天津海岸带经济开发的地质环境和环境工程地质问题   总被引：3，自引：0，他引：3       下载免费PDF全文

杨锦贤 《海洋开发与管理》1994,11(3):36-40

本文揭示了天津海岸带影响经济开发的四个方面的地质环境特点；着重探讨三个方面的环境工程地质问题；并防止其形成和减轻地灾害的对策进行了研究。  相似文献   

Chalk shore platform erosion in the vicinity of sea defence structures and the impact of construction methods     

Uwe Dornbusch  David A. Robinson  Rendel B.G. Williams  Cherith A. Moses 《Coastal Engineering》2007

Erosion of the intertidal chalk platform in the vicinity of groynes and seawalls is evident to the naked eye along many stretches of the engineered coastline of southeast England, leading to undermining and eventually failure of these structures. However, quantification of the magnitude and spatial extent of the erosion has been difficult to date because of a lack of data about the past elevation of the platform. The application of softcopy photogrammetry makes it possible to recreate past platform elevations from historic air photographs and to compare these with elevations from modern air photographs. Coastal sea defence structures have been installed along the chalk coast east of Brighton at various dates over the past 70 years. During this period, the construction methods have changed from predominantly manual labour to a reliance on heavy machines. The analysis of erosion patterns around structures built since the 1970s using heavy machinery show that surface lowering is 4 to 25 times greater in the vicinity of these structures than across the platform as a whole. In contrast, there is no similar pattern of increased erosion around structures built using predominantly manual labour in the 1930s. A four fold increase in average surface lowering is found also along a vehicle trackway that crosses the mid platform. Depressions developed by enhanced lowering in the front of seawalls generate their own dynamic of increased erosion by trapping pebbles and cobbles that enhance the abrasion of the chalk through bedload transport under standing waves in front of the walls.  相似文献   

Fractal Dimension and Fractals in Ocean Engineering   总被引：4，自引：0，他引：4  

Fu Yuhua Senior Engineer  China Offshore Oil Engineering Corporation  P. O. Box  Beijing 《中国海洋工程》1994,(3)

- This paper discusses the application of fractal dimension and fractals in ocean engineering. To handle some ocean environment problems, the existing fractal method, in which the fractal dimension is a constant, can be used. For some complicated problems in ocean engineering, this paper presents the concept of the variable dimension fractals (D = f(r)), i. e., the fractal dimension D is the function of characteristic scale r instead of a constant. By using variable dimension fractals, several deformation and stress states of offshore structures are described.  相似文献   

地质环境特征及工程适应性与选择性分析——青岛市城市地质环境研究     

贾永刚  谭长伟  宋卓利 《中国海洋大学学报(自然科学版)》1997,(2)

根据地形地貌、地质构造、水文地质条件将青岛市划分为６个工程地质亚区，论述了各亚区地质环境特征，结合不同城市建筑工程特点，进行了工程场地适应性和选择性分析评价，为充分合理利用城市地质环境提供良好依据  相似文献   

水下工程项目监理的任务与条件     

张国光 《海洋工程》2002,20(3):76-80

结合近年来参与有关水下工程检测和项目监理的实践体验 ,从总结水下工程项目的基本特征着手 ,分析了水下工程项目监理的主要任务 ,并结合对于实施水下工程项目监理必备装备条件的探讨 ,介绍了国内外现有水下监测技术装备的开发应用状况  相似文献   

东营城区高精度三维地震采集方法研究   总被引：3，自引：0，他引：3  

胡立新  刘怀山  张进 《中国海洋大学学报(自然科学版)》2004,34(6):1075-1080

根据东营城区内建筑物较多，环境干扰较大，地下构造复杂，断裂非常发育，目的层埋藏深，资料信噪比较低的特点，以地震老资料和钻井资料为基础，建立地震地质模型，利用射线追踪技术选取合适的观测系统参数。充分利用卫星数字地图，没计了灵活多变的观测系统，采用可控震源与炸药震源配合使用方法，及时对城区内地下面元的覆盖次数、方位角和炮检距的分布进行质量监控，利用现场处理系统对资料进行及时分析，提高了地震资料品质。所获得的东营城区高精度三维地震采集资料显示，其浅中层分辨率和中深层信噪比都有了明显改善，取得了良好的地质效果。  相似文献   

