水泥粉喷桩在双乳山水库西围堰基础防渗中的应用

:1 997年 ,我们引入建筑行业加固地基采用的水泥粉喷桩技术 ,成功地处理了忻州市双乳山水库西围堰砂土基础严重渗漏问题。粉喷桩桩径 5 0 0mm ,桩中心距 375mm ,成墙厚度 330mm ,桩深 1 2～ 8.1m ,桩体每 1m进尺喷灰量5 8.9kg ,待桩体凝固 2 8d后钻探取芯样室内试验并进行现场压水试验 ,渗透系数为 5 .5 4× 1 0 -5cm/s ,无侧限抗压强度 6 .8MPa,经一年多运行 ,防渗效果良好。实践证明 ,水泥粉喷法成墙技术在水利工程的堤坝加固和砂土基础防渗处理中具有广阔的应用前景。     

2006年广州老八区将实现污水百分百处理

为实现到 2 0 0 6年广州老八区污水处理率达到1 0 0 %的目标 ,在 2 0 0 4年至 2 0 0 6年间将新建 6个污水处理厂 ,1 2座泵站 ,包括流溪河在内的 4 6条截污河涌和新建 91 8km的截污管理。据初步估算 ,该项工程将超过 70亿元。根据有关部门预算 ,目前广州老八区每天产生污水量约为 1 91万m3 ,预计到 2 0 0 6年污水量将达到 2 0 4万m3 /d。目前原有及在建的污水项目总处理能力约为 1 4 2万m3 /d ,至今年年底广州市的污水处理率将达到 70 %。为实现 2 0 0 6年广州老八区污水处理率达到 1 0 0 % ,广州市在 2 0 0 4年至 2 0 0 6年将新增 98万m3 /d…     

垂直荷载作用下搅拌桩的现场试验

在长江中下游河漫滩软基上，建造5万m3大型油罐，软土层超过25m，地基承载力标准值仅为70kPa，拟用长26m的水泥搅拌桩加固。经试桩效果检验，复合地基承载力标准值达231kPa，桩土应力比为6～8。此外，对搅拌桩的应力传递、摩阻力分布和重复加荷对地基变形的影响等进行了探讨。     

免共振沉桩原位试验研究

为解决传统桩基施工过程中存在的环境污染、挤土效应、效率低及能耗高等突出问题,以某高架桩基工程为例,基于免共振液压振动锤系统沉桩施工工艺,通过原位沉桩试验测试、现场振动测试,研究钢管桩沉桩过程中桩周土体、地铁运行期间桥墩变形特征及其振动变化规律。研究结果表明:钢管桩沉桩过程中桩周土体水平位移集中分布在近地表0~2/3L(L表示桩长)范围内,地表以下0~1/4L范围水平位移较大,土体水平和竖向位移最大值分别为2.37 mm和3.13 mm,桥墩倾斜0.4‰~0.7‰,分析发现沉桩过程中挤土效应不明显;现场振动测试结果显示,当无地铁经过时桥墩振动速度最大峰值为0.823 mm/s,有地铁经过时为1.90 mm/s,充分表明沉桩过程对周边环境影响程度弱;实现了对环境“低影响”的效果,为沉桩施工新技术的研发提供理论和实践指导。     

荣成市水资源开发利用对策探讨

1　水资源开发利用现状荣成市地处胶东半岛最东端 ,水资源自成体系 ,几乎没有外域来水。全市多年平均降水量 775 .3mm,水资源总量 4 .0 9亿 m3,人均水资源占有量 6 0 0 m3,仅为全国人均占有量的 1/4 ,世界人均占有量的 1/16 ,大大低于国际公认的人均占有量 10 0 0 m3的缺水警戒     

立式储罐基础下陷的处理措施

1　前　言某厂新建一罐区 ,共 11台立式储罐。在罐体施工完毕进行充水试验后发现罐底发生了不同程度的凹凸变形 ,整体表现为罐底沉降 ,且罐底与罐基础间出现空隙 ,严重影响了罐区的正常使用。沉降最严重的一台储罐 (TA - 5 0 4 ) ,罐体直径Φ12 5 0 0mm ,高 12 2 0 0mm ,容积 14 96m3 ,罐基础环墙厚30 0mm ,底标高 - 0 .8m ,环墙内自上而下为 80～16 0mm厚沥青砂、30 0mm厚砂垫层、80 0mm厚素回填土、10 0mm厚C10素混凝土垫层。经对储罐 (TA - 5 0 4 )罐底测定并绘制罐底变形趋势图看出罐底表现为较为严重的波浪状变形 ,整体上呈周边高、…     

