磁流变变阻尼半主动控制结构的仿真分析   总被引：6，自引：2，他引：6  

付伟庆  王玉铨  王焕定  张永山 《地震工程与工程振动》2003,23(4):165-170

由于高阶单步法已成功地应用于结构非线性分析及考虑时滞的主动控制等，显示了它的稳定、精度高和计算迅速等特点。用于结构振动控制的磁流变阻尼器属于速度相关型变阻尼半主动控制器，已有的一些算法，或因计算时间过长不能用于实际控制，或因需要事先经过学习训练，控制效果取决于训练学习的情况。因此，本文将高阶单步法应用于磁流变变阻尼半主动控制系统，采用开关控制和连续控制两种控制率对磁流变液的剪切强度进行调节。仿真计算表明，该控制算法是一种能用于结构实际控制的变阻尼有效算法.  相似文献   

The use of surface monitoring data for the interpretation of landslide movement patterns   总被引：4，自引：1，他引：4  

D.N. Petley  F. Mantovani  M.H. Bulmer  A. Zannoni 《Geomorphology》2005,66(1-4):133

The Tessina landslide is a large, seasonally active slope failure located on the southern slopes of Mt. Teverone, in the Alpago valley of NE Italy, consisting of a complex system that has developed in Tertiary Flysch deposits. The landslide, which first became active in 1960, threatens two villages and is hence subject to detailed monitoring, with high quality data being collected using piezometers, inclinometers, extensometers, and through the use of a highly innovative, automated Electronic Distance Measurement (EDM) system, which surveys the location of a large number of reflector targets once every 6 h. These systems form the basis of a warning system that protects the villages, but they also provide a very valuable insight into the patterns of movement of the landslide.In this paper, analysis is presented of the movement of the landslide, concentrating on the EDM dataset, which provides a remarkable record of surface displacement patterns. It is proposed that four distinct movement patterns can be established, which correspond closely to independently defined morphological assessments of the landslide complex. Any given block of material transitions through the four phases of movement as it progresses down the landslide, with the style of movement being controlled primarily by the groundwater conditions. The analysis is augmented with modelling of the landslide, undertaken using the Itasca FLAC code. The modelling suggests that different landslide patterns are observed for different parts of the landslide, primarily as a result of variations in the groundwater conditions. The model suggests that when a movement event occurs, displacements occur initially at the toe of the landslide, then retrogress upslope.  相似文献   

Regional scale strain variations in Banded Iron Formations of Eastern India: results from anisotropy of magnetic susceptibility studies     

A. Mukherji  A. K. Chaudhuri  M. A. Mamtani   《Journal of Structural Geology》2004,26(12):2175-2189

Anisotropy of magnetic susceptibility (AMS) data are used as a tool to determine strain variations in different parts of the Banded Iron Formations (BIFs) of the Bonai Synclinorium, eastern India. AMS data of 88 cylindrical cores drilled from 29 samples collected from the limb and hinge parts of mesoscopic scale folds as well as different parts of the entire synclinorium are presented. It is found that the samples from limbs of small-scale folds and also from limbs of the regional scale synclinorium have higher degrees of anisotropy than the hinges. This is inferred to indicate that the limbs accommodated higher strain than the hinges. AMS orientation data are analysed in conjunction with field data. It is concluded that the magnetic fabric developed in the limbs as well as hinges of the BIFs of the study area is related to deformation and is not a manifestation of sedimentary fabric.  相似文献   

Seismic strain rates and distributed continental deformation in the northern Andes and three-dimensional seismotectonics of northwestern South America   总被引：1，自引：0，他引：1  

Freddy Corredor 《Tectonophysics》2003,372(3-4):147-166

Remote sensing and field studies of several extensional basins along the northern margin of the Gulf of Aden in Yemen show that Oligocene–Miocene syn-rift extension trends N20°E on average, in agreement with the E–W to N120°E strike of main rift-related normal faults, but oblique to the main trend of the Gulf (N70°E). These faults show a systematic reactivation under a 160°E extensional stress that we interpret also as syn-rift. The occurrence of these two successive phases of extension over more than 1000 km along the continental margin suggests a common origin linked to the rifting process. After discussing other possible mechanisms such as a change in plate motion, far-field effects of Arabia–Eurasia collision, and stress rotations in transfer zones, we present a working hypothesis that relates the 160°E extension to the westward propagation since about 20 Ma of the N70°E-trending, obliquely spreading, Gulf of Aden oceanic rift. The late 160°E extension, perpendicular to the direction of rift propagation, could result from crack-induced extension associated with the strain localization that characterises the rift-to-drift transition.  相似文献   

