共查询到20条相似文献，搜索用时 15 毫秒
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Mostafa Baniasadi Mohammad Reza Zare' Mehrjordi Hossein Mehrabi Boshrabadi Hamid Reza Mirzaei Khalilabad Abbas Rezaei Estakhrooye 《Ground water》2020,58(4):560-570
In recent decades, increased extraction of groundwater for human and agriculture consumption has led to a substantial drop in groundwater level in large areas of across the world. Declining groundwater levels is a serious problem in itself and has multiple economic, social, cultural, political, security-related, and environmental externalities. The negative economic-environmental externalities of overextraction of groundwater in the Orzouiyeh plain in the Kerman Province, Iran, were evaluated using methods such as replacement cost, production function, market prices, shadow price, and the value of the input marginal product. After evaluating externalities, the Positive Mathematical Programming method was used to evaluate different water policies to reduce the consumption of groundwater. The total economic losses due to the externalities were calculated to equal 2.8 U.S. million dollars. The damages caused by environmental externalities were calculated to equal 436.1 U.S. million dollars. The results related to the positive planning model show that the best policy among different options, such as deficit irrigation policy or combined policies, involves implementation of pressurized irrigation systems. 相似文献
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萧山-球川断裂是浙江地区1条大规模的北东向断裂,在该断裂附近曾发生过多次破坏性地震。本文通过地质调查、电法勘探和探槽开挖等方法,对萧山-球川断裂富阳—建德段第四纪活动性进行了研究。萧山-球川断裂富阳—建德段的遥感影像线性特征清楚,对地貌的控制作用较为明显,对山前的第四系发育有明显影响。通过对断裂露头剖面的分析,认为萧山-球川断裂富阳—建德段活动性质以走滑兼具逆冲为主。通过本次开挖的富阳峙山村探槽,结合ESR年龄测定,判定该断裂在第四纪早、中期有过活动,但未断错上覆中更新统上部地层,其最新活动时代为早、中更新世。 相似文献
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Yu. O. Kuzmin 《Izvestiya Physics of the Solid Earth》2013,49(5):626-642
The results of analyzing the long (20–50 years) time series of geodetic observations carried out in the regions with enhanced seismotectonic activity (Kopet Dag, Kamchatka, and California) are presented. It is established that recent vertical and horizontal displacements in the fault zones estimated by instrumental geodetic observations with increased spatiotemporal resolution indicate that the deformations in the fault zones paradoxically deviate from the movements inherited from the previous geological epochs. The paradoxes of high and low deformation rates in recent geodynamics lie in the reliably established empirical fact that extremely high local deformation rates (up to 10?5 per annum and higher) exist in the fault zones in the setting of weak regional deformations, whose annual rates are by two to three orders of magnitude lower. Very low annual average rates of relative horizontal deformations, which only measure 3–5 amplitudes of tidal deformations of the solid Earth, are revealed in the seismically active regions of Kopet Dag and Kamchatka as well as in the San Andreas Fault Zone in northern California. The fault-block dilemma arising in the interpretation of the observations of recent fault geodynamics is formulated. Either the role of active element, which forms the present anomalous deformations, is played by a block, while a fault plays the role of the passive element, or the fault zone itself is a source of anomalous movements, while the blocks are passive elements (hosting medium). It is shown that paradoxes of low and high deformation rates vanish if we assume that the recent anomalous geodynamics is formed by parametric excitation of the deformation processes in the fault zones in the conditions of quasi-static loading. 相似文献
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板岩作为一种浅变质岩在我国有着广泛的分布,对其地震波速度的研究将有助于对这类过渡性岩石的有效区分,对于浅层地壳的各向异性研究也具有重要意义.本文对采自云南丙中洛地区的板岩样品进行了地震波速度的室内实验研究,其中部分实验是在加拿大Dalhousie High Pressure Laboratory完成.实验获得了板岩在围压10~600 MPa条件下、不同构造主方向（X,Y和Z）上的地震波速度,在围压600 MPa时,X、Y、Z三个方向的P波速度分别为6.58、6.46、5.91 km/s,平均速度为6.30 km/s,S波平均速度约为3.62 km/s,VP/VS=1.74;并初步分析了板岩地震波速度、横波分裂及其波速各向异性随着围压的变化规律,发现所测量的板岩在较低围压（<150 MPa）时波速的各向异性随围压升高而迅速减小,主要是由于其内部微裂隙的定向排列引起的,而随着围压的继续增加（>150 MPa时）微裂隙基本闭合,黑云母、阳起石等片状矿物的定向排列成为其地震波各向异性的主导诱因,此时（围压为600 MPa）VP、VS的各向异性分别稳定在13%、16%左右.本研究所获取的基础实验数据及所探讨的板岩地震波性质将为确定地壳上部显微裂隙的优选定向、浅层地壳的各向异性分析、地球物理模型条件约束等提供基础. 相似文献
