【作者】 李德营；

【导师】 殷坤龙；

【作者基本信息】 中国地质大学 ， 岩土工程， 2010， 博士

【摘要】 20世纪中期以来,随着人口的快速增长和全球化工业活动的增加,大规模的人类活动对自然环境扰动很大,加之气候的急剧变化和地震灾害的频发,造成了大量了滑坡灾害。在世界范围内,每年由滑坡和其所引起的次生灾害(如滑坡涌浪)造成的人员伤亡数以千计,造成房屋、厂房、道路、桥梁、大坝、港口等建筑物破坏的损失数以百亿美元。我国三峡库区属于滑坡灾害高发区,每年滑坡灾害造成了巨大的损失。自2003年三峡水库蓄水之后,由于库水位的大幅度上升和水位周期升降的作用,恶化了三峡水库周边的地质环境条件,产生了大量新生滑坡和加剧了原有滑坡变形,使得库区地质灾害防治工作变得更加严峻。由于三峡库区所处的特征地质环境和库水位的周期涨落的影响,很多滑坡的累计位移-时间曲线的形状全部或一部分形如台阶状,这种具有台阶状位移特征的滑坡一般经历多次加速变形,变形速度受降雨、库水位等影响表现明显的波动性。此类型的滑坡在变形演化的过程中,降雨、库水位外界荷载作用时,累计位移呈现陡坎式增长,外力去除,累计位移则表现为较平稳。本文的研究对象就是具有台阶状位移特征的滑坡,该类型的滑坡在三峡库区造成了严重的经济损失和一定的人员伤亡。为了减小此类型滑坡所造成的损失,有必要对其预防方法进行研究。传统的减小滑坡灾害的方法主要有工程措施和滑坡预测预报两类方法。但是由于很多滑坡规模大且滑体厚度深,往往现有的工程技术条件难以达到稳定坡体的效果或者就是因为治理的费用过高而往往不采取工程措施。当工程措施失效时,为了减小生命财产的损失,采用滑坡预测预报方法变得尤为重要。论文通过现场调查、监测资料分析和理论研究相结合的方式,紧紧围绕三峡库区具台阶状位移特征的滑坡预测预报的各项研究内容展开讨论。论文共七章,第一章论文阐述了三峡库区具台阶状位移特征的滑坡预测研究的研究意义,并通过对国内外文献的分析,提出了此类滑坡预报研究中存在的问题和不足。针对这些不足,在前人研究的基础上,提出了一整套适合三峡库区具台阶状位移特征的滑坡预报的研究思路和体系。第二章对三峡库区具有台阶状位移特征的白水河滑坡、八字门滑坡、卧沙溪滑坡、新滩滑坡和卡子湾滑坡等滑坡实例进行了分析,分析内容主要包括滑坡简介、变形曲线、影响因素和变形破坏模式等。第三章全面分析了三峡库区具台阶状位移特征的滑坡变形时空演化特征,包括滑坡的渐进式破坏、变形速度的波动和滞后性、变形加速破坏阶段特征等时间演化特征和双层滑动、变形区域的划分、局部破坏等空间演化特征,并对其反映滑带的塑性或脆性破坏的力学机制、变形速度和外界影响因素的函数关系进行分析。第四章首先对滑坡的中长期预报模型进行了概述分析,针对上述模型的不足,建立了考虑降雨、库水位等外界影响因子的灰色GM(1,1)—BP神经网络模型,并通过白水河滑坡和八字门滑坡两个滑坡实例与灰色GM(1,1)、BP神经网络模型进行了对比分析。第五章详细的介绍了Voight模型及其适用性,针对台阶状滑坡的位移特征,建立了基于Voight模型的警戒速度预报方法,改变了传统以预报失稳时间的预报方法,并通过白水河滑坡和新滩滑坡对该预报方法进行了验证分析。第六章详细分析了变形速度、位移加速度、位移切线角、滑坡位移比、LURR值等滑坡单因子判据,并对其适用性进行了分析；针对滑坡单因子信息的不全面、充足性,建立了以滑坡变形速率比、裂缝的贯通比、宏观迹象作为三维为基本因子的滑坡三维立体综合判据。第七章对全文研究内容进行了总结,并针对研究过程中尚未很好解决的问题进行了展望。具体而言,论文在以下方面取得了阶段性成果：(1)三峡库区具台阶状位移特征的滑坡典型实例分析：通过对白水河滑坡、八字门滑坡、新滩滑坡、卡子湾滑坡、卧沙溪滑坡等5个具有台阶状位移特征滑坡的地形地貌、滑体特征、工程地质条件、影响因素、变形曲线特征和变形破坏模式等分析,发现该类型滑坡的累计变形-时间曲线表现为台阶式变化,在整个变形破坏过程都经历了多次加速,并不是一次加速失稳破坏,而且变形持续时间较长,累计变形量大。滑坡的变形表现出不均一性,整体破坏前都有局部变形,变形模式也是多样的,如蠕滑(滑移)-拉裂型、滑移-弯曲型；其破坏模型有牵引式,也有推动式。滑坡变形速度的波动与降雨、库水位等外界因素的变化有着密切的关系,按照影响变形的不同因素可以分为降雨诱发型滑坡和降雨与库水位联合作用型滑坡。由于该类型的滑坡往往规模大、滑体厚度深,在次生失稳时可能也会产生滑坡涌浪等次生灾害,故往往造成的损失也巨大。(2)三峡库区具台阶状位移特征的滑坡变形时空演化特征系统研究：通过滑坡地质学分析、滑动变形破坏机制识别、变形过程分析和影响因素判别等方法对三峡库区具台阶状位移特征的滑坡进行综合分析,并通过分析不同规模、岩土体类型和影响因素的滑坡实例,来了此类型滑坡的变形时空演化特征。此类型的滑坡经历了较长时间的变形过程,经历的是从局部破坏到整体破坏的渐进式变形破坏,土的应变软化作用使滑带土的剪切强度不断降低。外界因素的波动、地表产生大量裂隙和土的粘性力的存在使滑坡的变形速度存在较大的波动性。滑坡变形速度的改变相对外界因素的改变有一定的滞后性,这是由于外界因素的改变到影响到滑体的变形需要一个过程。此类型滑坡进入加速失稳破坏阶段,其变形速度倒数-时间的关系是渐进形式,速度并不是一直增加的,滑带经历的是塑性破坏。三峡库区此类型的滑坡大多是老滑坡、古滑坡,而且滑带都有一定的厚度,并不是新生成的剪切面,剪切区发生的塑性变形,基底的塑性变形决定了这种特征的变形样式。用无限斜坡模型解释了降雨诱发型滑坡的外界因素与变形速度的关系,还有条分法建立了降雨与库水位联合作用下外界因素与变形的内在函数关系。三峡库区具台阶状位移特征的滑坡除了具有上述变形时间演化特征外,还具有双层滑,动、变形区域的划分和局部破坏等变形空间演化特征。双层滑动主要取决于滑坡体的规模、影响因素的强度和滑体的结构,而且浅部和深部滑带相互影响,浅层滑动和深部滑动经常交替出现。推动式滑坡和渐进后退式滑坡两类不同的变形破坏模式其地表的变形性质有着显著的差异。滑坡在整体破坏前,都会出现局部破坏,局部破坏常给人带来滑坡整体滑动的错觉,如何区别滑坡的整体破坏和局部破坏是进行准确预报的关键。(3)建立了基于库水位和降雨等影响因子的灰色GM(1,1)-BP神经网络模型首先对滑坡中长期预报的统计预报模型、非线性预报模型、物理力学预报模型和耦合预报进行了概述,并上述模型进行了适用性分析。针对非线性模型和统计预报模型无法考虑影响因素、物理力学预报模型无法确定实际的剪切力、耦合模型无法建立实时的稳定性系数与变形速率的函数等不足,本文建立了基于库水位、降雨等影响因子的多因子灰色GM(1,1)-BP神经网络模型。根据分析确定了单月降雨量、两月降雨量、月库水位平均值、月间库水位变化量、当月库水位最大变化量为滑坡的影响因子,并把位移分解为趋势项和偏离量。该模型首先用GM(1,1)模型提取变形的趋势项,然后建立基于上述影响因子的BP神经网络预测位移的偏离量。通过对变形强弱不同的台阶状白水河滑坡和八字门滑坡的实例分析,并与GM(1,1)模型、BP神经网络模型进行了对比分析,发现本文模型拟合程度较高,而且预测的相对误差都小于6%,满足预测的精度要求,说明建立的模型适合此类滑坡的中长期预报。