深埋隧洞开挖过程中突水与突泥的机理研究

突水与突泥是隧洞施工过程中常遇的重要工程灾害之一,本文利用离散元法,采用颗粒流PFC3D软件,结合流体动力学数值模拟的有限体积法,建立了由裂隙岩体及断层组成的围岩隧洞突、涌水三维数值模型,模拟隧洞突水、突泥的全过程;探讨了集中水源 （断层） 水压力、岩体裂隙性状等对隧洞突水、突泥的影响。据此提出了工程突水、突泥预防中两个重要的概念：突水临界水压力和前方临界突水距离。并提出了隧洞突水、突泥的发生机理,认为突水发生的前提是存在集中的高压水源。水源压力的大小、开挖面至集中水源的距离、岩体强度、岩体裂隙性状是影响突水的主要因素。     

某水电站引水隧洞突水数值模拟

 离散元软件 UDEC 可以用来模拟裂隙岩体的开挖以及进行水力全耦合分析。采用 UDEC 来模拟裂隙岩体开挖后在水力耦合作用下渗流流量与其对应水压力的变化过程并预测可能发生的突水灾害。结果表明开挖洞室以后,在围岩渗流与应力耦合作用下,围岩中裂隙隙宽、裂隙中水压及其渗透流量三者相互作用、相互依赖。裂隙隙宽的减小使得结构面水力梯度变大,作用在裂缝上的渗透压力增大,促进导水裂缝扩展,裂隙连通性增加。裂缝隙宽增大,渗透能力增强,渗流量增大,其渗流压力相应降低。在一定条件下,裂隙隙宽的改变可导致局部水力通道的形成,高压水头从局部涌出,从而促进突水灾害的形成。西南某水电站在深部裂隙岩体中开挖引水隧洞,该处地应力高且外水压大,容易引起突水灾害,对其进行了突水数值模拟,提示了一些可能发生突水的位置。     

岩溶隧道涌水突泥过程演化研究

综合考虑地质构造、水文特征、施工建设等因素影响,将岩溶隧道涌水突泥过程演化抽象概化为4个阶段:①岩溶地质环境形成阶段为致灾构造的发育演化提供地质条件;②岩溶水系通道扩展阶段为涌水突泥体的储存和流动提供空间;③岩溶涌水突泥临界状态形成阶段主要受致灾泥水体和人为隧道开挖影响;④岩溶涌水突泥释能降压阶段是整个过程的结束,表明灾害已经发生。基于案例统计分析将岩溶隧道涌水突泥依据不同要素划分为3大类11种型:地质构造类(断层型、向斜型、背斜型、岩性分界面型),涌水通道类(裂隙型、管道型、溶洞型、暗河型),涌水突泥类(涌水型、突泥型、突水突泥型)。研究成果对隧道涌水突泥灾害控制的研究和隧道安全施工有一定的借鉴意义。     

引汉济渭秦岭隧洞突涌水原因及涌水量预测

针对隧洞开挖施工中常见的隧洞突涌水等地质灾害问题,在分析隧洞涌水区域水文地质条件、有限元渗流计算和达西定律的基础上,研究秦岭隧洞椒溪河段开挖涌水原因并预测涌水量。研究表明:在涌水发生的初期,涌水集中渗漏通道由断层泥及断层角砾填充,发生的流动为渗流,通过有限差分软件数值计算求得的隧洞开挖初期涌水量与实际隧洞开挖涌水初始阶段的涌水量非常接近;在涌水稳定阶段,涌水集中渗流通道发生类管涌的水力破坏,通过集中渗漏通道流入隧洞内的流量为1 671.55 m3/h,与现场实测隧洞涌水稳定时的最大涌水量1 700 m3/h接近。研究成果可应用于水文地质条件类似的隧洞工程涌水量计算。     

隧洞突泥涌水灾害处理施工

在地下工程施工过程中不可控施工风险较多，在众多灾害中，突泥涌水造成的工程损失规模一般较大，且在事故发生后，如何正确处理，避免二次灾害的发生尤为重要。通过对某隧道发生突泥涌水灾害后的处理措施进行详细介绍及总结，为后续同类工程在施工过程中遭遇突泥涌水处理时提供参考，尽可能地降低灾害影响。     

