强夯法在飞机坝防洪工程地基加固中的应用研究

本文介绍宜宾飞机坝防洪工程粉土类地基强夯法现场试验加固效果及检测结果.强夯加固地基检测结果表明1600kN.m夯击能有效加固深度达到8m,地基土的干密度明显增加,平均值从天然地基的1.48g/cm3增加到强夯后的1.57g/cm3,增幅达到6.1%;粉土层的孔隙比平均值从0.852减小到0.724;地基土的压缩模量平均值从5.42MPa提高到8.27MPa;渗透系数算术平均降低到天然地基的1/10以下,均值从2.5×10-4cm/s降低到3.5×10-6cm/s.强夯后,地基土满足了防洪堤地基的承载力和渗透稳定要求.     

混凝土面板堆石坝挤压式边墙试验研究

为了分析混凝土面板挤压式边墙的物理力学性能,结合黄河公伯峡、积石峡水电站挤压墙施工质量检测,通过配合比验证试验和现场检测结果,指出:当挤压墙混凝土湿密度在2.15～2.20 g/cm3范围内,即干密度为2.04～2.09 g/cm3、弹性模量在4 000～6 000 MPa时,能够满足施工要求和坝体渗透要求.     

护岸工程水下抛石的数量和质量控制

以长江重要堤防隐蔽工程岳阳长江干堤永济河段加固工程为例，介绍了水下抛护工程质量事前控制、过程控制以及事后把关诸方面的监理实践过程。对抛石的材质要求进行了讨论，建议抛石的物理力学指标定位为：①取样检测指标－温抗压强度RC湿≥MPa，干密度γ干≥260g/cm^3,软化系数α≥0．70；②现场检查指标－摩氏硬度＞3。     

潜水泵叶轮进出口参数的选择与分析

提高潜水泵的效率 ,可以采取缩小进口直径D0 ,并推荐进口速度系数K0 =3.7～ 4.0 ,加大叶片进口安放角β1,叶片进口冲角为 8°～ 15°。为适应井用潜水泵的特点 ,推荐ns=90～ 2 40的井用潜水泵的速度系数Ku2 、Km2 叶轮出口安放角 β2 以及相对速度W1/W2 随ns 变化的曲线。     

浅谈安图水库大坝护坡破坏原因及其防治措施

安图水库位于布尔哈通河支流福兴河下游 ,距安图县城 5ｋｍ。水库控制流域面积 370ｋｍ2 ,总库容 4746万ｍ3,是以灌溉、防洪、发电、养殖为主的综合性水利枢纽工程。该枢纽工程由大坝、泄洪洞、灌溉隧洞及水电站组成。大坝坝型为粘土心墙、风化砂坝壳 ,迎水坡采用干砌块石护坡 ,最大坝高 2 3 2ｍ3。水库于 1 968年 1 0月建完交付使用 ,运行至今已有 35年。1　大坝护坡破坏原因分析1 1　自然因素的影响安图县地理位置在东经 1 2 7°48′～ 1 2 9°0 8′ ,北纬 42°48′～ 43°2 4′之间 ,由于受季风的影响 ,夏季炎热多雨 ,最高气温达到 36 4…     

洞室爆破在满拉水利枢纽工程中的应用

1　堆石料场地质简介满拉水利枢纽工程堆石料场为沿公路分布的长条形山体 ,岩石主要为辉绿岩 ,含有细砂岩和石英砂岩透镜体 ,容重γ=0 .0 2 97N/ m3,岩石坚固系数 f =8～ 12 ,山体地面坡度在 40°～6 0°不等 .该地段的岩体节理裂隙较发育 ,而设计要求上坝堆石料粒径在 80 cm以下的级配连续 ,因此 ,给爆破施工带来了一定的难度 .2　爆破方案选择论证针对本爆破区岩体节理裂隙发育的特点 ,在总结前两次爆破经验和教训的基础上 ,在爆破方案上作了如下修正 .采用前方抵抗线与上方抵抗线之比 (W/ h)为 0 .5 .这样类似于崩塌爆破 ,大部分岩体靠…     

压实度控制在“635”主坝施工中的应用

1.概述 　　“ 635”主坝粘土填筑以Ⅰ＃土料为主要填筑材料，Ⅵ＃土料用于周边接触层填筑，用量较少 (填筑控制指标见表 1)。 　　从料场检查结果来看，Ⅰ＃、Ⅵ＃土料极不均匀，土料压实性变化很大，甚至在同一料场相距较近的位置，土的性质也有很大差别 (见表 2)。 表 1 土料填筑控制指标 土料干密度(g/cm3)含水量(％)压 实 度接触层坝肩 土区630以下630以上Ⅰ＃1.6319～23％//0.890.98Ⅵ＃1.5320～24％0.990.98//　　表 2土料场物理性质试验结果 项目粘粒含量(％)塑性指标最优含水量(％)最大干密度(g/cm3)渗透系数备注Ⅰ＃22～…     

钢渣粉煤灰用作路面基层材料的性能研究

针对我国目前大量钢渣未能有效利用的问题,考虑将其与粉煤灰混合作为路面基层材料。通过击实试验可以得到不同比例的钢渣粉煤灰的最大干密度与最佳含水率,最佳含水率最小为12.9%,最大干密度最大为2.04 g/cm3。钢渣粉煤灰配比为1:1、外加剂掺量为2.5%时抗压强度最大,达到了8.36 MPa,此配比的劈裂强度为0.82 MPa,其抗压强度与劈裂强度仅小于水泥稳定碎石。通过抗裂性能试验可以得到钢渣粉煤灰的平均干缩系数为25.91×10-6、平均温缩系数10.13×10-6,均小于水泥稳定碎石,因此钢渣粉煤灰是一种良好的路面基层材料。     