(4)建立了三峡库区具台阶状位移特征的滑坡的警戒速度预报方法首先对滑坡的蠕变理论和临滑得Voight模型进行了分析,并对35个滑坡临滑前的加速度和速度进行了统计分析,发现滑坡临滑前加速度与速度存在幂函数关系,符合Voight模型,并选用瓦伊昂滑坡和卧沙溪滑坡两个实例来说明此模型在具台阶状位移特征的滑坡中的适用性。对于具台阶状位移特征的滑坡,无法准确判断滑坡何时最后加速失稳阶段,故直接采用Voight模型预报临滑失稳时间则会产生误判,本文改变了传统以预报失稳时间的方法,建立了基于Voight模型的警戒速度预报方法。该方法采用Voight模型对累计位移-时间曲线进行非线性回归分析求得模型参数,在假定的时间下根据风险的要求求得不同状态的警戒速度值：紧急状态、警戒状态、提前警戒状态,并根据警戒速度阀值与实际监测数度的对比去评介滑坡所处的危险等级。通过白水河滑坡和新滩滑坡两个实例对该警戒速度预报方法进行了验证分析。(5)提出了基于滑坡变形速度比、裂缝贯通比和宏观迹象的三维立体综合判据.论文首先对常用的诸如变形速度、位移加速度、蠕变曲线角、滑坡位移比和LURR值等单因子滑坡进行了适用性分析,发现采用上述单因子滑坡判据所界定的阀值常常不能适合某些滑坡,用如此单因子判据会常常造成误判。滑坡的成功预报需建立在对滑坡类型、变形特征、变形演化机制等深入研究的基础上,以监测资料为基础,考虑宏观变形迹象等因素的综合判据。然后,对国内学者所建立的多因子的综合判据进行了分析,在滑坡综合判据中对多因子信息的表达上,本文提出了通过“立体”的概念耦合滑坡的多因子信息,建立了考虑变形速度比、裂缝贯通比和宏观迹象等关键因子信息的三维立体综合判据,通过判断表征滑坡当时状态的点是否落在体内来判断该滑坡是否进入临滑状态,该综合判据非常形象直观。变形速度比是通过警戒速度预报方法求得的,对于宏观迹象各个因子的处理方法采用的是模糊数学的方法。通过对已发生滑动的新滩滑坡和正在变形的白水河滑坡所建立的三维立体综合判据分析,发现此三维立体综合判据适合此类滑坡。更多还原

【Abstract】 With the fastest growing population and global industry development in the world since the mid-age of the 20th century, the expanding urbanization and changing land-use practices lead to many environmental problems, such as landslides.In addition, the climate change and frequent earthquakes are the important factors in increasing the frequency of their occurrence. Landslides, as one of the major natural hazards, account for enormous economical losses and human casualties each year in terms of both direct and indirect costs in the world A large number of landslides exsit in the Three Gorges Reservoir in China,which exert a heavy social, economic, and environmental toll. Since the first impoundment of the Three Gorges Reservoir in June 2003, a number of new landslides have occurred and existing landslides made worse.Due to the big rise and periodic fluctuation of water level, the shape of cumulative displacement-time curve of landlides in the special geology environment of the Three Gorges Reservoir is step-like. The landslides with step-like deformation behave multi-acceleration beforce failure.The velocity of displacement fluctuation with the combined effects of rainfall and water level in the reservoir. The displacement curve consists ’power law’ acceleration phases during the external loading separated by phases of decreasing velocity during the non-loading. The landslides with step-like deformation also result in the economic loss and human casualties.In order to reduce the risk and loss of the landslides, it is necessary to study the prevention methods. Remedial countermeasures are not often useful when coping with large landslides in the Three Gorges Reservoir because of the extremely high kinetic energy potentially and deep depth involved in the phenomena. In such conditions, landslide prediction is the only effective tool to reduce the vulnerability of the potentially involved areas by means of evacuation or river closure. Prediction of landslide failure is an inherently difficult task because of the difficulty in quantifying the temporal evolution of the driving forces and the shear resistances where both of which are complicated