堆积层滑坡水动力位移耦合预测参数及其评价方法研究

在系统分析滑坡的物质组成和失稳动因的基础上,分析和研究了地下水在滑坡稳定性演化过程中的卸载与加载动力作用及其位移响应规律和特点。从非线性系统动力学角度,提出了运用地下水卸加载动力与位移响应耦合预测参数来评价边坡稳定性演化规律与失稳特征,即以地下水位变化量作为堆积层滑坡的卸加载动力参数,以相应的位移作为其卸加载响应参数,建立和确定了地下水卸加载动力与位移响应比预测参数与评价模型。同时,运用损伤力学基本原理,建立了其卸加载响应比与坡体损伤变量和稳定性系数的定量关系以及失稳判据。以三峡库区典型堆积层滑坡分析为例,运用地下水动力与位移耦合预测模型对其稳定性进行了分析与评价,发现地下水动力位移耦合预测参数变化与边坡稳定性实际动态演化规律基本吻合。研究成果表明,所确定的参数是水诱发型堆积层滑坡的一种有效位移动力评价参数,可运用该参数对该类滑坡的动态稳定性进行实时监测预警与评价。     

Loading/Unloading response ratio theory applied in predicting deep-seated landslides triggering

Rainfall is the most relevant factor for the triggering of landslides and it is characterized by an extreme variability. Rainfall analysis is the most frequently adopted approach for predicting landslides. But predicting deep-seated landslides by means of rainfall thresholds is sometimes inadequate due to the complexity of such slopes. In this paper, further study of the loading / unloading response ratio theory applied in landslides prediction was carried out. As the aforementioned effect and character of rainfall was concerned, a prediction for the known Xintan landslide was carried out by means of the loading / unloading response ratio method, in which the action of water was regarded as loading/unloading measures. The results show that it is an effective method for landslides prediction, and it has an advantage over conventional rainfall thresholds or time sequences analysis method.     

Centrifugal model test on a riverine landslide in the Three Gorges Reservoir induced by rainfall and water level fluctuation

Frequent soil landslide events are recorded in the Three Gorges Reservoir area, China, making it necessary to investigate the failure mode of such riverside landslides. Geotechnical centrifugal test is considered to be the most realistic laboratory model, which can reconstruct the required geo-stress. In this study, the Liangshuijing landslide in the Three Gorgers Reservoir area is selected for a scaled centrifugal model experiment, and a water pump system is employed to retain the rainfall condition. Using the techniques of digital photography and pore water pressure transducers, water level fluctuation is controlled, and multi-physical data are thus obtained, including the pore water pressure, earth pressure, surface displacement and deep displacement. The analysis results indicate that: Three stages were set in the test (waterflooding stage, rainfall stage and drainage stage). Seven transverse cracks with wide of 1–5 mm appeared during the model test, of which 3 cracks at the toe landslide were caused by reservoir water fluctuation, and the cracks at the middle and rear part were caused by rainfall. During rainfall process, the maximum displacement of landslide model reaches 3 cm. And the maximum deformation of the model exceeds 12 cm at the drainage stage. The failure process of the slope model can be divided into four stages: microcracks appearance and propagation stage, thrust-type failure stage, retrogressive failure stage, and holistic failure stage. When the thrust-type zone caused by rainfall was connected or even overlapped with the retrogressive failure zone caused by the drainage, the landslide would start, which displayed a typical composite failure pattern. The failure mode and deformation mechanism under the coupling actions of water level fluctuation and rainfall are revealed in the model test, which could appropriately guide for the analysis and evaluation of riverside landslides.     

