Analysis of geocell-reinforced mattress with consideration of horizontal–vertical coupling     

Ling Zhang  Minghua Zhao  Xiaowei Zou  Heng Zhao 《Computers and Geotechnics》2010

Geocell reinforcement has been increasingly applied to road embankment engineering. Deformation calculation is one of the major concerns during the design process. In this paper, the power-series method was employed to investigate the performance of a geocell-reinforced mattress under symmetric loads. The geocell-reinforced mattress was idealized as a beam on a Winkler foundation. In the analysis, the soil–foundation beam interface resistance, related to the horizontal deformation coupling with the vertical deformation, was considered. Semi-analytic solutions were developed to assess the deformations and internal forces of the foundation beam and verified against an existing finite element method [9]. The results of the proposed method were close to the results from the finite element method. Moreover, the effects of various factors, such as height of embankment, horizontal and vertical foundation coefficients, composite elastic modulus and height of geocell-reinforced mattress, on the foundation beam settlement and the tension force within the beam are discussed. It was found that the interface resistance related to the horizontal deformation of the beam has a reduction effect on the embankment settlement, and it is beneficial to reduce the embankment settlement by increasing the beam rigidity and strengthening the subgrade soil body.  相似文献   

多功能旋挖钻机长螺旋钻具的研制          下载免费PDF全文

王三牛  李洪  宋刚  邵玉涛 《探矿工程》2010,37(5):45-48

通过对长螺旋钻进过程中阻力矩的计算,得出了不同直径和孔深情况下的阻力矩值,依此对长螺旋钻具的强度进行比对,给出了不同口径的长螺旋钻具参数。还介绍了长螺旋钻头的不同结构形式及配套器具,简述了多功能钻机长螺旋钻进施工工艺。  相似文献   

地质钻探中的井漏及堵漏材料研究     

毛洪江 《西北地质》2010,43(3):141-146

通过对钻探过程中井漏的复杂地质因素分析,提出了水化膨胀复合材料体系,并对该体系进行了膨胀性、封堵性及复合桥接堵漏模拟实验。实验结果表明,堵漏材料PAR具有很强的吸水膨胀性能,可膨胀至原体积的几十倍,且时间快有利于形成快速的封堵。材料PAR与稻谷和锯末形成的复合堵漏材料具有很强的堵塞率,可达70%以上。承压堵漏测量装置中测试表明:复合堵漏体系不仅能形成封堵,而且能够承受一定的压差。在云南临仓市勐简乡铅锌矿钻探过程中,运用复合堵漏体系满足了该地区复杂地矿钻探需要。  相似文献   

两种混养方式对异枝江蓠(Gracilaria bailinae)生长性能、表面附生细菌群落及抗生素抗性基因的影响     

李雯  张明清  赖星星  张翠萍  覃伟健  杨金霖  朱雅婷  舒琥 《海洋与湖沼》2022,53(1):235-246

为揭示"鱼-藻"和"鱼-虾-藻"混养对异枝江蓠(Gracilaria bailinae)生长性能、表面附生细菌群落和抗生素抗性基因(antibiotic resistance genes,ARGs)的影响,阐明异枝江蓠表面附生细菌群落与生长性能、ARGs之间的关系,利用16S rDNA高通量测序技术和Real-time qPCR技术分析了异枝江蓠表面附生细菌群落和ARGs的组成与差异,冗余分析(RDA)探讨细菌群落与生长性能、ARGs之间的关联。结果表明:(1)"鱼-虾-藻"混养会促进异枝江蓠的生长性能,增加表面附生细菌群落的多样性。(2)异枝江蓠表面附生细菌群落主要属于变形菌门、蓝藻门、浮霉菌门和拟杆菌门,不同混养方式中优势菌属组成不同,"鱼-虾-藻"混养优势菌属多样性较高。(3)"鱼-虾-藻"混养的异枝江蓠ARGs/MGEs的相对丰度大多高于"鱼-藻"混养。(4)RDA分析表明,生长性能主要与Ralstonia、Blastopirellula等显著相关,ARGs/MGEs主要与Nitrosomonas、Alteromonas、Pleurocapsa;CC-7319等显著相关。"鱼-虾-藻"混养能够增强异枝江蓠的生长性能,提高异枝江蓠表面附生细菌群落的多样性。但"鱼-虾-藻"混养能够增加异枝江蓠ARGs/MGEs的相对丰度,存在一定的生态风险。因此,在注重经济效益的同时也要关注可能存在的对人类健康的危害。研究结果将有助于海水养殖环境的优化,为大型海藻在海水养殖业中的应用与推广提供理论基础。  相似文献   

