开口桩中土芯形成、影响因素及判别方法研究     

李剑强  周建 《岩土力学》2008,29(2):449-454

开口桩打桩过程中桩端土体进入桩管内形成土芯,土芯在大直径钢管桩、新研发的大直径现浇混凝土薄壁筒桩的作用不容忽视,通过闭塞效应土芯会提高开口桩的承载力,减小桩的沉降量。比较分析了目前国际上两种土芯闭塞效应定义方法,研究认为,从土芯破坏机制出发定义土芯是否产生闭塞效应更为合理;并从土芯的形成出发,探讨了影响土芯形成及闭塞效应的各种因素,如桩径、桩端土的承载力、土芯与桩内壁的摩阻力等,此外还应考虑桩端土体侧向水平应力的影响。最后讨论了ICP方法中砂土及黏土中开口桩土芯闭塞效应的判别方式,认为该判别方式过于粗略,不能很好地反映土芯闭塞情况。  相似文献   

厄立特里亚Zara金矿大角度斜孔钻探施工技术          下载免费PDF全文

王洪涛  罗伟  焦卫兵  李希军 《探矿工程》2016,43(6):7-12

介绍厄立特里亚Zara金矿大角度斜孔钻探施工情况,重点针对防斜保直钻进技术要求、复杂地层护壁堵漏、“打滑”地层提速增效等钻探技术进行实践探索。阐述了钻具组合合理配置、冲洗液使用工艺、钻进参数合理选择、钻头合理选用等方面技术措施。在初次完成大角度斜孔钻探施工中摸索和积累施工经验,为今后类似项目的进一步开展打下技术和管理基础。  相似文献   

PLC聚合物交联凝胶在黄土层堵漏中的可行性试验研究          下载免费PDF全文

李伟  张文哲  邓都都  李红梅  王涛  王波 《探矿工程》2016,43(3):33-36

针对陕北延长油田黄土层漏失具有井底温度低、漏失严重、常规堵漏材料与方法堵漏效果差的特点,研究出了一种低温下快速实现交联的PLC聚合物交联凝胶。采用浓度6.5%的聚合物胶液与浓度2%的有机复合交联稳定剂,按聚合物胶液与有机复合交联稳定剂10∶1.3的交联比,在17.6～40 ℃条件下进行快速成胶试验。试验得出,PLC聚合物交联凝胶成胶时间短,抗污染能力强,与桥堵材料有很好的配伍性,二者配合使用对于封堵黄土层恶性漏失具有很好的应用前景。  相似文献   

抗高温随钻封堵材料研究进展          下载免费PDF全文

熊正强  陶士先  蒋睿  朱文鉴 《探矿工程》2016,43(12):33-36

钻遇渗透性漏失地层、破碎地层及低承压地层时,通常加入随钻封堵材料以防止钻井液漏失、提高孔壁稳定性和地层承压能力。深井高温地层及高温地热、高温干热岩钻探,遇到上述复杂情况时,需采用抗高温封堵材料。本文介绍了我国近年来抗高温随钻封堵材料研究与应用的进展情况,包括由桥接堵漏材料组成的抗高温随钻堵漏剂、膨胀型聚合物堵漏剂、超低渗透处理剂及弹性石墨等新型抗高温随钻堵漏材料。分析了4种抗高温随钻封堵材料的组分及其堵漏原理,并对抗高温随钻封堵材料的研究方向提出了建议。  相似文献   

东胜气田刘家沟组井漏与堵漏措施分析          下载免费PDF全文

孙庆春 《探矿工程》2016,43(2):53-56

自2013年东胜气田步入开发以来,随着水平井逐渐增多而井漏事故频发,单井堵漏时间大体占钻井周期的8%～50%,极大地制约了提速提效。主要漏层为刘家沟组,钻井液密度低时发生渗透性漏失,漏速约为3～5 m3/h,当钻井液密度高时,发生裂缝性漏失,漏速20 m3/h直至井口失返。裂缝会随井内液柱压力的增加而扩大延伸,极易造成井漏的反复。刘家沟组恶性漏失严重制约了该工区钻井的提速提效。通过对J58P13H井井漏特点与堵漏效果分析,探索复合堵漏法、大裂隙膨胀堵漏材料和膨胀管堵漏法等在裂缝性漏失堵漏中的适应性,以便在东胜气田试验推广。  相似文献   

涪陵页岩气井长水平段漏失井固井技术应用研究          下载免费PDF全文

陈勇  杨伟平  冯杨 《探矿工程》2016,43(7):42-44

涪陵页岩气井钻井过程中井漏频繁,类型多样,严重影响了工程质量,特别是三开长水平段发生漏失油基钻井液甚至固井时发生漏失,影响了固井质量及后期页岩气的开采。针对长水平段漏失井特点,研究了一系列井眼准备技术、高效纤维隔离液封堵技术、管外浆柱结构优化技术、漏失井固井压稳技术,增强堵漏性能,提高固井质量。随着区域不断地扩大,地质情况复杂多变,提出了下一步的研究方向及建议。  相似文献   