by the effects of rainfall and reservoir water level.Predticon of landslides with step-like in the Three Gorges Reservoir is researched based on site investigation and the analysis of monitoring data. There are seven chapters in the thesis, the first chapter introduces the practical significance of the research and discovers the existing questions by the means of literature review. The second one describes site condition, landslide deformation, influencing factors and failure mode of Baishuihe landslide, Xintan landslide, Bazimen landslide, Kaziwan landslide and Woshaxi landslide which belong to the landslides with step-like deformation. The third one discusses the temparal and spatial evolvement characteristics of landslide deformation, involving progressive failure, velocity fluctuation and hysteresis, movement patterns during the phase of acceleration, double sliding surface, local failure and deformation zoning of landslide surface. The fourth chapter firstly reviews prediction models of landslide. Then aiming at the exsiting problems of the traditional methods the couping GM(1,1)-BP model is established based on the influencing factors of the water level and rainfall. Finally, the validity of this model was confirmed by investigating two landslide cases through compairing the GM(1,1) model and BP model. The fifth chapter discusses the applicability of Voight model and proposes the prediction method of alert velocity on the basis of displacement curve shape. The alert velocity of Baishuihe landslide and Xintan landslide are computed. The sixth one analyzes the applicability of the single prediction criteria of landslide including velocity, acceleration, ratio of displacement, LURR. In order to improve the precision of landslide prediction,the three-dimensional criteria of landslide prediction is proposed on the basis of the alert velocity, earth crack of landslide surface and macroscopical evidences.The seventh part is the conclusions of the thesis and prospect of the next step research. The achievement are set forth in details as follows:(1) Typical landslides with step-like deformation in the Three Gorges Reservoir are investigated.Typical landslides incuding Baishuihe landslide,Xintan landslide, Bazimen landslide, Woshaxi landslide and Kaziwan landslide are introduced in the chapter 2, involving the site investigation, deformation character, influencing factors and tpyes of deformation and failure. The shape of displacement curve is step-like.There are multi-acceleration and the large displacement through long period’s deformation before landslide failure. The velocity fluctuates with the external factors of water level and rainfall. The failure modes are various, inculding retrogressive failure and advancing failure. Local failure often occurred before general failure. The landslides result in large loss of property and human life due to the scale and the secondary hazard arosed by the slope sliding.