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31.
川滇菱形块体边界的现今地壳形变   总被引:10,自引:2,他引:10  
吕弋培  廖华  苏琴  王兰 《中国地震》2002,18(1):28-37
依据川滇菱形块体边界带上所有跨断层测量资料,分析了各场地所处断裂的近期形变特征,结果表明;川滇菱形块体北段形变活动逐渐减弱,南段逐渐加强,各条断裂分别显示出不同的变形特征;菱形块体的现今水平形变以左旋走滑运动为主,垂直形变速度较低,且呈上盘抬升与下降交替出现的运动特征,部分场地的形变异常变化与其邻近的地震活动密切相关。  相似文献   
32.
用应变积累释放模型研究中国大陆地块分区地震活动   总被引:11,自引:1,他引:11       下载免费PDF全文
马宏生  刘杰  张国民  李丽 《地震学报》2002,24(6):569-578
依据活动地块假说及活动边界的划分,对中国大陆地震活动进行分区.在此基础上,应用应变积累释放模型,通过地震应变积累释放的计算,研究了中国大陆各活动地块分区的地震活动性,初步探讨了各地块的地震活动阶段划分.此外,还对应变积累释放模型的应用前提条件进行了必要的讨论,并对模型结果中可能出现的问题给予一定分析.   相似文献   
33.
中国大陆及邻近海域的Rayleigh波群速度分布   总被引:11,自引:5,他引:11       下载免费PDF全文
利用Rayleigh波群速度资料反演得到中国大陆及其临近海域的(70°E-145°E,10°N-55°N)15-120s周期的群速度分布图像. 塔里木盆地在15s处清楚地显示为低速,在16-33s左右没有显示,但在36-5s显示为高速,说明塔里木盆地有较深的根. 青藏高原块体是44s至120s图像中最为突出的低速块体,南面与印度板块的分界线以及与北面的塔里木盆地、柴达木盆地的分界清晰,其块体中西部的速度低于东部. 泰国清迈附近存在一尺度为1000km左右的低速带,可能是青藏高原块体的物质向东南方向迁移造成上地幔物质上涌的结果. 南北地震带表现为强烈的速度梯度带,西面为低速,东面为高速. 中国南海的中央、日本海中央、菲律宾海表现为海洋性地壳. 菲律宾海的图像与地形及地震带完全吻合. 环绕菲律宾海及日本海存在400km左右宽的低速带,可能是岩浆活动带.  相似文献   
34.
挡块对斜拉桥抗震性能的影响   总被引:1,自引:0,他引:1  
本文基于现有永和斜拉桥挡块设施的严重破损,引入非线性挡块元,采用有限元计算分析挡块对斜拉桥抗震性能的影响。结果表明,斜拉桥塔根挡块的调协对减震效果影响不大,但挡块具有减小塔顶残余变形的有利作用。鉴于此,对永和斜拉桥挡块进行修复是必要的。  相似文献   
35.
我国抗震设计规范(GB50011-2001)规定在6、7、8度区,混凝土小砌块结构分别可以建七、六、五层。由于混凝土小砌块结构的最大优势在于10-20层(与混凝土框架或框架剪力墙结构比)。本文按1/4比例制作了10层混凝土小砌块结构模型,按7度设防要求实施构造措施,通过振动台试验研究模型结构的抗震性能。结果表明,模型结构完全能够满足在7度区“小震不坏,大震不倒”的要求。圈梁、构造柱以及水平拉结筋构成的约束体系抗震作用是明显的。试验利用砌块的非注芯孔灌注铁砂来模拟墙体出平面动力效应。在本模型的构造措施下,平出面反应不对结构破坏起控制作用。  相似文献   
36.
文中回顾了1974年提出的“块、带、源、兆、触、报”六字预报思路,并基于近20年来的研究对此进行了补充和深化。  相似文献   
37.
针对牙轮钻头的滑动轴承和滚动轴承在实际工作中所存在的问题,提出一种牙轮钻头滚滑复合轴承,对滚滑复合轴承结构进行有限元对比分析、模拟对比试验和钻头现场验证实验,表明滚滑复合轴承是一种较先进的创新性轴承。  相似文献   
38.
由小震震源机制解得到的鄂尔多斯周边构造应力场   总被引:8,自引:4,他引:8       下载免费PDF全文
利用格点尝试法首先分区对鄂尔多斯地块周边的 30 0 0多个小震震源机制解进行了处理。结果显示 ,在震源机制解覆盖的时段内 ,地块周边地区的平均构造应力场有以下特征 :地块周边主要以水平构造作用力为主 ,且其主压应力轴走向以地块西南侧为中心 ,从北至东呈扇形展布。在分区基础上 ,对各区的平均主应力轴分布进行了扫描 ,得到了其随时间的变化过程。其中渭河、六盘山和银川区的构造应力场相对稳定 ,临汾和同心区的构造应力场变化复杂 ,临河、包头、呼和、大同和太原区的构造应力场变化与该区的几次中强地震有密切关系。另外 ,地块周边除个别区外大多数区域在 1992年和 1996年前后 ,主压应力轴走向有趋近于N75°E的现象  相似文献   
39.