高压喷射灌浆技术在某防渗墙施工中的应用

以洮河流域插补引水式水电站为例,介绍了高压喷射灌浆技术应用于厂房围堰防渗墙的施工工艺,并进行高压摆喷试验,确定了自下向上摆喷的方法及参数:摆角为30°;高喷灌浆高压水压力为35～38 MPa,流量为70～75 L/min;水泥浆液压力为0.7～1.0 Mpa,流量为60～70 L/min;气压为0.6 Mpa,流量为1 m3/min;灌浆浆液开灌水灰比为1?1或0.8?1,进浆密度为1.57～1.7 g/cm3,返浆密度≥1.2 g/cm3。经质量检查,成墙效果较好。     

海外文摘

池塘与湿地处理系统 -WaterScience&Technolo gy,2 0 0 3(5)在北方许多温带地区 ,常利用湿地来协助池塘处理废水。对 2 1个湿地系统的分析表明 ,TSS、BOD、NH4-N、TP和排泄物大肠杆菌的平均清除率分别为 67%、61 %、61 %、48%和 99.8% ,水力加载速率为 0 .1 4～ 55cm/d,清除面积为 0 .0 2～ 2 0 0hm2 ,纬度为 30°～ 54°N。随温度而变的一阶模型的校准结果显示 ,加载小时 ,氨的比例常数与季节有关 ;加载大时则与温度有关。磷的比例常数具有季节性 ,不受温度变化影响。BOD和TSS不受季节影响。湿地中上述成分的比例常数比池塘中的大…     

地下厂房施工过程的三维非线性数值模拟分析

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。     

Evaluation of freshwater mussel relocation as a conservation and management strategy

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.     

基于模型试验的河床砂砾石层基本特性研究

为了经济可靠地确定深厚覆盖层的基本特性参数,以大渡河双江口水电站坝基河床砂砾石层基本特性研究为工程背景,进行大尺寸模型试验,研究河床砂砾石层的旁压模量和动探击数随密度、级配以及上覆压力的变化规律。根据室内模型试验结果,结合现场旁压试验及钻孔试验成果,推断出坝址区河床砂砾石相关层位的密度,并依此进行砂砾石室内力学试验,获得设计所需力学参数。研究成果可为深厚覆盖层基本特性测试提供新的方法。     

Serial discontinuities in a Rocky mountain river. I. Distribution and abundance of plecoptera

Samples were taken year-round at eleven sites along the altitudinal profile (2900-1400 m a.s.l.) of the Gunnison River, a 329 km tributary of the Colorado River, to document the distribution of the Plecoptera and to evaluate responses to hypolimnial-release dams in the headwaters and middle reaches. Twenty-two species were present, with the greatest species richness occurring in an unregulated segment upstream of the middle reach dams; average nymphal biomass over the study period (175 organisms, 395 mg dry mass m^?2) was also greatest in this segment. Only four species (58 organisms, 48 mg m^?2) were present in the tailwaters of the headwater dam and values were greatly reduced (nine species; 35 organisms, 180 mg m^?2) below the middle reach dams. The stonefly community recovered ca. 80 km downstream from the last dam (15 species; 244 organisms, 250 mg m^?2), apparently in response to natural resetting of environmental conditions corresponding to those above the middle reach dams. At the most downstream site (11) only four species (four organisms, 16 mg m^?2) were present. The observed distributional pattern is a classic serial discontinuity in response to hypolimnial stream regulation in a temperate latitude river.     

基于BP神经网络-马尔科夫链模型的隧道围岩位移预测

在隧道工程施工中,围岩位移预测起着很重要的作用。将BP神经网络-马尔科夫链模型引入到隧道围岩位移预测中来,通过对训练样本的学习,利用BP神经网络实现了对位移时间序列的滚动预测,同时得到了实测值与预测值的相对误差;在此基础上利用马尔科夫链对相对误差进行修正,有效地提高了预测结果的精度。并将该模型应用于某公路隧道拱顶下沉位移时序预测中,结果表明该模型具有精度高、科学可靠的特点,为隧道围岩变形的预测提供了新的途径。     

Short communication. Pipelines as a refuge for freshwater snails

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.     

浙江省水域调查录入系统的设计和应用

浙江省水域调查录入系统将调查数据与电子地图相整合,对分类水域数据进行统计计算,并对输入数据进行合理性和完整性检查,得到调查范围内现有水域的详细数据,实现了水域调查数据输入、计算、统计和查询的数字化管理,提高了工作效率和工作质量,为各地下阶段水域保护规划编制和水域管理工作提供了数据支持。对该系统的设计原则、功能和技术设计等作了介绍。     

Automated system for removal and pneumatic transport of fly ash from electric precipitator hoppers

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. __________ Translated from élektricheskie Stantsii, No. 2, pp. 26–30 (2008).     

The flood pulse advantage and the restoration of river-floodplain systems

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.     

基于CT-连续加荷水泥乳化沥青混凝土细观损伤规律研究

利用CT技术对水泥乳化沥青混凝土的细观损伤过程进行实时扫描观测,获得了混凝土试件在连续加荷下的CT图像。通过采用直观分析法、CT数分析法、CT数与损伤变量关系3种方法分析表明,水泥乳化沥青混凝土的破坏过程可分为压密、扩容、裂纹扩展、破坏4个阶段,同时混凝土在受压过程中具有韧性,在极限荷载之前各断面处于压密和微扩容的强化阶段,极限荷载之后混凝土从损伤到破坏发展比较平稳。