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171.
岩质高边坡岩体变形参数及松弛带厚度研究   总被引:10,自引:0,他引:10  
预测岩质高边坡开挖后岩体变形模量的变化及松弛带厚度,是分析岩质高边坡在开挖后变形(位移)和作好防护设计的重要资料,运用波动力学关于平均应力与体积模量、岩体纵波速度与弹性模量、变形模量间的关系,通过部分实测资料及边坡应力场有限元分析的资料,分别建立了纵波速度与岩体变形模、岩体应力间的关系,研究了开挖边坡岩体变形模量的变化,预测了岩体松弛带的厚度。  相似文献   
172.
详细介绍了内江松柏寨的七山、七堰、八景等自然景观;对以般若寺为代表的寺庙、寨门以及历代名人所留下的行踪和墨迹作了生动描写;提出以生态旅游为理念进行统一规划,并采取保护性开发的若干建议。  相似文献   
173.
Ayako  Ozawa  Takahiro  Tagami  Masafumi  Sudo 《Island Arc》2004,13(3):466-472
Abstract   A recent K–Ar study elucidated that eruptive style in the eastern Izu peninsula changed from polygenetic to monogenetic volcano at 0.3–0.2 Ma. To narrow down the time of change, we determined 10 K–Ar ages on Togasayama Andesite of Amagi volcano, the youngest polygenetic volcano in the area, and Togasayama Monogenetic Volcano, one of the oldest monogenetic volcanoes in the area, which overlies a part of the Togasayama Andesite. Dating results showed that the Togasayama Andesite effused at least from 0.34 to 0.20 Ma, whereas the Togasayama Monogenetic Volcano erupted at 0.26–0.29 Ma, suggesting that the northern part of the Togasayama Andesite effused after the eruption of the Togasayama Monogenetic Volcano. Considering previous data, it is therefore inferred that change of eruptive style in the eastern Izu area occurred during the period 0.29–0.20 Ma, with considerable overlap of both polygenetic and monogenetic volcanism.  相似文献   
174.
Two models are tested on a shake‐table. One of the models is a normal reinforced concrete megaframe structure and the other is a multifunctional vibration‐absorption reinforced concrete megaframe structure in which the laminated rubber bearings are placed between the major frame and the minor frames. Two earthquake motions (the El Centro wave and the Taft wave) are used during the test. This paper presents the dynamic characteristic, the seismic responses and the failure mechanism of these two models under varying peak acceleration levels for each of the earthquake motions. The test results demonstrate that the aseismic behavior of a multifunctional vibration‐absorption reinforced concrete megaframe structure is much better than that of a normal reinforced concrete megaframe structure. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   
175.
This study investigates an electric‐type active mass driver (AMD) system for structural vibration control. Composed primarily of an electric servomotor and a ball screw, the electrical AMD system is free from noise problems, oil leakage, and labor‐intensive maintenance that commonly are associated with hydraulic AMD systems. The desired stroke amplification of the mass and the power demand of the servomotor can be adjusted via the ball screw pitch, which in turn affects the effectiveness and efficiency of the system. Meanwhile, an instantaneous optimal direct output feedback control algorithm is adopted. Numerical simulation is performed using a five‐story steel frame as the object structure under the conditions of the 1940 El Centro earthquake. The AMD system proves to be effective and efficient within a certain range of the ball screw pitch. The reductions of the peak responses can reach as high as 70% if properly designed. Requiring only the velocity measurement of the top floor for on‐line feedback control, the proposed control algorithm is recommended for practical implementation. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   
176.
重庆市的地学旅游资源极其丰富,可划分为岩石圈旅游资源等4个大类、地质旅游资源等11个基本类型、地层旅游景观等18种景观和黔江县上白垩统正阳组剖面等107个景区(景点)。它们具有类型齐全、分布广泛、岩溶精品和森林独特的特点。从加强岩溶旅游资源调查等6个方面入手,就可提高对它们的开发利用程度.  相似文献   
177.
