【作者】 朱大鹏；

【导师】 晏鄂川；

【作者基本信息】 中国地质大学 ， 地质工程， 2010， 博士

【摘要】 三峡水库蓄水至高水位及正常蓄水后1到3年,是库区库岸再造及滑坡变形活动的活跃期,会有大量堆积层滑体的复活。考虑到堆积层滑坡具有规模大、数量多、分布广等特点,一旦堆积层滑坡滑入江中,除直接造成滑坡体上大量人员伤亡、经济损失外,其诱发的次生灾害涌浪也会造成极其严重的后果。因此,对堆积层滑坡开展以复活机理及变形预测为目的的研究具有重要的理论意义和工程实践意义。基于此,以三峡库区堆积层滑坡为研究对象,以监测成果为基础,研究堆积层滑坡变形特征与库水位变动的响应规律,对引起堆积层滑坡变形的内因——工程地质模型进行深入研究,对堆积层滑坡复活变形的外因——地下水作用机理进行深入探讨,在此基础上建立堆积层滑坡的变形预测模型,为防灾减灾提供决策依据。本文主要研究内容及成果如下：(1)堆积层滑坡对库水位变动的响应规律研究。根据所在地区的库水位变化过程线,确定滑坡所在位置的库水位变化过程,研究了三峡库区两堆积层滑坡(玉皇阁滑坡、鹤峰乡场镇滑坡)在水位波动条件下变形、孔隙水压力等特征曲线,得到了典型堆积层滑坡变形等特征对库水位变动的响应规律,其中玉皇阁滑坡发生明显变形对应水位上升阶段,鹤峰场镇滑坡发生明显变形则对应水位下降阶段。(2)堆积层滑坡工程地质模型研究。以三峡库区秭归-万州段89个堆积层滑坡进行统计,得到了库区堆积层滑坡的体积、地形地貌、地层岩性、斜坡类型等分布规律,从滑体的组构特征、动力成因、变形运动特征和发育阶段四组主要控制性因素出发,建立滑坡的基本地质模型。由于堆积层滑坡大多处于库水位变动影响范围内,动力成因详细考虑了库水对不同类型堆积层滑坡的作用模式及库水作用下滑坡的变形特征,进一步划分为浮托减重、渗透力、浮托减重+渗透力(混合)三类,细化了水库型堆积层滑坡的基本地质模型。运用上述基本地质模型建模方法及理论,得出了巫山玉皇阁滑坡的基本地质模型为新生性孕育期渐进牵引式人工水库蓄水浮托减重型土质岩床滑坡,鹤峰乡场镇滑坡的基本地质模型为复活性孕育期剧动牵引式人工水库蓄水渗透压力型土质岩床(+土床)滑坡。(3)堆积层滑坡复活过程中地下水水力学作用效应。由于滑坡自身岩土渗透特性的不同,库水波动对其影响也各不相同,以三峡库水一个水文年的正常水位变动线为基础,以鹤峰乡场镇滑坡主剖面建立渗透计算模型,对库水位上升及下降阶段过程中不同渗透特性堆积层滑坡的地下水浸润线进行分析,根据浸润线的分布特征划分了不同水位阶段不同滑坡类型的地下水作用效应,从定性的角度分析了不同地下水水力学作用效应对滑坡稳定性的影响,即：库水位上升阶段时,’①当k>10-4m/s时,有a≤5°,地下水作用效应表现为浮托减重,不利于滑坡的稳定；②当10-5m/s<k<10-4m/s时,有5°<a<90°,地下水作用效应表现为浮托减重+渗透力(混合)型,对滑坡是否有利取决于谁占主导地位；③当k<10-5m/s时,有a≥90°,地下水作用效应表现为指向坡内的渗透压力,有利于滑坡的稳定。而在库水下降时,库水对滑坡的稳定性影响则与上述状况相反。根据上述计算成果应用于玉皇阁滑坡渗透系数反演分析,基于地下水水位监测与库水位的关系反演了渗透系数范围,然后基于孔隙水压力监测与库水位的关系在上述范围内进一步确定了渗透系数的大小。(4)地下水作用效应对三峡库区堆积层滑坡稳定性影响研究。地下水通过外部激励作用使得滑坡内部暂态的平衡系统被打破,稳定性发生变化。由于滑坡体本身的差异性,不同的地下水作用效应对稳定性影响也各不相同,这是不同类型滑坡在不同的水位阶段发生不同变形差异的主要因素。根据所选研究对象的不同,将地下水对岩土体的力学作用分为两种作用模式,并证明了两种作用模式的等效性；根据滑体内饱水部位与地下水浸润线的关系,稳定性计算时将滑块分为三种不同的状态(“上干下湿”、“饱和”、“上湿下干”)分别予以考虑；研究不同渗透特性滑坡在水位上升及下降阶段渗透力、浮托力导致的滑坡抗滑力及下滑力的影响,得到了稳定性系数随时间、库水位、滑体饱水面积比率等变化规律。及：当库水位上升时,①对强透水滑坡体(k≥10-4m／s),其稳定性系数的变化规律为随水位的上升起初呈加速减小趋势,直到水位恒定为175 m时,滑坡的稳定性系数为一定值。②对中等透水滑坡体(k=10-5m/s),其稳定性系数的变化规律为随水位的上升起初呈加速下降趋势,直到水位恒定为175 m时,定性系数呈减速下降趋势。③对中等透水-微透水滑坡体(k=10-6～k=10-8m/s),其稳定性系数随水位的上升起初呈加速上升趋势,直到水位恒定175 m时,稳定性系数然后呈减速下降趋势。且渗透系数越小,滑坡稳定性系数上升阶段上升也越快,相应下降阶段下降越慢。从上升阶段稳定性下降率与库水的关系来看,当k≥10-5m/s时稳定性系数下降率趋势相同,均为负值；当k≤10-6m/s时稳定性系数下降率亦趋势相同,均为正值。当库水位下降时,①对强透水滑坡体(k≥10-4m/s),其稳定性系数的变化规律为随水位的下降起初呈增长趋势,直到水位恒定145 m时,稳定性系数然后为一定值。②对中等透水滑坡体(k=10-5m/s),其稳定性系数的变化规律为随水位的下降升起初呈下降趋势,然后呈先加速后减速的上升趋势,直到保持某一定值。③对中等透水～微透水滑坡体(k=10-6～k=10-8m/s),其稳定性系数随水位的下降起初呈加速下降趋势,然后呈缓慢上升趋势。且多为负值。从稳定性下降率的角度看,当k≥10-4m/s稳定性系数变化率曲线具有相同的变化趋势,且均为正值；当k≤10-6m/s时稳定性系数下降率亦具有相同的趋势。基于上述研究成果,建立了水位升降条件下不同类型堆积层滑坡的稳定性随水位的标准变化曲线图。(5)典型堆积层滑坡复活变形机理研究。以典型堆积层滑坡——鹤峰乡场镇滑坡工程地质模型为基础,根据水位实际波动曲线所得到的坡体内浸润线的变化特征,得到了稳定性系数随水位变动的关系,建立了鹤峰乡场镇堆积层滑坡的三维数值-力学模拟模型,研究了水位变动条件下滑坡应力场、位移场、剪应变增量、塑性区的发展规律,从外因如何影响内因的角度揭示了典型堆积层滑坡复活变形机理,为滑坡的变形预测奠定了基础。(6)堆积层滑坡变形预测模型研究。以鹤峰乡场镇滑坡为例,根据所在地区的库水位变化过程线,调整地质-数值-力学模型中的水位线及岩土体参数,建立滑坡的综合预报模型,通过强变形区实际位移监测值与数值模型中模型监测点位移追踪对比,获得了FLAC3D模型中时步与实际时间的对应关系,通过时步的外延预测了未来一个水文年内滑坡的变形发展趋势。本文创新点主要有以下几点：(1)以玉皇阁滑坡、鹤峰场镇滑坡为例,得到了不同渗透特性滑坡对库水变动的响应规律,并构建了水库型堆积层滑坡的基本地质模型；(2)基于不同渗透特性滑体内的地下水对库水位变动的响应规律和地下水实时监测反演了滑体渗透系数；(3)建立了基于三峡水库设计水位变动的不同类型滑坡稳定性系数-水位标准变化曲线。综上所述,论文揭示了水库型堆积层滑坡的复活变形机理,从引起滑坡变形的内外因出发,对水位变动条件下滑坡变形进行预测预报,为防灾减灾提供科学决策依据。更多还原

