地下水封石油洞库渗流场的数值分析

对研究区水文地质条件和地下水封石油洞库、水幕系统进行了概化,利用Visual MODFLOW软件,建立了某地下水封石油洞库无水幕和有水幕条件下的三维地下水数值模拟模型,模拟了地下水封石油洞库区的渗流场。利用所建模型预报了2种条件下涌入地下水封石油洞库的涌水量、区域地下水降落漏斗扩展情况及洞库上方地下水位变化情况等。由预测结果可知,2种条件下洞库涌水量均逐渐减小并趋于稳定,而有水幕条件下的地下漏斗扩展范围和速度均比无水幕条件小;在洞库开挖初期水幕作用较小,随时间延长作用愈加明显,因此水幕系统在保证地下水封石油洞库的储油安全和保护周围地下水资源方面都起到重要作用。     

京杭运河续建工程韩庄枢纽船闸基坑开挖施工

韩庄船闸是京杭运河续建工程建设中重要工程,本文对船闸基坑大开挖施工以及施工过程中出现的问题和采取的处理措施进行了总结。     

京杭运河续建工程韩庄枢纽船闸基坑开挖掘施工

韩庄船闸是京杭运河续工程建设中重要本文对船闸基坑大开挖施工以及施工过程中出现的问题和采取的处理措施进行了总结。     

扩眼器在定向造斜段的应用可行性研究

随钻扩眼器可有效扩大下部井眼直径,对于优化井身结构、提高完井质量、提高钻进效率、降低后续作业风险具有重要意义。随钻扩眼时该工具相当于一个满眼扶正器,在直井段工作时扩眼器具有防斜作用,但在定向段随钻扩眼时该工具将改变常规造斜钻具的造斜特性,因此该工具在定向造斜段应用的可行性需要研究。以一套常用造斜钻具为例,计算了其初始造斜率以及直接扩眼工况和随钻扩眼工况的造斜率,发现使用扩眼器后对原有钻具组合的造斜特性影响很大。为达到原有造斜要求,通过单独和组合调整BHA参数（主要有螺杆钻具弯角、上稳定器外径、上稳定器距离钻头距离等）获得与原有BHA造斜特性基本相当的多种方案,这说明扩眼器可在既定的造斜要求下完成定向随钻扩眼钻进施工。     

垦利6-4区块含玄武岩地层钻探难点与对策探讨

地层可钻性差,岩石易水化膨胀是玄武岩地层钻探的主要难点。利用垦利6-4区块已钻井的测井资料对玄武岩地层可钻性以及井壁失稳机理进行了分析研究。并据此提出相应的技术措施,包括合理的钻头和钻具组合优化,以及良好的钻井液性能等。现场作业中,按照上述技术措施,实现了玄武岩地层的安全高效施工。     

青岛马斯特造船厂项目疏浚方案优选

港池疏浚产生的高浓度悬浮泥沙,对海域环境的影响不能忽视。在建立近海悬浮物二维输移扩散数值模型的基础上.采用有限元分步杂交方法求解,对两种不同施工方案下悬浮物的输移扩散进行预测模拟。根据预测结果,对比分析两种施工方法可能对附近海域水质环境适成影响的程度,为施工方案的选择提供科学依据。     

中国对虾(Fenneropenaeuschinensis)多性状复合育种方案的遗传和经济评估

设计中国对虾Fenneropenaeus chinensis多性状复合育种方案,模拟选择20个世代,预测和评估目标性状(收获体重(BW),存活率(SR)和饲料摄入量(FI))的遗传进展及经济效益。利用选择指数理论,估计目标性状的选择反应和遗传进展;通过三级金字塔传递系统(核心群、扩繁群和生产群)放大遗传进展并计算其经济效益;对影响利润(RP)和效益成本比率(BCR)的生物学参数(遗传力、育种目标是否包括FI),经济学参数(对虾价格、饲料价格、贴现率、初投资、年费用)和运行参数(首次回报年份、扩繁效率)进行敏感性分析。结果表明,在基础参数值下,BW、SR和FI每个世代的选择反应分别为0.81g、1.41%和1.30g;以1 000尾虾为单位计算,BW、SR和FI的经济加权值分别为32元,20元和-8元,育种目标的遗传进展为43.69元,育种方案执行20年产生的RP和BCR分别为8 660.99万元和14.34。敏感性分析显示,生物学参数中,目标性状遗传力变化对RP和BCR影响程度中等,遗传力值越高,RP和BCR越大;将FI经济加权值设为0,育种方案的RP和BCR明显高于基础参数。经济学参数中,对虾价格的变化对RP和BCR影响较大;饲料价格、贴现率和年费用的变化对RP和BCR影响较小,但初投资变化对BCR影响较大。运行参数中,首次回报年份越晚,RP和BCR越低。扩繁效率是影响RP和BCR的最重要因素。高扩繁效率下,生产群规模扩大1 736.15%,RP和BCR分别提高1 866.92%和1 736.75%。     