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Summary It has been proved that the formulae for determining the horizontal co-ordinates of the centre of gravity, derived by Gamburtsev in 1938 and adopted in many textbooks of gravimetry and other works, are not accurate. A method of estimating the co-ordinates of the centre of gravity of a disturbing body has been elaborated under the assumption that just the values of the vertical gradient of the disturbing gravitational potential in the xOy-plane are known. 相似文献
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Microzonation of the city of Basel 总被引：1，自引：0，他引：1
During the past centuries, the city of Basel has suffered damage caused by earthquakes. One extraordinary event described in historical documents is the strong earthquake which occurred in 1356. The 1356 event, one of the strongest earthquakes in northwest-Europe, was obviously much stronger than the low-magnitude earthquakes observed in the area during this century. Even though the present seismicity in the Basel area is low, strong earthquakes have to be expected due to the city's geographical location close to the northern boundary of the African-European convergence zone, at the southern end of the Rhinegraben. A crucial step towards preparedness for future events and mitigation of earthquake risk involves a microzonation study of the city. The study is carried out in three steps: (1) a detailed mapping of the geology and geotechnical properties of the area, (2) measurement, interpretation and modelling of ambient noise data, and (3) numerical modelling of expected ground motions during earthquakes. A qualitative microzonation of the centre of Basel is presented, and it is discussed by comparing it to the historically reported damage of the 1356 earthquake. 相似文献
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An electric furnace with oxygen-fugacity control was constructed. Oxygen partial pressure inside the furnace is controlled by flowing H2 and CO2 gas mixtures in different ratios. The system is set up inside a three-layer permalloy shield and a solenoid coil to produce an axial magnetic field. Oxygen fugacities are directly measured by an yttriadoped zirconia probe. The difference between the predicted and measured values of fugacities was small at 1,200°C, but a substantial discrepancy was observed at 780°C. Thermoremanent magnetization (TRM) was produced in various gas mixtures by heating the samples of recent basaltic lavas of Oshima (Japan) and Hawaii to 600 or 800°C for 1 h and cooling in a 0.4-Oe field. In general, the TRM is larger when produced in an oxidizing atmosphere and smaller in a reducing atmosphere. Alternating field demagnetization shows that the coercivity is also increased (decreased) when the TRM is acquired in oxidizing (reducing) conditions. However, these properties depend also on the previous heat treatments of the samples. 相似文献
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This paper develops a modal pushover analysis‐ (MPA) based approximate procedure to quantify the collapse potential of structural systems. The computationally demanding incremental dynamic analysis (IDA) of the structural system is avoided by MPA of the structure in conjunction with empirical equations for the collapse strength ratio for the first‐mode single‐degree‐of‐freedom (SDF) system; higher modes of vibration play essentially no role in estimating the ground motion intensity required to cause collapse of the structure. Presented are collapse fragility curves for 6‐, 9‐, and 20‐story regular special moment‐resisting teel frames computed by the exact and approximate procedures, demonstrating that the MPA‐based approximate procedure requires only a small fraction (1% in one example) of the computational effort inherent in exact IDA and still achieves highly accurate results. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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华北平原周边北西向强震地表地震断层及全新世断裂活动特征 总被引：8，自引：0，他引：8
讨论了华北平原周边１９７５年海城地震，１９３７年荷泽地震及１８３０年磁县地震３次强震的地表地震破裂特征以及这３个地区北西向断裂的全新世活动。研究结果表明，尽管这３次强震地表破裂显示较弱，断续分布，仍反映了存在北西向地表破裂带，活动方式呈左旋走滑兼正倾滑。 相似文献
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本文在理论上研究了对齐误差对测试地震计自噪声的影响。指出对齐误差影响到2台仪器记录间的计算互功率谱密度, 进而影响到被测仪器记录间相干函数计算, 最终影响到被测仪器的自噪声计算。发现当存在对齐误差时, 在信噪比较高频段计算得到的自噪声水平比仪器的实际自噪声水平要高, 在一般的实际测试中可能高20 dB以上。为了消除对齐误差对自噪声测试的影响, 提出通过投影逆变换把观测记录变换到标准坐标系下, 再用变换后的观测记录来计算地震计自噪声。给出了基于以上思路和传感参数对比测试方法的地震计自噪声计算处理流程, 合成数据、 实际测试数据的处理检验计算结果表明, 本文方法可以有效克服地震计自噪声测试中对齐误差的影响。 相似文献
