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修建在河流支流入汇口处的水利工程,同时受干、支流洪水共同作用,其防洪水位不但与洪水组合特性有关,还与洪水、水利工程行洪的耦合关系有关.已有采用设计洪水重现期对应的特征洪水组合,或者直接采用经验洪水组合进行调洪计算得到防洪设计水位的方法无法有效反映洪水与水利工程的相互作用.本文结合防洪标准的本质,利用Copula-蒙特卡罗模拟方法对修建在支流入汇口处的水利工程的防洪设计水位进行计算,并以珠江流域西江支流郁江广西桂平航运枢纽水闸为例展开研究.结果表明:Copula-蒙特卡罗模拟方法可以有效考虑干、支流洪水组合特性及其与水利工程行洪的耦合关系,以其计算得到的防洪设计水位唯一且可保证达到防洪标准的要求,可有效克服利用洪水重现期确定防洪设计水位存在的不确定性;在干、支流洪水共同作用下,以设计洪水重现期的不同特征组合计算得到的防洪设计水位相差非常大,且与达到防洪标准要求的防洪设计水位相比完全偏离了合理的误差范围,不宜以设计洪水重现期确定防洪设计水位;利用经验洪水组合计算难以合理反映不同工程的洪水及工程特性.研究成果可为修建在支流入汇口处受干、支流洪水共同影响的水利工程防洪设计提供更合理的理论依据和思路. 相似文献
223.
THE RELATIONSHIP BETWEEN REGIONAL SEISMIC ENERGY RELEASE AND RELATIVE MOTION BETWEEN BLOCKS ON BOTH SIDES OF YISHU FAULT ZONE
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Following the 11 March 2011 Japan MW9.0 earthquake, frequent moderate and small events occurred on the Yishu fault zone and its either side. Using continuous GPS data and a sliding block model, this work studies the relationship between the energy release of these shocks and the block relative motion of either side of the Yishu fault zone. The results show that(1)the equivalent magnitude M from released energy and the two blocks' relative motion are well correlated when earthquakes are selected in a retrieval circle(whose center is the midpoint of the Yishu fault zone)with a radius of 250~500km and using a sliding time window of 3~10 months. The best correlation coefficient between M and the two blocks' relative motion is 0.74 and the T test shows a significant linear correlation between them.(2)Spatial distribution of the correlation coefficients shows that the relative motion of the blocks on both sides affects the energy release in the area from the north part of Yishu fault zone to the Jiaodong Peninsula area and southwest Shandong-Henan border area obviously.(3)Since June 2014, the relative motion of the two blocks on both sides of the Yishu fault zone presents a wave of change, which may be an expression of the accumulation of seismic strain energy in the Yishu fault zone and its two sides. The linear relationship between the equivalent magnitude M from released energy and two blocks' relative motion V can be fitted by linear equation M=0.51*V+3.9, showing that strain energy accumulation could be released by the moderate and small earthquakes in a timely manner, which may favorable to delay the seismic risk in the study area. It also shows, on the other hand, that earthquake energy was not released so completely in the study area since the end of 2015 to 2016, which is likely associated with the Changdao earthquake swarm in 2017. 相似文献
224.
INFLUENCE OF PUMPING ON FOUR-COMPONENT BOREHOLE STRAIN AT TAI'AN SEISMIC STATION AND ITS INTERFERENCE MECHANISM
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JIA Yuan GAN Wei-jun LI Jie ZHU Cheng-lin YIN Hai-tao LU Shuang-ling JU Jia-bin 《地震地质》2019,41(6):1429-1443
Four-component borehole strainmeter (FCBS) is one kind of high-precision borehole strain observation instruments invented in China. As a kind of near-surface deformation observation instrument, FCBS is also easily disturbed by the external environment factors. As a common factor, pumping has significant influence on FCBS observation. Existing studies mostly identify the pumping interference from the perspective of observation curve morphology, relatively few studies focus on its interference mechanism. In order to truly capture earthquake precursor information, it is necessary to study the interference mechanism. In recent years, RZB-3 type FCBS at Tai'an seismic station has been seriously affected by pumping, so it is necessary and also feasible to study the interference mechanism of pumping. Since the influence of pumping interference on borehole strainmeter is common, this work would be very practical and be used for reference by other borehole strain observation stations.
We find that the original observation curves and observed surface strain, shear strain from RZB-3 type FCBS at Tai'an seismic station have the characteristics of synchronous change with the borehole water level, in which the linear correlation coefficient between the two observed shear strain curves and borehole water level reached 0.70 and 0.82 respectively. We further find that the principal strain direction of borehole and borehole water level after normalization meet the nonlinear function as y=1.217arctan(x)0.224-0.284. The above phenomenon indicates that the observation of RZB-3 type FCBS at Tai'an seismic station is significantly affected by the borehole water level, and the influence is more obvious and the gradient is larger at the stage of low water level. Pumping interference often appears in low water level stage and changes the rock pore pressure state. Statistics show that pumping interference affects the borehole strain state.