发展节水灌溉 促进经济持续稳定发展

1　苏家屯区基本情况　　苏家屯区位于沈阳市南部 ,辖 1 4个乡镇、 6个街道办事处 ,总人口 42万人。区域面积 762km2 ,耕地面积 4 4万hm2 ,其中水田面积 1 6万hm2 。全区多年平均降水量 734 5mm ,多年平均蒸发量 1 4 1 3 5mm ,水资源总量为 30 888 4万m3,其中地表水多年平均径流量为 1 37465万m3,可利用量 35 2 7 6万m3,地下水年综合补给量 1 742 3 4万m3,可利用量 1 31 33 7万m3,平均每人占有地表水量 368 9m3/(人·a) ,占全省人均占有量的 1 /3。苏家屯区农业灌溉用水占全区总用水量的80 %以上 ,2 0世纪 5 0年代末修建的两座灌区 ,经过多…     

三门峡水库蓄清排浑运用以来库区冲淤演变初步分析

水库蓄清排浑运用以来 ,黄河潼关 1974～ 1986、1987～ 1995、1996～ 2 0 0 2年均水量较 195 0～ 195 9年减少9 1% ,35 5 %、5 5 5 % ,沙量减少 4 0 9%、4 9 6 %、6 6 2 %。潼关以下三个时段年均淤积量为 0 0 4 2、0 16 1、0 2 0 8亿m3。呈水沙量递减 ,淤积量递增趋势。潼关同流量水位 2 9年升高 2 31m ,受上游冲淤下延影响升高 1 0 5m占 4 5 5 % ,其他因素影响升高 1 2 6m占 5 4 5 %。小北干流非汛期冲刷、汛期淤积格局未变 ,反映了水库运用对小北干流没有明显影响。渭河华县站 1974～ 1986年水量较大 ,渭淤 1～ 10断面仅淤积 0 0 6 5亿m3,华县同流量水位升高 0 0 3m。以 1974～ 1986年为准 ,1987～ 1995年、1996～ 2 0 0 2年华县年均水量减少 2 2 8%、5 6 2 % ,年均沙量减少 11 6 %、34 4 %。渭淤 1～ 10断面 1987～ 1995年淤积 1 72亿m3,特别是 1994和 1995年的中小洪水 ,汛期淤积 0 85亿m3主河槽萎缩 ,华县同流量水位升高 1 0 7m。     

预应力钢筋混凝土系杆拱桥系杆体外预应力加固施工

1 工程概况 通榆河阜宁城北公路桥桥孔布置为2×25+51+2×25m,全桥总长156m。桥面净宽9m,人行道宽2×1.5m,荷载标准为汽—20、挂—100、主跨采用51m下承式预应力混凝土系杆拱,边跨及边中跨为25m预应力T型梁;下部结构为混凝土双柱式桥墩,灌注桩基础,桥台为灌注桩桩柱式。主跨拱肋采用二次抛物线拱轴线,矢跨比为1/5(图1—a)。系杆及拱肋均采用工字型截面(图1—b、1—c),系杆内布12束6φ~j—15预应力钢铰线,其中第一批8束,第二批4束(图1—d),采用OVM锚具;吊杆为42φ~s5高强钢丝,DM锚具,外套φ102mm钢护套,吊杆分两次施加预应力。     

黄河冲积平原钻孔灌注桩施工注意事项

聊城市的地质成因为黄河冲积,属新生代第四纪,以河相冲积为主,湖相沉积为辅,其地质结构由上而下分别为杂填土、粉土、粉质粘土及粉砂。地质状况较为复杂,土的压缩系数在0·01≤a1-2≥0·05,属中高压溶性土。因此,高层建筑物的基础主要采用桩径为1200~500mm的钻孔灌注桩。为保证桩的质量和建筑物的安全,施工中应注意如下几点:1场地的布置及设备的安装为保障施工速度,泥浆池应为4m×4m×1·5m,且池顶应高于孔口0·3~0·5m。为保障钻孔的垂直度,钻机安放前,先清理平整场地,然后进行夯实,其干容重应为ra≥1·65。2钢筋笼的制作为保障钢筋的制作…     

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。     

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。     

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.