Headwater stream length dynamics across four physiographic provinces of the Appalachian Highlands          下载免费PDF全文

Carrie K. Jensen  Kevin J. McGuire  Philip S. Prince 《水文研究》2017,31(19):3350-3363

Understanding patterns of expansion, contraction, and disconnection of headwater stream length in diverse settings is invaluable for the effective management of water resources as well as for informing research in the hydrology, ecology, and biogeochemistry of temporary streams. More accurate mapping of the stream network and quantitative measures of flow duration in the vast headwater regions facilitate implementation of water quality regulation and other policies to protect waterways. We determined the length and connectivity of the wet stream and geomorphic channel network in 3 forested catchments (<75 ha) in each of 4 physiographic provinces of the Appalachian Highlands: the New England, Appalachian Plateau, Valley and Ridge, and Blue Ridge. We mapped wet stream length 7 times at each catchment to characterize flow conditions between exceedance probabilities of <5% and >90% of the mean daily discharge. Stream network dynamics reflected geologic controls at both regional and local scales. Wet stream length was most variable at two Valley and Ridge catchments on a shale scarp slope and changed the least in the Blue Ridge. The density and source area of flow origins differed between the crystalline and sedimentary physiographic provinces, as the Appalachian Plateau and Valley and Ridge had fewer origins with much larger contributing areas than New England and the Blue Ridge. However, the length and surface connectivity of the wet stream depended on local lithology, geologic structure, and the distribution of surficial deposits such as boulders, glacially derived material, and colluival debris or sediment valley fills. Several proxies indicate the magnitude of stream length dynamics, including bankfull channel width, network connectivity, the base flow index, and the ratio of geomorphic channel to wet stream length. Consideration of geologic characteristics at multiple spatial scales is imperative for future investigations of flow intermittency in headwaters.  相似文献   

论地理学面临的挑战与发展   总被引：22，自引：10，他引：12  

陈国阶 《地理科学》2003,23(2):129-135

地理科学研究地球表层系统特定时空层次下的系统有序度和变化。其发展正面临着几大挑战:①地球表层系统的复杂性难以精确定量描述;②人地关系变化速度超过人类认识与预警能力;③地球表层系统的模糊性与科学价值精确性存在矛盾;④地理学与其它学科的竞争剧烈;21世纪地理学研究主要趋势:①地理学研究人文化;②界面研究将成为自然地理研究热点;③全球研究是地理学重大题材;④地理学研究生态化;⑤山地研究将成为地理学重大领域;为着地理学的顺利发展,建议:①造就地理学思想家和战略家;②进行地理学方法论的集成和创新;③寻找适合各时代认识水平的定量化方法;④重点突出与人类命运攸关的重大课题,创立有震撼性、权威性的理论和成果。  相似文献   

An analysis method for the influence of tunneling on adjacent loaded pile groups with rigid elevated caps     

Rong‐Jun Zhang  Jun‐Jie Zheng  Li‐Min Zhang  He‐Fu Pu 《国际地质力学数值与分析法杂志》2011,35(18):1949-1971

Tunnel excavation could influence the working performance of adjacent pile foundations. How to accurately predict the tunneling‐induced pile responses is becoming an important issue in urban areas. Previous methods tend to neglect the influence of working loads on the tunneling‐induced pile responses. In this paper, a two‐stage analysis method is proposed to study the behavior of pile groups with rigid elevated caps subjected to tunneling‐induced ground movements, in which the pile–pile interaction, coupling of longitudinal and lateral deformation, and influence of working loads are considered. This method is validated by comparing the results with those from a general pile analysis program, GEPAN, centrifuge test data and field measured data. Thereafter, a series of parametric studies is carried out. The results show that the influence of working load on tunneling‐induced pile responses is significant. Three different features of the pile responses will take place for different depth ratios. With the increase in soil stiffness, the tunneling‐induced axial force increases linearly, whereas the bending moment increases nonlinearly. For soils with high stiffness, the maximum bending moment increases linearly with the ground loss ratio within the range of 0–5%; but for soils with low stiffness, this tendency becomes obviously nonlinear. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

屏障效应对生物地球化学异常形成的影响及找矿有效指示植物的选择     

宋慈安  雷良奇  杨仲平  文宗振 《地质科技情报》2012,31(1):1-8

采用光谱仪及透射电子显微镜对广西几个金属矿床的生物地球化学异常和植物细胞微观特征进行了研究,结果发现:生物地球化学异常对土壤地球化学异常有明显的物质性继承关系;生物地球化学异常的物质以金属聚集体(电子致高密度体物质)的形式沉淀在植物液胞中或细胞壁及膜边缘,其对植物的伤害可能只达到细胞或组织的水平.生物地球化学异常的形成...  相似文献