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高州水库建于广东省鉴江上游,由两个水库经人工渠联通而成,总库容量约11亿立方米,两座土坝坝高分别为52.5米和43.2米。60年代初建库时未能认真考虑地震影响,蓄水后二十余年库区地震平静,但到1983年中,距北库主坝4公里左右开始出现区震活动,至翌年中约一年时间共发生≥1.0级地震一百余次,(最高震级ML3.6)。从而引起工程部门严重关切,为此委托我们进行三方面研究工作: 1.判断1983年以来地震的性质(是诱发地震抑或天然构造地震)。 根据我们的工作结果,此水库发生诱发地震的概率仅为1.012,初步判断这次震群为构造地震(小震群);即使从诱发地震考虑,其最大震级也不会超过4级,不会对大坝构成威胁。 2.地震基本烈度复核和地震危险性分析。 根据地震基本烈度的传统评定方法,两个坝址的基本烈度均为Ⅵ度。根据地震危险分析,以使用年限为100年,超越概率为1.1计,两个坝址的基本烈度也为Ⅵ度(相应的超越概率分别为0.1091和0.0921)。因此,无论用传统的确定性烈度评价方法或是地震危险性分析的方法,高州水库的基本烈度宜为Ⅵ度。 3.大坝抗震稳定性分析。 虽然地震基本烈度为Ⅵ度,但发生更大地震的小概率事件也不是绝对不可能发生的,(例如坝受Ⅷ度影响的超越概率分别为0.0083和0.0055)因此必须了解大坝的最大抗震能力。
Gaozhou Reservoir was built in the upper reaches of Jianjiang River in Guangdong Province. It consists of two reservoirs that are interconnected through man-made tunnels and has a total reservoir capacity of about 1.1 billion cubic meters. The two earth dam sites are 52.5 meters high and 43.2 meters high respectively. In the early 1960s, the earthquake was not seriously considered in the construction of the reservoir. After the impoundment, the earthquake in the reservoir area remained calm for more than 20 years. However, by mid-1983, the seismic activity began to occur about 4 km away from the main dam of North Reservoir, There were altogether more than one hundred times of earthquakes ≥ 1.0 in the year (ML3.6 at the highest magnitude). Thus causing serious concern to the engineering department. To do this, we entrust us with three aspects of research work: 1. Judging the nature of the earthquake since 1983 (whether induced earthquake or natural tectonic earthquake). According to the results of our work, the probability of induced earthquake in this reservoir is only 1.012. The earthquake swarm was initially judged to be a structural earthquake (small swarm). Even if the earthquake was induced, its maximum magnitude would not exceed 4 and would not Pose a threat to the dam. 2. Earthquake seismic intensity review and seismic risk analysis. According to the traditional assessment method of earthquake basic intensity, the basic intensity of two dam sites are all Ⅵ degrees. According to the seismic hazard analysis, the basic intensity of the two dam sites is also Ⅵ (the corresponding transcendental probabilities are 0.1091 and 0.0921, respectively), taking the useful life of 100 years and the surpassing probability of 1.1. Therefore, the basic intensity of Gaozhou reservoir should be Ⅵ degree, no matter using the method of traditional deterministic intensity assessment or seismic hazard analysis. 3. Dam stability analysis. Although the basic seismic intensity is Ⅵ, it is not absolutely impossible for a small probability event to occur with a larger earthquake (for example, the probability of surpassing a dam affected by Ⅷ degrees is 0.0083 and 0.0055, respectively). Therefore, it is necessary to know the maximum seismic capacity of a dam .