Double-parameter threshold and its formation mechanism of the colluvial landslide: Xintan landslide, China

Data compiled from monitoring the displacement resulting from the Xintan landslide in China was analyzed. The stability of the demonstrated colluvial slope has a close correlation with two parameters, the velocity of the displacement and the angle of the surface vector. The stability trend can be described and evaluated by both the velocity of the displacement and the vector angles. The displacement vector angle, for which there is no substitute, serves as an explicit criterion for the stability of the slope, hence it is significant in the prediction of the catastrophic movement of landslides. A systematic analysis of the features of the vector angles of the surface displacement space and time was performed. The evolving mechanism of space-time and the characteristics of the displacement vector angles were deduced. On the basis of these deductions and by using principles of statistics, the double-parameter threshold for forecasting the stability of the colluvial slopes was established. According to the double-parameter threshold, a calculation and evaluation of stability was completed in terms of the monitoring data of the F-series of points on the Xintan slope. The forecast results coincided with the destabilized timetable, thus demonstrating that the double-parameter criterion has, to a certain extent, precision and practical application for forecasting of landslides.     

降雨诱发型堆积层滑坡的位移动力学特征分析

根据降雨诱发型堆积层边坡物质组成特点与位移构成性质,建立了边坡粘弹性位移动力学模型与位移动力学方程,并以此为基础系统分析了其位移动力学行为和特征以及位移与地下水位或降雨量定量关系,发现了边坡的位移动力学特征主要取决于边坡的地下水位及其变化规律,且其位移和位移速度在整体失稳前具有强烈的波动性。上述位移动力学规律表明,仅运用位移或位移速度作为单一动力学响应参数来评价与预测该类边坡稳定性存在一定局限性。因此,选择和建立堆积层滑坡的位移多源信息预测理论与模型将具有重要的理论意义与实用价值。     

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。     

Unload–load displacement response ratio parameter and its application in prediction of debris landslide induced by rainfall

As the traditional displacement value of a landslide is very easy to be affected by rainfall, it is very difficult to establish a stable and uniform destabilized criterion of landslide in terms of the displacement value. So, it determines that establishment of an effective and stable dynamic displacement prediction parameter is very important in forecast of the debris landslides caused by rainfall. In order to determine this kind of prediction parameter, this paper first completes analysis on the relationship between the destabilized mechanism of the debris landslide and the rainfall dynamic rules. The relationship above shows that the periodical change value of rainfall can be taken as the dynamic unload–load parameter (ULP) of landslide, and the homologous change value of mensal landslide displacement can be taken as the stability displacement response parameter (DRP). Then, on the basis of the relationship between the ULP and the stability DRP of this kind of landslide, the unload–load displacement response ratio (ULDRR) appraisal parameter of this kind of landslides is established in this paper. Finally, the stability of typical debris landslides in China has been systematically studied by means of ULDRR appraisal parameter and model. We find that the ULDRR values conform to the evolutional rule of slope deformation and instability. So, it has been proved that the ULDRR parameter and the appraisal model are suitable and effective for prediction and evaluation of stability and evolution rule of rainfall-induced landslides.     

库水变动下堆积层滑坡加卸载响应规律与稳定性预测

三峡库区堆积层滑坡稳定性受库水位变动影响十分明显,库水变动下堆积层滑坡的演化过程与稳定性预测研究对防灾减灾具有重要的指导意义。基于库水变动与滑坡变形的响应关系,建立库水动力加卸载与位移速率响应耦合的加卸载响应比预测模型;建立库水变动与滑坡稳定系数的响应关系,进而确定库水变动下滑坡体的渗流场类型,并以滑坡稳定系数的变化率的正负来判断库水变动的加卸载作用。以黄莲树滑坡为例,预测其稳定性,并对预测结果进行验证。结果表明:黄莲树滑坡水平方向位移变化与库水变动存在响应关系,且响应具有明显的滞后性;库水变动下该滑坡的渗流场属于动水压力型,每个水文年中库水动力对滑坡有6个月为加载过程,1个月为卸载过程;滑坡监测点的加卸载响应比在2011年出现整体上升并大于1,揭示滑坡趋于失稳,对库水变动加卸载作用的响应加强。结论得到了宏观变形破坏迹象的验证,说明改进的加卸载响应比预测模型具有良好的预测效果。     

