浅谈在1∶5万区域地质调查中有关层序地层野外调查的若干问题     

张国仁 《地质通报》1998,(2)

针对在１∶５万区调中层序地层学的野外调查方法,有关副层序、不整合面、饥饿段及最大海泛期沉积的特征和识别标志,区域地层格架的建立等问题进行了详细讨论。进一步阐明了层序地层与岩石地层关系及其对填图的指导作用,并提出了层序地层学的图面表达方式和内容。  相似文献   

High Performance Concrete and Its Typical Mixes     

Cai Yuebo  Kwan Kwokhung  Cheung Yaukai Chan Honchuen Senior Engineer  Material  Structure Department  Nanjing Hydraulic Research Institute  Nanjing P. H. Doctor 《中国海洋工程》1995,(3)

- With the modern development of chemical and mineral admixtures, it is now possible to produce much higher performance concrete than before. Higher performance does not only mean higher strength, but also better durability, lower risk of thermal cracking and higher dimensional stability etc. The three most effective admixtures for producing high performance concrete are superplastieizer, pulverized fuel ash and condensed silica fume. This paper outlines the properties of these materials and presents some practical guidelines for their usage.  相似文献   

Cascades of dense water around the world ocean   总被引：1，自引：0，他引：1  

V.V. Ivanov  J.M. Huthnance  P.N. Golovin 《Progress in Oceanography》2004,60(1):47-98

Dense water overflow off continental shelves (cascading) is one of the contributing processes of shelf-deep ocean exchange, and of topical interest to climate studies and nutrient fluxes. Dense water originating from cooling, evaporation, freezing and salinization on a shallow shelf spills over the shelf edge and may develop as near-bottom gravity current or an intermediate-depth intrusion. It is difficult to observe in nature due to its intermittent character.This paper provides an extensive inventory of observed cases of water cascades around the World Ocean, summarises their locations and individual properties, and provides statistics of the identified cases. The search for cascading was carried out using oceanographic databases and a literature review. This study identified 61 confirmed cases world-wide, including 25 cases in the Arctic seas, 12 at mid-latitudes, seven in sub-tropical and tropical regions, and 17 off the Antarctic shelves. Eighteen cascades had not been reported before. We analyze a set of numerical parameters of dense water cascades, allowing us to quantify, compare and contrast the properties of water cascades. The overall average density contrast between the confirmed cascades and ambient water is 0.37 (kg/m³); it can be as much as 2 (kg/m³) on some Arctic shelves. Frequently initiated by strong cooling at the surface, cascades often remain colder through the descent, thus supplying the deep ocean with colder and fresher water. In non-dimensional variables, the data from all climate zones fit well to a unique curve, which represents a relationship between a cascade’s internal structure and the parameters describing its forcing. On average, the down-slope volumetric flux provided by dense water cascades is estimated as 0.05 to 0.08 Sv per 100 km of shelf edge.Regional terms: Arctic, Antarctic, North Atlantic Ocean, Barents Sea, Mediterranean Sea, Skagerrak, Tasman Sea, Sea of Okhotsk  相似文献   

Calculation of the added mass of elliptical cylinders in shallow water   总被引：1，自引：0，他引：1  

David Clarke   《Ocean Engineering》2001,28(10)

In order to carry out any studies of ship motions, concerning either seakeeping or manoeuvring, it is usually necessary to have knowledge of the added mass of the hull section shapes. In deep water, the added mass can be found using conformal mapping techniques combined with residue calculus, or by means of surface singularity distributions. In shallow water, the need to utilise an infinite number of mirror images, to represent the effects of the seabed and the free surface, precludes the use of the deep-water methods in this case. In a previous paper, the author presented methods to evaluate the added mass of semi-circular sections. In this paper, a quite different but more general technique using Schwarz–Christoffel methods is developed. This technique gives entirely new results for the added mass of elliptical body sections and compares the special case of semi-circular sections with those from the previous paper.  相似文献   

沪宁城际高速铁路重点沉降观测地段监测方法探讨与研究     

刘大伟  曹军  张国庆 《测绘与空间地理信息》2015,(6):180-182

以沪宁城际铁路重点沉降观测地段监测工作为例,研究高速铁路运营期间监测工作的方法与实施,通过对多个地段监测数据的分析,验证重点监测地段方法的可行性,并对各重点监测地段的变形原因进行了分析。  相似文献   

碳酸盐岩铸体薄片面孔自动提取研究     

杜相仪  董少群  曾联波  何娟  孙福亭 《地质论评》2021,67(4):67050007-67050007

岩石孔隙是储层储集油气的重要场所,通过铸体薄片进行岩石孔隙结构分析对储层质量评价具有重要意义。碳酸盐岩孔隙结构较为复杂,铸体薄片图像中存在大量噪声和干扰因素,致使常规方法面孔提取效果不佳,因此本文引入一种多阈值铸体薄片面孔自动提取方法（ctsPore方法）进行孔隙区域提取和面孔率估计,方法综合利用HSV色彩空间中不同参数提取孔隙区域。本文针对碳酸盐岩储层的特点确定了一套ctsPore阈值参数,以解决溶蚀孔与噪声易混淆的问题。实验以伊拉克A油田中新统 Asmari组A段碳酸盐储层为例对所使用算法进行了效果检验。算法精度和效率分析实验表明,基于ctsPore方法的碳酸盐岩铸体薄片面孔提取误差小于0.24%。全井段铸体薄片分析结果表明,A段储层面孔率范围主要分布在6%~8%,储层较为致密,从上到下A1~A3小层的储层平均面孔率分别为6. 9%、11.7%、5.4%,与储层物性、沉积微相和岩性等纵向分布规律较为吻合。  相似文献   

