云南个旧打磨山钙质夕卡岩及石榴石的稀土元素地球化学特征   总被引：4，自引：3，他引：4  

韩松  黄忠祥 《岩石学报》1993,9(2):192-198

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Post-analysis simulation of the collapse of an open sabo dam of steel pipes subjected to boulder laden debris flow     

《国际泥沙研究》2020,35(6):621-635

The objective of the proposed method is to utilize a site investigation of a debris flow disaster and verify a real scale analysis to evaluate the impulsive load on an open sabo dam. The Nagiso debris flow disaster which occurred in Nagano in 2014, where damage caused by Typhoon Neogri was studied. The verification result of the site investigation demonstrated the weak components of the open Sabo dam experienced damage owing to the debris flow. A discrete element method is normally applied to a solid body to calculate an interaction function force with respect to the contact point between boulders and the dam. The numerical method initially concatenates elements that model the open Sabo dam. Moreover, the stiffness coefficient of flanges and coupling joints between pipes was expressed to utilize the sectional partition method to determine the structural characteristics. The method was improved to separate from the connecting elements beyond the boundary conditions. The debris flow model uses a water flow distribution model, and the debris flow flowed from 200 m upstream of the open sabo dam. Accordingly, the proposed method was examined to verify the primary cause of damage to the open sabo dam and used to reproduce the circumstances that evaluated the impulsive load occurrence mechanism in the case of a real disaster. In addition, the coupling joints between the hollow steel pipes utilized a ‘reproduction analysis’ for a real sabo dam and a ‘reinforced analysis’ for a reinforced sabo dam were applied to assess the weak point of the dam.  相似文献   

基于遥感空间信息的洪水风险识别与动态模拟研究进展          下载免费PDF全文

曾子悦  许继军  王永强 《水科学进展》2020,31(3):463-472

对地观测卫星遥感能够提供广泛可靠的空间信息,是洪水风险识别与动态模拟的重要支撑技术之一。为阐明卫星遥感技术对洪水研究的推动作用,回顾了洪水风险识别与动态模拟研究的发展历程及技术需求,以对地观测卫星遥感三大阶段的发展轨迹为主线,分析了遥感空间信息在洪水研究中的历史性贡献和阶段性效用,讨论总结了危险分区法、水文模型和微波遥感监测等3种洪水研究典型方法的应用进展。提出未来洪水风险识别与动态模拟研究的重点:遥感空间信息与模型算法的深度结合,遥感反演算法与系统的开发及应用,典型洪水研究方法集成系统的开发与应用,大数据方法与手段的应用。以期为提升洪水应急响应能力与灾害风险管理水平提供有效参考。  相似文献   

On strong ground motion synthesis with k −2 slip distributions     

František Gallovič  Johana Brokešová 《Journal of Seismology》2004,8(2):211-224

This study deals with the methodical aspects of k ^–2(Bernard et al., 1996) kinematic strong motions modelling: (1) it is shown how to incorporate the k-dependent rise time for 2D fault geometry in the strong motion synthesis according to the representation theorem, (2) it is suggested how to produce realistic k ^–2 slip models including asperity(ies), (3) modifications are introduced concerning the typeof used slip velocity function and the corner wave number in the slip distribution. High frequency effects of these generalized models are discussed.It is shown that, assuming the rise time proportional to the spatial slip wavelength at high wave numbers, the spectral decay of displacement at frequencies higher than the corner frequency is given just by the decay ofthe slip distribution spectrum, regardless of the type of slip velocity function. It is shown numerically that this model provides -squared source spectrum even in a vicinity of a 2D normal fault buried in 1D structure, which is an agreement with previous studies.  相似文献   

Geochemical and Isotopic Heterogeneities along an Island Arc-Spreading Ridge Intersection: Evidence from the Lewis Hills, Bay of Islands Ophiolite, Newfoundland   总被引：1，自引：0，他引：1  

KURTH-VELZ  MICHAELA; SASSEN  ANDREAS; GALER  STEPHEN J. G. 《Journal of Petrology》2004,45(3):635-668

This study focuses on the origin of magma heterogeneity andthe genesis of refractory, boninite-type magmas along an arc–ridgeintersection, exposed in the Lewis Hills (Bay of Islands Ophiolite).The Lewis Hills contain the fossil fracture zone contact betweena split island arc and its related marginal oceanic basin. Threetypes of intrusions, which are closely related to this narrowtectonic boundary, have been investigated. Parental melts inequilibrium with the ultramafic cumulates of the PyroxeniteSuite are inferred to have high MgO contents and low Al₂O₃,Na₂O and TiO₂ contents. The trace element signatures of thesePyroxenite Suite parental melts indicate a re-enriched, highlydepleted source with 0·1 x mid-ocean ridge basalt (MORB)abundances of the heavy rare earth elements (HREE). Initial_Nd values of the Pyroxenite Suite range from -1·5 to+0·6, which overlap those observed for the island arc.Furthermore, the Pyroxenite Suite parental melts bear strongsimilarities to boninite-type equilibrium melts from islandarc-related pyroxenitic dykes and harzburgites. Basaltic dykessplit into two groups. Group I dykes have 0·6 x MORBabundances of the HREE, and initial _Nd values ranging from +5·4to +7·5. Thus, they have a strong geochemical affinitywith basalts derived from the marginal basin spreading ridge.Group II dykes have comparatively lower trace element abundances(0·3 x MORB abundances of HREE), and slightly lower initial_Nd values (+5·4 to +5·9). The geochemical characteristicsof the Group II dykes are transitional between those of GroupI dykes and the Pyroxenite Suite parental melts. Cumulates fromthe Late Intrusion Suite are similarly transitional, with _Ndvalues ranging from +2·9 to +4·6. We suggest thatthe magma heterogeneity observed in the Lewis Hills is due tothe involvement of two compositionally distinct mantle sources,which are the sub-island lithospheric mantle and the asthenosphericmarginal basin mantle. It is likely that the refractory, boninite-typeparental melts of the Pyroxenite Suite result from remeltingof the sub-arc lithospheric mantle at an arc–ridge intersection.Furthermore, it is suggested that the thermal-dynamic conditionsof the transtensional transform fault have provided the prerequisitefor generating magma heterogeneity, as a result of mixing relationshipsbetween arc-related and marginal basin-related magmas. KEY WORDS: Bay of Islands ophiolite; transform (arc)–ridge intersection; boninites; rare earth elements, Nd isotopes  相似文献   