滑坡运动过程仿真分析

滑坡是一个动态过程，滑坡体的运动是一个集滑动，转动，拉张等运动方式的复杂运动过程，传统的极限平衡和计算和有限元分析均无法描述滑坡的运动学特点和运动过程。非连续变形分析（DDA）是最近发展起来的一种新的离散数值分析方法。该方法基于块体的运动学理论及数值分析，可以开展块体的静力和动力学计算。应用非连续变形分析方法对长江三峡区新滩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的划分，共划分成504个块体单元。模拟结果表明，新滩滑坡是以斜坡中部姜家坡一带的局部破坏为其运动的开始阶段，并进一步牵引上部滑体和推动下部滑体。代表性块体单元的位移变化曲线和滑动速度变化曲线反映了滑动过程中滑坡体块体系统的变形是非连续的，各处块体的动态形态各异，从而很好地再现了新滩滑坡的整个动态过程，揭示了滑坡的运动机制。     

长江三峡新滩滑坡滑动机制

新滩滑坡是长江三峡大型滑坡之一,是由巨厚崩积物构成的一大型滑坡。强烈上升并有活动断层通过的峡谷斜坡是滑坡形成的特殊地质环境。上硬下软的地层组合为山体崩塌提供了有利条件。而丰沛的大气降水在滑坡活动过程中有着特殊重要的意义。降雨不仅淋滤细小粘土颗粒沉淀于风化页岩顶面,构成软弱滑带,而且常常是滑坡复活的诱发因素。     

降雨型堆积层滑坡特征及稳定性分析

堆积层滑坡是滑坡的一种基本类型,其物质组成、结构等有别于其它类型滑坡。堆积层滑坡失稳绝大多数是由降雨或地下水位的变化而引起的,在降雨诱发堆积层滑坡稳定性分析中,必须考虑渗透力的作用。系统分析了堆积型滑坡发育环境及特征,推导了基于总应力法和有效应力法的可考虑渗透力的传递系数法,采用有效应力法计算滑坡稳定系数时,既要考虑地下水浮力作用,又要考虑地下水流动时的渗透力作用;采用总应力法计算滑坡稳定系数时,仅需考虑地下水流动时的渗透力作用。对一个工程实例进行了深入剖析,验证了考虑渗透力的传递系数法的可靠性。     

地下水渗流对崩坡积滑坡稳定性和变形的影响——以湖南安化春风滑坡群为例

为了研究地下水渗流对崩坡积滑坡变形的影响,通过分析现场调查勘察资料,在研究该滑坡所处的地质环境条件、滑坡的形态特征和变形特征的基础上,探讨了该滑坡的形成机制,对比了地下水渗流对崩坡积滑坡和老滑坡的影响,并开展了数值模拟。取得的认识有:（1）地形地貌、地层岩性、大气降水、人类工程活动是该滑坡形成的主要原因。在这些因素共同作用下,滑坡最终失稳变形,过程中可能发生多次滑动,形成现今的堆积形态。（2）降雨引起的地下水渗流对该崩坡积滑坡稳定性和变形的影响是十分显著的。对于局部架空现象较严重的崩坡积组成的Ⅲ号滑坡体,雨水更易入渗进入坡体,地下水渗流对其稳定性和变形的作用十分明显;而对于优势通道较少的Ⅰ号和Ⅱ号老滑坡体,局部架空现象相对较差,地下水渗流对其稳定性和变形的作用不显著。（3）降雨时间和降雨强度与滑坡稳定性负相关。降雨强度较小时、一定时间内降水对滑坡稳定性影响不大,但降雨较大时,滑坡稳定性将快速降低。     