铜鼓航道建设对珠江口中华白海豚自然保护区的环境影响研究

铜鼓航道是连接大濠水道与深圳西部港口、在原有铜鼓水道的基础上疏浚挖深与拓宽的深水航道,其航道路线穿越珠江口中华白海豚自然保护区,在对珠江河口水域进行生态环境与中华白海豚资源状况调查的基础上,根据中华白海豚的生理与生态特性,结合铜鼓航道工程建设内容、规模、施工方案、航道营运计划等情况,研究分析工程施工与营运分别可能对珠江河口中华白海豚种群及自然保护区生境造成的影响,并分别提出航道施工与营运期间对中华白海豚种群和保护区生境影响的缓解措施,以达到有效保存与保护中华白海豚保护区生境及该种群的目的。     

基于遗传算法的缓波型立管多目标集成优化

缓波型立管由于设计参数较多且优化目标之间相互影响,设计结果具有很大的不确定性。随着代理模型和智能优化算法的发展,针对缓波型立管的优化可以提出更好的解决方案。以提高力学性能和经济效益为优化目标,采用基于Kriging插值模型和NSGA-II算法的多目标优化策略,对考虑顶部浮体影响的深水缓波型立管进行动力响应分析,并开展线型—截面双目标优化集成设计和线型—浮筒三目标优化集成设计。将处于不同几何尺度的设计变量进行集成,旨在各目标存在相互竞争的情况下,与截面、浮筒设计形成有效互动以提高线型设计的总体性能。结果表明,Pareto最优解集可提供多个选择方案,以满足工程实际需要。将所选最优方案与初始设计进行对比,并以疲劳性能和成本估算作为优化的校核指标,取得了理想的优化效果。     

考虑截面形状影响的混凝土内硫酸根离子扩散反应过程数值模拟

针对截面形状(矩形、圆形截面)对混凝土内硫酸根离子扩散反应规律的影响,根据Fick第二定律建立了不同截面形状下硫酸根离子的扩散反应方程。运用COMSOL Multiphysics有限元分析软件,分别模拟了一维和二维条件下硫酸根离子在混凝土中的扩散反应过程,分析对比了硫酸根离子在矩形截面和圆形截面中的浓度分布情况。结果表明:相同条件下,选择圆形截面构件代替矩形截面构件,能有效提高混凝土抗硫酸盐侵蚀的能力以及混凝土的耐久性。     

桂林洞穴滴水对应CaCO3沉积物的稳定同位素特征与环境意义

桂林地区降水及茅茅头大岩滴水滴速和现代碳酸盐的碳氧同位素研究表明:(1)滴水沉积的δ18O达到了同位素沉积平衡,洞穴滴水的δ18O与同期降雨的δ18O值呈正相关关系;(2)在旱季和湿季交替时,滴水δ18O值滞后于降雨δ18O,受活塞效应的影响;(3)δ13C难以达到同位素沉积平衡,主要受滴水动力学影响;(4)同一洞穴不同滴水对环境的响应不同,如果洞穴顶板覆盖较厚,水分在土壤和岩层中滞留时间较长,滴水则反映受到平滑作用的降雨,反之则波动较大.     

A prediction model for overlying rock thickness of subsea tunnel: A hybrid intelligent system

Abstract

The overlying rock thickness of a subsea tunnel controls its vertical line. It not only ensures the safety and stability of tunnel construction period and operation period, but also ensures the economy of subsea tunnel. In the current research, few papers give full consideration to the complex indicators of prediction the overlying rock thickness. However, in this study, a hybrid intelligent system was established to predict the overlying rock thickness of a subsea tunnel based on Qingdao Kiaochow Bay Subsea Tunnel, China. The sea depth, basic quality index of rock mass, soft soil layer thickness, permeability coefficient, and construction management level were selected as the main factors influencing the overlying rock thickness. Using the data obtained from project site exploration, objective weight factors were calculated using rough set theory, and subjective weight factors were calculated using the analytic hierarchy process. Furthermore, the combination of weights was obtained for each factor. Finally, the weight of influencing factors was incorporated into the extension model, and the overlying rock thickness of pending section was calculated. The results of overlying rock thickness prediction model are consistent with the actual value, indicating that the model has good engineering applicability and application value.     

