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为了测试柔壁渗透仪的可靠性及其性能,采用水泥土样和普通土样与常用的变水头渗透仪进行了对比测试,并进行了柔壁渗透仪不同渗透压、不同试样高度和直径的对比测试。试验结果表明:柔壁渗透仪测试结果准确、性能可靠,柔性壁密闭性好,对制样要求不高,试样高度和直径可在一定范围内选择;可采用高渗透压快速完成渗透系数测试;仪器可用于测试渗透系数小于1×10~(-5)cm/s的水泥土样、水泥浆样和塑性混凝土样,以及渗透系数小于1×10~(-6)cm/s的硬土样测试。 相似文献
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通过肖河东沟排水倒虹吸基底15%水泥土换填碾压试验,先确定符合碾压试验压实度要求的铺土厚度和碾压遍数,通过单位压实遍数的压实厚度进行比较,其中单位压实遍数的压实厚度最大者为最经济合理,由此确定合理的碾压技术参数。试验结果表明,铺土厚度为30 cm,20 t凸块振动碾行进速度为2.0 km/h,碾压10遍,压实度不小于0.98,干密度达到1.76 g/cm3,确定了肖河东沟排水倒虹吸基底15%水泥土换填最优碾压技术参数。现场碾压无弹簧、无涌土、无光面、无表面龟裂、无剪切破坏现象,经检查,上下层土结合良好,无明显分层现象。 相似文献
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土质心墙堆石坝是目前水电站设计的主要坝型之一,其坝高已达到300 m级,该坝型解决的首要问题是心墙防渗土料的抗渗性能。为得到贴近实际的渗透系数,对几个水利水电工程心墙防渗土料的原位渗透和室内渗透试验成果进行对比分析。研究发现原位渗透试验所得渗透系数基本上都大于1×10-5cm/s,超出规范要求,而室内渗透试验成果基本上都小于1×10-5cm/s。从边界条件和外界影响等因素综合分析,室内渗透试验方法所得渗透系数更贴近实际,该结论对于类似工程设计和施工具有一定的参考意义。更多还原 相似文献
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为研究不同压实度下脱硫石膏动模量与阻尼比特性,分别对压实度为0.85,0.90,0.95的3组脱硫石膏试样进行动三轴试验。试验分为等压固结和偏压固结试验2部分,等压固结试验固结应力比为1,围压分别为100,200,400 kPa;偏压固结试验围压为100 kPa,固结应力比分别为1.0,1.5,2.0。试验结果表明:随压实度增大,脱硫石膏动模量逐渐增大,阻尼比在动应变<10-5时差异不明显,动应变>10-5时逐渐减小;初始动模量与压实度具有良好的幂相关关系,建立了考虑压实度影响的初始动模量公式,进而推求了考虑压实度影响的动模量衰减全过程曲线;归一化的脱硫石膏动模量和阻尼比差异较小,试验用脱硫石膏参考动应变取值范围为1×10-4~4×10-4。 相似文献
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为研究防渗土体在掺入食盐后的工程特性变化,测定符合设计规范要求的掺盐量,分别在水库大坝和河道堤防的防渗土样中掺入不同类型、不同掺量的食盐,进行土样物理化学及力学特性试验。试验结果表明:低液限黏土在精盐掺量不大于3.29%,混合盐掺量不大于2.99%时,水溶盐质量分数均符合规范要求;在试验的掺盐范围内,渗透系数均在1×10-7~7.9×10-7cm/s之间,满足规范要求,其他指标虽有变化,但变幅不大。 相似文献
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卢晓鹏 《水利水电科技进展》2013,33(1):49-52
为了解龙虎水库大坝防渗心墙料(当地泥岩风化料)的压实情况,以便为大坝的填筑施工提供科学依据,对泥岩风化料进行现场碾压试验。试验结果表明,由于料源母岩以软岩为主,在碾压和击实过程中砾石破碎率大于30%,压实性满足设计要求;按碾压试验确定的参数施工,防渗性能满足设计要求;料场天然含水率高于且接近最优含水率,施工时不用调整含水率可直接上坝,但要立采混合均匀方可进行填筑;该土料渗透系数小于5×10-6cm/s,具有较高的抗渗透变形稳定性。经复核试验验证及蓄水检验,当地泥岩风化料在龙虎水库大坝防渗心墙填筑中的应用是成功的。 相似文献
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隧洞围岩含水率及渗透情况对隧洞开挖工艺、降排水及支护的设计具有重大影响。通过对引洮供水二期工程地质钻孔地层情况及孔内赋水情况分析,选定典型隧洞围岩段,通过在杂色黄土状土围岩段进行钻孔常水头注水试验和在新近系砂质泥岩强风化段进行提水试验,确定其围岩含水量大小及渗透系数,经过试验和计算确定:杂色黄土状土、新近系砂质泥岩强风化层的渗透系数在1.0×10-5~1.0×10-6 cm/s数量级,两类地层渗透系数很小,富水性贫乏,岩体透水性属较差和很差级别。可为引洮供水二期地下透水性隧洞围岩的开挖工艺、降排水及支护设计提供可靠的水文地质资料。 相似文献
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为了配合长江重要堤防隐蔽工程建设,采用试验的方法,对湖北省荆南长江干堤的土质进行了研究。结果表明:①干堤堤身填筑质量较差,大多数堤段的压实度达不到92%的要求,堤身填土的平均压缩系数均在0.3MPa^-1左右;渗透系数大多为10^-5-10^-6cm/s量级;堤射填筑压实度不均匀。②堤基土土层分布复杂,密度普遍较低,各种类型土的孔隙比大多数在0.70-1.00这间,处于较为松散的状态。③堤基土的pH值在7.05-8.95之间,属弱碱性,不会对土的液塑限及抗剪强度产生太大的影响。土的易溶盐含量在0.01%-0.52%之间,不会对土的力学性质产生大的影响。 相似文献