位移-应力协同分析在新近纪软岩质滑坡监测中的应用——以陕西宝鸡市北坡滑坡为例

强降雨可诱发新近纪软岩质滑坡滑移变形。1955年至今,降雨在陕西宝鸡诱发超过十起大型滑坡灾害。2011年9月19日,宝鸡市区72 h内的降雨量达到332 mm,北坡金鼎寺、簸箕山与高家崖滑坡出现裂缝,威胁市区居民安全。为分析滑坡的变形机制与降雨触发的滑体内地下水位的波动关系,2012—2015年,开展了降雨量、地下水位、孔隙水压力、滑坡应力与位移等物理量的实时监测,统计分析了它们的频率、活动强度及累积变化规律,提出了滑坡的位移扩展模型。研究显示:(1)地下水的活动会影响新近纪软岩质滑坡的变形,但降雨量、地下水位、孔隙水压力、滑坡体应力与位移等物理量变化机制有差异,地下水位、孔隙水压力呈周期性变化,滑坡体的应力、位移的变化具有累积效应;(2)宝鸡市北坡滑坡运动变形具有蠕变、快速滑移两个阶段。降雨会触发的滑坡体各物理量出现加速变化,地下水位波动幅度为0.27~1m,孔隙水压力的变化幅度为10kPa,滑体浅层的水平应力变化幅度为5.6kPa;(3)在判断降雨能否诱发滑坡快速滑移过程中,既需分析滑体应力、位移变化的累积效应,又需分析新近纪软岩质滑带的摩擦破坏机制。     

基于系统动力学的卸加载响应比参数及其在堆积层滑坡稳定性评价中的应用

针对堆积层滑坡的物质组成和力学性质,从系统动力学角度,提出以卸加载响应比作为滑坡稳定性评价参数,并对卸加载响应比参数与加卸载响应比参数进行了比较和分析,指出卸加载响应比参数在边坡的稳定性评价和工程实践中更具有理论意义和实际应用价值。通过论证分析,确定了构成卸加载响应比的卸加载参数和卸加载响应参数,并论证了其合理性与可行性,在此基础上建立了月降雨量-位移加速度卸加载响应比模型。并以新滩典型堆积层滑坡为例,运用该模型进行分析计算,发现卸加载响应比时序曲线所反映的稳定状态与滑坡的实际状况基本吻合,当Y' Y'-且Y'0时,滑坡整体失稳,说明卸加载响应比参数和评价模型用于预测滑坡的变形阶段和作为失稳判据是行之有效的。     

Comparison on landslide nonlinear displacement analysis and prediction with computational intelligence approaches

Landslide displacement is widely obtained to discover landslide behaviors for purpose of event forecasting. This article aims to present a comparative study on landslide nonlinear displacement analysis and prediction using computational intelligence techniques. Three state-of-art techniques, the support vector machine (SVM), the relevance vector machine (RVM), and the Gaussian process (GP), are comparatively presented briefly for modeling landslide displacement series. The three techniques are discussed comparatively for both fitting and predicting the landslide displacement series. Two landslides, the Baishuihe colluvial landslide in China Three Georges and the Super-Sauze mudslide in the French Alps, are illustrated. The results prove that the computational intelligence approaches are feasible and capable of fitting and predicting landslide nonlinear displacement. The Gaussian process, on the whole, performs better than the support vector machine, relevance vector machine, and simple artificial neural network (ANN) with optimized parameter values in predictive analysis of the landslide displacement.     

崩塌诱发其下部滑坡变形过程的分析研究

崩塌冲击或崩积物重力加载作用都可能诱发坡脚滑坡的变形或失稳。在查明坡体结构的基础上,采用3DEC离散元数值模拟方法,对高陡斜坡在地下开采作用下崩塌所产生的机理、失稳模式、破坏规模、运动轨迹进行了全过程模拟,特别是斜坡失稳后和坡脚滑坡的相互作用效应进行了深入分析。结果表明:通过地下开采诱发的崩塌过程模拟及其研究,发现斜坡在地下开采的扰动下会产生大规模的崩塌,其滚石会对滑坡体产生强烈的冲击作用,且所形成的崩积物会对滑坡体产生重力加载作用。再通过监测数据以及现场收集的资料分析得出滑坡的蠕滑变形主要是由于崩积物重力加载作用引起的,且有继续变形的趋势,在暴雨季节时,滑坡的变形速率可能会增大,有潜在大规模滑动的危险,需做好相应的防护工作。     

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.     

