滑坡变形发展的阶段性变形现象、标志和临界诱发因素分析,初步提出3个层次的滑坡预警预报判据27条,包括:(1)滑坡空间预测识别判据11条,主要用于滑坡或潜在危岩体空间识别和危险性区划,是滑坡空间预测的基本判据;(2)滑坡状态判据7条,主要用于滑坡单体稳定性评价的亚临界-临界状态预警判据,是滑坡状态预警判据系统的重要组成部分;(3)滑坡临界时间预报判据9条,主要用于单体滑坡剧烈变形或临滑预报,是滑坡时间预报研究的关键判据.     

复杂地层方形抗滑桩旋挖成孔工艺及工程应用

为提高方形抗滑桩开挖成孔效率,研究适用于复杂条件岩质滑坡抗滑桩快速成孔的工艺,以成都东部某大型岩质滑坡101根大截面抗滑桩为对象,通过现场调查、理论分析及工程试验等方法,研究了方形抗滑桩工程成孔工艺、施工特征和不同地层成孔工艺适用体系。研究表明,研制的“旋挖钻孔+人工辅助清边”成孔工艺作业效率大大提高,在该抗滑桩工程中实施达到日平均进尺2.0 m高效率,顺利达到工期要求,进而解决了岩石成孔效率慢、工艺落后的问题;根据滑坡所处条件选择合适的施工工艺对抢险救灾工程至关重要,对于交通条件好、工期要求高的大型滑坡治理工程,优先考虑“旋挖钻孔+人工辅助清边”工艺;对于交通条件差、作业受限的小型滑坡治理工程,采用风镐开挖土体、水磨钻开挖岩石成孔工艺。     

万州近水平地层区堆积层滑坡成因与变形破坏特征

近水平地层区堆积层滑坡作为一类典型的滑坡,有其特殊的成因与变形破坏特征。文章在研究万州近水平地层区堆积层滑坡的基础上,详细分析了其物质来源、结构成因、形成模式以及变形破坏特征。通过总结万州堆积层滑坡的滑体和滑床特征,得出了近水平地区堆积层滑坡的物质来源和结构成因为:崩塌堆积为主,冲、洪积为辅;形成模式为:后部陡壁形成,滑床形成,滑体底部物质形成,滑体土石混合体形成,滑体表层物质形成,滑动解体等6个阶段。变形破坏特征为:滑动多沿堆积层和基岩接触面滑动,同时也会沿软弱夹层发生滑动;滑体存在多层剪切带,并在不同位置的剪切带其变形速率和累计变形量差别较大,滑体存在着差异变形,对此文章结合实例进行了分析。     

灾难性地震和降雨滑坡的体积与运动距离研究

为预测和评价灾难性滑坡的致灾机制,基于国内近年来地震和降雨诱发的灾难性滑坡资料,对地震和降雨滑坡的等价摩擦系数H/L、最大水平运动距离L、最大垂直运动距离H与滑坡体积V的关系进行分析。研究灾难性地震和降雨滑坡的远程运动特征以及不同规模滑坡最大水平运动和垂直运动的优势距离。研究结果表明,滑坡的H/L、L、H与V具有幂律关系,其中H/L与V具有负幂律关系,L、H与V具有正幂律关系。同一规模等级的地震和降雨诱发灾难性滑坡的水平和垂直运动距离不同。以H/L＝0.42作为滑坡远程运动的标准,地震诱发的灾难性滑坡与滑坡远程运动的关系较小,而降雨诱发灾难性滑坡与滑坡的远程运动的关系较大。根据滑坡运动距离的累积分布表,以80%滑坡的运动距离所分布的范围,建立了滑坡不同规模等级的优势运动距离区间,同规模等级的地震滑坡和降雨滑坡在水平和垂直运动的优势距离区间上存在差异。灾难性滑坡的运程不仅受滑坡体积的控制还与其诱发机制相关,其研究成果可为由地震和降雨诱发的灾难性滑坡的致灾区域和致灾强度的预测和评价提供参考依据。     

坡脚开挖诱发古滑坡复活的机制分析

黄土地区存在许多古滑坡体,由于滑后土体土质疏松,裂隙发育,在坡脚开挖作用下极易发生变形破坏,造成大量财产损失,同时也对开挖施工安全构成了极大的威胁,因此对坡脚开挖诱发古滑坡复活的失稳机制的研究十分迫切和必要。以延安市王窑村滑坡为例,通过室内试验分析了三轴应力环境下围压、含水量对土体变形破坏的影响,并运用数值模拟研究了开挖过程中最危险滑面上的应力及强度变化趋势,揭示了坡脚开挖诱发古滑坡复活的变形破坏机理。研究结果表明:坡脚开挖改变了坡体中下部的应力分布,抗滑段土方开挖减小了滑坡抗滑力,增大了下滑力,最终滑坡下滑力超过抗滑力,导致古滑坡复活。     

灌溉诱发型滑坡风险控制关键技术

长期灌溉引起地下水位上升诱发滑坡发生是灌溉诱发型滑坡的基本特征,有效控制地下水位是灌溉诱发型滑坡风险管理的根本措施.通过灌溉量控制、竖向混合孔疏排水、水平疏排水3种排水措施,可以实现灌溉诱发型滑坡的风险控制.采用数值模拟的手段,计算了不同灌溉量下地下水动力场及其对应的台塬斜坡稳定性,模拟了不同布井方式下的竖向混合井疏排地下水的效果,结果表明,灌溉量控制在350×10 4m3/a以下可实现滑坡风险控制,竖向混合排水井间距为40m时可提高单体斜坡的稳定性.统筹考虑各种因素,提出了以控制灌溉量为主,辅以竖向混合孔排水和水平排水的黑方台灌区滑坡的风险控制措施.     

