A time-domain viscous damping model based on frequency-dependent damping ratios

This paper introduces the mathematics and procedures used in developing a time-dependent damping model for integration analyses of structural response. To establish the time-dependent viscous damping model, frequency-dependent damping ratios of the structure under a series of steady-state unit impulses corresponding to actual loads are first calculated. For simplicity, the ratios can be incorporated with the static stiffness of the structure to model approximately the impulse induced damping spectrum. According to the nature of the problem, these ratios can be calculated from the theoretical impedance functions and experimental observations. With the computed damping spectrum, the damping coefficient in the time domain can be obtained with the Fourier transform technique. Adopting the impulse–response method, the damping can be modeled rationally through integration with changing loads. Numerical examples are presented to show the feasibility of this model while the transform criterion is satisfied.     

高盐变质流体对我国绿岩带金矿的制约

高盐变质流体为绿岩带原岩在变质 -混合岩化过程中产生的液体 ,其含盐度高达 30～ 40 wt% Na Cl,富含 K、Na、Ca、Mg碱金属离子 ,K/ Na≈ 1,呈强碱性 ,有利于绿岩中 Au的活化和迁移 ,使绿岩带起到金的矿源层作用 ,并且间接地控制了变质期后绿岩型金矿的形成和分布 ,控制了绿岩型金矿的规模大小     

断层摩擦系数及其演化定量研究的新途径

在活断层的力学性质参数中 ,摩擦系数有着特别重要的意义 .它是建立活断层运动学与动力学之间物理力学关系进而促进地震地质研究沿着“由静到动、由定性到定量”方向深入发展的关键性参数之一 ,也是建立活断层重新滑动准则从而定量评估断层稳定性或地震危险性不可缺少的物理参数 .目前 ,断层摩擦系数主要是应用双剪法对采自断层的断层泥进行实验室测试和研究而取得的 .这样取得的结果很难说能够代表断层实际摩擦系数 ,尤其很难反映断层深部摩擦性状 ,采用实验室方法是无法测知不同地质时期断层活动所显示的摩擦性状及其演化特征的 .因此 ,必须寻找定量确定断层摩擦系数及其演化特征的新途径 .通过理论研究和实际应用提出了根据对活断层运动学实测资料的分析并结合年代学测试定量确定断层摩擦系数和动力学主要参数及其演化特征的新途径 .     

Microstructural tectonometamorphic processes and the development of gneissic layering: a mechanism for metamorphic segregation

The Mary granite, in the East Athabasca mylonite triangle, northern Saskatchewan, provides an example and a model for the development of non-migmatitic gneissic texture. Gneissic compositional layering developed through the simultaneous evolution of three microdomains corresponding to original plagioclase, orthopyroxene and matrix in the igneous rocks. Plagioclase phenocrysts were progressively deformed and recrystallized, first into core and mantle structures, and ultimately into plagioclase-rich layers or ribbons. Garnet preferentially developed in the outer portions of recrystallized mantles, and, with further deformation, produced garnet-rich sub-layers within the plagioclase-rich gneissic domains. Orthopyroxene was replaced by clinopyroxene and garnet (and hornblende if sufficient water was present), which were, in turn, drawn into layers with new garnet growth along the boundaries. The igneous matrix evolved through a number of transient fabric stages involving S-C fabrics, S-C-C' fabrics, and ultramylonitic domains. In addition, quartz veins were emplaced and subsequently deformed into quartz-rich gneissic layers. Moderate to highly strained samples display extreme mineralogical (compositional) segregation, yet most domains can be directly related to the original igneous precursors. The Mary granite was emplaced at approximately 900 °C and 1.0 GPa and was metamorphosed at approximately 750 °C and 1.0 GPa. The igneous rocks crystallized in the medium-pressure granulite field (Opx–Pl) but were metamorphosed on cooling into the high-pressure (Grt–Cpx–Pl) granulite field. The compositional segregation resulted from a dynamic, mutually reinforcing interaction between deformation, metamorphic and igneous processes in the deep crust. The production of gneissic texture by processes such as these may be the inevitable result of isobaric cooling of igneous rocks within a tectonically active deep crust.     