To investigate the interference mechanism of pumping to RZB-3 type FCBS at Tai'an seismic station, we take a known pumping as an example, in which we study the principal strain state of the borehole in three periods of normal pumping, interruption of pumping and resuming pumping respectively. During each period, we solve 3 parameters of the principal plane strain state, i.e. the maximum principal strain rate, the minimum principal strain rate and the maximum principal strain direction from four observation equations of FCBS by nonlinear iterative least squares algorithm. On the other hand, concentrated load model (CLM) is used to simulate the mechanical mechanism of pumping. Firstly, the depth of FCBS relative to pumping source and the concentrated load at pumping source are inversed, then, the strain state surrounding the pumping well, including the state at RZB-3 borehole, is simulated by forward modeling. By comparing these results, we find that:
(1)The concentrated load at pumping source inversed by CLM during periods of normal pumping and resuming pumping are both located at or near the bottom of the pumping well, which is consistent with the actual situation, indicating that mechanism and degree of the influence of pumping on borehole strain are well simulated by CLM.
(2)The observed strain state is consistent with the simulation result of pumping interference by forward modeling, indicating that the principal strain state of borehole calculated based on observation of FCBS reflects the true strain state of borehole under different pumping states.(3)The inversed concentrated load at pumping source during pumping periods is significant greater than the load of the pumped water, indicating that the pumping process has more significant influence on the pore pressure of rocks than the load of the pumped water.
Even though CLM is an approximate simulation since it's based on some elastic assumptions, the interference mechanism of pumping on RZB-3 type FCBS at Tai'an seismic station is well explained, which is maybe very helpful for studying the influence of pumping interference on other deformation instruments, locating the unknown pumping source and studying the characteristics of pore pressure of rocks. 相似文献
225.
传统观点认为交易型展览只有商品销售、国际贸易和市场营销功能。在互联网时代,这些功能在一定程度上受到电子商务的挑战。事实上,现代展览还可能具有政治、外交、教育、娱乐和创新等功能。对国内外相关文献进行分析,发现:有关交易型展览创新功能的研究文献主要涉及营销学和经济地理学,而不是旅游学。其中,营销学学者和经济地理学学者分别将展览视为临时市场和临时集群,并从多角度进行了研究。虽然营销学学者和经济地理学学者各自特别重视展览现场的信息沟通和知识转移对企业创新的影响,但都认为国际展览比国家和区域型展览具有更高的创新价值,并且参展者之间的关系建设是信息沟通和知识转移的重要前提。20世纪以来,两大学科学者(特别是国外学者)对交易型展览创新功能的研究日益增加。这些研究集中于解释展览的创新功能和探索展览创新功能发挥的机制。对主要研究成果从营销学和经济地理学两个角度按出版时间顺序进行了回顾,根据研究者的研究对象和建议提出了未来研究的四个主要方向:(1)重视展览类型对创新类型或阶段的影响;(2)展览溢出效应对企业创新的负面效应;(3)展览与其他会展活动的协同创新机制;(4)展览对城市产业和社会创新的贡献。 相似文献
226.
结合测震学和大地测量学方法分析日本2011年9级地震之后依舒断裂带北段的地震活动性认为,2012年至今研究区地震活动相对平静是由于日本地震对区域应力场的影响。依舒断裂带北段震后1 a内受影响较大,2 a后地震活动减弱,b值的时间扫描表现出其目前处于低应力场控制。依舒断裂带北段2012年至今5 a未发生4级以上地震,当前存在发生4级地震的可能。 相似文献
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微动HVSR(Horizontal-to-Vertical Spectral Ratio)法是一种简单有效的被动源地震勘探方法,当测点下方介质存在明显的速度变化时,HVSR曲线会呈现相应的异常形态。为探索该方法在岩溶区探测地下河管道和溶洞的有效性,选择桂林毛村地下河流域内的大岩前村作为研究区,并在此开展野外试验。研究区发育有一条地下河管道,通过精准的洞穴测量,获得了此地下河管道的平面位置和洞高等信息。在研究区的地下河管道上方地面布设3条物探测线,均进行微动HVSR法测量,并用探地雷达法测量作对比。结果表明,两种物探方法的异常位置与测线下方地下河管道的实际平面位置基本一致,证明微动HVSR法可作为一种有效的地下河管道和溶洞探测方法。 相似文献
230.
重庆西阳县洞岩铅锌矿床位于川东南褶皱带中,为一中低温热液铅锌矿床,预测Zn金属量10.14万t。矿(化)体主要沿NNE向、NWW向断层呈脉状分布,或沿层间破碎带呈似层状分布。赋矿围岩为奥陶系碳酸盐岩。川东南褶皱带中这一类型铅锌矿床的形成时代以及与NNE向断层相互关系研究薄弱。本文运用闪锌矿Rb-Sr同位素测年方法,测得洞岩铅锌矿床成矿年龄为(157.7±3.3) Ma,表明该矿床的主成矿阶段年龄为晚侏罗世。闪锌矿(87Sr/86Sr)i值为0.71347,远高于早期及同期沉积碳酸盐比值,可能与大气淡水加入有关。川东南褶皱带为推覆-滑脱的薄皮构造,褶皱变形的主要时期为中晚侏罗世的燕山运动早期。洞岩闪锌矿的Rb-Sr等线年龄与上述构造变形时代一致,说明矿床的形成与早燕山构造变形事件有关。 相似文献