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针对西部某库岸公路工程边坡,低强度泥岩分布广泛,尤其是高海拔且地震频发的的地区,滑坡现象尤为严重。为探究涉水泥岩层边坡安全稳定性的影响因素,文中通过数值计算的方法,在考虑泥岩边坡的开挖坡角、物理力学参数和地震作用等因素下,开展边坡安全稳定性系数影响因素的研究。结果表明:随着岩土体材料容重的增加,涉水边坡的安全稳定性系数逐渐降低;而随着岩土体材料粘聚力和内摩擦角的增加,安全稳定性系数也随之增加;且边坡安全稳定性系数对岩土体材料参数中的粘聚力最为敏感。岩土体材料的粘聚力是涉水边坡安全稳定性是边坡稳定分析过程中的重点考虑因素;在考虑地震因素的情况下,涉水边坡相比于在静态条件更加容易失稳;随着边坡坡角的增加以及边坡材料粘聚力的减小,涉水边坡的稳定性逐渐降低。 相似文献
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《南昌工程学院学报》2015,(3)
矿山酸性水作用是矿山边坡体破坏的一种特殊方式,通过对"类土质"边坡表层岩土体及深层岩土体在酸性水作用下进行剪切、抗压强度及纵波波速试验,结合某露天矿山边坡的工程地质条件及类土质边坡的地质特征,分析了露天矿山"类土质"边坡在酸性水作用下的力学性质及失稳机理,为矿山边坡维护加固提供理论依据。 相似文献
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考虑劣化效应的三峡库区某岸坡抗震性能分析 总被引:1,自引:0,他引:1
三峡库区蓄水之后,在库水位大幅度升降变化、降雨、高频中低强度地震等因素作用下,库岸边坡岩土体物理力学特性不可避免地存在逐渐劣化的趋势,这将直接影响库岸边坡的变形稳定。基于此,以三峡库区某库岸边坡为研究对象,考虑岩土体抗剪强度参数的劣化效应,对其抗震性能进行了分析评价。结果表明:对于该库岸边坡,①在各特征水位情况下,随着库水位的上升,岸坡的整体安全系数略有增加,随着地震加速度的增加,岸坡安全系数降低趋势明显;②在各级地震作用下,考虑岩土体抗剪强度参数劣化效应之后,岸坡的抗震能力逐渐降低,岸坡堆积体中下部可能出现局部失稳破坏,随着库水位的上升,岸坡不稳定区域的后缘逐渐上升。研究思路和成果可为库岸边坡长期稳定性评价和加固提供较好的参考。 相似文献
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为了解那卡河水库边坡的受力状态及稳定性,采用有限元法对具有代表性的水电站左侧边坡进行数值模拟,从边坡变形(位移)情况、应力情况和塑性区分布情况等方面来分析边坡岩土体的力学响应特性,以及可能的内在变形破坏机理,采用有限元强度折减系数法对水电站边坡在正常运行工况下的边坡进行稳定性、破坏模式进行分析。结果表明,在正常运行工况下的边坡稳定性系数为1.27。其破坏模式为沿着浅部的泥岩层面产生塑性剪切屈服,并顺着层面滑动,并在坡脚岩体内部产生剪切破坏。破坏时的屈服区分布是在坡脚和泥岩层面位置均产生剪切屈服区,在泥岩层面的顶部坡脚位置也出现拉应力屈服区。破坏时的变形特征为:以坡体沿着层面滑动,并在坡脚位置剪出。 相似文献
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不同类型的边坡有着不同的特点,边坡的变形方式不同导致其破坏方式也不同。对于岩土体结构,岩土体弱化性能有很大差异,如果对所有岩土体进行全局折减,势必会对坡体的稳定性分析造成很大的误差。利用Phase2分析3种不同工况下库岸边坡的稳定性,当对消落带和强风化层进行局部强度折减时,其计算结果与实际监测数据相吻合。由于库水位的升降变化,消落带在长期干湿循环作用下,岩土体结构发生变化,强度降低,岸坡内发生剪切破坏和张拉破坏的区域范围不断增发,由坡脚处逐渐向上延伸,直至崩滑体后缘。 相似文献
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以反倾层状岩质边坡为研究对象,通过振动台试验对地震作用下反倾层状岩质边坡的变形破
坏过程进行了研究,观察记录了在不同频率、振幅、持时地震波作用下模型边坡的宏观变形破坏特征。
在此基础上,对模型边坡的变形破坏模式进行了分析。试验结果表明:地震作用下边坡变形破坏特征与
地震动参数密切相关;结构面对边坡的变形破坏有着控制作用;地震作用下反倾层状岩质边坡的变形破
坏模式可概化为:地震诱发———顶部及浅表部松动变形———坡体裂缝发育、扩展及层间错动加剧———顶
部及浅表部破坏加剧———坡脚拉张裂缝扩展及层间错动加剧,引起边坡大规模崩塌溃坏,散落岩体堆积
坡脚。 相似文献
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陡倾顺层岩质斜坡动力倾倒变形机理研究 总被引:1,自引:0,他引:1
通常认为顺层岩质斜坡动力变形破坏以滑移—拉裂、滑移—弯曲模式为主,但是通过现场调研发现,在陡倾顺层斜坡中存在一类特殊的动力变形破坏方式——倾倒变形。为了得出该类型斜坡动力倾倒变形机理,以四川汶川县水磨沟陡倾软硬相间顺层斜坡在"5.12"汶川地震作用下失稳为例,在充分总结滑坡区工程地质条件和分析其动力破坏特征后,利用二维离散元数值模拟方法开展研究。结果表明:在地震荷载作用下,在斜坡表面PGA放大系数随着高程的增加总体表现节律性变化,在坡肩呈现峰值;斜坡失稳机理为坡内软岩和硬岩差异式拉剪破坏导致层面抗剪强度急剧降低,岩土体沿优势层面下滑;由于坡体下部岩层锁固作用,坡体向下滑动受阻,坡脚附近岩土体翘曲隆起,而坡顶震裂松弛岩土体在巨大地震惯性力下沿优势结构面滑动剪出过程中,受坡肩"关键块体"阻挡而向临空面发生倾倒变形,整个斜坡发生滑移—下部弯曲—上部倾倒式失稳破坏。研究成果为类似地区的边坡工程地震失稳分析提供参考和依据。 相似文献
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根据冗各电站地下厂房开挖支护的施工顺序,以隐式杆单元模拟锚杆,以壳单元模拟混凝土喷层,采用三维非线性有限元技术,对洞室群的开挖支护动态过程进行了模拟计算。通过三维非线性有限元计算分析得到:洞室群动态开挖过程中围岩应力变形的分布规律,围岩塑性区的发展规律,锚杆受力变化情况。计算结果表明:整个开挖过程中,洞周围岩位移变化规律正常,量值较小,塑性区主要分布在洞室周边,围岩稳定性较好;但在洞室交叉口处围岩的变形较大,出现较大范围的塑性区,在此基础上提出了支护措施优化方案,并对优化方案的效果进行了评价。 相似文献
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The relocation of unionacean mussels is commonly used as a conservation and management tool in large rivers and streams. Relocation has been used to recolonize areas where mussel populations have been eliminated by prior pollution events, to remove mussels from construction zones and to re-establish populations of endangered species. More recently, relocation has been used to protect native freshwater mussels from colonization by the exotic zebra mussel Dreissena polymorpha. We conducted a literature review of mussel relocations and evaluated their relative success as a conservation and management strategy. We found that 43% of all relocations were conducted because of construction projects that were forced to comply with the Endangered Species Act 1973 and that only 16% were monitored for five or more consecutive years. Most (43%) relocation projects were conducted from July to September, presumably a period when reproductive stress is relatively low for most species and the metabolic rate is sufficient for reburrowing in the substrate. The mortality of relocated mussels was unreported in 27% of projects; reported mortality varied widely among projects and species and was difficult to assess. The mean mortality of relocated mussels was 49% based on an average recovery rate of 43%. There is little guidance on the methods for relocation or for monitoring the subsequent long-term status of relocated mussels. Based on this evaluation, research is needed to develop criteria for selecting a suitable relocation site and to establish appropriate methods and guidelines for conducting relocation projects. 相似文献
