钻孔灌注桩施工中的几个问题探讨：以上海华夏门广场工程为例     

巫虹 《世界地质》1997,16(4):75-79

针对华夏门广场钻孔灌柱桩施工中有关循环用泥浆指标，围护桩施工方法等展开讨论结合工程实践提出了关于泥浆指标变动范围，围护桩施工的跳打方式等观点。  相似文献   

内蒙古东乌珠穆沁旗查干哈达音亨嘎高温型强过铝质花岗岩年代学、地球化学特征及其地质意义     

贺瑾瑞  郭丽  郝春燕  徐吉祥  邹滔  宋庆伟  冉淑红  程素珍  张翊超  何付兵 《地质通报》2018,37(6):1050-1060

内蒙古东乌珠穆沁旗查干哈达音亨嘎强过铝质岩体位于华北板块与西伯利亚板块之间的中亚-蒙古造山带中东段的兴蒙褶皱带,主要岩石类型为含石榴子石二云母二长花岗岩。基于锆石U-Pb同位素定年、地球化学分析和构造环境判别,结合区域对比,认为查干哈达音亨嘎岩体源区可能与变质泥岩部分熔融有关,晚古生代,强过铝质花岗岩形成之前,二连—东乌旗一带已经发生了碰撞造山作用,之后为后碰撞-造山后的伸展扩张时期。经研究确定,查干哈达音亨嘎岩体为鲜有报道的石炭纪—早二叠世具有典型后碰撞特征的高温型强过铝质S型花岗岩类。  相似文献   

内蒙古索伦山地区三叠纪侵入岩锆石U-Pb年龄、岩石地球化学特征及地质意义          下载免费PDF全文

连琛芹  李钢柱  于洋  姚佛军  张思源  王丕军  崔舜铫 《地球科学》2021,46(1):87-100

内蒙古索伦山地区朱恩道欧恩呼尔新识别出一套早中生代侵入岩,主要由角闪二长岩和二长闪长岩组成.通过LA-ICP-MS锆石U-Pb定年确定,角闪二长岩的结晶年龄为248±1 Ma(MSWD=1.1),表明该岩体形成于早三叠世.它们的SiO₂含量介于51.82%~60.17%之间,具有高镁(Mg#=53.17~59.03)、富碱(K₂O+Na₂O=7.36%~9.83%)、富钠(K₂O/Na₂O=0.25~0.53)特征,属于准铝质碱性岩.样品稀土总量变化范围为117.52×10-6~160.89×10-6,表现出一致的稀土元素和微量元素配分型式,即呈现出轻稀土元素相对于重稀土元素富集((La/Yb)_N=9.57~15.42)的右倾曲线,且无明显Eu异常(δEu=0.76~1.00),并富集Ba、Sr等大离子亲石元素,亏损Nb、Ta、Ti、Y等高场强元素,高Sr、低Y、高Sr/Y比值,具有高镁埃达克质闪长岩的地球化学特征.综合岩石地球化学特征及区域构造背景,朱恩道欧恩呼尔早中生代高镁埃达克质闪长岩类是由残余俯冲洋壳部分熔融形成的熔体与地幔橄榄岩相互作用而形成.朱恩道欧恩呼尔富碱侵入岩的形成与华北板块与西伯利亚板块碰撞后的伸展作用有关,这些新的年龄和岩石地球化学数据表明古亚洲洋闭合早于248 Ma.   相似文献   

双向螺旋挤土灌注桩（SDS）的技术优势与施工问题研究          下载免费PDF全文

肖光庆  袁桂华  张勇  陈筱艳  苏志东 《探矿工程》2015,42(3):61-64

双向螺旋挤土灌注桩（SDS）技术是在CFG地基处理的基础上通过对钻头的改进,减少出土量,充分发挥桩间土的承载力,进而减少混凝土用量。首先从设备上的关键结构来说明其工作原理;再通过已完成的工程实例与传统工艺相比较来佐证SDS技术的技术和经济优势;最后针对施工过程中出现的问题,分析其原因和提出处理措施。  相似文献   

Variation in the post‐copulatory guarding behavior of Neohelice granulata (Brachyura,Grapsoidea, Varunidae) in two different habitats          下载免费PDF全文

María P. Sal Moyano  María A. Gavio  Colin L. McLay  Tomás Luppi 《Marine Ecology》2015,36(4):1185-1194

Crab guarding behaviors are influenced by the biological and physical characteristics that each population experiences in a particular habitat. We studied post‐copulatory guarding behavior and the factors affecting it, such as the presence of burrows, female receptivity duration, operational sex ratio (OSR) and male size, in two different populations of Neohelice granulata: Mar Chiquita coastal lagoon (MCL) and San Antonio Oeste (SAO). Laboratory experiments showed that post‐copulatory guarding duration varied between the study areas. In MCL, it depended upon the presence of burrows and female receptivity duration, whereas it was independent of the OSR and male size. In SAO, it was dependent upon the OSR and female receptivity duration, whereas it was independent of the presence of burrows and male size. Thus, N. granulata males display different reproductive strategies related to their post‐copulatory guarding behavior pattern in different habitats. These strategies are related to the fact that this species constructs and defends a burrow that provides shelter and a place to mate, something that other varunids do not have.  相似文献   

Post‐mining landform evolution modelling: 2. Effects of vegetation and surface ripping     

