顶山地区乌伦古河组铀成矿水文地质条件分析     

冯世荣  周剑  王果  师志龙  王新华 《铀矿地质》2003,19(3):161-166

本从区域水地质及构造特征出发，分析了顶山地区乌伦古河组铀成矿水地质条件总结了该地区铀成矿模式，并对该地区铀成矿前景做出预测。  相似文献   

新型组合连梁控制结构体系   总被引：9，自引：0，他引：9  

邓志恒  潘峰  陶晓光  唐光暹 《世界地震工程》2003,19(3):6-11

分析了连梁在水平力作用下的破坏机制，对连梁结构体系的发展及结构抗震控制进行了评述，在此基础上提出一种新型组合连梁控制结构体系，并对其进行了概念分析，提出了有待研究的若干关键问题。  相似文献   

中国西北叠合盆地的主要构造特征   总被引：7，自引：2，他引：7  

汤良杰  贾承造  金之钧  马宗晋 《地学前缘》2003,10(Z1):118-124

探讨了中国西北地区大型叠合含油气盆地的主要特征 ,研究表明 ,在中国西北叠合盆地发展演化过程中 ,构造变革和构造耦合起着主导作用。构造变革包括大地构造格局的转变、沉积区和剥蚀区的转换、盆地类型的转换、大型区域性不整合的出现以及发生盆地构造反转等 ,这种构造变革具有多期性。叠合盆地构造耦合的方式主要涉及深部和浅部构造的耦合和盆山耦合等。盆山转换、盆山过渡带深部浅部构造的耦合、盆地沉降与造山带隆升耦合以及不同方向构造的耦合 ,反映了盆山耦合的多样性和复杂性。中国西北叠合盆地构造特征主要表现为构造的分层性、分带性、分段性、交叉性以及区域构造应力场的多变性 ,喜马拉雅运动对于中国西北叠合盆地最后的构造改造以及构造定型起着重要的制约作用。  相似文献   

河南省文峪金矿床构造控矿规律研究   总被引：6，自引：2，他引：6       下载免费PDF全文

徐叶兵  范永香 《地质与勘探》2003,39(5):30-34

峪金矿床是小秦岭金矿带内一大型金矿床，属韧—脆性叠加剪切带石英脉型金矿，构造是其首要控矿因素。早期韧性剪切带只对矿脉起宏观控制作用。晚期的脆性断裂为含金石英脉的直接控矿构造。成矿期脆性断裂的多次继承性活动分别控制了热液期4个成矿阶段。脆性断裂形成的空间形态对矿体形态产状具控制作用。有利的矿化富集部位为：①显示压扭性质的近东西向断裂沿走向产状变化处，沿倾向由陡变缓处，断裂面的凹凸转变处；②断裂分支复合部位；③成矿期断裂多次脉动的启张部位；④成矿期断裂构造继承性活动强的部位等。在构造控矿研究的基础上，结合前人部分研究成果。构建了该矿床构造控矿模式。  相似文献   

Statistical performance analysis of seismic‐excited structures with active interaction control     

Yunfeng Zhang  Wilfred D. Iwan 《地震工程与结构动力学》2003,32(7):1039-1054

This paper presents a statistical performance analysis of a semi‐active structural control system for suppressing the vibration response of building structures during strong seismic events. The proposed semi‐active mass damper device consists of a high‐frequency mass damper with large stiffness, and an actively controlled interaction element that connects the mass damper to the structure. Through actively modulating the operating states of the interaction elements according to pre‐specified control logic, vibrational energy in the structure is dissipated in the mass damper device and the vibration of the structure is thus suppressed. The control logic, categorized under active interaction control, is defined directly in physical space by minimizing the inter‐storey drift of the structure to the maximum extent. This semi‐active structural control approach has been shown to be effective in reducing the vibration response of building structures due to specific earthquake ground motions. To further evaluate the control performance, a Monte Carlo simulation of the seismic response of a three‐storey steel‐framed building model equipped with the proposed semi‐active mass damper device is performed based on a large ensemble of artificially generated earthquake ground motions. A procedure for generating code‐compatible artificial earthquake accelerograms is also briefly described. The results obtained clearly demonstrate the effectiveness of the proposed semi‐active mass damper device in controlling vibrations of building structures during large earthquakes. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Inelastic displacement ratios for evaluation of existing structures     

Jorge Ruiz‐García  Eduardo Miranda 《地震工程与结构动力学》2003,32(8):1237-1258

Results of a detailed statistical study of constant relative strength inelastic displacement ratios to estimate maximum lateral inelastic displacement demands on existing structures from maximum lateral elastic displacement demands are presented. These ratios were computed for single‐degree‐of‐freedom systems with different levels of lateral strength normalized to the strength required to remain elastic when subjected to a relatively large ensemble of recorded earthquake ground motions. Three groups of soil conditions with shear wave velocities higher than 180m/s are considered. The influence of period of vibration, level of lateral yielding strength, site conditions, earthquake magnitude, distance to the source, and strain‐hardening ratio are evaluated and discussed. Mean inelastic displacement ratios and those associated with various percentiles are presented. A special emphasis is given to the dispersion of these ratios. It is concluded that distance to the source has a negligible influence on constant relative strength inelastic displacement ratios. However, for periods smaller than 1s earthquake magnitude and soil conditions have a moderate influence on these ratios. Strain hardening decreases maximum inelastic displacement at a fairly constant rate depending on the level of relative strength for periods of vibration longer than about 1.0s while it decreases maximum inelastic displacement non‐linearly as the period of vibration shortens and as the relative‐strength ratio increases for periods of vibration shorter than 1.0s. Finally, results from non‐linear regression analyses are presented that provide a simplified expression to be used to approximate mean inelastic displacement ratios during the evaluation of existing structures built on firm sites. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Predictive instantaneous optimal control of elastic structures during earthquakes     