The Sponge Community in a Semi-Submerged Temperate Sea Cave: Density, Diversity and Richness

Abstract. The sponge communities inhabiting a temperate semi-submerged sea cave were investigated at Lough Hyne Marine Nature Reserve, Co. Cork, Ireland. Thirty-one species of sponge were reported, the majority of which exhibited either an encrusting or massive morphology. Sponge density (averaged over depth) increased with horizontal distance (5  m intervals) into the cave until approximately 30  m, corresponding to the maximum algal intrusion (algal information from Norton et al. , 1971) . Species diversity and richness (averaged over depth) were highest at 10  m horizontal distance from the cave entrance. Variability in sponge density, diversity and richness was observed with increasing vertical depth (0.5  m intervals) at most horizontal intervals sampled (5  m apart). These three variables increased initially with depth, but then decreased towards the seabed. Bray-Curtis Similarity Analysis and Multi-Dimensional Scaling (MDS) showed cave sponge community composition to have greater similarity (50 %) with local loose rock habitats than the nearby cliffs. Similar processes structuring cave and loose rock sponge communities may account for this situation. Information collected from this and previous studies on the biotic (algal communities, other fauna and competition) and abiotic factors (water flow rate, depth, aerial exposure, light, cave morphology, nutrient depletion and humidity) affecting this and other caves is discussed with respect to its influence on the sponges inhabiting different parts of the cave. Although horizontal zonation patterns have been considered analogous to vertical distribution patterns for algal communities (due to similar decreases in light), this was not the case for the studied sponge communities.     

Alien biodiversity in Mediterranean marine caves

The number of alien species in the Mediterranean Sea is increasing rapidly, but few attempts have been made to evaluate impacts on specific habitat types. The present study investigated alien biodiversity in Mediterranean marine caves, both by contributing new records of Eastern Mediterranean cave aliens, and by reviewing the scattered existing literature; the main goals were to highlight potential impacts and investigate the importance of cave environments for the expansion of alien species. Seven new alien species were found in marine caves of the Aegean and Ionian seas, raising the total number of aliens reported from Mediterranean marine caves to 56 species, classified as molluscs, cnidarians, bryozoans, polychaetes, crustaceans, macroalgae, fishes and tunicates. Most cave aliens (66%) were recorded from the Southeastern Levantine coasts, specifically from Lebanese caves. Shipping and Lessepsian migration have been suggested as the main pathways of alien introduction into caves of the Mediterranean Sea. The comparison of alien cave biodiversity with the updated Mediterranean alien inventory (32 species added to the latest inventory) showed similar patterns and trends for species richness, biogeographical origin and major introduction pathways, corroborating previous findings on the high local representativeness of Mediterranean cave biodiversity. Alien species seem to have invaded mostly the entrance and semi‐dark zones of shallow and/or semi‐submerged caves and tunnels, whereas only a few have reached the dark inner sectors or caves of the anchialine type; thus, the unfavourable cave environment seems to be naturally protected from impacts related to opportunistic invasive species, at least to a certain point. Currently there is no research confirming any direct impacts of alien biota on the native cavernicolous one. However, some issues have emerged, implying potential threats that need to be further explored: (i) the presence of a considerable proportion of aliens in most studied marine caves of the Southeastern Mediterranean basin, (ii) the recently observed population explosion of alien cave‐dwelling fishes in the same area, (iii) several indications that alien diversity in marine caves is much higher than we know today. Quantitative surveys and monitoring schemes are needed in order to evaluate potential effects of alien diversity on cave community structure and the role of marine caves as stepping stones for its expansion in the Mediterranean.     

钱塘江强潮河段江道缩窄治理研究

对钱塘江强潮河段江道缩窄治理进行研究。首先,回顾治理方案的比选,江道全线缩窄时河轴线线路和河道宽度的确定原则,以及不同河段的指数放宽率。然后,介绍了在涌潮汹涌、滩涂淤坍变化剧烈的强潮河段,实施筑堤所采取的工程措施的步序与要点。最后,分析论证了大规模江道缩窄治理后河床、潮汐、洪水位及涌潮高度等特征值的变化。可供进一步深入理论研究和工程施工参考运用。     

快速筑堤技术——鲎式轻质堤坝的结构和筑堤方法

针对软基堤坝稳定性差,容易沉陷滑移,土石方堆不上,工期长,无法快速施工等问题,提出了鲎式轻质堤坝结构和筑堤方法,又称"松垒筑堤法".它减轻了易沉陷部位的质量,均衡堤坝荷重,增强整体稳定性,提高强度,使堤坝与地基溶为一体,消除了堤坝的不均匀沉降;是一种在软弱地基上应用仿生结构的筑堤方法.     