(2)The temparal and spatial evolvement characteristics of landslide deformation are systemically studied.The temparal and spatial deformation characteristics of landslide are investigated by means of the analysis of engineering geology condiction, deformation process, deformation mechanism and influencing factors. The landslides often deformed for long time due to progressive failure of the sliding belt when experiencing from local failure to general failure.The descending shear strength with time may arise from the strain weakening soil. In addition to expericing the strain weaking process of the sliding one, the displacement velocity of landslide movement flucutated with rainfall and water level and there is hysteresis. The possible reseasons are the occurrence of the flucutation of the external factors, earth crack of landslide surface and soil viscosity. The pattern of movement approaching the landslide failure displays ian asymptotic form in a plot of 1/v against time (v is velocity). The style occurs where movement is taking place across existing sliding belt or as a result of ductile deformation processes. The slice method and infinite slope method are adopted to elucidate inherent function relationship between external factors and displacement change.The existence of viscous force.is crucial to the change of displacement velocity.The double sling of the landslides with step-like deformation is affectd by the external factors, landslide scale and the thickness of the sliding body. The shallow and deep sliding surfaces are interactional. The different deformation property in the landslide surface including tension zone, compression zone, sliding zone and falling zone ocurred in different landslides. Local failure often occurered before landslide sliding in whole. Therefore, the distinguish of local failure and general failure of landslide is important in landslide prediction.(3) Based on the affecting factors of the water level and rainfall, the couping GM(1,1)-BP model is established for landslide displacement prediction.The chapter reviews the statistical models, nonlinear models, physically-based mechanical models, the coupling models and discusses the applicability of their methods. The traditional methods of landslide prediction are used to modeling the displacement-time curve, not consideing the influencing factors. Or the uncertaintie related to the heterogeneity of soil/rock mass, the geological boundaries, the pore pressures acting on the sliding surface makes the models based on the stress-strain relation unrealistic. Aim at the exsiting shortages of the methods, the couping GM(1,1)-BP model is established on the basis of the water level and rainfall. Firstly, the displacement is divided into trend part and departure part. The trend part is extracted using GM(1,1) model. Secondly, BP model is used in calculating departure part consideing the water level and rainfall. One month rainfall, two months rainfall, the elevation of the water level, maximum change of reservoir water in one month, water level change between two months are chosen according to the literature review. The couping model, GM(1,1) model and BP model are compared througth the analysis of Baishuihe landslide and Bazimen landslide. The results find that the proposed model is the best and the precision of the model is less 10% by comparing the prediction displacement and the monitoring one.