Through numerical simulation for GPS data, aseism/c negative dislocation model for crustal horizontal movement during 1999-2001 in the northeast margin of Qinghai-Xizang block is presented, combined with the spatial distri-bution of apparent strain field in this area, the characteristics of motion and deformation of active blocks and their boundary faults, together with the place and intensity of strain accumulation are analyzed. It is shown that: a) 9 active blocks appeared totally clockwise motion from eastward by north to eastward by south. Obvious sinistral strike-slip and NE-NEE relative compressive motion between the blocks separated by Qilianshan-Haiyuan fault zone was discovered; b) 20 fault segments (most of them showed compression) locked the relative motion between blocks to varying degrees, among the total, the mid-east segment of Qilianshan fault (containing the place where it meets Riyueshan-Lajishan fault) and the place where it meets Haiyuan fault and Zhuanglanghe fault, more favored accumulation of strain. Moreover, the region where Riyueshan-Lajishan fault meets north boundary of Qaidam block may have strain accumulation to some degree, c) Obtained magnitude of block velocities and locking of their boundaries were less than relevant results for observation in the period of 1993-1999.  相似文献   
40.
Movement and strain conditions of active blocks in the Chinese mainland   总被引:2,自引:0,他引:2  
The definition of active block is given from the angles of crustal deformation and strain. The movement and strain parameters of active blocks are estimated according to the unified velocity field composed of the velocities at 1598 GPS stations obtained from GPS measurements carried out in the past years in the Chinese mainland and the surrounding areas. The movement and strain conditions of the blocks are analyzed. The active blocks in the Chinese mainland have a consistent E-trending movement component, but its N and S components are not consistent. The blocks in the western part have a consistent N-trending movement and the blocks in the eastern part have a consistent S-trending movement. In the area to the east of 90°E, that is the area from Himalayas block towards NE, the movement direction of the blocks rotates clockwisely and the movement rates of the blocks are different. Generally, the movement rate is large in the west and south and small in the east and north with a difference of 3 to 4 times between the rates in the west and east. The distributions of principal compressive strain directions of the blocks are also different. The principal strain of the blocks located to the west of 90oE is basically in the SN direction, the principal compressive strain of the blocks in the northeastern part of Qingzang plateau is roughly in the NE direction and the direction of principal compressive strain of the blocks in the southeastern part of Qingzang plateau rounds clockwisely the east end of Himalayas structure. In addition, the principal strain and shear strain rates of the blocks are also different. The Himalayas and Tianshan blocks have the largest principal compressive strain and the maximum shear strain rate. Then, Lhasa, Qiangtang, Southwest Yunnan (SW Yunnan), Qilian and Sichuan-Yunan (Chuan-Dian) blocks followed. The strain rate of the blocks in the eastern part is smaller. The estimation based on the stain condition indicates that Himalayas block is still the area with the most intensive tectonic activity and it shortens in the NS direction at the rate of 15.2±1.5 mm/a. Tianshan block ranks the second and it shortens in the NS direction at the rate of 10.1±0.9 mm/a. At present, the two blocks are still uprising. It can be seen from superficial strain that the Chinese mainland is predominated by superficial expansion. Almost the total area in the eastern part of the Chinese mainland is expanded, while in the western part, the superficial compression and expansion are alternatively distributed from the south to the north. In the Chinese mainland, most EW-trending or proximate EW-trending faults have the left-lateral or left-lateral strike-slip relative movements along both sides, and most NS-trending faults have the right-lateral or right-lateral strike-slip relative movements along both sides. According to the data from GPS measurements the left-lateral strike-slip rate is 4.8±1.3 mm/a in the central part of Altun fault and 9.8±2.2 mm/a on Xianshuihe fault. The movement of the fault along the block boundary has provided the condition for block movement, so the movements of the block and its boundary are consistent, but the movement levels of the blocks are different. The statistic results indicate that the relative movement between most blocks is quite significant, which proves that active blocks exist. Himalayas, Tianshan, Qiangtang and SW Yunnan blocks have the most intensive movement; China-Mongolia, China-Korea (China-Korea), Alxa and South China blocks are rather stable. The mutual action of India, Pacific and Philippine Sea plates versus Eurasia plate is the principal driving force to the block movement in the Chinese mainland. Under the NNE-trending intensive press from India plate, the crustal matter of Qingzang plateau moves to the NNE and NE directions, then is hindered by the blocks located in the northern, northeastern and eastern parts. The crustal matter moves towards the Indian Ocean by the southeastern part of the plateau.  相似文献   
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