PBL剪力键破坏形态及极限承载力试验研究     

王振海  李乔  赵灿晖 《地震学刊》2011,(5):517-522

根据已有试验结果,总结了有贯穿钢筋类PBL剪力键（perfobond rib shear connector）的3种破坏形态,其中充分发挥承载力的破坏形态为贯穿钢筋剪切破坏。为了研究PBL剪力键的极限承载力,对4组21个试件进行了静载破坏试验,结合文献[10]的试验结果,研究了各种因素对PBL剪力键极限承载力的影响,提出了有贯穿钢筋类PBL剪力键极限承载力计算公式。结果表明：有贯穿钢筋类PBL剪力键的极限承载力主要与贯穿钢筋面积及强度有关,与混凝土强度、混凝土榫面积无关,横向钢筋面积及强度对其的影响较以前试验所得结果小。  相似文献   

贡嘎山海螺沟冰川消融区表面消融特征及其近期变化   总被引：4，自引：1，他引：3  

刘巧  刘时银  张勇  张盈松 《冰川冻土》2011,33(2):227-236

冰川消融过程与水热条件、气象要素、冰面局地和周边地形以及冰川表面状况等密切相关.利用海螺沟冰舌段GPS测量的结果,对冰舌段的冰川近期变化包括规模变化和厚度减薄进行了新的评估.结果表明:自1989年以来冰舌段冰川厚度减薄约26%,远显著于20世纪60年代以来冰川面积的减少比例4.05%.基于对海螺沟冰川消融区冰舌段详细消...  相似文献   

Combined tree-ring width and ��13C to reconstruct snowpack depth: a pilot study in the Gongga Mountain, west China     

Xiaohong Liu  Liangju Zhao  Tuo Chen  Xuemei Shao  Qiao Liu  Shugui Hou  Dahe Qin  Wenling An 《Theoretical and Applied Climatology》2011,103(1-2):133-144

Tree-ring width (TRW) and stable carbon isotope (??¹³C) in tree-ring cellulose of subalpine fir (Abies fabri) were used to develop high-resolution climate proxy data to indicate snow-depth variations in the Gongga Mountain, west China. Tree radial growth- and ??¹³C-climate response analyses demonstrated that the TRW and ??¹³C at the timberline (3,400?m.a.s.l.) are mainly influenced by temperature and precipitation of previous growth seasons and current summer (June to August) under cold and humid conditions. Considering the analogous control factors on both tree growth and carbon isotope discrimination (??¹³C) and snow accumulation, the negative and significant relationships between tree-ring parameters (TRW and ??¹³C) and mean monthly snowpack depth were found. Herein, by combining two tree-ring parameters, a primary snow-depth reconstruction (previous October to current May) over the reliable period A.D. 1880?C2004 was estimated. The reconstruction explains 58.0% of the variance in the instrumental record, and in particular captures the longer-term fluctuations successfully. Except the period with extreme higher snowpack depth around 1990, the snowpack depth seems to fluctuate in a normal way. The reconstruction agrees with the nearby snowpack depth record in Kangding and the mean observed snowpack-depth variations of the stations on the Tibetan Plateau, particularly at long-term scales. The snowpack depth in low-frequency fluctuations, during the past century, agrees quite well with the Eastern India precipitation covering the period of previous October?Ccurrent May. Our results suggest that combing tree-ring width and ??¹³C in certain subalpine tree species growing on the Tibetan Plateau may be an effective way for reconstructing regional snowpack variations.  相似文献   

Geological Characteristics and Model Ages of Marius Hills on the Moon     

黄俊  肖龙  贺新星  乔乐  赵健楠  李卉 《中国地质大学学报(英文版)》2011,(5)

Marius Hills is a volcanic plateau on the nearside of the Moon.It is of great interest for its high concentration of volcanic features,including domes,cones,ridges,and rilles.However,the morphological and chronological characteristics of this plateau were not well studied due to the low resolution of early mission data.This study describes the detailed morphology of the volcanic features using the latest high spatial resolution images of the Terrain Camera(TC) onboard Selene-1(10 m/pix) and Narrow Angle Cam...  相似文献   

地下水农业面源污染研究现状与展望   总被引：3，自引：0，他引：3  

李巧  周金龙  贾瑞亮 《地下水》2011,33(2):73-76

农业面源污染是造成地下水污染最普遍也是最难治理的主要因素.综述了地下水农业面源污染的危害,主要影响因素,污染物测定方法,数值模拟、RS、GIS技术的应用及其防治对策,并对今后的地下水农业面源污染研究进行了展望.  相似文献   