Non-local impact of large-scale engineering in harbors and gulfs on the environment     

Eduard  Svetlana  Valentin 《Ocean Engineering》2002,29(7):739-752

A system of numerical tools to predict the non-local long-term impact of large-scale constructions on the environment is described. The predictions have to be results of successive examination of free water oscillations, turbulent boundary layers on the sea bottom, and turbulent pulsation effects on sediment transport. Numerical results related to free water oscillations in diverse gulfs are shown, and non-local effects of the dam construction are found for an example of the Baltic Sea. Feasibility of suggested tools for turbulent flow is manifested.  相似文献   

九龙江河口区表层水铀同位素的粒级分布          下载免费PDF全文

吕娥  张磊  陈敏  邱雨生  邢娜  杨伟锋  李艳平  黄奕普 《海洋学报》2007,29(4):59-68

利用微滤和超滤技术研究了九龙江河口区表层水中铀及其同位素组成的粒级分布和地球化学行为.结果表明,溶解态(<0.4μm)中低分子量组分(<10 000 u)占主要份额,胶体态(10 000 u~0.4μm)238U所占比例不足1%,且随盐度的增加其所占份额逐渐降低.溶解态、低分子量组分和胶体态238U的比活度与盐度之间存在良好的线性正相关关系,证实它们在九龙江河口区呈现保守行为.在颗粒态(>0.4μm)中,各粒级组分238U所占份额主要受控于相应颗粒物的浓度,在盐度小于20的区域,各粒级颗粒组分238U占颗粒态的份额有如下变化次序:10~53μm>2~10μm>0.4~2μm>大于53μm,而在盐度大于30的近外海站位,该次序发生一些变化:0.4~2μm>10~53μm>2~10μm>大于53μm,最小粒级颗粒组分238U的贡献有所增加,反映了自生铀贡献的加强.九龙江河口区表层水中溶解态(包括低分子量组分和胶体态)的234U/238U)_A.R.均大于1,显示出234U过剩的特征,而各粒级颗粒组分中的234U/238U)_A.R.则接近于平衡值(1.0).这一现象与陆地岩石风化过程中水体对铀的淋滤释出量及234U的优先浸出有关.对232Th/238U质量比的研究显示,溶解态及其所包括的低分子量组分和胶体态的232Th/238U质量比均小于1,而颗粒态及其所包括的4个粒级组分中的232Th/238U质量比均大于1,反映了向外海输送过程中铀、钍地球化学行为的差异.  相似文献   

Discussion: A review on the behaviour of helical piles as a potential offshore foundation system     

Shah Neyamat Ullah  Yuxia Hu 《Marine Georesources & Geotechnology》2020,38(9):1121-1127

Abstract

Helical piles have emerged as an attractive foundation system for offshore applications with renewed interest from the offshore community. Significant research gap currently exists in transferring this technology offshore and this paper discusses how existing and emerging knowledge can be successfully used to bridge some of the gaps. We focus on the Coupled Eulerian Lagrangian (CEL) large deformation finite element (LDFE) modelling technique that is commercially available and can be used to model the three-dimensional installation process with consideration of strain rate and softening effects in soft offshore clays. A helical pile of L?=?7.5?m long is modelled with one or two large-diameter helices (D?=?2?m) attached to a central shaft of d?=?0.5?m in diameter.The net effect of strain rate and softening is to increase the installation torque. The measured torque is within the range of 200–400?kN.m for the offshore clay and the pile geometry studied. Additional helices increase the uplift force but to a lesser degree than that of the measured torque. Remoulding induced strength reduction is found to be within the range of 25–33% of the intact clay strength. Issues of extracting and reusing offshore helical pile foundations are discussed.  相似文献   

Behaviour of uranium during mixing in the delaware and chesapeake estuaries     

M.M. Sarin  Thomas M. Church 《Estuarine, Coastal and Shelf Science》1994,39(6)

  相似文献