A Block-Based Theoretical Model Suited to Gravitational Sliding     

Tinti  Stefano  Bortolucci  Elisabetta  Vannini  Cesare 《Natural Hazards》1997,16(1):1-28

An original theoretical model has been devised to simulate mass flow over hill slopes due to gravitational sliding. The sliding mass is discretized into a sequence of contiguous blocks which are subjected to gravitational forces, to bottom friction and to surface resistance stresses that are generally negligible for subaerial flows, but are relevant for submarine slides. The blocks interact with each other while sliding down the hill flanks because of internal forces that dissipate mechanical energy and produce a momentum exchange between the individual blocks, yet conserving the total momentum of the mass. Internal forces are expressed in terms of interaction coefficients depending on the instantaneous distance between the block centers of mass, which is a measure of the deformation experienced by the blocks: the functional dependence includes three parameters, namely the interaction intensity ¯, the deformability parameter and the shape parameter , by means of which a wide range of interaction types can be fully accounted for. The time integration is performed numerically by solving the equations for the block velocities and positions at any time ti by means of the block accelerations at the previous time t_i-1, and by subsequently updating the block accelerations, which allows to proceed iteratively to the following times. The model has been tested against laboratory results available from literature and by means of several numerical experiments involving a simplified geometry both for the sliding body and the basal surface, with the purpose of clarifying the influence of the model parameters on the slide dynamics. The model improves the performance of the existing kinematic models for slides, moreover preserving an equivalent numerical simplicity. Future applications and possible improvements of this model are suggested.  相似文献   

On　the　physical　model　of　earthquake　precursor　fields　and　the　mechanism　of　precursors＇timespace　distribution──origin　and　evidences　of　the　strong　body　earthquake──generating　model     

梅世蓉 《地震学报(英文版)》1995,(3)

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Spinel–sapphirine–quartz bearing composite inclusion within garnet from an ultrahigh-temperature pelitic granulite: Implications for metamorphic history and P–T path     

Toshiaki Tsunogae  M. Santosh 《Lithos》2006,92(3-4):524-536

We report here a multiphase mineral inclusion composed of quartz, plagioclase, K-feldspar, sapphirine, spinel, orthopyroxene, and biotite, in porphyroblastic garnet within a pelitic granulite from Rajapalaiyam in the Madurai Granulite Block, southern India. In this unique textural association, hitherto unreported in previous studies, sapphirine shows four occurrences: (1) as anhedral mineral between spinel and quartz (Spr-1), (2) subhedral to euhedral needles mantled by quartz (Spr-2), (3) subhedral to anhedral mineral in orthopyroxene, and (4) isolated inclusion with quartz (Spr-4). Spr-1, Spr-2, and Spr-4 show direct grain contact with quartz, providing evidence for ultrahigh-temperature (UHT) metamorphism at temperatures exceeding 1000 °C. Associated orthopyroxene shows high Mg/(Fe + Mg) ratio ( 0.75) and Al₂O₃ content (up to 9.6 wt.%), also suggesting T > 1050 °C and P > 10 kbar during peak metamorphism.

Coarse spinel (Spl-1) with irregular grain morphology and adjacent quartz grains are separated by thin films of Spr-1 and K-feldspar, suggesting that Spl-1 and quartz were in equilibrium before the stability of Spr-1 + quartz. This texture implies that the P–T conditions of the rock shifted from the stability field of spinel + quartz to sapphirine + quartz. Petrogenetic grid considerations based on available data from the FMAS system favour exhumation along a counterclockwise P–T trajectory. The irregular shape of the inclusion and chemistry of the inclusion minerals are markedly different from the matrix phases suggesting the possibility that the inclusion minerals could have equilibrated from cordierite-bearing silicate-melt pockets during the garnet growth at extreme UHT conditions.  相似文献   

一种实现依比例街区自动合并的算法     

朱蕊  周滨  邰茜 《测绘学院学报》2005,22(1):58-61

针对依比例街区的图形特征，介绍了一种实现街区自动合并的有效算法，即利用数学形态学和模式识别对栅格数据进行追踪，然后提取街区轮廓线，编辑后就得到最终合并的街区。  相似文献   