基于全基因组重测序技术的浙江近岸海域耐盐金黄色葡萄球菌(Staphylococcus aureus)耐药机制解析<     

张旨轩  王子言  王泽  刘岩  刘松怡  钱鹏宇  叶欢  韩姣姣  周君  苏秀榕 《海洋与湖沼》2022,53(2):394-404

金黄色葡萄球菌(Staphylococcus aureus)是近岸海域海水中的主要病原菌,严重威胁接触者的安全。抗生素处理是治疗金黄色葡萄球菌感染的重要手段,其耐药性的发生受到了高度重视。采用全基因组重测序与KEGG富集分析结合的方法,对红霉素(erythromycin)、氯霉素(chloramphenicol)和万古霉素(vancomycin)处理后的耐盐金黄色葡萄球菌(S.aureus ZS01)和不耐盐金黄色葡萄球菌(S.aureus 502A)进行耐药机制研究。结果表明,S.aureus 502A经抗生素处理后发生突变的程度大于S.aureus ZS01,二者在经过氯霉素处理发生了更大程度的突变。红霉素、氯霉素和万古霉素处理主要影响了金黄色葡萄球菌的致病能力;红霉素和氯霉素可能通过影响金黄色葡萄球菌脂类的代谢引起其耐药性的变化。除此之外,三种抗生素处理均出现了较多TIGR01741家族蛋白和假设蛋白基因的突变,推测与菌株的耐药性和致病性相关。耐盐金黄色葡萄球菌可通过外排系统作用产生红霉素耐药性,不耐盐菌株因细胞壁成分相关基因的突变提高了对万古霉素的耐受性。研究结果可为耐盐和不耐盐金黄色葡萄球菌的耐药机制及抗生素对金黄色葡萄球菌致病性影响的研究提供基础数据。  相似文献   

高黎贡山羚牛生境适宜性评价及廊道建设     

冯鸿能  杨德宏  饶定齐  魏旋 《测绘通报》2023,(1):134-140

以高黎贡山羚牛为研究对象,选取了植被类型、植被覆盖度、海拔、坡度、水源、土地覆被、主要道路、居民点8个影响因子,基于GIS技术,构建阻力面,从而探测多因子影响作用下高黎贡山羚牛适宜生境。结果表明：区域内羚牛的适宜生境面积整体占比较少,适宜区域主要分布在研究区的中西部及西南地区,在北部区域也有零散分布。羚牛的迁徙受到人类活动的干扰及道路阻隔的影响,其生境遭到一定程度的破坏。结合现有羚牛栖息地分布及最小阻力模型,建立区域内羚牛的生态廊道,结果显示：廊道主要分布于高黎贡山保护区南段、马边瓦底中段、子巴、俄恰沙迪、马士打亚窟、其期北段、四克洛娃俎及木当一带。  相似文献   

Variations in spring leaf phenology and leaf freezing damage of common woody species in China北大核心CSCD     

陶泽兴  戴君虎 《地理科学进展》2023,(4):766-781

Freezing damage results in the dehydration of plant cells and reduces the photosynthetic capacity of plants, which causes significant losses to ecology and economy. Over the past 40 years, global warming has reduced the frequency and intensity of frost events while bringing forward the spring phenology of plants, increasing the exposure of their leaves and flowers to harsh cold temperatures. Therefore, the dual effects of climate warming should be considered in order to accurately assess the changes of plant freezing damage. To date, there is no systematic analysis of plant freezing damage in different climatic regions of China. Based on phenological observation records from the China Phenological Observation Network, leaf frost damage of four common woody plants (Ulmus pumila, Robinia pseudoacacia, Salix babylonica, Fraxinus chinensis) in the spring over the past 40 years was calculated, and the spatio-temporal patterns were analyzed. We also investigated the change in the occurrence time of maximum frost damage (TMFD) and its relationship with plant phenology. The results show that: 1) Most species presented an overall trend towards an earlier leaf unfolding date, and the advancing trend was significant and greater than 1 d/a in about 60% of the regions (P<0.05). 2) The TMFD occurred earlier in 72.22%-83.03% of the regions, which was closely related to plants' earlier leaf unfolding date. The TMFD of all species advanced the most (8.3 days) in the temperate climate zone, followed by the warm temperate, subtropical, plateau, and cold temperate zones. 3) The leaves of U. pumila, R. pseudoacacia and S. babylonica suffered more freezing damage in the spring, and the most significant freezing damage was mainly found in the north of 50°N region and part of the west of the Qinghai-Tibet Plateau. In comparison, the leaves of F. chinensis suffered less frost damage due to later leaf unfolding date and stronger leaf frost resistance. With regard to interannual variations, the average freezing damage of U. pumila, R. pseudoacacia and S. babylonica increased significantly (P<0.05), but that of F. chinensis did not change obviously. In addition, the freezing damage of U. pumila and S. babylonica increased the most in the cold temperate zone, while that of R. pseudoacacia increased in about 10% of the regions in the plateau climate zone, and 3%-6% of the regions in the cold temperate, temperate, and warm temperate climate zones. The freezing damage of F. chinensis merely increased in the warm temperate zone. The results of this study can provide a reference for assessing the risk of plant freezing damage accurately and help develop regional-specific response and adaptation strategies to climate change. © 2023, Editorial office of PROGRESS IN GEOGRAPHY. All rights reserved.  相似文献   