三峡库岸滑坡变形特征及影响因素分析

三峡库区涉水滑坡主要影响因素是水位和降雨量,也是库区滑坡体失稳的主要影响因素和诱发因素。库区每年重复着水位升降不利于滑坡的稳定,而降雨特别是大强度的降雨也诱发产生滑坡。当水位波动遇到降雨,出现工况叠加,滑坡将加剧。因此,有必要对影响滑坡变形的主导因素进行了解分析。2016年6月三峡库区全面展开了自动化监测,使得数据统计方便可靠。本文采用滑坡变形速率、降雨量、库水位变化、最大水位变化速率、淹没程度,运用灰色关联度分析法对涉水滑坡进行了计算分析。水位下降阶段,文中土质滑坡变形受库水位影响最大。水位上升阶段,该土质滑坡上部变形受降雨影响最大,下部受水位影响最大。文中岩质滑坡总是受库水位影响最大。     

巫溪县西溪河北岸高位高危碎屑流滑坡特征与机理研究

巫溪县构造上位于南大巴山弧形褶皱带的核心部位,八面山弧形褶皱构造带的北缘,地理上位于三峡库区奉节—巫山段北部,区内以发育近平行的褶皱构造为主,岩层中构造节理裂隙发育。区内地形切割强烈、起伏大,表现为中高山峡谷地貌,年降雨量大,地质环境条件脆弱。研究区西溪河北岸多发育高位高危碎屑流型滑坡,具有隐蔽性强、危害性大等特点。论文在Lidar影像分析、野外详查、钻探等手段的基础上,详细分析了滑坡地质环境背景、滑坡的特点及运动堆积过程,认为风化层厚度大、高陡的地形地貌、特殊的构造条件、典型的斜坡结构是滑坡发育的主要因素,持续性的降雨是滑坡发育的直接诱发因素,斜坡上部二叠系炭质灰岩、灰岩的崩落是导致斜坡中下部原本就处于孔隙水饱和状态下的志留系粉砂岩碎屑失稳并转化为碎屑流的重要因素。针对这类高位高危碎屑流型滑坡,提出了高位崩滑—高速启动—碰撞解体—高速铲刮—抛射堆积的成灾模式,为三峡库区此类滑坡的防治提供技术依据。     

降雨和库水位联合作用下库岸滑坡模型试验研究

受库区水位波动和降雨影响,库岸大量老滑坡体变形加剧,地质灾害问题十分突出。为研究库岸滑坡影响因素、变形演化规律及失稳条件,以大型物理模型试验为手段,选取三峡库区黄土坡滑坡临江Ⅰ号崩滑体为对象,通过考虑水位波动、降雨及其组合作用等诱发因素,开展了一系列的库岸滑坡模型试验研究。试验结果表明：水位升降,变形主要集中于模型坡体前缘,其中,水位抬升过程中,滑坡模型变形较小,变形加速阶段出现于水位下降期间,且变形速率与水位下降速率成正比,即临江Ⅰ号崩滑体为典型的动水压力型滑坡;降雨影响下坡体变形在时间和空间上存在明显分区现象,时间上,变形发展主要集中于坡体浅表层饱和之后,即短时降雨对坡体变形未产生显著影响,空间上,坡体前缘和后缘变形剧烈;库水位下降和强降雨联合作用下坡体前缘产生局部流滑破坏,并溯源发展至前缘整体破坏,为典型的牵引式破坏模式。试验揭示处于临滑阶段坡体,其孔隙水压力、土压力变化呈现异常频繁的波动现象,可为滑坡预警预报提供一定参考依据。     

三峡库区典型顺斜向岩质滑坡变形破坏特征及失稳机制分析

近年来,三峡库区城集镇开发区顺斜向岩质滑坡失稳破坏现象时有发生,研究顺斜向岩质滑坡的变形破坏特征及失稳机制对防治此类滑坡具有重要意义。本文以巫山县白杨湾滑坡为例,通过现场踏勘、钻探和多种监测手段,对这一典型顺斜向岩质滑坡的变形破坏特征及失稳机制进行了深入研究。此滑坡所处地层为巴东组第二段泥岩,岩体破碎,地下水较丰富。滑坡岩层向右边界倾斜,右边界受断层控制,断层面与岩层面相交切割形成楔形体顺斜向滑移。滑坡体积约320×104 m3,滑动方向与岩层倾向夹角60°。受坡脚开挖和坡体建筑荷载等人类工程活动的影响,滑坡于2019年7月开始出现显著变形,滑坡中部的位移速率达到2～5 mm/d。2019年9月中旬,滑坡前部设置应急抗滑桩后,滑坡变形开始减缓至0～0.5 mm/d。白杨湾滑坡对城集镇开发区金科城造成巨大威胁,建议采取“搬迁避让+工程治理+专业监测”的防治对策。本文的研究成果对指导三峡库区顺斜向岩质滑坡防治和人工开挖诱发滑坡的防治具有重要借鉴意义。     