水流冲击管道内滞留气团的刚性数学模型   总被引:3,自引:0,他引:3       下载免费PDF全文
通过数学分析证明,在不计局部水头损失时,目前常用的几种简化刚性数学模型的最大气压计算结果相等,并与管道内初始充水段长度无关。但算例表明,对于初始充水段较短或滞留气团体积很小情况,这些简化模型的计算误差将达到不容忽视的程度,甚至导出错误结论。笔者导出的完整刚性数学模型,弥补了简化模型的不足,同时指出了刚性模型的理论缺陷和适用条件。  相似文献   
178.
喻望  卢书强 《矿产与地质》2004,18(3):282-286
通过大量的现场调查数据与统计工作结果,采用了多种岩体质量分级评价方案,对澜沧江某水电站左岸地下式厂房岩体质量进行了精细的评价,最后将各种结果进行对比分析,得到一个合理、科学的综合岩体质量综合评价分级。并根据评价结果,作出了研究区坝址左岸地下式厂房岩体在不同高程的岩体质量分区图,为下一步的参数选取工作奠定了必要的基础。  相似文献   
179.
Rock Mass Rating (RMR) measurements from 65 sites within Huntly East underground coal mine are presented. All measurements are in coal, for which the dominant discontinuities are vertical cleat. Basic RMR values using two discontinuity spacings are presented: overall RMR based on the average spacing of all individual discontinuities; and cleat zone RMR based on the average spacing between zones of cleat. Cleat orientations are highly variable, but on average approximately parallel horizontal stress axes (face cleat follows maximum horizontal stress axis, butt cleat follows minimum horizontal stress axis).Contours of RMR variations throughout the mine are used to compare rock mass conditions with geological structure. It is apparent that: (1) RMR is least within downthrown fault blocks, and particularly immediately on the downthrown sides of faults, and greatest in upthrown fault blocks; and (2) RMR contours parallel horizontal stress axes within fault-bounded blocks, and bend to parallel faults at block boundaries. From similar contours for parameters contributing to RMR, the Rock Quality Designation (RQD), groundwater rating, and discontinuity condition rating create most of the observed variations in RMR. RQD is determined from the measured discontinuity frequency and hence is a measure of the degree of fracturing of the rock mass. This is interpreted as influencing the groundwater and condition parameters directly by allowing greater water ingress. Discontinuity frequency is greatest (least spacing) in the immediate vicinity of faults, and in downthrown fault blocks, generating low RMR values. Within fault blocks RQD varies little, so RMR contours align with cleat orientations.As RMR contours, faults, stress field and cleat orientation are clearly interrelated, there is unequivocally a connection between RMR and structural geology; this allows some predictive capacity in terms of ground conditions. If geological features can be accurately defined through either drilling programs or seismic surveys, then ground conditions may be predicted before panels are driven.  相似文献   
180.
Re-examination of the Skaergaard intrusion in the context ofits regional setting, combined with new data from explorationdrilling, has resulted in a revised structural model for theintrusion. It is modelled as an irregular box, c. 11 km fromnorth to south, up to 8 km from east to west, and 3·4–4km from the lower to the upper contact. The walls of the intrusionare inferred to follow pre-existing and penecontemporaneoussteep faults, and the floor and roof seem largely controlledby bedding planes in the host sediments and lavas, similar toregional sills. The suggested shape and volume are in agreementwith published gravimetric modelling. Crystallization alongall margins of the intrusion concentrated the evolving meltin the upper, central part of the intrusion, best visualizedas an ‘onion-skin’ structure inside the box. Thetotal volume is estimated to c. 280 ± 23 km3, of which13·7% are referred to the Upper Border Series (UBS),16·4% to the Marginal Border Series (MBS) and 69·9%to the Layered Series (LS). In the LS, the Lower Zone (LZ) isestimated to constitute 66·8%, the Middle Zone (MZ) 13·5%and the Upper Zone (UZ) 19·7%. The new volume relationshipsprovide a mass balance estimate of the major and trace elementbulk composition of the intrusion. The parental magma to theSkaergaard intrusion is similar to high-Ti East Greenland tholeiiticplateau basalts with Mg number c. 0.45. The intrusion representsthe solidification of contemporary plateau basalt magma trappedand crystallized under closed-system conditions in a crustalreservoir at the developing East Greenland continental margin. KEY WORDS: bulk composition; emplacement; mass proportions; Skaergaard intrusion; structure  相似文献   
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