大别山造山带前陆深地震反射剖面   总被引：18，自引：0，他引：18       下载免费PDF全文

董树文 高锐李秋生  刘晓春钱桂华黄东定  匡朝阳李三忠管烨  白金贺日政  李朋武 《地质学报》2005,79(5):595-601

在大别山南部和扬子地块前陆实施的深地震反射剖面(140 km)揭示出大别山造山带前陆地壳的精细结构。总体北倾的地壳内部结构与向北缓倾的叠瓦状莫霍面反射揭示出扬子陆块向北俯冲的行迹。莫霍面向北插入大别山造山带下与南大别山地壳内南倾反射震相叠置,构成交叉反射图像,刻画出扬子前陆与大别山造山带的碰撞构造面貌。  相似文献   

基于MPI的机群并行计算系统平台构建   总被引：4，自引：1，他引：4  

荣莹  曹俊兴 《物探化探计算技术》2005,27(1):89-91

在高性能计算机领域,机群并行系统已成为一种重要的系统结构。这里介绍了机群并行系统的特点和发展现状;给出了将PC机或工作站通过高速以太网连接,使用TCP/IP作为标准的通信协议,利用MPI作为分布式的并行计算软件环境,在Windows平台和Unix平台上搭建用户自己的PC机群系统的两种方法;还给出了MPI安装中需要注意的关键步骤。实践表明,PC机群系统具有高性能、高可用性和极高的性价比。  相似文献   

南海西南部曾母盆地早中新世以来沉降史分析   总被引：2，自引：2，他引：2       下载免费PDF全文

吴庐山 邱 燕解习农  刘晓峰江 涛 《中国地质》2005,32(3):370-377

采用回剥法和局部均衡模式研究曾母盆地早中新世以来的沉降史，并探讨了该盆地构造演化特征。曾母盆地自早中新世以来经历了17．5-11．6Ma、11．6-5．5Ma、5．5-3．0Ma和3．0-0Ma的4次快速沉降作用，其构造演化受控于曾母地块与南沙地块及婆罗洲地块的碰撞和盆地两侧的万安-卢帕尔断裂与廷贾走滑断裂的综合作用，可划分为南北双向挤压（晚始新世-早中新世）、走滑改造（中中新世-晚中新世）和区域沉降（上新世-第四纪）3个演化阶段。  相似文献   

川西北松潘-甘孜地块大石包组玄武岩成因及其形成构造背景   总被引：9，自引：0，他引：9  

肖龙  许继峰 《岩石学报》2005,21(6):1539-1545

川西北松潘-甘孜地块内二叠世大石包组玄武岩富集大离子亲石元素和高场强元素，具有与洋岛玄武岩相似的地球化学性质，形成于大陆板内环境。通过与典型峨眉山玄武岩之地球化学组成的对比研究，认为大石包玄武岩与峨眉山玄武岩中的高钛类玄武岩性质相同，两者具有一个共同的成因，即都是峨眉山地幔柱活动的产物。由此推测峨眉山玄武岩不仅分布在扬子地块内部，向西还有一定的延伸，同时暗示了峨眉山地幔柱头部可能具有比现在所认识的更大的规模。  相似文献   

一个简单海气耦合模式预报性能评估     

岳彩军  陆维松陶丽 《南京气象学院学报》2005,28(5):704-709

对改进初始强迫风场后的Zebiak-Cane海气耦合模式预报性能进行了全面评估。结果表明：1）耦合模式在20世纪90年代预报能力小于80年代；提前0～5个月的耦合模式预报能力小于同期持续预报能力，之后则相反；耦合模式对Nino3区指数预报能力最强。2）在1997／1998年El Nino事件期间，耦合模式对东太平洋SSTA场预报能力大于其对中西太平洋SSTA场的预报能力，且提前0～2个月之后的耦合模式对东太平洋SSTA场预报能力远远大于持续预报。  相似文献   

油田污水中Fe2+,S2-,DO及pH值对HPAM-酚醛CDG成胶性能影响的研究     

陈艳玲  王红梅  谭中良  朱怀江  费琪 《地质科技情报》2002,21(3):61-64

在对河南油田双河矿区油田污水进行全分析的基础上，研究了污水中Fe^2 ,S^2-，溶解氧（DO）及污水的pH值对有机交联体系聚丙烯酰胺（HPAM）－酚醛胶态分散凝胶（CDG）成胶性能的影响。研究结果表明，Fe^2 ,S^2－，DO及污水的pH值对HPAM－酚醛体系的成胶性能都有影响当ρ（Fe^2 )=1.6mg/L,ρ（S^2-)=0.1mg/L,ρ（DO）=1.6mg/L，HPAM－酚醛体系就不能成胶；随着污水pH值的增大，CDG强度变弱。  相似文献