【作者】 邹陈；

【导师】 石豫川；

【作者基本信息】 成都理工大学 ， 地质工程， 2010， 硕士

【摘要】 我国是一个地质灾害频发的国家,尤其是西南地区,崩塌、滑坡、泥石流等浅表生地质灾害异常突出。据中科院统计资料显示,近10余年来泥石流、滑坡造成的经济损失达25亿～40亿元,每年有500～1000人丧生。随着人口的急速增长和土地资源的过度开发,边坡问题已变成同地震和火山相并列的全球性三大地质灾害(源)之一,严重威胁着国家财产和人民生命安全。本文拟研究的堆积体位于大渡河沙坪二级水电站坝址左岸,紧靠坝肩。坝址位于官料河河口上游约230m处,初拟坝型为混凝土闸坝,坝顶高程557m,最大坝高63.0m,坝顶长320.2m。正常蓄水位554m,水库库容2084万m~3,总装机容量为345MW。堆积体沿SWW方向呈喇叭形展布。前缘高程约545m,直抵大渡河;后缘高程790m左右,为坡度陡缓交界处。前后缘高差约245m,纵向长约375m,横向最长可达390m,分布面积约10.6×10~4m~2,平均厚度约20m,体积约200×10~4m~3。如此规模庞大的堆积体恰又位于左岸坝肩部位,其稳定与否,将对坝线选择及电站的安全运营造成严重影响。一旦失稳,将直接危及大坝与其它枢纽建筑的安全,因而有必要对其岩土体的力学参数进行研究,再进一步对其稳定性情况进行深入细致的分析。为准确判断该堆积体的稳定状态,本文在环境地质背景条件研究的基础上,建立其地质力学概念模型。从堆积体基本特征、变形破坏模式、成因机制及影响因素等方面入手,着重针对其覆盖层岩土体的力学参数进行研究。研究方法选取室内试验、经验公式、工程类比和计算反演4种方法,其中室内试验采用大剪试验、真三轴试验和直剪试验。研究结果表明:在这3种试验方法中,大剪试验的统计结果略高,但总体上3种方法的统计值均较为接近。同时,试验方法所得出的参数值处于类比统计值范围之内、略高于经验公式计算值和反演分析结果。将这几种方法的参数取值进行综合对比、统计分析,最终确定该堆积体的计算参数取值。在前述堆积体力学参数研究的基础上,进一步通过数值模拟和极限平衡计算,对堆积体整体和局部稳定性进行预测。极限平衡法分别计算堆积体在天然、暴雨、地震和开挖工况下的整体稳定性。除此之外,针对堆积体前、中、后部潜在不稳定体进行搜索计算。再利用FLAC软件对其进行模拟计算,分析堆积体的应力场、变形场和稳定性特征。研究结果表明:堆积体天然工况下稳定性较好,暴雨工况下处于基本稳定状态,地震工况下处于极限平衡～失稳状态。堆积体前缘由于受开挖的影响,失稳方量相对较大;中部存在有小方量的失稳体;后部无局部不稳定体。与开挖前相比,堆积体坡脚开挖面上部水平位移明显增大,剪应变增量集中带进一步延伸,易沿开挖面发生垮塌破坏。最后在堆积体破坏形式及破坏规模分析的基础上,探讨堆积体失稳的工程影响。研究结果表明:堆积体前缘局部失稳体进入水库,产生的涌浪高度较低,不存在翻坝的危险。淤积方量不大,对水库有效库容影响微弱。更多还原

【Abstract】 China is a country prone to geological disasters, mostly are the superficial department disasters such as collapse, landslide, debris flow, etc, particularly in the southwest region. According to statistics from Chinese Academy of Sciences, debris flows and landslides caused economic losses of 2.5 billion to 4 billion, and which killed 500 to 1,000 people each year over the past 10 years. With the rapid population growth and over-exploitation of land resources, slope problem which parallels with the earthquake and volcano has become one of the three global major geological disasters. It’s a serious threat to the safety of state property and people.The accumulation, in this article, located in the left bank of the ShapingⅡHydropower Station dam in the Dadu River. The dam is about 230m from the Guanliaohe estuary, concrete dam, which top elevation is 557m and the length is 320.2m, the maximum height is 63.0m. The normal water level of the hydropower station is 554m, reservoir storage capacity is 2084 million m~3, total capacity is 345MW. The accumulation body flared along the SWW direction, like a trumpet. Front elevation was about 545m, closing to the Dadu River; posterior margin elevation was about 790m, the junction of steep slope relief. Its elevation from front to posterior margin was about 245m, vertical length of about 375m, horizontal length of about 390m, the distribution area of about 10.6×10~4m~2, the average thickness of about 20m, the volume of about 200×10~4m~3. Such a large accumulation body just located in the left bank of dam, so the choice of dam location and the security operation of hydropower station are seriously affected by its stability. Once collapsing, it will directly endanger the dam and other important construction safety. So that it is necessary to research its mechanical parameters, and go further to analyze its stability in depth and detailedly. In order to accurately judge the stability of the accumulated body, based on the research of geological environment, establish conceptual model of geological mechanics. According to basic features, pattern of deformation and failure, formation mechanism and influence factors analysis, focus on researching the mechanical parameters of rock and soil covering on the slope. The research selects four methods such as laboratory experiments, empirical formula, engineering analogy and inverse calculation. To laboratory experiments, it includes large shear experiments, true triaxial experiments and direct shear experiments. The research shows that the large shear experiments statistical results are a little higher than another two experiments, however all of the experiments statistical results are almost closer as a whole. At the same time, the experiments results are within the scope of engineering analogy statistical results, which are slightly higher than empirical formula results and inverse calculation results. By comprehensive comparison and statistical analysis of several methods results, determining the calculation parameters of the accumulation body finally.Based on the research of accumulation mechanical parameters, going further to forecast its overall and local stability by numerical simulation and limit equilibrium calculation. Based on the research of accumulation mechanical parameters, go further to forecast its overall and local stability by numerical simulation and limit equilibrium calculation. The overall stability is calculated in nature、heavy rain、earthquake and excavation condition. Also search and compute its potential unstable block. Then use FLAC sofeware to simulate and analyze its stress、deformation and stability feature. The research shows that the accumulation body is stable in nature, basic stable in heavy rain, limit equilibrium～instability in earthquake. Because of excavation, the volume of unstable body in front is more than which is in the middle. There is not existing unstable body in the posterior edge. To contrast before excavation, the horizontal displacement increased clearly in part of body foot on the excavation face, the increased concentrating strip of shear strain extended further. So that it is easy to collapse along excavation face.Finally based on the form of damage and scale of destruction of the accumulation body, go further to analyze the engineering effect while collapsing. The research shows that there does not exit danger by climbing over the dam because of a lower surge height which caused by unstable body in front. And it also influences faintly to reservoir storage capacity by a lower volume of alluvial object.更多还原