Field investigation of force and displacement within a strata slope using a real-time remote monitoring system

Research on monitoring and forecasting technology for slope stability is important for ensuring railway operation. This paper presents field investigation of force and displacement within a strata slope using a real-time remote monitoring system. Based on the interactions of the landslide body, the landslide bed and the monitoring anchor of slope, the mechanical principle of relative movement between the landslide body and the landslide bed can be found. This paper puts forward stress data obtained from a monitoring anchor as the main criterion for landslide stability. The stress will change continually inside the slope mass before the occurrence of a landslide. When the sliding force is larger than the anti-sliding force, deformation and landslides will occur; thus, the change in stress occurs before the change in displacement. In this study, the internal stress, deep displacement and surface strain of a railway slope were measured by a real-time remote-monitoring system, and a vibration metre was installed on the surface of the railway slope to study the influence of the train vibration load on the stability of the slope. The monitoring results are synthetically analysed temporally and spatially, then a railway slope forecasting model is proposed. According to the railway slope field application, the forecasting model makes successful predictions.     

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。     

堆积层滑坡临滑预报的新判据

研究表明，仅用速率大小作为滑坡的临滑判剧是不充分的。笔者在分析新滩堆积层滑坡位移矢量角动态特征的基础上，提出了堆积层滑坡临滑预报的新判据。     

关键影响因子作用下三峡库区堆积层滑坡分布规律及变形破坏响应特征

三峡库区崩滑地质灾害频发,堆积层滑坡是最常见的滑坡类型。在分析三峡库区145处库岸堆积层滑坡资料基础上,选取地形地貌、地质岩性和斜坡构造作为控制因素、降水和库水波动作为主要诱发因素,探究堆积层滑坡在上述关键影响因子下的分布发育规律及变形破坏响应特征,阐明内在机理,结果表明:(1)受区域地质构造和基岩地层岩性显著控制,滑坡发育频次和规模沿长江存在显著空间差异性;(2)砂页岩夹煤层岩组(SC)和泥灰岩与砂泥岩互层岩组(MSM)对库区堆积层滑坡危害最大,软岩、“软-硬”互层二元结构和水-岩(土)相互作用是主导滑坡发育的主要影响因素;(3)大多数滑坡涉水,主要发育在10°~30°斜坡上,前缘高程集中在100~175 m,受库水波动影响严重,岸别和斜坡结构对堆积层滑坡发育没有明显控制作用;(4)库区滑坡主要由降雨-库水下降联合诱发滑体前缘滑移-拉裂,引发牵引式滑坡,降雨与库水波动各自对滑体的影响格局和程度存在明显差异。以期研究成果为有针对性的库区滑坡总体防治提供一定的科学指导。     

皖南山区阳台古滑坡形成机制研究

陡倾层状岩质斜坡易产生倾倒变形,在山区可见大量由倾倒变形发展形成的大型滑坡,研究其形成机制对于正确评价边坡稳定性具有重要意义。本文以皖南山区阳台滑坡为例,在工程地质勘察的基础上,采用定性分析、二维离散元和有限元相结合的方法,详细研究了阳台滑坡的变形破坏过程及其影响因素。研究结果表明,阳台古滑坡的形成包括河流下切岩体卸荷回弹、倾倒变形逐步发展、滑面发展整体破坏、堆积体次级变形4个阶段。这类滑坡的防治应重点控制滑坡前缘的变形,并做好截排水工作。     

不同类型滑坡渐进破坏过程与稳定性研究

滑坡的类型一般可分为牵引式滑坡、推移式滑坡和复合式滑坡,根据其滑面的发展形态,依次表现为前进式渐进破坏模式、后退式渐进破坏模式和复合式渐进破坏模式。基于岩土体应变软化特性,揭示了滑坡渐进破坏过程的本质是滑带力学参数弱化的过程,初步探讨了3种类型滑坡渐进破坏过程的远动特点和力学特征和滑坡渐进演化过程。以不平衡推力法和3种类型滑坡的演化特征为基础,提出3种类型滑坡渐进破坏过程中临界状态条块确定方法,通过建立滑坡渐进破坏稳定性计算模型和计算公式,提出滑坡随着渐进演化过程的滑带参数取值方法,并阐述了渐进破坏过程的稳定性计算实现过程,实现不同类型滑坡渐进破坏过程的稳定性分析。以3个典型滑坡为例,分析得出滑坡渐进破坏过程中牵引式滑坡和复合式滑坡稳定性降低速率由大到小再到大和推移式滑坡稳定性降低速率由小到大的过程,3种类型滑坡在渐进破坏过程中不同部位对稳定性的贡献不同,验证了不同类型滑坡的变形规律。研究结论可对不同类型滑坡的稳定性发展进行初步预测和为滑坡治理提供指导意义。