(4) The prediction method of aler velocity is set up for the landslides prediction.The Voight’s relation through the analysis of acceleration and velocity of 35 landslide appoaching the failure was foud that the logarithm of acceleration is proportional to the logarithm of the velocity of slope displacement. Voight model is widely used in landslide failure time predition. Due to the step-like displacement of the landslides, the final acceleration phase of deformation could not be identified. Therefore, Voight mothed could not be directly used in prediction of failure time. As a result, a more practical and much simpler method based on the Voight model has been suggested to assess the phases of a landslide by means of threshold values of velocity by Crosta. This method has been attempted in a large rock slide and validated by analyzing historical landslide failures. Crosta’s proposal give us to a new insight in changing the prediction of failure time to forecasting the alert velocity where the similar deformation patterns occurred in the landslides with step-like deformation.According to the same procedure, alert velocity could be got from the Voight’s method and the paraments of the model are obtained from the nonlinear regression. In estimating the parameter values of the Voigt model, a better fit could be obtained by adopting the displacement as the variable rather than velocity. Alert velocity thresholds (corresponding to 7,15 and 30 days before predicted failure) can be computed according to Voight model, allowing the definition of different thresholds of velocity according to the needs of the emergency management.The feasibility of the method are validated through the cases of Baishuihe landslide and Xintan landslide. The calculated alert velocities are very cosed to the monitoring displacement of Xintan landslide.(5) The three-dimensional criteria of landslide prediction is proposed on the basis of the alert velocity, earth crack and macroscopical evidences.The applicability of the single prediction criteria of landslide including velocity, acceleration, ratio of displacement, LURR is researched through the landslide cases. In order to improve the precision of landslide prediction and avoid the shortage of information, the synthetical prediction criteria are also discussed. It is crucial for synthetical prediction criteria that how to express the multi-factor. The multi-factor is exhibited through the multi-dimension body. The three-dimensional criteria of landslide prediction is proposed on the basis of the alert velocity, earth crack of landslide surface and macroscopical evidences. The alert velocity could be obtained from the Voight’s method.The three-dimensional criteria was proved by the analysis of Baishuihe landslide and Xintan landslide.更多还原