Double-couple earthquake focal mechanism: random rotation and display     

Yan Y. Kagan 《Geophysical Journal International》2005,163(3):1065-1072

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Slope stability evaluation using Back Propagation Neural Networks   总被引：4，自引：0，他引：4  

H.B. Wang  W.Y. Xu  R.C. Xu 《Engineering Geology》2005,80(3-4):302-315

The Yudonghe landslide, located in western Hubei Province of China, consists of eastern and western subunits as well as a main landslide mass with upper and lower slip surfaces. As an important landslide close to Shuibuya Dam on the Qing River, its stability is crucial, as the slide might reactivate because of a change in ground-water level caused by filling of the Shuibuya Reservoir. Existing weakness zones, growth of ruptures, the downslope attitude of geologic strata, and water infiltration, which reduced the strength of rocks and soils, have been found to be the most important factors contributing to the Yudonghe landslide. With regard to the landslide processes, it can be noted that the original large-scale slide activity was due to erosion by the Qing River, the second sliding resulted from the fall of blocks from the head scarp, and the final activity was the growth of the eastern and western secondary slides. A base failure was the main type of slope movement, however, it was obvious that more than one sliding event occurred, as inferred from striations and fractures detected by microstructure analysis of soils along the failure surfaces. Slope instability was evaluated by the method of Back Propagation Neural Networks (BPNN), in which a four-layer BPNN model with five input nodes, two hidden layers, and two output nodes was constructed using a training data set of landslide samples throughout the Qing River area. The predicted results of this analysis showed that the factor of safety was 1.10, which indicates that the Yudonghe landslide is currently in a marginally stable condition.  相似文献   

南水北调中线水源工程丹江口水库坍岸问题浅析   总被引：2，自引：0，他引：2  

黄振伟  李云安  黄胜华 《地质科技情报》2005,24(Z1):156-159

南水北调中线水源工程大坝加高后,丹江口库区内的部分库段在库水作用下易发生坍岸问题.为了预测水库坍岸范围和发生坍岸的难易程度,对丹江口水库的地形、地质条件和坍岸的影响因素和型式进行了分析.在此基础上,通过大量的调查,采取工程地质类比法预测了坍岸范围和难易程度,为对坍岸范围内的对象采取针对性的处理措施提供了地质依据.  相似文献   

CGD-1型大口径全套管冲击抓斗的设计和应用          下载免费PDF全文

冯起赠  宋志彬  王年友 《探矿工程》2005,32(6):38-40

CGD－1型大口径全套管冲击抓斗主要是配套全套管钻机施工而研制的。该抓斗主要适用于复杂地层的施工。介绍了该抓斗的技术参数、性能特点、主要结构及试验情况。  相似文献   

岩土钻掘设备的液压步履机构          下载免费PDF全文

王世玉  薛军 《探矿工程》2005,32(6):41-43

因液压步履移位最方便，辅助时间短，换向灵活，移位对孔准确，大型岩土钻掘设备施工的群孔现场实现近距离的自行迁移多采用液压步履机构。详细叙述了双向移动和单向移动加转向步履机构的结构和特点。  相似文献   

厦门市海沧区北市花岗岩矿滑坡形成机制及治理设计     

王广和张海生  王慧珍 《中国地质灾害与防治学报》2005,16(B12):41-45

厦门市海沧区北市花岗岩矿滑坡发生于2004年10月30日14时。滑坡位于呆场的西端帮顶部的第四系填土和淤泥质土层中，滑体将该区域原设的抗滑桩剪断、拔出、推移，土石迅速越过矿区运输公路，塌落到采场工作面，将正在作业的2名工人和生产设备掩埋。滑坡宽度约60m，最大垂直厚度约14m，总体积约13000m^3。由于滑坡对原有防护体系的破坏，根据滑体调查和极限平衡计算结果，滑坡处于不稳定状态，直接威胁着整个采场设备和未来生产的安全。必须对北市花岗岩矿滑坡进行专项治理。滑坡宜采用治水、削坡减载和支挡相结合的综合治理措施。  相似文献   

人口生态生产:人地作用机制下"三江并流"世界遗产保护的新视角     

熊理然  骆华松 《云南地理环境研究》2005,17(6):69-73

基于不同人口需要而进行的人类活动对“三江并流”区的地理环境产生了巨大影响,形成了独具特色的人地作用机制。这一作用机制一方面对“三江并流”世界遗产的保护构成了威胁,但另一方面,通过人口生态生产,实现人口数量、质量、结构和分布的生态化,改进人类活动,也可优化“三江并流”区的地理环境,保护“三江并流”世界遗产,实现该地区的可持续发展。  相似文献   

Mixing of event and pre‐event water in a shallow Entisol in sloping farmland based on isotopic and hydrometric measurements,SW China          下载免费PDF全文

Pei Zhao  Xiangyu Tang  Peng Zhao  Wei Zhang  Jialiang Tang 《水文研究》2016,30(19):3478-3493