Kevin K. F. Wong  Rong Yang 《地震工程与结构动力学》2003,32(14):2161-2177

A predictive instantaneous optimal control (PIOC) algorithm is proposed for controlling the seismic responses of elastic structures. This algorithm compensates for the time delay that happens in practical control applications by predicting the structural response over a period that equals the time delay, and by substituting the predicted response in the instantaneous optimal control (IOC) algorithm. The unique feature of this proposed PIOC algorithm is that it is simple and at the same time compensates for the time delay very effectively. Numerical examples of single degree of freedom structures are presented to compare the performance of PIOC and IOC systems for various time delay magnitudes. Results show that a time delay always causes degradation of control efficiency, but PIOC can greatly reduce this degradation compared to IOC. The effects of the structure's natural periods and the choice of control gains on the degradation induced by the time delay are also analyzed. Results show that shorter natural periods and larger control gains are both more sensitive and more serious to the degradation of control efficiency. Finally, a practical application of PIOC is performed on a six‐story moment‐resisting steel frame. It is demonstrated that PIOC contributes significantly to maintain stability in multiple degree of freedom structures, and at the same time PIOC has a satisfactory control performance. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

易门式大型铜矿床构造成矿动力学模型   总被引：5，自引：1，他引：5  

韩润生  刘丛强  马德云  王红才  马更生 《地质科学》2003,38(2):200-213

针对金属矿床隐伏矿定位预测的关键问题,在提出构造成矿动力学的分支学术方向的基础上,以易门式大型铜矿床为例,从成矿地质背景、矿田构造、构造地球化学和成矿构造应力场等方面进行构造成矿动力学研究,阐述在构造应力场控制下成矿流体运移和聚集的规律。构造地球化学研究认为,构造地球化学异常反映矿体的原生晕;构造地球化学异常受构造控制,其分带特征可指示成矿流体的流向,并提供矿床成因和隐伏矿(化)体相对埋深的信息。构造应力场的控矿特征主要表现在:构造应力场导致控矿构造的形成,并驱动成矿流体的运移;构造应力场控制了成矿能量场;应力和能量的高值集中区分布特点可反映某些构造型式。在此基础上建立构造成矿动力学模型,概括隐伏矿成矿预测准则,据此提出若干重点找矿靶区和靶位,其中部分靶区得到工程验证,表明构造成矿动力学方法对隐伏矿定位预测和评价具有重要的指导意义。  相似文献   

The role of sediment specific gravity and availability on cluster evolution     

A. N. Papanicolaou  K. Strom  A. Schuyler  N. Talebbeydokhti 《地球表面变化过程与地形》2003,28(1):69-86

The objective of this experimental study was to account for the role of sediment availability and specific gravity on cluster formation and cluster geometric characteristics (spacing and size). To isolate the effects of sediment availability and specific gravity on cluster evolution, mono‐sized spheres were used to simulate the cluster evolutionary cycle. Overall, twelve experimental runs were carried out in the laboratory flume. Six of these tests were performed by using glass spheres (specific gravity, SG = 2·58) and the other six by employing an equal combination of glass and Teflon spheres (SG = 2·12) of the same diameter to evaluate the role of specific gravity on cluster evolution. The three sediment availability conditions that were investigated here simulated isolated gravel elements, pool–riffle sequences and densely packed gravel‐bed. An advanced image analysis technique was employed to track the evolution of cluster microforms and provide quantitative information about the size and shape of clusters and the number of clusters per unit area. The results of this study showed that: (1) sediment availability affects the architecture and size of cluster microforms; and (2) clusters consisting of mono‐sized sediments start disintegrating at twice the incipient conditions. By performing complementary tests for the isolated gravel elements case, it was found that the evolutionary cycle of individual clusters could be described as follows, in order of increasing stress: no cluster→two particle cluster→comet→triangle→rhomboid→break up. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Sliding fragility of block‐type non‐structural components. Part 1: Unrestrained components     

D. Lopez Garcia  T. T. Soong 《地震工程与结构动力学》2003,32(1):111-129

Motivated by the development of performance‐based design guidelines with emphasis on both structural and non‐structural systems, this paper focuses on seismic vulnerability assessment of block‐type unrestrained non‐structural components under sliding response on the basis of seismic inputs specified by current seismic codes. Two sliding‐related failure modes are considered: excessive relative displacement and excessive absolute acceleration. It is shown that an upper bound for the absolute acceleration response can be assessed deterministically, for which a simple yet completely general equation is proposed. In contrast, fragility curves are proposed as an appropriate tool to evaluate the excessive relative displacement failure mode. Sample fragility curves developed through Monte‐Carlo simulations show that fragility estimates obtained without taking into account vertical base accelerations can be significantly unconservative, especially for relatively large values of the coefficient of friction. It is also found that reasonable estimates of relative displacement response at stories other than the ground in multistorey buildings cannot in general be obtained by simply scaling the ground acceleration to the peak acceleration at the corresponding storey. Failure modes considered in this study are found to be essentially independent of each other, a property that greatly simplifies assessment of conditional limit states. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献