茨哈峡水电站左岸斜坡演化机制研究

发布时间：2018-10-29 12:20

【摘要】：在大量的工程建设中经常见到反倾层状岩质边坡发生失稳破坏,研究表明反倾层状岩质边坡变形破坏模式主要为倾倒变形破坏,其发展都要经历一个长期的地质演化过程,在不同的演化过程具有不同的变形破坏特征,且倾倒变形破坏特征在不同时空具有一定的差异性。黄河上游的茨哈峡坝址区左岸发育有三个大型倾倒体及两松动体,其倾倒变形机制及演化过程有待进一步研究,基于此本文依托“层状岩质边坡复杂变形破坏机理、失稳模式以及治理措施研究”项目,对该岸坡坡体结构进行了细化,通过野外地质调查资料及变形破坏分布规律对倾倒变形机制及演化特征进行分析,对研究区倾倒程度进行划分,并利用数值模拟分析对反倾层状边坡的倾倒演化过程进行验证,得到以下几点研究成果:(1)根据研究区基本地质环境可知,茨哈峡坝址区左岸斜坡坡体结构主要有陡倾斜向内软岩层状岩质斜坡(IV21)、陡倾斜向内硬岩层状岩质斜坡(IV22)、陡倾反向软岩层状岩质斜坡(III12)、正交硬岩层状岩质斜坡(V1)、正交硬岩夹软岩层状岩质斜坡(V2),根据不同坡体结构将左岸岸坡由上游至下游分为4大段7小段。(2)考虑岩层倾倒要素(岩层倾角变化幅度、层内最大拉张量、岩体卸荷变形、岩体风化特征、岩体波速特征)提出岩层倾倒划分等级标准,将倾倒程度划分为强烈倾倒区、中等倾倒区、弱倾倒区及微倾倒区。(3)对左岸倾倒体边坡演化过程进行分析研究可知,倾倒体边坡变形破坏模式为弯曲-拉裂,其变形破坏具有长期性和阶段累进性。黄河的下切促使岩层发生初期的弯曲变形,随着黄河继续下切和其他因素的影响,边坡岩体向深部和下部继续发展。根据变形破坏特征倾倒体演化过程可分为初期变形阶段、弯曲拉裂变形阶段以及弯曲折断贯通阶段。(4)数值模拟再现了反倾层状边坡的演化过程,根据对现阶段边坡倾倒变形破坏的模拟分析可知,此阶段边坡处于弯曲拉裂变形阶段,在岩体内部逐渐形成断续的拉裂折断面,边坡岩体变形破坏的后续发展是在岩体内部形成潜在的贯通滑移面。
[Abstract]:In a large number of engineering construction, instability and failure of anti-dip bedded rock slope are often seen. The research shows that the deformation and failure mode of anti-dip bedded rock slope is mainly toppling deformation and failure, and its development has to undergo a long-term geological evolution process. The characteristics of deformation and failure are different in different evolution processes, and the characteristics of toppling deformation and failure are different in different time and space. There are three large toppling bodies and two loose bodies on the left bank of the Zha Gorge dam area in the upper reaches of the Yellow River. The mechanism and evolution of the toppling deformation and its evolution need to be further studied. Based on this, this paper relies on the complex deformation and failure mechanism of the layered rock slope. According to the research of instability model and treatment measures, the slope structure of the bank is refined, and the mechanism and evolution characteristics of toppling deformation are analyzed through the field geological survey data and the distribution law of deformation and failure. The tipping degree of the study area is divided, and the process of the toppling evolution of the inverted stratified slope is verified by numerical simulation analysis. The following research results are obtained: (1) according to the basic geological environment of the study area, The slope body structure of the left bank slope in the Zha Gorge dam area is mainly composed of steeply inclined inner soft rock slope (IV21), steeply inclined inner hard rock slope (IV22), steep-dip reverse soft rock stratum rock slope (III12). Orthogonal hard rock slope (V1), orthogonal hard rock intercalated soft rock slope (V2), According to the structure of different slope bodies, the left bank slope is divided into 4 sections and 7 segments according to the structure of different slope bodies. (2) considering the factors of rock tipping (variation range of rock stratum inclination angle, maximum pulling Zhang Liang in layer, unloading deformation of rock mass, weathering characteristics of rock mass, etc.) The characteristics of rock mass wave velocities). (3) the classification standard of rock strata toppling is put forward, and the dumping degree is divided into strong dumping area, middle dumping area, weak dumping area and micro-dumping area. (3) the evolution process of the left bank slope is analyzed and studied. The deformation and failure mode of toppling slope is bending-tensile crack, and its deformation and failure is long term and progressive. The bottom cutting of the Yellow River promotes the initial bending and deformation of the strata. With the influence of the Yellow River and other factors, the rock mass of the slope continues to develop to the deep and the lower part. According to the characteristics of deformation and failure, the evolution process of toppling body can be divided into three stages: initial deformation stage, bending tensile deformation stage and bending fracture through stage. (4) numerical simulation reappears the evolution process of reverse dip stratified slope. According to the simulation analysis of the toppling deformation and failure of the slope at this stage, the slope is in the stage of bending and tensile crack deformation, and the intermittent fracture surface is gradually formed in the rock mass. The subsequent development of deformation and failure of slope rock mass is the formation of a potential through slip plane inside the rock mass.
【学位授予单位】：兰州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV223

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