宁南弧形构造带甘肃大沟—内蒙古乱井中上地壳电性结构          下载免费PDF全文

闵刚  程建华尹秉喜蔡学林夏时斌 《中国地质》2014,41(5):1464-1475

利用大地电磁探测方法在宁南弧形构造带内蒙古乱井—甘肃大沟段进行了中上地壳电性结构特征研究,通过二维反演获得了研究区的电性结构模型,模型清楚揭示出了该区典型的电性结构特征:(1)中上地壳电性结构整体表现为"碎块状"的构造特征,其中走廊构造带总体表现为相对低阻,北祁连碰撞造山带总体表现为相对高阻;(2)海原地震震源区的震源断裂所反映的低阻带构造样式既不像走滑断裂那样陡峭,也不像逆冲断裂那样平缓,而是兼具走滑与逆冲断裂带的双重特征;(3)研究区壳内低阻层呈现不连续分布,总体表现为南深北浅的构造样式,一般都终止于高阻地块边缘或与逆冲推覆构造的滑脱面相交汇处;(4)清水河裂褶带内发育的高阻地块可能为晚古生代或早中生代发育在元古宙基底上的古隆起,为该区燕山期构造运动提供了深部大地电磁资料证据。  相似文献   

考虑桩-土体系渐进破坏的单桩承载特性研究   总被引：1，自引：0，他引：1  

林春金  张乾青  梁发云 《岩土力学》2014,35(4):1131-1140

针对目前桩基承载特性确定时未考虑桩-土体系渐进变形过程的现状,采用现场试验和理论分析等手段对考虑桩-土体系渐进破坏的单桩承载特性展开研究。首先,利用现场试验数据对侧阻和端阻的软化特性展开深入探讨,提出了侧阻和端阻软化模型,明确了模型中各参数取值方法,并验证了其合理性。同时,根据提出的侧阻和端阻软化模型,建立了一种可考虑桩-土体系渐进破坏的单桩承载特性的迭代算法。算例分析表明,计算获得的破坏性单桩承载特性与实测值有较好的一致性,且可反映侧阻和端阻的破坏特性。实际工程中,结合单桩承载特性分析算法,可根据单桩的实际受力特点灵活选用不同形式的侧阻和端阻荷载传递函数来分析不同桩顶荷载水平下的单桩受力特性。  相似文献   

豫陕鄂交界区县域综合发展水平测度及障碍因子分析   总被引：1，自引：0，他引：1  

李许红  王永生  刘释疑 《地理科学》2022,42(10):1757-1766

以豫陕鄂交界区为研究对象,测度2000—2017年豫陕鄂交界区县域的综合发展水平,探析其空间分异特征、演化趋势和障碍因素。结果表明：① 2000—2017年,豫陕鄂交界区县域综合发展水平逐步提升,年均增速为6.08%,县域间发展的空间差异逐渐增大;② 县域综合发展水平在空间上呈正相关性,热点显著区呈现由东南部向西南部再向东南部迁移变化特征,冷点显著区在2005年前主要分布在安康市和商洛市,之后主要聚集在南阳市;③ 人文和经济要素为中度和中高障碍水平,资源和环境要素为极低和低障碍水平;随着时间的推移,障碍因子在不同县域空间阻力的分异特征更加显著。④ 豫陕鄂交界区县域发展空间阻力模式可划分为3种类型,其中人文资源要素制约型是主要的空间阻力模式。最后,基于不同空间阻力模式特征解析,提出了分区发展策略。  相似文献