Shear Alteration, Mass Transfer and Gold Mineralization: An Example from Jiaodong Ore Deposit Concentrating Area, Shandong, China

Taking the gold ore deposit concentrating area of Jiaodong area in Shandong, China for an example, based on geological analysis, and applying Gresens’ equation, Grant’s isocon diagram and O’hara microelement calculation method, a thorough study on shear alteration, mass transfer and gold mineralization was carried out. The authors also made mathematic simulation and geochemical analysis. The work reveals temporal spatial changing regularities of temperature field and velocity field of fluids, and also reveals fluid transport chemical reaction coupling metallogenic dynamics of the Jiaojia gold ore concentrating area. During shear alteration process of the Jiaodong gold ore concentrating area, all kinds of components transferred with different amounts, fluid rock ratio was rather high and volume strain was of dilation type. Fast flow of ore forming fluid favors the occurrence of mixed fluid. Shear fractured zones are places where there was strong transportation reaction coupling mineralization. Ore bodies were located in dilation space of shear structure where there was the greatest fluid flux. After the emplacement of the rock body, a convex heat field was formed around the rock body. It is one of the main metallogenic forces. The major reason for mineralization is the mobilization, migration and enrichment of ore forming elements induced by shear compressive extensional tectonism. Inclusion gold dominant low grade ores were formed in the early ore forming stage, while high grade ores, which contained fissure gold and polymetallic veinlets, were formed in late ore forming stage.

Strain transfer mechanism of passive wireless surface acoustic wave torque sensors using shear lag theory

A shear-lag theory was developed to investigate the strain transfer from the metal substrate to the surface acoustic wave （SAW） resonator through a bonding layer. A three-layer model of host structure-adhesive layer-resonator layer was established. The strain transfer was theoretically analyzed, and the main factors impacting the SAW sensor measurement were studied. The relationship between the sensor response and the individual effect of all these factors under static loads was discussed. Results showed that better accuracy could be achieved with increase in the adhesive stiffness or resonator length, or decrease in the adhesive thickness. The values of the strain transfer rate calculated from the analytical model agreed well with that from the available experiment data.

常泰长江大桥组合索塔锚固结构钢-混传剪构造足尺模型试验研究

常泰长江大桥索塔锚固结构采用钢箱-核芯混凝土组合结构,为研究该新型组合索塔锚固结构钢-混传剪构造的受力特性,进行钢-混传剪构造足尺模型试验研究。制作2个锚固结构足尺节段试验模型,通过压剪试验研究锚固结构的荷载~滑移曲线及应力、应变分布等受力特性,并通过有限元模型分析锚固结构的传力机理和各组件的内力分配比例,推导剪力钉剪力计算方法。结果表明:在2.14倍单索最大索力荷载作用下,锚固结构保持弹性状态,钢壁板未产生明显滑移,钢-混界面最大滑移不超过0.25 mm,该锚固结构中钢-混传剪构造至少具有2.14倍的安全系数;荷载作用下,剪力钉剪力从上至下逐渐增大,锚腹板附近底部3排剪力钉剪力较大,钢-混传剪构造至少存在剪力钉和界面摩擦力2种传剪机制,钢-混传剪构造的承载能力显著提高;钢-混传剪构造受力过程分为粘结力传力阶段和局部滑移阶段,剪力钉剪力分布不仅与沿剪切方向长度分布有关,也与荷载的大小线性相关。