Inhibition of the S(IV) Autoxidation in the Atmosphere by Secondary Terpenic Compounds     

W. Pasiuk-Bronikowska  T. Bronikowski  M. Ulejczyk 《Journal of Atmospheric Chemistry》2003,44(1):97-111

To better understand the role of terpenic compounds in atmospheric chemistry the influence of sobrerol, a water-soluble product of photochemical autoxidation or ozonolysis of -pinene, on the rate of S(IV) autoxidation was studied. Laboratory experiments were performed under heterogeneous conditions, at constant supply with S(IV) by dissolution of CaSO₃.1/2 H₂O fine particles and with air oxygen by diffusion through a planar gas-liquid interface. The progress of S(IV) autoxidation, uncatalysed or catalysed by Fe₂(SO₄)₃ or CoSO₄, was followed conductometrically. The inhibiting effect of sobrerol was discussed in terms of the chain reaction terminated in a step linear with respect to sulphoxy radicals. A method was proposed for quantification of the inhibiting effect and the rate constant (2.0–3.8)10⁸ M^–1s^–1 was given for the step eliminating sulphate radicals. Further consequences of the inhibition: shifting the reaction locus from the gas-liquid (droplet) interface to the liquid (droplet) bulk and strong oscillations in the rate of S(IV) autoxidation resulting of the activity of sobrerol-derived radicals were also shown.  相似文献   

华北地区成组地震前后的地电阻率异常特征   总被引：3，自引：0，他引：3  

张学民  刘素英 《华北地震科学》2003,21(4):10-18

分析了自有地电阻率观测资料以来华北地区发生的三次成组地震前后的异常特征,其中包括1976年唐山地震组、1989年大同地震组和1998年张北地震组.结果发现(1)成组地震的地电阻率异常持续时间都比较长,主震发生后异常一般会继续下降或维持低值异常不恢复,整个成组地震的趋势背景非常清楚;(2)主震前异常台站范围比较广,异常台站数目比较多,后续地震的异常多集中在震源区;(3)成组地震结束后,异常一般都很快恢复.最后探讨了成组地震的地电阻率异常发展特征与孕震机理的关系.  相似文献   

The 1786 earthquake-triggered landslide dam and subsequent dam-break flood on the Dadu River, southwestern China   总被引：17，自引：1，他引：17  

F.C. Dai  C.F. Lee  J.H. Deng  L.G. Tham 《Geomorphology》2005,65(3-4):205-221

Chinese historic documents recorded that on June 1, 1786, a strong M=7.75 earthquake occurred in the Kangding-Luding area, Sichuan, southwestern China, resulting in a large landslide that fell into the Dadu River. As a result, a landslide dam blocked the river. Ten days later, the sudden breaching of the dam resulted in catastrophic downstream flooding. Historic records document over 100,000 deaths by the flood. This may be the most disastrous event ever caused by landslide dam failures in the world. Although a lot of work has been carried out to determine the location, magnitude and intensity of the 1786 earthquake, relatively little is known about the occurrence and nature of the landslide dam. In this paper, the dam was reconstructed using historic documents and geomorphic evidence. It was found that the landslide dam was about 70 m high, and it created a lake with a water volume of about 50×10⁶ m³ and an area of about 1.7 km². The landslide dam breached suddenly due to a major aftershock on June 10, 1786. The peak discharge at the dam breach was estimated using regression equations and a physically based predictive equation. The possibility of a future failure of the landslide seems high, particularly due to inherent seismic risk, and detailed geotechnical investigations are strongly recommended for evaluating the current stability of the landslide.  相似文献   

基于固体潮观测的高精度垂直摆倾斜仪   总被引：5，自引：0，他引：5  

肖峻  莫易敏  胡国庆 《武汉大学学报(信息科学版)》2004,29(11):973-976,989

针对地球固体潮汐监测的要求，介绍了高精度垂直摆倾斜仪的组成和工作原理；论述了差动电容测微传感器技术在垂直摆倾斜仪中的应用；采用空间多体中心构形理论进行倾斜仪机械结构设计；利用复杂双摆理论分析了摆体的动力学特性，并进行了摆体摆动误差的分析计算；提出了用静电进行垂直摆倾斜仪的标定方法。同时，对垂直摆倾斜仪的使用环境和应用情况进行了说明。  相似文献   

基于Java3D的网络地理信息可视化   总被引：7，自引：2，他引：7  

侯哲威  王青山程辉 《测绘学院学报》2004,21(4):302-304

在分析WebGIS中地理信息可视化研究现状的基础上，详细介绍了Java3D开发库的基本开发机制，并讨论其关键技术与解决方案，成功实现了基于Java3D的网络地理信息Web浏览器。实验表明，通过Java3D建立数字球面，并利用Java3D空间数据模型表达地理信息模型，实现在数字球面上映射地理信息，是实现网络地理信息可视化的新途径和新思路。  相似文献