Water percolation and flow processes in subsurface geologic media play an important role in determining the water source for plants and the transport of contaminants or nutrients, which is essential for water resource management and the development of measures for pollution mitigation. During June 2013, the dynamics of the rainwater, soil water, subsurface flows and groundwater in a shallow Entisol on sloping farmland were monitored using a hydrometric and isotopic approach. The results showed that effective mixing of rainwater and soil water occurred in hours. The rebound phenomenon of δD profiles in soils showed that most isotope‐depleted rainwater largely bypassed the soil matrix when the water saturation in the soil was high. Preferential‐flow, which was the dominant water movement pattern in the vadose zone, occurred through the whole soil profile, and infrequent piston‐flow was mainly found at 20–40 cm in depth. The interflow in the soil layer, composed of 75.2% rainwater, was only generated when the soil profile had been saturated. Underflow in the fractured mudrock was the dominant flow type in this hillslope, and outflow was dominated by base flow (groundwater flow) with a mean contribution of 76.7%. The generation mechanism of underflow was groundwater ridging, which was superimposed upon preferential‐flow composed mainly of rainwater. The quick mixing process of rainwater and soil water and the rapid movement of the mixture through preferential channels in the study soil, which shows a typical bimodal pore size distribution, can explain the prompt release of pre‐event water in subsurface flow. Water sources of subsurface flows at peak discharge could be affected by the antecedent soil water content, rain characteristics and antecedent groundwater levels. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Refined modeling and movement characteristics analyses of irregularly shaped particles          下载免费PDF全文

Y. W. Zeng  L. Jin  X. Du  R. Gao 《国际地质力学数值与分析法杂志》2015,39(4):388-408

Irregularly shaped (IRS) particles widely exist in many engineering and industrial fields. The macro physical and mechanical properties of the particle system are governed by the interaction between the particles in the system. The interaction between IRS particles is more complicated because of their complex geometric shape with extremely irregular and co‐existed concave and convex surfaces. These particles may interlock each other, making the sliding and friction of IRS particles more complex than that of particles with regular shape. In order to study the interaction of IRS particles more efficiently, a refined method of constructing discrete element model based on computed tomography scanning of IRS particles is proposed. Three parameters were introduced to control the accuracy and the number of packing spheres. Subsequently, the inertia tensor of the IRS particle model was optimized. Finally, laboratory and numerical open bottom cylinder tests were carried out to verify the refined modeling method. The influence of particle shape, particle position, and mesoscopic friction coefficient on the interaction of particles was also simulated. It is noteworthy that with the increase of mesoscopic friction coefficient, the fluidity of IRS particle assembly decreases, and intermittent limit equilibrium state may appear. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Insights into the complexity of crustal differentiation: K2O‐poor leucosomes within metasedimentary migmatites from the Southern Marginal Zone of the Limpopo Belt,South Africa          下载免费PDF全文

G. Nicoli  G. Stevens  J‐F. Moyen  A. Vezinet  M. Mayne 《Journal of Metamorphic Geology》2017,35(9):999-1022

Differentiation of the continental crust is the result of complex interactions between a large number of processes, which govern partial melting of the deep crust, magma formation and segregation, and magma ascent to significantly higher crustal levels. The anatectic metasedimentary rocks exposed in the Southern Marginal Zone of the Limpopo Belt represent an unusually well‐exposed natural laboratory where the portion of these processes that operate in the deep crust can be directly investigated in the field. The formation of these migmatites occurred via absent incongruent melting reactions involving biotite, which produced cm‐ to m‐scale, K₂O‐poor garnet‐bearing stromatic leucosomes, with high Ca/Na ratios relative to their source rocks. Field investigation combined with geochemical analyses, and phase equilibrium modelling designed to investigate some aspects of disequilibrium partial melting show that the outcrop features and compositions of the leucosomes suggest several steps in their evolution: (1) Melting of a portion of the source, with restricted plagioclase availability due to kinetic controls, to produce a magma (melt + entrained peritectic minerals in variable proportions relative to melt); (2) Segregation of the magma at near peak metamorphic conditions into melt accumulation sites (MAS), also known as future leucosome; (3a) Re‐equilibration of the magma with a portion of the bounding mafic residuum via chemical diffusion (H₂O, K₂O), which triggers the co‐precipitation of quartz and plagioclase in the MAS; (3b) Extraction of melt‐dominated magma to higher crustal levels, leaving peritectic minerals entrained from the site of the melting reaction, and the minerals precipitated in the MASs to form the leucosome in the source. The key mechanism controlling this behaviour is the kinetically induced restriction of the amount of plagioclase available to the melting reaction. This results in elevated melt H₂O and K₂O and chemical potential gradient for these components across the leucosome/mafic residuum contact. The combination of all of these processes accurately explains the composition of the K₂O‐poor leucosomes. These findings have important implications for our understanding of melt segregation in the lower crust and minimum melt residency time which, according to the chemical modelling, is <5 years. We demonstrate that in some migmatitic granulites, the leucosomes constitute a type of felsic refractory residuum, rather than evidence of failed magma extraction. This provides a new insight into the ways that source heterogeneity may control anatexis.  相似文献