基于桩-土界面剪切特性的单桩沉降和承载问题研究

近年来,西北地区出现了许多高填方场地,为减小建筑物基础的不均匀沉降,基础类型广泛使用桩基础。与一般场地不同,黄土填方场地中的单桩桩周土受力后仍会产生较大的变形,该类场地单桩沉降机制复杂。桩顶总沉降计算是桩基设计的重要依据,为此,建立了高填方黄土场地单桩桩顶总沉降计算模型。基于传统的荷载传递法和剪切位移法,分别考虑桩-土界面的桩-土相互作用和桩-土界面外剪切带土体的剪切变形。依据桩端边界,将单桩类型分为摩擦桩和端承摩擦桩,分别建立桩周土弹性阶段和塑性阶段的桩身位移控制微分方程,结合边界条件进行求解,得到桩身位移、轴力、侧摩阻力,并通过弹塑性理论求解了桩周土剪切带土体剪切变形,进而通过叠加原理求得桩顶总沉降。用桩长与桩周土塑性发展深度的比值,定义了桩基承载力安全系数K。通过算例分析与现场试验数据对比分析,研究结果表明:使用新的模型计算得到的桩顶总沉降与现场试验结果相近;当桩顶荷载较小、桩周土处于弹性阶段时,桩端边界对桩身轴力、位移和侧摩阻力影响很小,但桩周土进入塑性滑移阶段后,桩端边界的影响开始变大,考虑桩端土的承载能力会极大提高单桩极限承载力;建立了将荷载传递法和剪切位移法综合起来的计算模型,不仅可以考虑桩-土界面的相对滑移,还可以计算桩-土界面外土体剪切带的剪切变形,使得桩顶总沉降计算更加精确,可为类似场地中单桩沉降的分析与控制提供一定的参考。

基于扰动理论修正的桩-土接触面荷载传递模型及其应用

利用硬化模型、双曲线模型、指数模型以及软化模型模拟的桩-土接触关系存在参数取值困难、误差大的问题。为深入研究土-结构接触面的强度与变形机理,基于扰动理论,假定完整状态接触单元的抗剪强度服从线弹性模型,而扰动部位则服从塑性模型,建立修正的桩-土接触面荷载传递模型。该模型参数分析表明,参数k、η对模型τ-s曲线形态影响大,而参数τf、ζ对模型τ-s曲线形态影响很小;并通过大型桩-土接触面室内直剪试验,量化接触面上剪切应力与剪切位移的关联性,进一步确定修正桩-土接触模型内部计算参数。结果表明模型τ-s曲线与试验曲线吻合较好,验证了模型的合理性。扰动桩-土接触模型既能描述桩侧应变软化也能描述硬化特性,有助于理解复杂应力条件下桩-土接触面的强度计算与变形机理。

Shear-Warp算法中基于边界模型的传递函数及其修正

基于Shear-Warp算法提出一种改进的体绘制算法·在对传递函数进行预设定时,基于边界模型并结合交互式操作,可以方便地设定最优传递函数值·在重采样过程中,结合Shear-Warp算法的特点对传递函数值进行修正,以保证重建后的图像质量·实验结果证明:该算法不仅效率高,而且显示效果好·

纤维复合材料剪滞理论的改进与参数分析

对于纤维复合材料,传统剪滞理论没有考虑基体轴向应变的影响,导致无法反映基体在应力传递中的作用。通过对剪滞理论的改进,解决了上述问题,推导了纤维轴向应力、纤维轴向变形、基体轴向应力、基体轴向变形、纤维/基体界面剪应力、纤维/基体相对滑移量的分布公式,分析了界面弹性模量对应力传递机制的影响,结果符合现有研究成果。经与有限元分析结果对比,验证了改进理论的合理性。

地铁车辆段上盖的全框支剪力墙结构设计探讨

根据地铁车辆段上盖全框支剪力墙结构设计实践,提出该结构按现行规范设计存在的问题,包括重力二阶效应验算,周期折减系数影响,框支柱剪力调整和厚板设计验算等问题。针对上述问题,建议重力二阶效应验算采用屈曲因子不小于20作为不考虑条件;少砌体墙的(框支)框架层考虑周期折减系数的影响,对(框支)框架层楼层剪力作折减;对于特一级或一级的框支柱的弯矩或剪力调整系数下调,避免调整后剪力远大于中震剪力的不合理情况;盖上剪力墙对厚板的冲切验算用作图法验算。