地质钻探高强度铝合金钻杆研制及其应用          下载免费PDF全文

孙建华  梁健  张永勤  刘秀美  彭莉  王铁  朱彦彬  王汉宝 《探矿工程》2011,38(7):5-8,62

铝合金钻杆的设计制造技术属高新技术范畴,世界上只有俄罗斯、美国等少数发达国家能够批量生产。简要介绍了我国地质钻探用铝合金管材研制、铝合金钻杆制造关键技术及野外试验情况,并对今后铝合金钻杆的研发和应用方向提出了建议。项目工作成果对今后我国开发特深孔铝合金绳索取心钻杆和超深孔铝合金钻杆具有重要价值。安徽彭桥煤矿区的铝合金钻杆钻探试验最大孔深超过1000 m,应用效果良好,开辟了我国地质钻探铝合金钻杆在中深孔应用的先河。  相似文献   

新疆乌拉根矿区复杂地层绳索取心钻进技术   总被引：1，自引：0，他引：1       下载免费PDF全文

乔彦斌 《探矿工程》2011,38(11):18-20,23

在分析了新疆乌拉根矿区绳索取心钻探技术难点的基础上,介绍了在调整钻头、钻具级配,泥浆应用,操作技术等方面采取的技术方法,并对比了钻探技术效果。  相似文献   

Intercomparison between observed and simulated variability in global ocean heat content using empirical mode decomposition, part I: modulated annual cycle     

Xianyao Chen  Yuanling Zhang  Min Zhang  Ying Feng  Zhaohua Wu  Fangli Qiao  Norden Eh Huang 《Climate Dynamics》2013,41(11-12):2797-2815

This study proposes a new more precise and detailed method to examine the performance of IPCC AR4 models in simulation of nonlinear variability of global ocean heat content (OHC) on the annual time scale during 1950–1999. The method is based on the intercomparison of modulated annual cycle (MAC) of OHC and its instantaneous frequency (IF), derived by Empirical Mode Decomposition and Hilbert-Huang Transformation. In addition to indicate the general agreement in gross features globally between models and observation, our results point out the problems both in observation and in modeling. In the well observed Northern Hemisphere, models exhibit extremely good skills to capture nonlinear annual variability of OHC. The simulated MACs are highly correlated with observations (>0.95) and the IF of MACs varies coherently with each other. However, in sparsely observed Southern Hemisphere (SH), even though the simulated MACs highly correlate with observations, the IF shows significant difference. This comparisons show that the models exhibit coherent variability of IF of MACs in SH with each other, but not with observations, revealing the problems in the objective analyzed dataset using sparse observations. In the well observed tropic region, the models lack the coherence with the observations, indicating inadequate physics of the models in the tropical area. These results illustrate that the proposed method can be used routinely to identify problems in both models and in observation of the global ocean as a critical component of global climate change.  相似文献   

Development of Climate and Earth System Models in China: Past Achievements and New CMIP6 Results     

Tianjun Zhou  Ziming Chen  Liwei Zou  Xiaolong Chen  Yongqiang Yu  Bin Wang  Qing Bao  Ying Bao  Jian Cao  Bian He  Shuai Hu  Lijuan Li  Jian Li  Yanluan Lin  Libin Ma  Fangli Qiao  Xinyao Rong  Zhenya Song  Yanli Tang  Bo Wu  Tongwen Wu  Xiaoge Xin  He Zhang  Minghua Zhang 《Acta Meteorologica Sinica》2020,34(1):1-19

The Earth-Climate System Model (ECSM) is an important platform for multi-disciplinary and multi-sphere integration research, and its development is at the frontier of international geosciences, especially in the field of global change. The research and development (R&D) of ECSM in China began in the 1980s and have achieved great progress. In China, ECSMs are now mainly developed at the Chinese Academy of Sciences, ministries, and universities. Following a brief review of the development history of Chinese ECSMs, this paper summarized the technical characteristics of nine Chinese ECSMs participating in the Coupled Model Intercomparison Project Phase 6 and preliminarily assessed the basic performances of four Chinese models in simulating the global climate and the climate in East Asia. The projected changes of global precipitation and surface air temperature and the associated relationship with the equilibrium climate sensitivity under four shared socioeconomic path scenarios were also discussed. Finally, combined with the international situation, from the perspective of further improvement, eight directions were proposed for the future development of Chinese ECSMs.  相似文献   

恩施断裂中段第四纪活动特征与位移速率     

蔡永建  雷东宁  李恒  乔岳强  吴建超  Wu Jianchao 《大地测量与地球动力学》2011,31(1):39-43

对恩施断裂中段构造地貌、断裂剖面与洪积扇变形的分析表明,断裂在第四纪活动明显,以正倾滑兼右旋走滑为特征.根据洪积扇位错的水平距离、垂直高差以及形成时代,估算出断裂在中更新世晚期至晚更新世早、中期的右旋运动速率为0.43～0.5 mm/a,垂直运动速率0.07～0.17 mm/a.  相似文献