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901.
讨论了井田构造特征。按形态,性质及展布方位划分为四个构造单元,并分析了各构造单元的形成机制及演化。  相似文献   
902.
The generalized minimum variance (GMV) algorithm for the control of civil engineering structures is developed and presented in this paper. This algorithm needs the knowledge of the seismic excitation model to derive the autoregressive moving average exogen model of the structure. Then the GMV control is applied. The control is designed such that the variance of the generalized cost function is minimized. To demonstrate the effectiveness of this control technique, simulation tests using a single‐degree‐of‐freedom structure are performed. The results show that the relative displacement of the structure and the control effort are significantly reduced. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   
903.
本文从检测之系统性,科学性,准确性说明了雷达技术用于工程质量检测方面具有较大优越性,在扼要阐明雷达波在混凝土介质中的传播规律与特征的基础上,详细分析了雷达技术在无损检测混凝土构(物)件质量的分辨率,以2个无损检测工程实例,说明了该项技术在无损检测混凝土构(物)件质量的有效性和实用性。  相似文献   
904.
The structural response to high‐frequency ground motions is complicated due to the involvement of local‐mode vibration. At present such a characteristic is not well recognized and this can cause confusion over the analytical and experimental modelling of the corresponding response and damage. The fact that most existing regulatory guides for limits on allowable construction vibrations are necessarily simplified for administrative reasons calls upon the derivation of more sophisticated approaches for special cases. This requires accumulation of pertinent experimental evidence. This paper attempts to provide some insights into the local‐mode dynamic response characteristics, with emphasis on appropriate modelling techniques and experimental measurements. A preliminary testing program is reported, in which efforts were made to reproduce high‐frequency response with a reduced scale reinforced concrete model with shaking table facilities. The results demonstrate the dependence of the response amplitudes with the excitation frequency. On a ppv‐basis, the current test results indicate that a substantial increase of the allowable ppv value from those specified by various standards may be considered for structural damage to reinforced concrete building structures. More analytical and experimental data are needed for further evaluation of the local‐mode effects and to quantify their impact on the structural damage process. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   
905.
东喜马拉雅构造结经历了前期楔入和后期垮塌变形.楔入事件发生于~60Ma、~23Ma和~13 Ma,垮塌开始于6~7Ma.哀牢山红河构造带同样经历早期走滑和后期正断,走滑年代分别为58~56Ma、23Ma和13Ma,后期正断开始于5.5 Ma.上述年龄的意义在于~60Ma的变形代表印度与欧亚大陆的初期碰撞;2 Ma为青藏高原及邻区的主变形期;13Ma的变形也代表一次汇聚事件,并形成青藏高原的东西向伸展.6~7Ma以后的垮塌作用代表了青藏高原的快速隆升.  相似文献   
906.
In 1983, Ghana embarked on a program of structural adjustment under the auspices of the World Bank and the International Monetary Fund, to resuscitate the economy and to foster development. This paper utilizes the Lagos Plan of Action, a comprehensive, continent‐wide effort and African‐led policy strategy for the economic development of the African continent, to examine the contribution of adjustment to the development of an integrated economy in Ghana. Adjustment is examined as a form of structural transformation, as evidenced by the emergent intranational (intra‐ and inter‐sectoral) and international linkages in the formal wood processing industry, a key sector with tremendous potential for such linkages. Intranationally, this study shows that, as in the pre‐adjustment years, inter‐sectoral linkages, although important, were not dynamic enough to play a significantly galvanizing role in the nation's economic development. However, intra‐sectorally, a dramatic expansion in lumber exports led to an unprecedented constriction in the traditional forward linkage between sawmills and downstream processors. This forced the latter to depend on the informal sector for inputs. Internationally, Ghanaian firms operated as subcontractors of convenience for firms overseas (particularly in Europe) via an expanded forward linkage, reflecting a new “colonial relationship” under the program.  相似文献   
907.