桐柏山北部的黑硬绿泥石变质带

桐柏北部的黑硬绿泥石变质带位于桐柏大别山造山带北部,紧邻桐商断裂带的构造混杂岩带中。含黑硬绿泥石变质岩的矿物组合由黑硬绿泥石+阳起石+绿帘石+白云母+钠长石土黑云母±绿泥石±石英组成。其变质原岩为辉长岩和斜长花岗岩类。变质温压条件约为1±0．3GPa,703．15±323．15K,是印支期(230Ma)区域构造糜棱岩化过程中辉长岩和斜长花岗岩块应变退化变质作用的产物。     

潼关小秦岭地区金的热穹窿成矿地质模型

根据对小秦岭地区大地构造位置的最新认识,在对一系列野外地质矿产信息综合研究的基础上,提出了“板内Ａ型俯机制下变质核杂岩内岩浆热穹窿金成矿地质模型”。认为小秦岭地区金矿的矿质来源于华北陆块南缘上地慢,成矿介质为下渗的地表水,成矿机制是以燕山斯花岗岩基熔体为中心的热穹窿所形成的热力系统。热穹窿的成生、演化,消亡过程不仅从时间上决定了矿化发生的有序性及叠加规律。并且通过对变质核杂岩构造的改造,利用,决定     

赣中变质岩带的组成及构造变质变形特征

赣中变质岩带不是简单的一套震旦纪地层 ,而是由结晶基底中元古界中深变质岩系 (斜长角闪岩的Sm Nd全岩等时线年龄为 1113± 4 9Ma)和褶皱基底变质较浅的震旦系组成。两者之间以具热流体参与的混合岩化、韧性剪切带和递进变质三位一体组成的动热变质带接触。结晶基底经历了4期构造变质变形的叠加改造 ,每期构造变形都在变质岩石构造单元内留下各种变形形迹 ,变质作用表现为时间上的递进和空间上的叠加演化系列 ,是一套以众多的不平衡结构和多相共生混存的矿物组合 ,热变质带为一套动热变质塑性变形带 ,空间上依次形成绢云母—绿泥石带、黑云母带、石榴石带、十字石带以及夕线石带     

五台山区太古宙铁建造型金矿成矿流体性质和成因

五台山区铁建造金矿经历初生成矿作用和叠加成矿作用。初生成矿作用形成于变质峰期之后 ,与区域变质作用有关。矿石富含水溶液包裹体。包裹体均一温度 171～ 2 55℃ ,压力 0 .12～ 0 .31GPa。流体成分模式Au -H2 S NaCl-CO2 -H2 O。氢氧同位素具变质水和雨水双重性 ,流体主要来源于变质热液 ,受雨水混合。叠加成矿作用可能受岩浆活动影响 ,矿石富含CO2 包裹体 ,均一温度 30 6～ 385℃ ,压力 0 .6～ 1.0 5GPa ,流体盐度较高 ,成矿流体可能与岩浆热液有关。     

刚性动力荷载作用下地基动力反应的若干问题

研究了地基表面在刚性动力荷载作用下的动力反应,给出了柱坐标解。在此基础上获得一个实用的地基动力刚度。定性地讨论了地基刚度和阻尼及其相互关系。并提出一个求取地基动力刚度和粘滞系数的实用化方法。     

松辽盆地徐家围子断陷芳深9井区火山岩储层裂缝预测

本文在松辽盆地北部徐家围子芳深9井区构造地质、石油地质及构造应力场分析的基础上,对早白垩世嫩江组末期、晚白垩世明水组末期和现今三个构造时期在营城组火山岩地层中的构造应力场进行了三维有限元数值模拟,进而分析了三维构造应力场在裂缝预测分析中的应用,研究结果与构造地质、石油地质分析结论相一致,对油气勘探开发具有指导意义。