娄江特大桥深孔泵吸反循环工艺的改进

随着国家基础设施投入的加大,桩径1000－2000 mm、孔深100－130 m的钻孔灌注桩在各类工程中屡被采用。泵吸反循环传统上被用于孔深不超过80 m的深孔,在京沪高铁第六标段娄江特大桥钻孔灌注桩施工中,通过对现有的反循环钻机进行改进,很大程度上提高了泵吸反循环的工作效率,顺利地完成了孔深131 m、桩径1.8 m桩孔的施工,产生了很好的经济效益。     

右江裂谷区三叠系岩石物性特征及其与金矿化的关系

本文阐述了右江裂谷区微细粒浸染型金矿床控矿层位三叠系百蓬组泥质粉砂岩及砂质泥岩的粒度，比表面、孔隙度及孔隙类型和渗透率等物性特征，讨论了与其成矿流体的循回、水岩反应及其有效浸取围岩矿物质的关系。在此基础邮成矿流体和矿矿物质主要来自于地层；由于热液躲避低势能方向迁移，造成断理解发的盆地边缘区和水下隆起周围的环状断裂带为金矿床沉淀的场所。并通过形成金矿所需热液量的估算得出，该区金矿床的形成，是由于热流     

The tethyan oceanic gates : A tectonic approach to major sedimentary changes within Tethys

Abstract

— Accepting that the opening or closure of seaways has consequences on the oceanic circulation which in turn influences sedimentation, major changes in Tethyan geometry are checked against major changes in sedimentation. Time relationships can be demonstrated between the two group of phenomena and causal links are discussed. As the causes for major sedimentary changes are numerous and their respective roles controversial, it is speculated if the observed change in geometry could have had a positive effect on the associated change in sediments.

Ever since the birth of the Mesozoic Tethys which formed from the break-up of Pangea till its death through multiple collisions, this ocean played a major role in the world ocean circulation, being the sub-equatorial seaway which permitted a circumterrestrial circulation at low latitudes. Five successive steps, separated by four major changes, are recognized : i) during the Trias and the Jurassic, the young Tethys was a triangular cul-de-sac expanding westward through distensive tectonics and subsidence, and influenced along its southern margin by a westward current and associated upwelling; radiolarites take a growing part in its sedimentation; ii) during the Tithonian, radiolarites were abruptly replaced by pelagic limestones (Majolica) in many places and the corresponding CCD drop is tentatively correlated with the full opening of the Tethyan seaway which reached the Pacific Ocean through the Caribbean and with the corresponding reorganization of currents; iii) during the Early Cretaceous, Apulia began its collision with the precursor elements of the European margin, thus hindering deep water exchange; this pre collision favoured the mid Cretaceous anoxia with affected sedimentation in numerous basins; iv) during the Late Cretaceous, repeated distension and subsidence (since the Aptian) between Apulia and Africa gave a growing importance to the south Apulian seaway; this new opportunity of water exchange favoured the end of anoxia and the deposition of new pelagic limestones (scaglia); as a matter of fact, the location of the Late Cretaceous to Early Eocene phosphorites testify to a well-established westward current along this south-Apulian seaway; v) the late Eocene to Oligocene general collision was responsable for the death of this current and the corresponding breakdown of the Tethyan seaway into independent groups of basins.     

High-Resolution Seismic Reflection Evidence for Middle Holocene Environmental Change, Owasco Lake, New York

Approximately 70 km of new decimeter-resolution seismic reflection profile data from Owasco Lake, New York define a middle Holocene (4600 ¹⁴C yr B.P.) erosion surface in the north end of the lake at water depths as great as 26 m. Beneath the lake, post-glacial sediments are up to 9 m thick and represent about 10% of the total sediment fill. Early to middle Holocene sediments, 6 m thick, contain biogenic gas at the south end of the basin and a large (4 km×300 m×15 m) subaqueous slide deposit along the east-central portion of the lake. Late Holocene sediments are thinner or absent, particularly at the north end of the lake. The middle Holocene erosion surface may have been produced by a drop in lake level. Alternatively, it may represent a change in climate during the transition between the relatively warm Holocene hypsithermal and cool neoglacial. At this time (4600 ¹⁴C yr B.P.) circulation in Owasco Lake appears to have evolved from sluggish to active. The increased circulation, which persists today, probably resulted from atmospheric cold fronts with strong southwesterly winds that piled up water at the north end of the lake. The increased water circulation may have been ultimately driven by decreasing insolation, which produced an increased pole-to-equator thermal gradient and, thus, stronger global winds that began at the transition between the hypsithermal and neoglacial.     

CJF-20冲击反循环钻机钻进工艺技术分析

根据冲击碎岩理论和冲击反循环钻进中的工艺技术参数,结合工程施工实例对ＣＪＦ－２０冲击反循环钻机的钻进工艺技术进行了初步的分析探讨,实践表明,ＣＪＦ－２０冲击反循环钻机应用于复杂地层钻进成孔可取得了较好的技术经济效果。     

四川九寨沟-黄龙核心景区景观地质环境和水循环系统研究

介绍了九寨—黄龙核心景区地质环境和水循环研究进展情况,提出地质环境容量的计算不仅要考虑到游人数量还要考虑到其他多种因素,水循环模式的选择要结合景区的实际进行计算,提出环境保护综合治理的建议。     

节水钻探系统井下工况判断水力模型

节水钻探是基于解决干旱地区和漏失地层钻探严重缺水问题而发展起来的一项最新技术,其通过实现钻井液的孔底局部循环,使钻进过程中的用水量降为原来的5%～20%。节水钻探系统在使用过程中,由于孔内不返水,在地表只能通过观察压力表的变化量来判断孔内工况,精度不高。通过研究,最终解决通过地表压力变化值来判断孔内工作情况的量化问题,建立初步理论模型,从而更加准确地判断孔内的工况,使这套钻具更快地应用到实际工程中。     

襄樊汉江四桥大口径灌注桩成孔施工实践

介绍了使用泥浆护壁气举反循环回转钻进工艺进行襄樊汉江四桥大口径嵌岩桩的施工实践。施工中采用下置双护简隔离卵石层，合理选用钻头类型(卵砾石层采用五翼合金刮刀钻头，基岩采用球齿滚刀钻头)和钻进参数(混合器沉没深度，尾管长度，孔内空气流量与压力)，摸索与总结出一套复杂地层成孔施工经验。     

Alpine Evidence for Atmospheric Circulation Patterns in Europe during the Last Glacial Maximum

The configuration of Alpine accumulation areas during the last glacial maximum (LGM) has been reconstructed using glacial–geological mapping. The results indicate that the LGM ice surface consisted of at least three major ice domes, all located south of the principal weather divide of the Alps. This implies that the buildup of the main Alpine ice cover during oxygen isotope stage (OIS) 2 was related to precipitation by dominant southerly atmospheric circulation, in contrast to today's prevalent westerly airflow. Such a reorganization of the atmospheric circulation is consistent with a southward displacement of the Oceanic Polar Front in the North Atlantic and of the associated storm track to the south of the Alps. These results, combined with additional paleoclimate records from western and southern Europe, allow an interpretation of the asynchronous evolution of the different European ice caps during the last glaciation. δ¹⁸O stages (OIS) 4 and 3 were characterized by location of the Polar Front north of 46°N (Gulf of Biscay). This affected prevailing westerly circulation and, thus, ice buildup in western Scandinavia, the Pyrénées, Vosges, and northern Alps. At the LGM, however, the Polar Front lay at 44°N, causing dominating southerly circulation and reduced precipitation in central and northern Europe.