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In the lower River Murray, Australia, populations of gastropods have declined markedly over the past 40 years. Of the native fauna of about 18 species, only the ancylid Ferrissia petterdi remains common (but in patches), and another five species feature in sporadic local resurgences. Until recently the viviparid Notopala was thought to be extinct. The introduced physid Physa acuta is widespread, but in low numbers. The decline probably is associated with flow regulation, high turbidity and the introduction of common carp. Snail populations have persisted, however, in irrigation pipelines fed from the river, where they periodically cause blockages. This paper reports the discovery of the only known populaion of Notopala hanleyi in a pipeline where the inner wall accumulates microbial and other organic matter, providing high quality food for snails. In the Murray before regulation most of the periphytic biomass was probably microbial, as fluctuating water levels would have maintained littoral communities in a highly productive, early state of succession his postulated that, by stabilizing seasonal water levels, regulation has promoted the production of filamentous green algae, an inferior food source, and so displaced snail populations from the open aquatic environment. 相似文献
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简述天湖水电站投运以来各种故障的表现形式,分析其原因,提出了相应的处理方法及措施,并对合理利用国内外设备提出建议。 相似文献
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Various designs of low‐head dams are used to rehabilitate streams or forestall upstream channel incision after channelization. We report on the efficacy of using notched sills and grade control structures (GCS) to restore the fish assemblage in Luxapallila Creek, Mississippi. We tested the null hypotheses that habitat variables and species richness, evenness, and assemblage structure would not differ among: (1) a channelized segment with no modifications; (2) a channelized segment mitigated by the installation of sills and GCS; (3) a segment upstream of the installations and undergoing channel incision; and (4) an unaltered segment. Although habitat variables changed, neither species richness, evenness, nor fish assemblage structure differed between mitigated and channelized segments with both exhibiting less richness and different assemblage structures than the unaltered segment. Lack of differences in species richness between the incised and unaltered segments suggest that the GCS may have halted the negative effects of upstream channel incision before species were extirpated. Conspicuous habitat differences between the altered (channelized and mitigated) and unaltered segments were lack of backwaters and canopy coverage and finer substrates in the altered segments. Our results suggest a more comprehensive rehabilitation strategy is required in Luxapallila Creek. Published in 2003 by John Wiley & Sons, Ltd. 相似文献
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NUMERICAL STUDY OF WAVE EFFECTS ON SURFACE WIND STRESS AND SURFACE MIXING LENGTH BY THREE-DIMENSIONAL CIRCULATION MODELING 总被引:1,自引:0,他引:1
LIANG Bing-chen LI Hua-jun LEE Dong-yong 《水动力学研究与进展(B辑)》2006,18(4):397-404
1. INTRODUCTION Coastal and continental shelf regions are characterized by intensive interaction between wave and current. These regions are of great economic significance to mankind. Therefore, the modeling of wave and current as well as their mutual int… 相似文献