基于非饱和渗流的水库库岸滑坡稳定性计算

三峡水库蓄水后,库水位涨落和降雨入渗是导致滑坡的主要因素。本文以秭归县下土地岭滑坡为例,在一个水文年内根据库区水位调控方案并考虑库区降雨情况,运用非饱和土力学的渗流和抗剪强度理论,对滑坡稳定性进行了分析,得出在库水位涨落和降雨条件下滑坡渗流和稳定性的变化规律,对库区滑坡稳定性评价和治理有一定的指导作用。     

The regional distribution regularity of landslides and their effects on the environments in the Three Gorges Reservoir Region, China

On the basis of research and analysis of the landslide system of the Three Gorges Reservoir area, this paper systematically analyzes and studies the temporal–spatial distribution law of landslides of this reservoir area and their impacts on environment of this area. The paper puts forward that the temporal–spatial distribution of this area’s landslides is mainly controlled by lithologic characters of strata, geological structure, valley landscape, and types of bank slope structure; landslide deformation and failure have such characteristics as simultaneity, laggardness, cyclical instability, and stage. Besides, the paper systematically analyzes and studies the main impacts of landslide on environment and points out that landslides and collapses will bring about relatively serious impacts on relocation and layout of cities and towns along the banks. These impacts mainly include the increase of relocation investment, number of migrants, and compensation for losses. Much attention and evaluation should be paid to the impacts of Xintan Landslide and Lianziya Landslide—large landslides near the Dam—on the construction and safety of the Three Gorges Project. However, landslides have relatively small impacts on shipping and reservoir capacity. The above-mentioned research is of great guiding significance for the construction of the Three Georges Project, planning and construction of cities and towns along the banks, and protection of geological environment.     

A study of the factors influencing the occurrence of landslides in the Wushan area

Due to the complex natural geological conditions, many slope-related geological hazards occur in the Three Gorges Reservoir area in China. This study focuses on the characteristics of landslide development and their underlying mechanisms in this area. A statistical analysis is conducted to determine the characteristics of landslide development in the Wushan area, including the landslide distribution as a function of the elevation, slope, landslide material composition, scale, lithology, boundary conditions, instability mechanism, stratigraphic age, attitude, and sliding direction. The mechanisms of slope instability and the effect on the occurrence of landslides are analyzed. This study provides important reference material for landslide research in the Three Gorges Reservoir area and similar stratigraphic areas.     

基于位移比模型的三峡库区云阳县域内蠕变型滑坡降雨预警

建立高效合理的区域滑坡灾害降雨预警模型对滑坡防治具有重要意义.然而以往的研究多侧重于临滑预警,对蠕变型滑坡在强降雨工况下的短暂加速变形的预警研究还有待深入.以三峡库区云阳县域内滑坡为例,首先根据滑坡地表位移监测数据的特点对统计样本进行合理筛选.再通过降雨因子与滑坡发生的相关性分析以及对滑坡在降雨条件下位移变化情况的数值模拟,确定了适用于不同时间阶段的降雨统计变量.然后将考虑了滑坡规模特征的滑坡位移比（累计位移与滑坡纵长之比）作为变形指标,分时段统计滑坡地表位移监测数据与历史降雨信息,建立了日降雨数据与月位移数据的对应关系,得到了可用于确定降雨量阈值的位移比模型,并获得了云阳县蠕变型滑坡的五级预警分区.最后分别选用研究区滑坡险情实例、长年位移监测数据及极端降雨事件对模型预警效果进行检验.结果显示基于专业监测数据的位移比模型的滑坡降雨预警结果与实际情况相符,可为蠕变型滑坡的预警预报提供依据.      