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本文提出我国北方含水量高的低洼地段公路工程中路基填方铺设方法,重点研究了材料配合比不确定、工程地质条件复杂、充填施工质量不易控制等问题,进行二灰土击实与压缩性能的试验研究,得出了石灰、粉煤灰和土3种充填材料的配合比,并针对工程特点,提出了确保施工质量的措施。室内试验及现场施工均取得了较满意的结果,该研究为公路路基填方提供了可借鉴的经验。 相似文献
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巢湖沉积物重金属富集特征与人为污染评价 总被引：15，自引：6，他引：9
本文分析了巢湖主要入湖河流河口区表层沉积物及西部湖心区沉积岩芯中Al、Fe、Ni、Cr、Cu、Zn、Pb、Li、V等金属元素变化特征,采用地球化学方法对金属元素变化的"粒度效应"进行矫正,并以Li、V为参照元素对矫正结果进行检验;参考历史沉积物,对河口区及西部湖心区沉积物重金属人为污染特征进行分析;结合沉积岩芯210Pb年代结果,估算西部湖心区近150a来Ni、Cr、Cu、Zn、Pb等重金属元素的人为污染贡献量.结果表明,河口表层沉积物重金属污染具有显著的空间差异,南淝河河口重金属人为污染最重,其中Ni、Cr、Cu、Zn、Pb的人为污染贡献量分别为12.2、32.2、25.3、479.9和76.0 mg/kg,分别占总含量的35%、37%、64%、92%和77%;其次是柘皋河河口,主要重金属污染元素为Cu、Zn和Pb,人为污染贡献量达57.6、57.0和19.5 mg/kg,分别占总含量的73%、47%和36%;而派河、白石山河、杭埠河等河口表层沉积物中重金属元素人为污染程度较弱.巢湖西部湖心区主要污染元素为Cu、Zn、Pb,人为污染开始于1950s,1980年以来其人为污染贡献量显著增加,平均为16.2、245.6、47.8 mg/(m2.a),分别占各元素沉积通量的23%、61%和37%;Ni人为污染开始于1980s初期,人为污染贡献量平均为12.6 mg/(m2.a),占其沉积通量的13%左右;Cr基本未受人为污染影响.西部湖心区沉积岩芯及南淝河河口表层沉积物中重金属污染程度均表现为Zn>Pb>Cu,而且南淝河河口沉积物重金属污染程度显著高于西部湖心区.结合主要入湖河流径流量与河口沉积物重金属污染特征,认为巢湖西部湖心区重金属污染主要通过南淝河输入,来自合肥等城市的废水是主要的污染源. 相似文献
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The degree and distribution of damage to buildings subjected to earthquakes is a concern of the Chinese Government and the public.Seismic damage data indicates that seismic capacities of different types of building structures in various regions throughout mainland of China are different.Furthermore,the seismic capacities of the same type of structure in different regions may vary.The contributions of this research are summarized as follows:1)Vulnerability matrices and earthquake damage matrices of masonry structures in mainland of China were chosen as research samples.The aim was to analyze the differences in seismic capacities of sample matrices and to present general rules for categorizing seismic resistance.2)Curves relating the percentage of damaged masonry structures with different seismic resistances subjected to seismic demand in different regions of seismic intensity(VI to X)have been developed.3)A method has been proposed to build vulnerability matrices of masonry structures.The damage ratio for masonry structures under high-intensity events such as the Ms 6.1 Panzhihua earthquake in Sichuan province on 30 August2008,was calculated to verify the applicability of this method.This research offers a significant theoretical basis for predicting seismic damage and direct loss assessment of groups of buildings,as well as for earthquake disaster insurance. 相似文献
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Xuan Tinh Nguyen Minh Thanh Tran Hitoshi Tanaka Trung Viet Nguyen Yuta Mitobe Cong Dien Duong 《国际泥沙研究》2021,36(1):1-16
The current study presents the effects of seasonal variations in the depth-of-closure(Dc)on shoreline evolution using a numerical,one-line shoreline model.Beach erosion of the southern beach of the Nha Trang Coast,which is located in south central of Vietnam,is selected as the study area.This study area is immensely influenced by the tropical monsoon climate that has a clear pattern of large waves in the northeast monsoon season and calm waves in the non-monsoon season.The analysis of the long-term measured shoreline variations from a video-camera system has found a strong correlation of these variations to the monsoon-dominated wave characteristics in the Nha Trang Bay.Therefore,a new approach for determining the depth-of-closure with consideration of the seasonal wave climate changes is purposed in the current study.By implementing this new approach into a numerical,one-line shoreline model,it is found that the seasonal variations of Dc appear to better describe the periodical shoreline evolution due to the monsoon-dominated wave characteristics for the Nha Trang Coast.Such important findings are considered to commonly apply for monsoon-dominated coastal regions in general.These findings are useful information not only for scientific readers but also for the coastal authorities and managers in order to make better countermeasure plans against this kind of erosion mechanism in the future. 相似文献
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目的：探讨韧带样纤维瘤的影像学表现。方法：结合文献分析4例经术后病理证实的韧带样纤维瘤的病理、临床及影像学表现。结果：本组4例发病部位分别为腹腔、腹壁、胸壁及腋窝和股骨下段。典型的韧带样纤维瘤表现为较均质的单发病灶,CT平扫比相邻软组织密度稍高或相等,在MRI上可因肿瘤内成分不同而引起T2WI信号的变化。增强后有轻度、... 相似文献
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研究了华东地区１５个地震序列的振幅比、初动方向和初动半周期资料。得到：大震（主余型序列中的主震或震群型序列中最大地震）前后的Ｐ波初动方向，除人们熟知的由优势分布转化为紊乱外，还有可能呈优势分布，优势方向改变的特征。余震序列的Ｐ波初动方向和振幅比特征可能有助于预测强余震。初动半周期特征可能用于区别的前震和余震。 相似文献