【作者】 梁学战；

【导师】 陈洪凯；

【作者基本信息】 重庆交通大学 ， 港口、海岸及近海工程， 2013， 博士

【摘要】 三峡水库运行期间，库水位一年一度在145m至175m之间蓄水和消落，水库蓄水和水位的周期性升降必然引起沿江两岸消落区及生态屏障区范围内库岸边坡稳定性劣化，造成库岸边坡的失稳破坏。从以往岸坡地质灾害发生情况看，库岸边坡具有突发性、剧烈性及长期性等特点，对长江及沿岸的危害巨大，三峡水库蓄水以来，对库岸边坡研究已经成为工程地质研究领域的一个重要和热门研究课题。本文以三峡库区土质岸坡为研究对象，采用现场调查与观测、结构试验、理论分析和数值模拟等研究手段，研究水位周期性升降作用下水与岩土体的相互作用机理、周期性浸泡条件下岸坡土体力学参数劣化特性、水位周期性升降过程中坡体渗流场及坡面裂缝发展演化过程、水库运行期间土质库岸稳定性变化规律及水库运行期间土质岸坡突发性崩滑机制，主要取得了以下成果：（1）将三峡水库水位周期性升降作用下岸坡破坏机制分为缓变机制和突变机制两种，其中缓变机制指岸坡稳定性变化，突变机制指岸坡突发性破坏。（2）基于试验研究和理论分析，研究了水位周期性升降作用下水与岩土体的相互作用机理，把三峡库区库水位升降过程中水与岩土体作用系统分为水与岩土体力学作用、水与岩土体物理作用及水与岩土体化学作用三种。（3）选取三峡库区典型岸坡不同高程天然土体，采用土工实验、X衍射光谱分析等方法，纵向分析了同一坡体不同高程土体粒度、矿物成分及抗剪强度参数的变化特性，得到了不同高程天然土体物理力学参数变化的共有性质及随高程变化的不同特性。（4）以三峡库区不同区域典型土质岸坡为研究对象，进行岸坡的土体参数试验，横向分析了不同岸坡土体矿物成分、密实度、含水量、土石比的变化及水体周期性浸泡对岩土参数的影响，并对不同试验类型相同参数之间、相同试验类型不同参数之间进行相关性分析，得出了不同试验类型相同参数的相关系数及同种试验不同参数之间的相关系数、关系拟合式及拟合系数。（5）通过对三峡库区典型岸坡土体周期性浸泡实验，分析了周期性浸泡条件下不同饱和状态和不同浸泡次数土体物理力学参数变化特性，揭示了周期性浸泡下土体强度参数的演化规律。（6）建立了三峡水库岸坡破坏机制地质试验模型，拟定库水位升降变化实验工况，通过模型试验，得到了坡体滑面不同高程处孔隙水压力值随水位变化曲线以及水位升降过程中坡体表面裂缝时空演化分期配套规律。（7）以非饱和渗流理论为基础，基于模型试验提供的坡体材料物理力学参数及试验所测数据，运用渗流分析软件Geostudio进行水位升降条件下的瞬态渗流场模拟，揭示了库水位升降过程中坡体浸润线分布变化规律及渗流场的变化特性。（8）针对三峡库区水位周期性升降对不同岸坡稳定性可能造成的影响，以库区典型土质滑坡为模型，在相同的入渗条件下，选择代表三峡库区不同土体材料6个数量级的饱和渗透系数，采用饱和-非饱和数值方法模拟了库水位周期性升降过程中不同渗透系数滑坡体浸润线分布变化规律及渗流场动态变化特性。（9）考虑库水位周期升降过程中非饱和土基质吸力和渗流场的瞬态变化情况，用Morgenstern-Price法分析了库水位升降过程中不同渗透条件下岸坡稳定性变化趋势，揭示了土质岸坡在水库运行期间的稳定性变化规律，稳定性变化总体表现为库水位上升期间岸坡稳定性呈减速衰减-稳定型和库水位下降期间岸坡稳定性呈加速衰减-稳定型。（10）针对三峡水库土质岸坡地质结构，将145m水位以下部位假定为应变软化区段，145m至175m之间部分假定为弹性区段；基于突变理论、能量原理构建了岸坡破坏尖点突变力学模型，并提出了岸坡破坏判据，揭示了水库运行期间土质岸坡突发性破坏机制。更多还原