【Abstract】 1 to 3 years, after the high water level and normal water of the Three Gorges Reservoir, are active period of the reservoir bank rebuilding and the landslide deformation activity in reservoir area, and a large number of accumulative Landslides will revive. As known, the landslide has the features of large scale, large quantities and wide distribution and so on, so once the landslide slips into the Yangtze river, it will result in the heavy casualties and economic losses. Additionally, the serious consequence is caused by that landslide induced secondary disasters surge, so it has important theoretical and engineering significance to study the revival mechanism and deformation prediction of the accumulative landslide.In view of the above situation, the accumulative landslide deformation features on the responses of the reservoir water level variation was studied based on monitoring achievements. As the internal cause inducing the accumulative landslide deformation, engineering geological model was further researched, and as the external cause of revival deformation of the accumulative landslide, effect mechanism of groundwater was further discussed, and then deformation prediction model of accumulative landslide was established, it has reference for disaster prevention and mitigation.In this paper, the research contents and results are shown as follows.(1) Accumulative landslide deformation features on the responses of the reservoir water level variation. According to the changed process level of reservoir water in the Three Gorges Reservoir, reservoir water level on landslide location was determined, and characteristic curves (e.g. deformation, pour water pressure) of two accumulative landslide (e.g.YuHuangge landslide, Hefeng landslide) with water level fluctuations was get to study typical landslide feature rules on the responses of the reservoir water level variation. Significant deformation of YuHuangge landslide occurred at water level rising phase.However, significant deformation of Hefeng landslide occurred at water level drawdown phase.(2) Engineering geological model of accumulative landslide. Statistics of 89 accumulative landslides in Zigui-Wanzhou section in Three Gorges Reservoir shows the distribution rules of volume, terrain and physiognomy, formation litho logy, slope types. Four major controlling factors involving fabric characteristics of sliding mass, dynamic causes, deformation characteristics and developmental stages, and the based landslide engineering geological model was established. As the most accumulative landslide is in the influential area of water level changes, detailed dynamic causes consider the action mode of the reservoir water on different types of landslide, so dynamic causes were further divided into three categories such as float effect weight reduction, penetration, float weight and penetration (mixed), which refine the basic geological model of accumulative landslide. Use the above basic methods and theory building geological model and get the basic geological model of Yuhuangge landslide that it is the artificial reservoir float effect weight reduction soil sliding mass and rock bed landslide which belong to the freshmen gestation period and is progressive traction, in addition, the basic geological model of Hefeng landslide is the artificial reservoir osmotic pressure soil and rock bed (and soil bed) landslide that it is the revived gestation period and is dynamic traction.