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新丰江水库于1959年10月蓄水后发生地震,当即对大坝及时进行了加固,并统一组织有关部门广泛协作,对水库区地震活动的特点及成因、地面运动的特征及其对大坝的影响等问题,进行了多方面的研究。 本文根据多年来的观测和研究结果,论述了库区地震地质条件,以及水库蓄水对构造应力场的影响,指出十三年来地震主要沿峡谷区水域边缘多裂隙花岗岩体中的“软弱带”分布,震源机制与构造应力场具有一定的对应性。由于地震震源的应力状态是由地应力和水庳渗透压力等因素综合形成的,因此,地震序列在其发生、发展的过程中具有一些区别于构造地震的特点。 本文还择要介绍了与坝体抗震有关的部分研究成果,包括对大坝两期抗震加固的设计论证、工程实践及其经受住了Ⅷ度强震考验的概况。通过模拟实测记录的不规则波振动试验,和用有限单元逐步积分法进行动力分析等途径,分析了Ⅷ度强震时部分坝段顶部出现裂缝的原因。探明了顶部动力放大倍数高、高阶振型和应力集中的影响等问题,是导致大坝顶部成为抗震薄弱部位的重要因素。
Xinfengjiang Reservoir in October 1959 after the earthquake occurred in the water, immediately dam reinforcement in a timely manner, and the unified organization of a wide range of departments in collaboration, the reservoir area of the characteristics and causes of earthquake activity, the characteristics of ground motion and its large Dam impact and other issues, carried out a wide range of research. Based on the observations and research results over the years, this paper discusses the seismic geological conditions in the reservoir area and the impact of reservoir water storage on the tectonic stress field. It is pointed out that the “soft zone” in the fissured granite along the margin of the gorge area over the past 13 years indicates that " Distribution, focal mechanism and tectonic stress field have a certain correspondence. Because the stress state of the earthquake source is formed synthetically by the factors of geostress and osmotic pressure, the seismic sequence has some characteristics different from the tectonic earthquake in its occurrence and development. In this paper, we also introduce some research results related to the seismic behavior of the dam, including the design proof of the two-period seismic strengthening of the dam, the engineering practice and the general situation of the test that has withstood the test of strong earthquakes of degree VIII. The causes of cracks in the top of some dam sections during severe intensity Ⅷ intensity are analyzed by simulating the irregular wave vibration tests recorded by the measured units and the dynamic analysis by finite integral element method. Proved the top of the power magnification high, high-order mode and the impact of stress concentration and other issues, is leading to the top of the dam to become an important part of earthquake-resistant factors.