超大断面炭质千枚岩隧道新型支护结构长期稳定性研究   总被引：1，自引：0，他引：1  

原小帅  张庆松  李术才  李利平  刘钦 《岩土力学》2011,32(Z2):556-561

针对兰渝铁路两水隧道岩质软、跨度大的特点,采用加厚初喷、二衬和双层型钢拱架的新型支护方式。通过对现场岩样的室内三轴蠕变试验,研究炭质千枚岩蠕变特性。试验结果表明,伯格斯蠕变模型能比较准确地描述其长期流变行为。运用大型岩土工程分析软件FLAC3D,结合现场新型支护方式,模拟隧道建成后DK357+976处围岩的流变力学行为,分析隧道在运营过程中围岩的变形和支护结构的受力情况。结果表明：在隧道100 a的使用期限内,二次衬砌能有效地减小围岩蠕变变形,支护结构中仅拱顶初喷在后期产生破坏,现场支护方式可以保证隧道的长期稳定性。  相似文献   

贵州台江八郎凯里组层序地层及海平面变化初探   总被引：4，自引：0，他引：4  

王约  喻羑艺  彭进  王平丽 《地层学杂志》2006,30(1):i0001-i0002

贵州台江八郎凯里组以含钙质泥岩—泥灰岩、含钙质泥岩—粉砂岩和含钙质泥岩—灰岩等3种韵律性沉积为主,沉积体系域类型主要包含有大陆边缘体系域、海侵体系域和早期高水位体系域。在凯里组沉积初期,台江地区的水体相对较浅、生物相对较少;随着海平面的上升,生物在分异度和丰度上的大大增加,构成了台江生物群;当海平面升至最高点时,台江沉积区处于一个相对深水的环境,以大量的浮游类和较强游泳能力的生物为特征,成为了凯里生物群的开始;海平面逐渐下降,浮游生物逐渐减少;至凯里组沉积晚期,海平面的下降使台江地区的水体再度变浅、生物化石相对稀少。在台江八郎剖面上,凝缩段之下早寒武世的三叶虫Bathynotus消失,Orycto-cephalusindicus等三叶虫在凝缩段底界出现。凝缩段底界与下、中寒武统界线基本一致,表明了凝缩段是该区下、中寒武统地层划分、对比的关键。  相似文献   

滇黔桂盆地及其邻区二叠系与三叠系之交的淹没不整合面   总被引：1，自引：0，他引：1  

郑宽兵  邓军  李浩  冯彩琴  唐晓川 《现代地质》2004,18(4):564-571

滇黔桂盆地及其邻区在晚二叠世长兴晚期发生快速海侵,导致了第I幕淹没事件,研究区内的连陆台地大部分被淹没,形成大隆组硅质泥页岩系凝缩段地层和其下相对局限发育的第I幕淹没不整合面;在早三叠世印度初期发生更大规模的快速海侵,导致更大的第Ⅱ幕淹没事件,研究区内的连陆台地和孤立台地均被淹没,形成罗楼组、马脚岭组等同时异相沉积地层底部的钙质泥页岩系凝缩段地层和其下全区普遍发育的较为典型的第Ⅱ幕淹没不整合面。这两幕淹没不整合面合称二叠系与三叠系之交的淹没不整合面,它们是三级层序SQ₂₆的底界面,具有明显的穿时性;凝缩段是它们的主要标志。中二叠世冷坞末期和晚二叠世吴家坪末期的两幕东吴运动导致的研究区古地理背景的重大改变对淹没不整合面的发育有重要的影响。淹没不整合面的形成与二叠纪末期发生的全球淹没事件基本同步,是全球海平面急剧上升的结果,它对研究区的石油勘探具有积极的地质意义。  相似文献   

冀中地区早第三纪海泛特征及其层序地层学意义   总被引：8，自引：0，他引：8  

魏魁生  徐怀大 《现代地质》1993,7(3):274-284

作者近年来在冀中地区首次发现了钙质超微化石,首次在不同层位发现了海绿石,结合其它古生物、岩石矿物和地球化学标志,表明区内早第三纪时曾多次发生过海泛。本文对海泛特征作了详尽的描述,并依据层序地层学理论分析了海泛层位在时间和空间上的变化,指出受海泛影响最大的层位即密集段。近海内陆盆地受海水进侵或海洋气候的影响,故湖盆基准面与海平面的升降变化趋势近似,从而为在陆相断陷盆地中开展层序地层学研究奠定了基础。文中对海水进侵方向（通道）也作了探索性研究。  相似文献