Analysis of Baishuihe landslide influenced by the effects of reservoir water and rainfall

Since the impoundment of the Three Gorges Reservoir in June 2003, a number of new landslides have occurred and existing landslides have been made worse. The 1,260 × 10⁴ m³ Baishuihe landslide, located at 56 km west of the Three Gorges Dam, began to deform more noticeably after the first impoundment in early July 2003. The sliding of the two blocks comprising the landslide, one an active block and the other a relatively stable block, became apparent after approximately 5 years of monitoring. Field recordings show that the landslide displacement is affected by the combined effects of the rainfall and water level in the reservoir. These effects have been investigated in the present paper, including the deformation characteristics (movement pattern, direction, displacement and velocity) earmarking the temporal evolution of the active block. Based on a practical creep model of a large rock slide, alert velocity thresholds for pre-alert, alert and emergency phases have been computed corresponding to the imminence of failure. The alert velocity thresholds are being proposed to be included as a part of an early-warning system of an emergency plan drawn up to minimize the adverse impact in the event of landslide failure. The emergency plan is intended to be implemented as a risk management tool by the relevant authorities of the Three Gorges Reservoir in the near future.     

三峡库区特大滑坡灾害防治工程评价方法初探

以三峡库区特大滑坡灾害为研究对象,汇总、分析了库区72处特大滑坡灾害的防治工程措施,总结了三峡库区特大滑坡灾害防治技术的特点。通过对三峡库区特大滑坡灾害防治工程的基本类型与防灾特点的分析,建立了特大滑坡灾害防治措施的评价指标体系,并依照评价指标和标准对滑坡灾害防治工程效果进行分级。     

New data and interpretations of the shallow and deep deformation of Huangtupo No. 1 riverside sliding mass during seasonal rainfall and water level fluctuation

The original Badong County, Hubei, China, was mainly below the highest water level of the Three Gorges Reservoir, which is 175 m above sea level. The new downtown of Badong was rebuilt in the Huangtupo area between 1982 and 1991. After detailed geological investigation in the Huangtupo area, four independent landslides were identified, making it one of the largest and most harmful landslide group in the Three Gorges Reservoir area. Since 2003, abundant data have been obtained from the Huangtupo No. 1 sliding mass about rainfall, water level, earth surface deformation and deep deformation. The monitoring data indicate that the earth surface and deep deformation of this landslide is closely related to the seasonal rainfall and water level fluctuation of the reservoir. During increases in the water level, the earth surface deformation velocity decreases, and then increases obviously in the subsequent water level decreasing stage. Because the water level drawdown period overlaps with the rainy season in this area, the earth surface deformation is affected by both rainfall and water level. The deformation velocity of the earth surface caused by rainfall is about 5 mm/month, while that caused by water level decrease is 5–7 mm/month. On the contrary, the deformation velocity of the deep sliding mass accelerates 2 to 3 times faster than average during water level increase. The distinction of surface and deep deformation regulations indicates that the effects of seasonal rainfall and water level fluctuation on the stability of reservoir wading landslides are different. Based on all monitoring data, we also found that the Huangtupo No. 1 riverside sliding mass is creeping seasonally during the seasonal rainfall and periodic reservoir water level fluctuation. The deformation velocities of the east regions of the sliding body indicate acceleration, making these regions even more dangerous.     

三峡库区巫山金鸡岭滑坡成因机制与变形特征

三峡库区新城区迁建多采用就地后靠方式,工程扰动叠加强降雨往往诱发滑坡失稳。基于重庆巫山江东小区金鸡岭滑坡,对其影响因素和成因机制进行探讨。工程扰动不仅是传统认为的后缘加载、前缘削脚作用,更重要的是坡体表层土方堆填阻断了滑坡体地表水泄流通道,使地表水向地下水转化。强降雨作用下滑坡体内地下水位明显升高,导致金鸡岭滑坡2018年8月1日前后发生较大变形。采取降水井抽排地下水等应急处置后,滑坡变形明显趋缓,可见工程扰动导致的地下水升高是该滑坡诱发的关键因素。数值模拟表明,工程扰动后稳定系数明显降低,对应堆填区渗流场变化明显,渗流加剧,孔隙水压力、水力梯度、总水头上升,结合达西定律与有效应力原理可知渗透力增加,抗剪强度削弱,诱发滑坡变形。     