K.G. Evans  G.R. Willgoose 《地球表面变化过程与地形》2000,25(8):803-823

Computer simulations of the topographic evolution of the proposed post‐mining rehabilitated landform for the ERA Ranger Mine, showed that for the unvegetated and unripped case, the landform at 1000 years would be dissected by localized erosion valleys (maximum depth = 7·6 m) with fans (maximum depth = 14·8 m) at the outlet of the valleys. Valley form simulated by SIBERIA has been recognized in nature. This indicates that SIBERIA models natural processes efficiently. For the vegetated and ripped case, reduced valley development (maximum 1000 year depth = 2·4m) and deposition (maximum 1000 year depth = 4·8m) occurred in similar locations as for the unvegetated and unripped case (i.e. on steep batter slopes and in the central depression areas of the landform). For the vegetated and ripped condition, simulated maximum valley depth in the capping over the tailings containment structure was c. 2·2 m. By modelling valley incision, decisions can be made on the depth of tailings cover required to prevent tailings from being exposed to the environment within a certain time frame. A reduction in thickness of 1 m of capping material over tailings equates to c. 1 000 000 Mm³ over a 1 km² tailings dam area. This represents a saving of c. $1 500 000 in earthworks alone. Incorporation of SIBERIA simulations in the design process may result in cost reduction while improving confidence in environmental protection mechanisms. Copyright 2000 © Environmental Research Institute of the Supervising Scientist, Commonwealth of Australia.  相似文献   

一些与韧性剪切带有关的金矿地质特征     

郝雅  刘鹏 《地质与资源》1993,2(1):54-61

目前,在世界范围内已发现越来越多的金矿赋存于韧性剪切带中,根据其主成矿期与韧性剪切带形成时间的关系可分为同韧性剪切型金矿和韧性剪切后型金矿。同韧性剪切型金矿主成矿时代同容矿韧性剪切带的发生、形成是同步的,韧性剪切活动不仅为成矿提供了空间,而且与成矿直接有关,容矿围岩为超糜棱岩、糜棱岩、初糜棱岩等,靠化学品位圈定矿体,矿石类型以浸染状为主;韧性剪切后型金矿成矿时代明显晚于韧性变形期,二者间隔时间较长,剪切活动仅为成矿提供空间,矿石类型完全取决于成矿前之容矿带的变形特征。  相似文献   

黄土地区后压浆钻孔灌注桩承载力特性试验研究   总被引：2，自引：0，他引：2  

马天抒  龚维明  戴国亮 《岩土力学》2009,30(Z2):362-366

通过对西安地区某工程中采用桩端后压浆的2根钻孔灌注桩压浆前、压浆后单桩竖向静载荷试验和桩身轴力测试的对比,分析了黄土地基中后压浆钻孔灌注桩桩身轴力的传递规律、桩侧阻力及桩端阻力的发挥性状,探讨了后压浆技术对提高黄土地基中钻孔灌注桩承载力的影响  相似文献   

A chronology of post‐glacial landslides suggests that slight increases in precipitation could trigger a disproportionate geomorphic response          下载免费PDF全文

Bradley G. Johnson  Jacqueline A. Smith  John A. Diemer 《地球表面变化过程与地形》2017,42(14):2223-2239

Large, deep‐seated landslides are common throughout the south‐eastern San Juan Mountains of Colorado and New Mexico, but their timing and initiation are not well understood. Determining when the landslides occurred would aid in clarifying the mechanisms for initiating landslides in the region and would help us to understand post‐glacial landscape evolution. We studied seven pre‐historic landslides located within the Tertiary volcanic rocks of the San Juan Volcanic Field. The landslides range in area from ~0.8 km² to ~11.3 km² and most are located in areas that were previously mapped as having been ice‐covered during the last glaciation. Landslide deposits were dated using a variety of methods including surface exposure dating (chlorine‐36, ³⁶Cl), radiocarbon dating of basal bog sediments and organic material buried in soils, and relative soil development. The resulting limiting ages range from approximately 14 ka to 2 ka and show that deep‐seated landsliding has occurred throughout the post‐glacial period. This broad range in ages is inconsistent with our initial hypothesis, which proposed that landslides were likely the result of debuttressing of glacial walls during glacial retreat. Furthermore, the timing of landslides does not seem to correlate with documented post‐glacial climatic shifts. Therefore, we conclude that landsliding in the region was the result of wetter than normal periods lasting months to years acting on weak bedrock preconditioned to failure and prepared by glacial debuttressing. Our findings suggest that the study area is likely still susceptible to deep‐seated landsliding and may become even more prone to large‐scale slope failure if future climate change increases precipitation in the San Juan Mountains. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

Integrating visual damage simulation,virtual inspection,and collapse capacity to evaluate post‐earthquake structural safety of buildings          下载免费PDF全文

Henry V. Burton  Gregory G. Deierlein 《地震工程与结构动力学》2018,47(2):294-310

A methodology is introduced to assess the post‐earthquake structural safety of damaged buildings using a quantitative relationship between observable structural component damage and the change in collapse vulnerability. The proposed framework integrates component‐level damage simulation, virtual inspection, and structural collapse performance assessment. Engineering demand parameters from nonlinear response history analyses are used in conjunction with component‐level damage simulation to generate multiple realizations of damage to key structural elements. Triggering damage state ratios, which describe the fraction of components within a damage state that results in an unsafe placard assignment, are explicitly linked to the increased collapse vulnerability of the damaged building. A case study is presented in which the framework is applied to a 4‐story reinforced concrete frame building with masonry infills. The results show that when subjected to maximum considered earthquake level ground motions, the probability of experiencing enough structural damage to trigger an unsafe placard, leading to building closure, is more than 2 orders of magnitude higher than the risk of collapse.  相似文献