Vortex-Induced Vibrations of A Long Flexible Cylinder in Linear and Exponential Shear Flows

A numerical study based on a wake oscillator model was conducted to determine the response performance of vortex-induced vibration(VIV) on a long flexible cylinder with pinned-pinned boundary conditions subjected to linear and exponential shear flows. The coupling equations of a structural vibration model and wake oscillator model were solved using a standard central finite difference method of the second order. The VIV response characteristics including the structural displacement, structural frequency, structural wavenumber, standing wave behavior,travelling wave behavior, structural velocity, lift force coefficient and transferred energy from the fluid to the structure with different flow profiles were compared. The numerical results show that the VIV displacement is a combination of standing waves and travelling waves. For linear shear flow, standing waves and travelling waves dominate the VIV response within the low-velocity and high-velocity zones, respectively. The negative values of the transferred energy only occur within the low-velocity zone. However, for exponential shear flow, travelling waves dominate the VIV response and the negative energy occurs along the entire length of the cylinder.

陆上可控震源技术的未来发展与思考

本文首先回顾了陆上可控震源技术的发展历程,又介绍了目前具有国际领先水平的可控震源技术—高精度可控震源(EV-56)技术和新型横波可控震源(EV-56RS)技术。针对目前可控震源技术的工业化推广应用和研究现状,提出了可控震源技术面临的一些技术挑战和难点,同时给出了关于当前可控震源技术的发展和提高的一些技术思路与思考,希望能为广大震源科研技术人员提供一些技术层面的帮助和研究参考。

Analytical method of load-transfer of single pile under expansive soil swelling

The elastic differential equations of load-transfer of single pile either with applied loads on pile-top or only under the soil swelling were established,respectively,based on the theory of pile-soil interaction and the shear-deformation method.The derivation of analytic solution to load-transfer for single pile in expansive soil could hereby be obtained by means of superposition principle under expansive soils swelling.The comparison of two engineering examples was made to prove the credibility of the suggested method.The analyzed results show that this analytic solution can achieve high precision with few parameters required,indicating its' simplicity and practicability in engineering application.The employed method can contribute to determining the greatest tension along pile shaft resulting from expansive soils swelling and provide reliable bases for engineering design.The method can be employed to obtain various distributive curves of axial force,settlements and skin friction along the pile shaft with the changes of active depth,vertical movements of the surface and loads of pile-top.

Effects of fluid recirculation on mass transfer from the arterial surface to flowing blood

The effect of disturbed flow on the mass trans- fer from arterial surface to flowing blood was studied nu- merically, and the results were compared with that of our previous work. The arterial wall was assumed to be vis- coelastic and the blood was assumed to be incompressible and non-Newtonian fluid, which is more close to human arte- rial system. Numerical results indicated that the mass trans- fer from the arterial surface to flowing blood in regions of disturbed flow is positively related with the wall shear rates and it is significantly enhanced in regions of disturbed flow with a local minimum around the reattachment point which is higher than the average value of the downstream. There- fore, it may be implied that the accumulation of cholesterol or lipids within atheromatous plaques is not caused by the reduced efflux of cholesterol or lipids, but by the infiltration of the LDL （low-density lipoprotein） from the flowing blood to the arterial wall.

某树状高层建筑结构设计和分析的若干关键技术问题

主要针对某树状高层建筑在结构设计和分析过程中遇到的建筑大悬挑方案的结构实现、竖向力传力路径分析、抗连续倒塌分析、关键构件性能化设计、楼面体系抗拉承载力分析、节点详细有限元分析等关键技术问题进行了分析和研究,与此同时,也对结构的抗风设计、南北侧双核心筒的设置、局部墙体的偏拉、重力二阶效应等技术问题进行了展开并提供了解决方案。结果表明虽该高层建筑存在体型复杂、大悬挑、平面形状不规则、核心筒偏置等难点,但是通过合理的平面和竖向布置,辅之以详尽的结构分析能够保证结构的安全性。尤其是在通过局部斜撑转换较好地实现建筑大悬挑效果的同时,也能够很好地实现竖向荷载的可靠、直接和简洁的传递,分别从依次拆除斜撑和一次性拆除斜撑两个工况进行了抗连续倒塌分析,从完全不考虑楼板作用和考虑后浇相关层楼板的施工模拟两个角度来复核楼面体系的抗拉承载力,对梁-撑转换节点进行了精细化有限元分析等,最终通过进一步验算保证其在不同水准地震作用下仍能很好地满足预定的性能化设计目标。