Analysis and optimization design of submarine tunnels crossing fault fracture zones based on numerical simulation

Abstract

Fault fracture zones have always been a key problem in the construction of submarine tunnels. To efficiently summarize the safety impact of different construction schemes on a submarine tunnel crossing a fault fracture, a theoretical model using numerical simulation has been established via the benching tunnelling construction method, three-step method, Center Diaphragm method (CD method), both sides heading method, Cross Diaphragm method (CRD method) and two kinds of supporting methods: pre-grouting and shotcreting. Numerical simulation studies on the excavation and support of submarine tunnels crossing fault fracture zones have been carried out. The research indicates: the fracture zone is the main area where sedimentation instability occurs; the CRD method has the lowest horizontal convergence under the support of the diaphragm; increasing the grouting strength is more effective in controlling the deformation of the surrounding rock than increasing the range of the pre-grouting and the thickness of the shotcrete in the initial support is increased, and its resulting effect is obvious. To optimize the construction scheme, we compared the settlement, horizontal convergence and surrounding rock stress of the tunnel according to the simulation results of different excavation support methods, which could provide theoretical guidance for better on-site construction techniques.     

广州港新沙港区板桩码头结构设计方案比选分析

介绍了广州港新沙港区板桩码头主要内力计算方法及常用软件,结合设计过程、工程地质情况、现场实际施工情况,着重从受力合理性、施工便利性、节省造价方面,对提出的钢板桩方案、钢管板桩方案进行比较分析,确定了钢管板桩结构更合理,并对优势进行总结。研究表明相对于钢板桩结构,钢管板桩结构在抗弯、抗变形、拉杆拉力和锚碇墙稳定性、对复杂地基(软弱土层较厚、岩层标高较高的地基)适应性、兼顾桩基基础、施工速度等方面更具备优势,且钢管板桩结构可更好的适应码头的大型化和深水化发展,在类似工程设计中可优先采用钢管板桩结构。     

A Study of the Performances of Different Turbulence Schemes in Numerical Simulation of Hydrodynamics of a Semi-Closed Sea (Persian Gulf)

Complex process of turbulent mixing in Persian Gulf that is a semi-closed sea makes it a good media to test the performance of different turbulence schemes. In this research, we used the 3D ocean model COHERENS (COupled Hydrodynamical Ecological model for REgioNal Shelf seas) for the Persian Gulf with the open boundary in the Hormuz Strait. Of the turbulence schemes for the vertical diffusion available in the COHERENS, we tested four models to investigate the hydrodynamic characteristics of the Persian Gulf. The results show that all of the schemes presented the sea surface salinity (SSS) distribution rather accurately but the k-l and flow-dependent models results have better agreements with observations. The most noticeable difference between the results of four schemes is the differences found in the simulation of turbulent parameters. The turbulent closure schemes generally provide better results, but the algebraic schemes show turbulent parameters far from reality and they do not show substantial changes with time. Generally, the vertical structures of turbulence in the water basins and parameterization of turbulence in water column is very sensitive to the selection of the type of the turbulence scheme. However, large-scale structures that take place within the inflow and outflow area are approximately quasi-horizontal, and the vertical small-scale turbulence does not affect them as much. As a result, they show less sensitivity to the performance of various turbulence schemes.     

The distribution of iodide and iodate in anchialine cave waters — Evidence for sustained localised oxidation of iodide to iodate in marine water

A study of inorganic iodine speciation in the waters of seven Croatian coastal caves is described. These are anchialine caves as they are connected hydraulically with Adriatic Sea surface water, with the tide inside the cave rising and falling with that outside, but replenishment of the water is restricted by the karst rock. In effect, the water in the cave probably acts more like a piston, and although moving slightly vertically, has a long residence time compared to a fully-flushing cave. Anchialine environments display a number of unusual features, e.g., a well-developed pycnocline, hypoxia and endemic fauna. Iodate and iodide were determined by differential pulse voltammetry and cathodic stripping square wave voltammetry, respectively. Low iodide concentrations (< 10 nM) have been consistently identified in the bottom water of the caves where concentrations of 90–100 nM would ordinarily be expected from intrusion of Eastern Adriatic surface seawater. Where total inorganic iodine concentrations behave conservatively with salinity the loss of the iodide implies oxidation to iodate. As iodide oxidation remains one of the enduring academic problems of the marine iodine system the study of iodine in anchialine caves may help unravel it. Iodate reduction was observed in mid-water, at the halocline, and mechanisms for the reduction involving either respiration or chemolitho-autotrophic bacteria are considered. The respiration mechanism is favoured because of enhanced alkalinity found in the near surface waters of the caves.