千将坪滑坡动力学过程仿真模拟

滑坡体的失稳破坏是一个动态过程,动力学行为起着非常重要的作用。采用DDA方法对长江三峡库区千将坪滑坡的运动全过程进行了数值模拟研究。模拟方案充分依据该滑坡的地质、地形特征,按不同岩土体和地质结构面类型进行块体单元划分,模拟了滑坡发生、发展的渐进破坏过程以及滑坡触发后的运动情况。模拟结果表明,千将坪滑坡是以斜坡坡脚的局部破坏为其运动的开始阶段,并进一步牵引上部滑体,在地下水压力作用下最终产生整体滑动。     

On evaluating the stability of the Baiyian ancient landslide in the Three Gorges Reservoir area,Yangtze River: a geological history analysis

Numerous landslides have occurred during the construction of the Three Gorges Reservoir of the Yangtze River. Although the underlying causal factor of these landslides was heavy rainfall, the construction process was the trigger of some of them. We report here a systematic study aimed at reconstructing the geological history of an ancient landslide and, based on our results, an evaluation of the role of the history on current landslide stability. Data from detailed field surveys and the studies on geological dating revealed that the Baiyian landslide was composed of five structural parts of different geological ages, such as a sliding belt, disturbed rocks, ancient colluvium, alluvium of the Yangtze River and slope wash. The succession of ancient climates, terraces and tectonic processes in the study area were examined from 300 ka ago. The evolutionary history of the Baiyian ancient landslide can be divided into five distinct stages: development, occurrence, deposition, collapse and disintegration. Some parts of the ancient landslide are currently prone to instability due to the combination effects of heavy rainfall and construction of the reservoir.     

Using an extreme learning machine to predict the displacement of step-like landslides in relation to controlling factors

In the evolution of landslides, besides the geological conditions, displacement depends on the variation of the controlling factors. Due to the periodic fluctuation of the reservoir water level and the precipitation, the shape of cumulative displacement-time curves of the colluvial landslides in the Three Gorges Reservoir follows a step function. The Baijiabao landslide in the Three Gorges region was selected as a case study. By analysing the response relationship between the landslide deformation, the rainfall, the reservoir water level and the groundwater level, an extreme learning machine was proposed in order to establish the landslide displacement prediction model in relation to controlling factors. The result demonstrated that the curves of the predicted and measured values were very similar, with a correlation coefficient of 0.984. They showed a distinctive step-like deformation characteristic, which underlined the role of the influencing factors in the displacement of the landslide. In relation to controlling factors, the proposed extreme learning machine (ELM) model showed a great ability to predict the Baijiabao landslide and is thus an effective displacement prediction method for colluvial landslides with step-like deformation in the Three Gorges Reservoir region.     

三峡库区滑坡台阶状位移趋势预测的警戒速度方法

对不同类型的35个滑坡进行统计分析,发现滑坡临滑前加速度和速度符合Voight模型的幂函数关系。由于无法准确判断三峡库区具台阶状位移特征的滑坡何时处于最后加速失稳阶段,故不能直接应用该模型进行预报。根据台阶状位移特征的滑坡变形特征,本文采用了基于Voight模型的警戒速度方法。该方法是基于Voight模型采用非线性回归分析求得模型参数,按不同风险级别要求求得紧急状态、警戒状态、提前警戒状态的速度阀值,并与实际监测的速度对比去预报滑坡所处的危险等级。采用警戒速度方法对白水河滑坡和新滩滑坡进行了分析,发现预测结果与实际较为接近,预测效果较好。     

Establishing a monitoring network for an impoundment-induced landslide in Three Gorges Reservoir Area, China

A methodology for monitoring system of an impoundment-induced landslide in Three Gorges Reservoir Area, China is introduced. Currently, based on landslide geological classification, the monitoring regions and methods which include types of monitoring instruments, placement and calibration precision of instruments, and appropriate periods for instrumental placement is confirmed. To optimize the monitoring system, sensitivity analysis of displacements and the water table in landslides affected by reservoir surface fluctuation is completed to determine the layout of the monitoring cross sections and the monitoring points. As a case study, the behavior of displacements and the potential fluctuation of the water table in the Shiliushubao landslide, produced by the gradual water impoundment at Three Gorges Reservoir, has been simulated using 3D finite element method analysis. The sensitivity analysis of Shiliushubao landslide is investigated by the fuzzy set evaluation method. As a result, the monitoring network of Shiliushubao landslide is established.