某部分框支剪力墙结构等效刚度比控制分析

转换层下部结构刚度对部分框支剪力墙结构的竖向刚度规则性和地震剪力传递突变程度有较大影响,等效刚度比是衡量转换层下部结构相对刚度的重要设计指标。本文对8度区某部分框支剪力墙结构等效刚度比的控制进行分析讨论。首先,通过转换层下部结构高度线性插值对等效刚度比进行修正,其次,通过调整转换层层高和转换层下部结构剪力墙厚度两种方式,分析不同等效刚度比对结构整体指标、构件受力和结构整体抗震性能的影响。结果表明,等效刚度比越大,转换层与其上一层的层间位移角比和有害层间位移角比越小,等效刚度比小于1.0时,转换层与其上一层的有害位移角比突变增大;设置转换层对转换层以上3层的地震剪力分配产生了较大影响;框支框架的相对刚度比越大,水平力传递突变程度越小;随着等效刚度比增加,结构主要屈服部位由结构底部转移至转换层以上部位。

Parameters Effect on Heat Transfer Augmentation in a Cavity with Moving Horizontal Walls

Mixed convection flow is one of the essential criteria of fluid flow and heat transfer. And its application has been increased due to modernization of society. So, to compete with the global world an analysis has been investigated numerically. In this study we have considered 2D double lid driven cavity with two-sided adiabatic walls. This problem is illustrated mathematically by a collection of governing equations and the developed model has been solved numerically by using Finite Difference Method (FDM). The goal of the present study is to analyze numerically the thermal behaviour and parameters effect on heat transfer inside the 2D chamber. Also this analysis has been observed for the case where the upper wall is moving at positive direction and lower wall is moving at negative direction with constant speed. Furthermore, we have tried to analyze the velocity and temperature profiles for a vast range of dimensionless parameters namely Reynolds number (Re), Richardson number (Ri)?and Prandtl number?(Pr)?and presented graphically. Moreover, it is found that these flow parameters have significant effects in controlling the flow behavior inside the cavity. A comparison has been done to validate our code and found a good agreement. Finally, average Nusselt number (Nu)?has been studied for the effects of these parameters and presented in tabular form.

基于双向渐进结构优化算法的预制拼装箱梁剪力键设计研究

为研究单项和多项荷载组合作用下节段预制拼装箱梁接缝处剪力键受力状况,以郑州南四环全预制装配高架桥为背景,采用Abaqus软件和双向渐进结构优化(BESO)算法,建立典型箱梁节段分析模型,研究剪力键在单位轴力、剪力、扭矩、弯矩和不同荷载组合作用下的布置规律。结果表明:轴力作用时剪力键应布置于顶板;剪力作用时剪力键应布置于腹板和底板;扭矩作用时剪力键应布置在顶板、腹板交接处和腹板外侧;横桥向弯矩作用时剪力键应布置于顶板、腹板下侧和底板;竖向弯矩作用时,剪力键应布置于顶板翼缘。轴剪组合作用下,当剪力占比小于50%时,轴力对剪力键布置起控制作用;当剪力占比达95.24%时,剪力对剪力键布置起控制作用。弯剪组合作用下,当剪力占比超过4.76%时,剪力对剪力键布置起控制作用;当剪力占比小于0.50%时,横桥向弯矩对剪力键布置起控制作用。扭剪组合作用下,当剪力占比超过0.10%时,剪力对剪力键布置起控制作用。预制拼装箱梁剪力键布置受荷载类型及荷载组合影响显著,应考虑不同位置剪力键的实际受力状况进行设计。

