【作者】 雷建成；

【导师】 高孟潭；

【作者基本信息】 中国地震局地球物理研究所 ， 固体地球物理学， 2011， 博士

【摘要】 本文的研究目标是：以大渡河干流梯级电站系统为分析实例,考虑汶川8.0级地震后地震环境的变化,研究复杂地震环境对梯级电站工程系统地震危险性的影响特征,在对梯级电站大坝以及梯级电站系统进行一些简化和假定的基础上,将全部梯级电站作为一个整体,考虑上游大坝对下游相邻大坝的附加危险性影响,提出梯级电站系统地震危险性评价的新方法。本文充分收集了西南地区现代地震实际资料,统计、转换得出了西南地区地震烈度、基岩地震动衰减关系。充分收集近年来地震安全性评价工作中取得的资料和成果,广泛、深入地吸收汶川8.0级地震后取得的新资料、新认识,对大渡河流域及邻区的地震构造环境和地震活动特征进行了深入研究。根据区域地震活动、地质构造的具体特点,在较小的空间尺度上划分了甘南川北地震带、川滇块体地震带和四川盆地地震带3个地震带,统计求出了相应的地震活动性参数。采用小尺度的地震带划分方案,可以更加真实地反映区域的地震活动的水平,较好体现控制建筑物抗倒塌的地震作用的水平。本文开创性地提出了双场点地震危险性分析方法,用以计算在相同地震构造环境中,在相同的地震作用下,相邻两个工程场点同时超越给定地震动参数的概率。该方法是确定系统的危险段落、场点遭受的附加地震危险的有效工具。大坝单元的地震危险性来源分析表明,其联合地震危险性由以下2部分构成：(1)在给定的地震环境中,该大坝单元遭遇超标地震作用而获得的自身地震危险性；(2)上游大坝破坏失效后,由于灾难性库水溢出的传递,而对该大坝单元产生的附加地震危险性。考虑到库容因素,本文引入一个调洪系数来衡量水库对上游洪水的承接消减能力。文中还对附加地震危险性的来源和计算方法进行了详细研究。把梯级电站系统简化为串联系统,计算得出梯级电站系统的地震危险性。此外,根据梯级电站系统各大坝单元的联合地震危险性,可以确定梯级电站系统的薄弱环节。在众多影响梯级电站系统地震危险性的因素中,本文只考虑地震因素引起的大坝失效,重点关注结构破坏、垮坝、漫顶等3种很可能直接导致灾难性库水溢出的失效模式。根据美国西部大坝的抗震设防目标和标准、在地震作用下的失效概率,以及我国大坝年平均溃决概率与美国西部大坝年平均溃决概率基本持平的事实,分析得出大坝在遭遇超标地震时发生失效的条件概率为P(F|E)=3.137×10-2。在梯级电站系统的地震危险性评价的基础上,本文对梯级电站系统的地震失效风险进行了初步研究。对大渡河干流梯级水电站系统的实例研究发现,在当前的地震环境下,各个大坝的地震危险性与原设计目标有一定的差别。通过大坝的联合地震危险性发现,危险程度最高的几个电站依次是：铜街子、沙坪、龚嘴、老鹰岩、龙头石、卜寺沟、达维、硬梁包等。进一步分析表明,上游大坝的附加地震危险性对梯级电站系统地震危险性评价结果有重大影响,必须予以考虑。提高梯级电站系统最薄弱的几个电站的设防参数,是提高系统地震安全性的最有效的途径。更多还原

【Abstract】 By taking the cascade hydropower station system(CHSS) in the mainstream of Dadu River(MSDR) as a case study and considering the change of seismic background after Wenchuan 8.0 earthquake in 2008, this paper investigate the influence of complicated geoseismic environment upon the seismic hazard of CHSS. The paper also make some supposes and simplifications to cascade hydropower station dam and CHSS. By considering the additional hazard from upstream dams upon the nearby downstream dam and taking all the cascade hydropower station dams as one whole system, the paper submits a new method to assess seismic hazard of CHSS.The paper fully collects available investigation data of modern destructive earthquakes in Southwest China and establishes the attenuation relations for seismic intensity and acceleration motion on bed rock by regression and conversion. The paper deeply absorbs the new data and results of the seismic hazard assessment for significant construction programs in recent years. The paper also takes advantage of the new information and knowledge of Wenchuan 8.0 earthquake. Then the paper carefully study the seismotectonics background and seismicity features around MSDR. According to the characteristics of regional seismotectonics and seismicity, the paper divides out three seismic belts in relative smaller spatial scale, i.e. Southern Ganshu-Northern Sichuan belt, Sichuan-Yunnan-block-area belt and Sichuan Basin belt. The paper also calculates out the seismic parameters of all the seismic belts at the same time. The paper further indicates that small-belt scheme shows better performance in presenting actual regional seismicity level and possible earthquake action for anti-collapse design of buildings.The paper creatively proposes a bisite seismic hazard analysis method to calculate the exceedance probability of two nearby sites located in a same seismotectonics environment and suffered seismic acceleration exceeding their given values within a same earthquake. This new method is an effective tool for determining the dangerous segment of a linear spread system and calculating the additional seismic hazard from its neighbor site upon a given site.The paper analyses the seismic hazard components of a dam and find out that the united seismic hazard is composed by self seismic hazard and additional seismic hazard. The self seismic hazard is the exceedance probability which seismic acceleration great than its design acceleration for a dam in a give seismic background. The additional seismic hazard comes from upstream dam seismic hazard and is passed by the catastrophic overflow flood of upstream dam failure. Considering of reservoir capacity, the paper leads in a flood adjustment coefficient to measure the reservoir ability of bearing and reduction the overflow flood from upstream. Furthermore, the paper detailed study out the source and calculation method of additional seismic hazard. The paper then establishes a method to assess the seismic hazard for CHSS by simplifying CHSS as a series system. Moreover, the weak link in CHSS can be determined by its united seismic hazard.There are many factors that play important role on seismic risk of CHSS. The paper only focuses its aim on the dam failure caused by earthquake and mainly takes account of three failure modes, i.e. dam structure failure, arch collapse and overtopping, which may directly cause catastrophically sudden, rapid, and uncontrolled release of impounded water. Based upon the achievement of dam antiseismic design target, regulation and dam failure probability caused by earthquake in USA dams, and also upon the fact that the annual dam failure probability in China is the same as that in USA, the paper derives out the conditional failure probability of P(F|E)=3.137×10-2 when dam is suffered a seismic load over its design parameter. Then the paper gives out a preliminary seismic risk assessment for CHSS.Taking CHSS in MSDR as a case study, the paper finds out that the seismic hazard for each dam in present seismic background is somewhat different from its original design value. From the dam united seismic hazard, the paper points out the most dangerous dams in MSDR are as follows in order:Tongjiezhi, Shaping, Gongzhui, Laoyingyan, Longtoushi, Busigou, Dawei, Yinliangbao, et al. The paper further finds out that the additional seismic hazard has significant effect on the seismic hazard assessment for CHSS and then must be taken into account. It is the most effective path to enhance the seismic safety of CHSS by promoting the seismic design parameters of a few weakest dams.更多还原