(3) Mechanical effect of groundwater water in the accumulative landslide revival process. Due to the different permeability of rock and soil mass of the landslide itself, reservoir fluctuations has different effect on landslide body. Based on the normal changed water level of a hydrological year of Three Gorges reservoir, the groundwater seepage line of different permeable landslide body with the rising and falling process of water level was analyzed, the groundwater effects were divided according to the distribution of invasive lines at different stages of water level and different types of landslide. Different mechanical effect of groundwater have different effect on the landslide stability from qualitative view, so reservoir-landslide was future divided into float effect weight reduction, penetration, float effect weight reduction and penetration (mixed).When the water level rises, if permeability coefficient k>10-4m/s, a≤5°, effects of groundwater acts as float weight, so it favorable to landslide stability, if permeability coefficient 10-5m/s<k<10-4m/s,5°<a<90°,effects of groundwater acts as weight reduction and penetration (mixed), so it favorable to landslide stability or not depends on which is the dominant, and if permeability coefficient k<10-5m/s, a≥90°, effects of groundwater acts penetration pressure towards inner slope mass. When the water level drawdown, effects of groundwater acting landslide stability are contrary to the above conditions.The above calculation results were used in the inversion of permeability coefficient of Yuhuangge landslide as follows. first, the permeability range was inversed based on the relationship between ground water monitoring and water level, and then the size of the permeability coefficient is further determined in the context of the relationship.(4) Stability factor of the typical accumulative landslide with mechanical effect of groundwater water. Internal transient balance of landslide would be disturbed when it was inspired by external ground water, and at the same time the stability changed. For differences of landslide mass itself, different groundwater water effects have different influence on stability, and this is the main reason why deformation differences of landslide mass caused under the different water level. According to different research objects, two effect models of water to soil-rock mass were divided and they were confirmed to be equivalent. According to the relationship between saturated parts of landslide mass and saturation line, the slide block will be viewed as three different conditions when stability factor was calculated, and then the stability equation of penetration landslide is improved as well. Penetration pressure or float pressure will changed with rise and down of reservoir water level, and it effect the resistance and the sliding force of landslide mass with different permeability, and then variation regularity of stability coefficient with time, water level, ratio of saturated area is obtained.When the water level rises, and for strong permeable landslide (k≥10-4m/s), factor of stability with water level is accelerating decrease trend in the beginning, and it not keeps a certain value until water level reaches 175m.for medium permeable landslide (k=10-5m/s), factor of stability is accelerating decrease trend with water level in the beginning, and then it is decelerating decrease trend after water level reaches 175m.for medium to micro permeable landslide (k=10-6～k=10-8m/s), factor of stability is accelerating increase trend with water level in the beginning, and then it is decelerating decrease trend after water level reaches 175m.From relation between decreasing rate of the stability and reservoir water, decreasing rate has a the same trend when k≥10-5m/s it