滇中引水工程白云岩砂化隧洞涌水突泥处理研究

为了解滇中白云岩砂化特征，剖析其形成机理，探索滇中白云岩砂化隧洞涌水突泥的处置方法和措施，以滇中引水工程松林隧洞为例，对上述3个方面进行系统研究。研究结果表明：(1)滇中白云岩砂化为白云岩中可溶的方解石溶蚀流失后，不溶物石英砂颗粒填充溶蚀通道形成的砂化现象。由于进入白云岩砂化洞段前围岩条件好，导致涌水突泥具有突发性。(2)白云岩砂化段因结构松散易发生垮塌，在地下水的持续冲蚀下，断层带内松散的岩块发生软化和进一步垮塌形成空腔，产生集中涌水通道，形成反复涌水突泥。(3)白云岩砂化洞段涌水突泥处理措施包括快速抽排清淤、反压及封闭掌子面、布置超前排水孔降低空腔水压、对渣体进行灌浆形成支撑体、采用超前大管棚和小导管灌浆、利用超前探孔找出空腔位置并采用混凝土回填等方面。(4)超前地质预报是预防白云岩砂化洞段涌水突泥的基础，初期塌方快速封闭和反压处理是预防涌水突泥的关键。     

引汉济渭引水隧洞穿椒溪河段突涌水数值模拟

陕西省引汉济渭工程引水隧洞突涌水问题是制约工程顺利开展的关键技术问题之一。针对横穿椒溪河段的典型区段突涌水问题,采用ADINA软件建立水文地质概念模型,计算不同工况下该区段的地下水位、流速矢量、涌水量等。结果表明:断层位置受开挖扰动影响较大,出现了集中渗漏,因此在断层位置极易形成渗漏通道,发生突涌水。     

狮子山隧洞突涌介质特性与致灾模式

为了掌握玄武岩地层向斜构造不良地质体构造特征与突泥突水机制,以滇中引水工程狮子山隧洞穿越乌龙坝向斜构核部附近突水突泥灾害为例,研究了该段突水突泥灾害演化与致灾地质构造、致灾介质基本特征与致灾动力及诱发机制。结果表明：(1)突涌原因为构造向斜上盘节理裂隙密集带储水构造使下位凝灰岩裂缝扩展发育崩解软化、泥化,连接上部储水构造体,导致致灾介质体突涌;(2)突水突泥致灾介质类似稀性泥石流,瞬时爆发涌出,携带巨大能量;(3)隧洞卸荷坍塌、地下水作用及应力释放等共同作用导致了灾害形成。研究成果对隧道穿越褶皱构造防治突泥突水灾害具有一定指导意义。     

夹岩水利枢纽及黔西北供水工程猫场隧洞4号施工支洞涌水、突泥处理施工技术

猫场隧洞4号施工支洞为具有多种不良地质情况的辅助施工隧洞,施工中多次发生了特大涌水、突泥等不良地质灾害。通过对隧洞涌水、突泥灾害产生的原因进行详细的分析研究,采取一系列行之有效的处理施工措施,并对洞身进行了超前帷幕灌浆堵水和超前地质预报,快速而有效的完成了涌水、突泥不良地质洞段的施工。介绍猫场隧洞涌水、突泥灾害情况及采取的灌浆堵水处理措施。     

河南某工程引水隧洞突泥突水原因分析与处理措施

隧洞施工过程中,突泥突水现象比较常见,但其原因各有不同。隧洞突泥突水往往会给工程施工造成巨大危害,如果处理不当还会造成巨大的财产损失,并危及人员安全。文章通过对河南某引水工程的突泥突水原因进行分析:从隧洞的基本地质条件入手,分析了地质构造、气象条件和水文地质条件与突泥突水的关系,并就其处理措施进行了介绍,供类似工程参考和借鉴。     

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。     

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。     

浅谈天湖水电站水轮机运行故障及处理措施

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。     

Fish assemblage response to recent mitigation of a channelized warmwater stream

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.     

NUMERICAL STUDY OF WAVE EFFECTS ON SURFACE WIND STRESS AND SURFACE MIXING LENGTH BY THREE-DIMENSIONAL CIRCULATION MODELING

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…