【Abstract】 During the running of Three Gorges Reservoir, reservoir water level wouldfluctuated between145m and175m annual. Eservoirs impoundment and water levelcyclical fluctuation will necessarily cause the degradation of bank slope stability indrawdown area and ecological barrier area along the both sides of Yangtze river. Thebank slope has the characteristics of sudden, severe and long-lasting from past bankslope geological disaster which harm to the Yangtze river and its coastal area. Since theimpoundment of the Three Gorges Reservoir,the research of reservoir bank slope hasbecome an important and hot research topic in the field of engineering geologicalresearch. Based on soil bank in the Three Gorges Reservoir Area as the research object,using field investigation and observation,the structure experiment, theoretical analysisand numerical simulation,the following problems are studied:Interaction mechanism ofwater and rock-soil body under water level cyclical fluctuation.The degradationcharacteristics of mechanical parameters for bank slope soil under the condition ofcyclical immersion.The development evolution process of slope body seepage field andslope surface fractures in the process of water level fluctuation. Changing rule of soilbank slope stability and the sudden collapse mechanism of soil bank slope during thereservoir operation. Mainly achieved the following results:（1）Under the action of water level cyclical fluctuation in the Three GorgesReservoir, bank slope failure mechanism can be divided into graded mechanism andmutation mechanism, the former refers to changes of the bank slope stability, while theother one is accidental damage to the bank slope.（2）Based on the experimental study and theoretical analysis, this article hasstudied the interaction mechanism between water and rock-soil body under the waterlevel cyclical fluctuation.what’s more, the writer put the system of interactionmechanism between water and rock-soil body into three three types who aregeotechnical strength effect, water and rock-soil body physical and water and rock-soilbody chemistry in the process of water level cyclical fluctuation in the Three GorgesReservoir.（3）Selecting natural soil at different elevation of typical bank slope and usinggeotechnical test and X-ray diffraction spectrum analysis,the writer analyzedlongitudinally grain size, mineral composition and shear strength parameters of soil at different elevation about the same slope,and got common features of natural soilphysical parameters changes at different elevation and different characteristics ofnatural soil physical parameters with elevation changes.（4）Making an soil parameters test of bank slope,with typical soil bank slope indifferent regions of the Three Gorges Reservoir Area as the research object, the writeranalyzed horizontally the influences of mineral composition,density,watercontent,soil-rock ratio changes and water cyclical immersion on geotechnicalparameter,and analyzed the correlation of the same parameters in the different test typesand the different parameter in the same test type.Finally the writer obtained correlationcoefficient of the same parameters in the different test types and relationship fittingformula and fitting coefficient of the different parameter.（5）Based on soil cyclical immersion test on the typical bank slope in the ThreeGorges Reservoir,the writer analyzed soil physical and mechanical parameters changecharacteristics with different saturation state and different immersion times undercyclical immersion,and revealed the evolution law of soil strength parameters undercyclical immersion.（6）The writer established geological test model to simulate failure mechanism ofbank slope in the Three Gorges Reservoir and formulated experiment operatingconditions to water level changes.The writer obtained change curve of pore waterpressure value at different height of a slope body sliding surface and laws of surfacecracks for slope body spatial evolution in different deformation periods in the process ofthe water level fluctuation by model test.（7）Based on the unsaturated seepage theory, the writer made use of physicalmechanical parameters of slope body material and the test data provided by modeltest,and applied the software Geostudio for seepage analysis to simulate transientseepage field under the condition of water level fluctuation.It Reveals that phreatic linedistribution change law and seepage field change characteristics of slope body in theprocess of water level cyclical fluctuation.（8）Aiming the influence on the stability of different bank slope made under waterlevel cyclical fluctuation, based on typical soil landslide as model, the writer selected6orders of magnitude saturated permeability coefficient on behalf of the different soilmaterials in the Three Gorges Reservoir Area and used saturated-unsaturated numericalmethod to simulate phreatic line distribution change law and seepage field dynamicchange characteristics of different permeability coefficient of landslide body in the process of water level cyclical fluctuation.（9）Considering the transient change of unsaturated matrix suction and seepagefield in the process of water level cyclical fluctuation, stability change trend to bankslope was analyzed under the condition of different permeability withMorgenstern-Price method,which reveal stability changing rule of the soil bank slopeduring reservoir operation.Stability change overall display stability for the bank slope isslow attenuation-stable during the water level rise and acceleration attenuation-stableduring the water level decline.（10）Aiming at the geology structure of soil bank slope in the Three GorgesReservoir, the part below the water level145m is assumed to be strain softening extentsand the part between145m and175m is assumed to be elastic extents. Based oncatastrophe theory and energy principle, the cusp mutation mechanical model of bankslope destroy was builded and bank slope failure criterion is proposed,which wouldeveal sudden failure mechanism of the soil bank slope during reservoir operation.更多还原