The determination of statistical and deterministic hydrological landslide-triggering thresholds

 Hydrological landslide-triggering thresholds separate combinations of daily and antecedent rainfall or of rainfall intensity and duration that triggered landslides from those that failed to trigger landslides. They are required for the development of landslide early warning systems. When a large data set on rainfall and landslide occurrence is available, hydrological triggering thresholds are determined in a statistical way. When the data on landslide occurrence is limited, deterministic models have to be used. For shallow landslides directly triggered by percolating rainfall, triggering thresholds can be established by means of one-dimensional hydrological models linked to the infinite slope model. In the case of relatively deep landslides located in topographic hollows and triggered by a slow accumulation of water at the soil-bedrock contact, simple correlations between landslide occurrence and rainfall can no longer be established. Therefore real-time failure probabilities have to be determined using hydrological catchment models in combination with the infinite slope model. Received: 15 October 1997 · Accepted: 25 June 1997     

地震破裂带特殊部位大型滑坡及其基于构造地貌发生模型的机制解释:以东河口抛射型滑坡为例

汶川地震在龙门山地区激发了大量的次生地质灾害,其中尤以滑坡灾害分布最为广泛和严重。在所有滑坡灾害中,东河口滑坡发生在北川破裂带的北东端点,具有相当的特殊性,并造成了大量的生命财产损失。东河口滑坡是一种抛射型滑坡,具有与其他如重力或者降雨作用导致的滑坡不同的特点,即没有统一连续的滑动面,由上部比较深陡和下部比较浅缓的截然分开的两部分组成,在强地震加速度的作用下,滑坡体被抛射并在与地面发生碰撞之前沿抛物线轨迹运行。文章综合分析了东河口抛射型滑坡发生的地质地貌条件,并解释了该抛射型滑坡发生的动力源机制。结果显示,东河口滑坡区的滑坡带和翼状裂隙带在北川破裂带两侧的规则分布受控于断层的运动方式和滑坡的空间分布位置;此外,除地震动水平加速度和地质地貌条件外,垂直加速度和断层的运动方式对地震滑坡的激发也起着重要的作用。     

白龙江流域坪定-化马断裂带滑坡特征及其形成演化

沿坪定-化马断裂带发育数个大型或巨型滑坡。这些断裂带滑坡特点明显,成因类似,各滑坡一般发育多个次级滑坡体,滑坡岩土体由次生黄土、断裂带强风化带、断裂破碎带组成,具双层或三层结构。滑坡总体顺断裂走向下滑,历史上曾多次活动。近年来变形监测资料表明,断裂带滑坡目前处于匀速蠕变阶段,表现为蠕滑→拉裂（塑流拉裂）→次级滑坡体启动下滑的特征。它是在断裂活动、地震、降雨、人类工程活动等内外动力耦合作用下形成的,坪定-化马断裂的长期活动为滑坡形成提供了前提条件,断裂带的岩土体性质是滑坡长期活动的物质基础,而降雨、地震、坡脚开挖等是滑坡体失稳下滑的主要诱发因素。因而,有必要进一步研究断裂带滑坡在内外动力耦合作用下的成灾机理,为滑坡灾害防治预警提供科学依据。     

A comparison of the predicted vulnerability zones with the data based on hazard zones of landslide in the Kurseong hill subdivision,Darjeeling district,West Bengal,India

Kurseong hill subdivision, being one of the three (Kurseong, Sadar and Kalingpong) subdivisions of the hilly portions of the Darjeeling district, West Bengal, India, is affected by severe landslide incidence in the rainy season every year. These landslides and related phenomena frequently create social and economic instability disrupting communication system, claiming property and even sometimes life. Curbing landslide threat, therefore, becomes very much essential over this area. Individual landslide treatments are seen to be taken up by the construction engineers and geo-technical experts almost every year from government level. But reoccurrence of landslides on the same spots or surrounding places clearly reveals that construction works and filling procedures (usually taken up) are not the adequate measures to heal up the problem unless the area is treated as zones of landslides than individual spots of landslide occurrences. Therefore, the assessment of spatial probability of landslide occurrence in various magnitudes in the form of landslide vulnerability zones becomes essential. This spatial probability should also be compared with temporal probability based on the data of landslide incidence of the area for justification of match or mismatch between the inference drawn from the diagnostic criteria based assessment of the possibility level of landslide occurrence and the reality of the landslide scenario in the light of historical perspective of the area. This comparison will finally help to achieve the predicted vulnerability zones of landslide with desirable accuracy to put forward for planning decision. Moreover, such predicted vulnerability zonation can be taken as a standard estimate to use in planning purpose for the areas where historical data of landslide incidences are inadequate or unavailable. With this view in mind, the present paper takes an attempt to verify and compare landslide vulnerability zones derived from Spatial Terrain Parameter Evaluation (STPE) and Anthropogenic Criteria Identification (ACI) methods with the landslide hazard zones prepared from historical data, i.e. landslide inventory of certain length of time. Careful observation reveals that different degrees of landslide vulnerability zones significantly correspond with the similar magnitudes of the landslide hazard zones determined by past occurrence data of landslides over this hill subdivision and therefore validate the predictability procedure of landslide vulnerability zonation. The accuracy performance of the landslide vulnerability zonation model has further been verified by the occurrence dataset of landslide events through receiver operating characteristic curve analysis where area under curve evaluation showed 81.77 % correctness.     

基坑水泥搅拌桩帷幕止水施工质量控制

基坑止水,对基坑(特别是深基坑)开挖及地下结构施工至关重要。根据多年的工程施工实践,总结和分析用于基坑开挖止水的水泥搅拌桩施工工艺流程和质量控制方面的有关问题。