正断层生长和侧向连接是最基本的三维地质构造问题,深入剖析其三维时 空演化过程对理解沉积盆地内正断层系统的形成与演化至关重要。 南海扩张时间和影响范围一直是国内外地学界研究的热点问题之一。南海北部珠江口盆地陆丰凹陷发育大量正断层,并覆盖有高精度二维地震反射剖面,成为研究上述问题的理想地区之一。本研究以陆丰凹陷为研究对象,开展三维构造解析和建模研究,为正断层系统三维时 空演化过程提供一个实例。研究结果表明:陆丰凹陷主控断层F1的生长和连接过程主要分三个阶段:晚白垩世—早古新世,两条断层分别形成并以孤立断层模式分别向两侧生长;早古新世—早渐新世,断层发生侧向连接作用合并为F1断层,连接处发育侧断坡;晚渐新世—中中新世,F1断层继续向两侧生长。基于F1断层定量分析(生长指数和断距),发现F1断层活动强度表现为先增加然后突然降低,其转折时间对应于T60界面,~23 Ma,较好地对应了西北次海盆扩张终止时间,说明南海北部扩张已经影响到陆丰凹陷。结合前人对珠江口盆地构造变形和演化研究,初步认为南海北部扩张波及的范围已跨过陆丰凹陷向大陆方向继续延伸,其北部边界可能对应于华南大陆南缘的滨海断裂带。本研究可为正断层系统三维生长过程研究提供案例,同时为南海扩张过程研究提供基础数据支撑。  相似文献   
908.
Exploratory variography was used to examine the spatial continuity of water–well yields in the Pinardville 7 Minute Quadrangle in southern New Hampshire and to link the variography to the characteristics of the fractured igneous and metamorphic rocks within the aquifer system. In addition to the analyses of variograms computed by using data from 939 wells, analyses were performed on subsets of the data that were stratified according to the level of yield and to five rock types. The stratification according to yield was defined by using the industry standard of a high-yield well that produces 40 gallons per minute or more. The stratification of the low-yield wells by rock type was defined by using the classification on the bedrock map for the State of New Hampshire. Although the variability is high in the low-yield wells, as indicated by the large nugget value, overall continuity ranges to 6000 feet in the fracture zones in which these wells have been drilled. This continuity is dominant in the northwesterly direction, as indicated by the directional variography. This result is consistent with the general trend in the larger tectonic configuration of the region. A lack of spatial correlation for 81 high-yield wells is consistent with the geologic interpretation that these wells occur in locally determined configurations of sheeting and steeply dipping fractures. Yield data in only three of the five rock types were sufficient for variography. Within these three, the dominant direction of the correlation structure ranged from northwesterly for the Massabesic Gneiss Complex to northeasterly for the Rangeley Formation to northerly for the Spaulding Granite, where the signature of the continuity in the low-yield wells is predominately attributed to the fracture system.  相似文献   
909.
焦远碧 《内陆地震》1993,7(2):106-113
对地震活动性进行层次结构分析可划分出不同的地震区带,中国大陆的地震活动可分为9个地震区带,分析各个区带的地震活动性可作出某一活跃期强震发生主体地区的判别,对某一个地震区带的地震活动进行层次结构分析可作出地震危险区预测。用震源面投影图代替点投影的震中分布图可更合理地解释一个构造带上强震的发生过程,更清楚地勾画出未来强震的孕震范围。对强震破裂区闭锁段、背景空区、孕震空区的关系用实测震例进行了解释。  相似文献   
910.
哈纳斯湖地区地貌与湖的成因   总被引:1,自引:0,他引:1  
哈纳斯湖位于阿尔泰山深处,最大水深188.5m,平均水深122.1m。横断面具典型的箱形形态,在其底部存在现代活动地堑。湖盆的成因是强烈的构造断陷加上山谷冰川的创蚀及终碛垄的堰塞。随着终绩垄被出流下切,湖泊面积变小。  相似文献   
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