is negative, but when k≤10-6m/s it is positive.When the water level drawdown, and for strong permeable landslide (k≥10-4m/s), factor of stability is increase trend with water level in the beginning, and it not keeps a certain value until water level reaches 145m. for medium permeable landslide (k=10-5m/s), factor of stability is decrease trend with water level in the beginning, and then it is accelerating and then decelerating decrease trend after water level reaches 145m.for medium to micro permeable landslide (k=10-6～k=10-8m/s), factor of stability is accelerating decrease trend with water level in the beginning, and then it is slow increase trend after water level reaches 145m.From relation between decreasing rate of the stability and reservoir water, decreasing rate has a same trend when k≥10-5m/s it is positive, but when k≤10-6m/s it is negative.Based on above result, last the standard change chart of stability with water level was get under decreased and increased condition.(5) Revival deformation mechanism of the typical accumulative landslide. Stability coefficient of the typical accumulative Hefeng landslide with the water level was obtained according to the variation of the saturation line in landslide body got by the actual water level fluctuation curve, and then Numerical-Mechanical simulation model was established, the development law of the Landslide stress field, displacement field, shear strain increment, the plastic zone under water level changes were obtained, so revival deformation mechanism of the typical accumulative landslide was revealed by that how the external cause effect internal cause, and it lays the foundations of deformation prediction of landslide. (6) Deformation prediction model of the accumulative landslide. Taking Hefeng landslide for example, and according to the changed water level in landslide zone in the Three Gorges Reservoir, water level and the rock mass parameters of the geological-mechanical model were adjust, and last the comprehensive prediction model of landslide was established, and then comparing the actual monitoring displacement in strong deformation zone and the displacement tracking model points in numerical model, the correspondence between the actual time and the step in FLAC3D model was obtained, and deformation trends of landslide was forecast for next hydrological year by the extension of the time step.In this paper, the Innovation of this paper as follows.(1) Taking Yuhuangge landslide and Hefeng accumulative landslide for example, landslide deformation features of different permeability on the responses of the reservoir water level variation were obtained, the basic geological model of reservoir accumulative landslide was built.(2) Based on groundwater inner the landslide body of different penetration on the esponses of the reservoir water level variation and real-time monitoring groundwater, the permeability coefficient of landslide was obtained in the inversion.(3) The standard curve of landslide stability with water level under decreased and increased condition.Summary, this paper reveals the revival mechanism of typical accumulative landslide in the Three Gorges Reservoir, and established the comprehensive prediction model of landslide based geological-mathematics-mechanical model, and then forecast the deformation trends of landslide, and it has great scientific reference for disaster prevention and mitigation.更多还原