新马德里地震带的岩石圈强度与板内形变          下载免费PDF全文

刘澜波  MarhD．Zoback 《地球物理学报》1998,41(Z1):1-14

提出一个简单的假说来解释为什么在相对稳定的板块内部地区会存在高地震活动区与高构造形变区．首先,对于大多数板内地区而言,特别是大陆地盾地区与老的海洋盆地,下地壳与上地幔的温度相当低,那里的岩石相对坚硬在这些地区不可能发生明显的岩石圈变形,因为岩石图累积强度大大超过板块驱动力．相反,如果下地壳与上地幔温度相对较高,板块驱动力则主要由上地壳承受,因为下地壳与上地幔相对软弱在这种地区,由于岩石圈累积强度与板块驱动力大小相当,构造形变相对较快．本文将这种假说应用在位于美国中部的新马德里地震带与周围地区．地震带内部热流密度值约为60mw／m2,略高于本区背景热流密度值45mW／m2．计算得到的地温梯度与实验室结果所揭示的延性流动定律表明,在地震带内下地壳与上地幔相当软弱,板内应力主要由上地壳传递．那里的形变速率相对较高．与此相反,在周围地区热流值相对较低,岩石四累积强度大大超过板块驱动力,构造应力由地壳与上地幔共同承受热流值的大小和下地壳上地幔的受力状态是决定地震活动性在地震带内与周围地区强烈对比的主要因素．  相似文献   

变形分解作用研究综述     

陈桂华  徐锡伟 《华南地震》2004,24(4):11-20

变形分解作用是描述总的构造应变变形如何分解到一定意义分量的一个运动学概念。变形分解作用形成的构造应变变形分量之间的分解可以是表现在应变场的不均一性，也可以是同一应变场的，还可以是表现在构造力学性质、变形机制等的差异。因此，作为一种运动学概念，它涉及多个构造应用领域，研究者建立了多种不同的变形分解作用运动学模型并讨论其控制因素。为构造变形分解作用的研究提供了一种系统思维的研究思路，有利于更系统的认识相关地质构造之间存在的联系。综述了国内外学者对变形分解作用的研究。  相似文献   

山西晋城市的地震与断裂活动     

李小壮 《山西地震》2004,(3):35-38

收集了晋城地区的地震活动情况。分析了晋城市地震活动特征与断裂活动的特征。得出了晋城市的地震活动主要与晋获断裂带的活动有关的结论。  相似文献   

昆仑山口西8.1级地震前高台钻孔应变异常特征   总被引：6，自引：1，他引：6  

尹亮  李兴坚  陈兰新  武银  刘晓明  陈建军  刘鸿斌  许玉红  李东生  雷登学 《高原地震》2002,14(1):83-86

研究分析了2001年11月14日昆仑山口西Ms8．1级地震前高台钻孔应变资料的异常特征，通过对资料长趋势异常和短临异常的探讨，总结了本台钻孔应变的映震能力。  相似文献   

川滇地区应变强度比动态图像分析   总被引：5，自引：0，他引：5  

张希  江在森  王双绪  陈兵 《高原地震》1999,(3)

利用从跨断层形变资料中获取应变强度比动态图像的方法,结合震例对川滇地区８０年代以来跨断层形变资料选择方法不同所获得的应变强度比分布动态图像的２种结果进行分析,并给出中短期强震危险区判定指标  相似文献   

双层结构岩质边坡的滑带扰动厚度计算方法研究     

王根龙  伍法权  刘建友  任爱武 《工程地质学报》2008,16(1):104-108

双层结构岩质边坡进行稳定性评价通常可以实现,但合理确定滑体引起的滑带扰动厚度却比较困难。根据能量法原理,可以推导得出上部硬岩滑体的能量法稳定系数上限解计算公式。进一步按照能量平衡方程,综合考虑滑体、滑带在重力作用下所做的外力功率,以及滑带产生的内能耗散,推导得到了计算滑带扰动厚度的解析公式。在分析典型算例基础上,提出了滑带扰动分带的概念,并将滑带按照扰动程度分为剧扰动带、强扰动带、中等扰动带、弱扰动带和微扰动带。对于双层结构的岩质边坡进行加固治理时,其治理的深度范围应该大于微扰动带的底面。  相似文献