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心墙是土石坝防渗体系的重要组成部分,砾石土在土石坝心墙填筑中应用越来越广泛;因此要严格保证砾石土的级配和压实度满足设计要求。以长河坝水电站为依托,介绍了砾石土心墙料碾压参数的确定方法。后期现场应用表明,长河坝水电站砾石土心墙料碾压后全料压实度不小于97%,细料压实度不小于100%,土料P5含量为30%~50%,碾压遍数为静2+振12遍,铺土厚度30 cm,采用26 t的自行凸块振动碾,行走速度控制在(2.5±0.2)km/h,可满足设计要求。 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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V. K. Konovalov O. V. Yashkin V. V. Ermakov 《Power Technology and Engineering (formerly Hydrotechnical Construction)》2008,42(2):105-109
A system for removal and pneumatic transport of fly ash is examined, in which air pulses act on batches (pistons) of ash formed
in a duct. Studies are made of the effect of several physical parameters on the force required to displace a piston of ash
and these serve as a basis for choosing a system for removal and pneumatic transport of ash simultaneously from several hoppers
of an electric precipitator. This makes it possible to separate the ash particles according to size without introducing additional
components. Formulas are given for calculating the structural and dynamic parameters of this system and measurements of indirect
dynamic parameters are used to calculate the input-output characteristics of the system. In order to optimize the system,
configurations for summing several ducts into a single transport duct for pneumatic ash transport are proposed. Some variants
of dry ash utilization and the advantages of producing of size-separated particles are considered.
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Translated from élektricheskie Stantsii, No. 2, pp. 26–30 (2008). 相似文献
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Peter B. Bayley 《河流研究与利用》1991,6(2):75-86
The ‘flood pulse advantage’ is the amount by which fish yield per unit mean water area is increased by a natural, predictable flood pulse. Evidence for this increase is presented from tropical and temperate fisheries. It is argued that increasing multispecies fish yield by restoring the natural hydrological regime is consistent with increasing production of other trophic levels and with restoration from ecological and aesthetic viewpoints. When applied to a river-floodplain system, this restoration would provide a large, self-sustaining potential for recreation, commercial exploitation, and flood control. An interim ‘natural flood pulse’ restoration approach is proposed for systems modified for navigation. This approach approximates the natural hydrological regime in a river reach and is intended as a first step in the long process of restoring the watershed. 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