Thermophysical Properties and Supercritical Heat Transfer Characteristics of R515A

The heat transfer of supercritical fluids is a vastly growing field, specifically to find suitable alternative to replace conventional R134a, which can be beneficial for climate change. A considerable suggestion is R515A which possesses considerably lower global warming potential. The present simulations are designed to study supercritical fluid R515A under cooling conditions in horizontal position. The effect of pressure, mass flux, heat flux and tube diameter were considered for horizontal tube in the vicinity of pseudo critical temperature. Numerical investigations on heat transfer characteristics of supercritical fluid R515A were performed using widely used shear-stress transport (SST) model. Moreover, heat transfer correlations were developed and suggested to accurately predict Nusselt number within 10% accuracy. The simulation results showed about 3.98% average absolute deviation.

轻型木结构剪力墙保温性能测试与分析

以国内首栋六层梁柱框架-轻型木结构剪力墙——山东鼎驰木业有限公司研发大楼为研究对象,对其一楼质检部墙体A与二楼仓库墙体B的传热系数进行测定分析。热流计分别呈横向与纵向布置,分别采取空调加热和电暖器加热,测试不同部位墙体的保温隔热性能;参照标准GB 50176—2016计算墙体理论传热系数;采用Abaqus软件对墙体传热系数进行模拟并对墙体内部温度与热流密度分布展开分析。研究结果表明:墙体A(横向)与墙体A(纵向)的平均传热系数分别为0.463、0.465 W/(m^(2)·K),墙体B的平均传热系数为0.374 W/(m^(2)·K),均达到了寒冷地区甲类公共建筑外墙标准;各测点传热系数实测值有一定差异,墙体保温性能不均匀,受施工条件与结构形式影响较大;墙体传热系数的理论结果与数值模拟结果分别为0.238 W/(m^(2)·K)和0.233 W/(m^(2)·K);保温层墙骨柱区域热流密度相比于保温棉区域显著提高,墙骨柱处易形成热桥,导致热流量和传热系数大幅上升,保温隔热性能下降。

《钢结构与钢-混凝土组合结构设计方法》的理解与应用——钢柱脚

根据《钢结构与钢-混凝土组合结构设计方法》,详细介绍了钢柱脚的轴力传力机制以及外包式钢柱脚的弯矩传力机制。对于外包式钢柱脚,指出规范关于外包混凝土最小高度要求的实质,提出了钢柱传递至外包混凝土的轴力、界面抗剪、外包混凝土的抗冲切等计算公式,并对《高层民用建筑钢结构技术规程》(JGJ 99—2015)关于外包式钢柱脚极限受剪承载力的计算公式提出了改进建议。现行规范关于钢柱下混凝土的局部受压计算,偏不安全,提出了基于壁板以及钢柱整体的混凝土局部受压计算方法。

Simulation of Random Waves and Associated Laminar Bottom Shear Stresses

This work presents a new approach for simulating the random waves in viscous fluids and the associated bottom shear stresses. By generating the incident random waves in a numerical wave flume and solving the unsteady two-dimensional Navier-Stokes equations and the fully nonlinear free surface boundaiy conditions for the fluid flows in the flume, the viscous flows and laminar bottom shear stresses induced by random waves axe determined. The deterministic spectral amplitude method implemented by use of the fast Fourier transform algorithm was adopted to generate the incident random waves. The accuracy of the numerical scheme is confirmed by comparing the predicted wave spectrum with the target spectrum and by comparing the nanlerical transfer function between the shear stress and the surface elevation with the theoretical transfer function. The maximum bottom shear stress caused by random waves, computed by this wave model, is compared with that obtained by Myrhaug＇ s model （1995）. The transfer function method is also employed to determine the maximum shear stress, and is proved accurate.