PZ系列组合式牙轮钻头在大直径嵌岩桩施工中的应用效果     

阮广招  陈亨顺 《福建地质》1995,14(2):144-148

本文通过大口径桩孔基岩钻进，探讨了ＰＺ系列组合式牙轮钻头结构特点、合理钻进参数的确定及碎岩机理。工程实践证明，牙轮钻头是我国目前大直径桩孔嵌岩施工较为理想的工具，应用效果良好。  相似文献   

用NOAA卫星气象资料计算复杂地形下的流域蒸散   总被引：5，自引：0，他引：5  

陈乾  陈添宇 《地理学报》1993,48(1):61-69

本文提出一种采用NOAA卫星AVHRR和地形高度等资料,估算流域蒸散的方法。NOAA AVHRR资料用于地表覆盖分类,据此可得出各类下垫面由可能蒸发转换成实际蒸散的折算因子。该资料还可用于计算地面反射率和气温,本文利用与卫星象元相匹配的1.2'经纬度网格上的海拔高度资料将流域内少数气象站观测的气象要素作为高度的函数插到此网格上,然后用改进的彭曼模式计算了甘肃省河西内陆河10个流域中各类下垫面的蒸散和蒸发。然后与少数雪面和高山草甸区实测的资料以及用水份平衡方法估算的相应流域的蒸散比较,验证了用此方法估算逐月流域蒸散量的可靠性。  相似文献   

Complex upper-mantle deformation beneath the North China Craton: implications for lithospheric thinning   总被引：3，自引：0，他引：3  

Liang Zhao  Tianyu Zheng 《Geophysical Journal International》2007,170(3):1095-1099

The mechanism of lithospheric thinning of the North China Craton (NCC) remains controversial. To constrain the mechanism, this study investigated the upper-mantle deformation pattern of the craton by measuring shear wave splitting at the cratonic edge. The results, derived from data recorded at 47 stations, reveal a complex pattern of mantle deformation. Inside the eastern craton, the majority of fast direction trends SE–NW parallel to the tectonic extension direction accompanying with the lithospheric thinning. At the cratonic edge, 15 stations with only null splitting results indicate undetectable anisotropy beneath the stations. This may be due to upwelling or chaotic ascension of mantle flow. To the north, off the craton, large delay times and variation of splitting parameter with backazimuth are generated by the combination of lithospheric and asthenospheric anisotropy. Based on comparison of the splitting results and the predicted ones by the compelling models, it is likely that lithospheric delamination dominated the lithospheric thinning at the north edge of the NCC during the Mesozoic to Cenozoic.  相似文献   

Researching Progress and Application Status of Eutrophication Evaluation Method of Seawater   总被引：1，自引：0，他引：1  

Xiaojuan Lin  Shan Gao  Tianyu Zhang  Guimei Liu 《地球科学进展》2018,33(4):373-384

The concept of eutrophication of seawater and its impact on the ecosystem were briefly summarized. The commonly used evaluation methods in China for eutrophication of seawater were introduced, including single factor, eutrophication index, water quality index and nutritional status, etc. In recent years, the second generation of seawater eutrophication evaluation methods, including OSPAR (Oslo-Paris Convention) Assessment Tool and NEEA-ASSESSMENT (United States National Estuarine Eutrophication Assessment) and HELCOM (Helsinki Commission) Eutrophication Assessment Tool, has developed in the world, and the second generation method has had more refined evaluation standards, which provide some criterion to judge the eutrophication effects to the environment. The present situation of the application of seawater eutrophication evaluation method in our country at present stage was described, especially in the coastal and estuary areas, eutrophication degree of regional dividing was carried out, which aimed to put forward the application status and characteristics of various water eutrophication evaluation methods to provide references for the selection of eutrophication evaluation methods in different areas. Finally, the future prospects of the application of eutrophication assessment were put forward, and the guidance of the monitoring and management of water quality monitoring and the forecasting and defensing of marine eco-environmental disasters were presented.  相似文献   

基于DGT技术对土壤硒生物有效性及其影响因素的分析     

蒋天宇  余涛  侯青叶  戚洪彬  王珏  马旭东  杨忠芳 《现代地质》2021,35(3):637-646

硒是生态环境中重要的微量元素之一,如何准确评估其生物有效性一直存在争议。在四川省广安市邻水县采集了60套农作物及其根系土样品,分析其Se含量和理化性质。同时基于梯度扩散膜技术对土壤有效Se含量进行分析,并对土壤有效Se含量的影响因素进行探究。结果表明,研究区土壤Se含量为0.15~2.42 mg/kg,均值为0.48 mg/kg,不同类型土壤Se含量差异明显,石灰土(1.06 mg/kg)>黄壤(0.78 mg/kg)>紫色土(0.28 mg/kg)>水稻土(0.27 mg/kg)。石灰土和黄壤有机质含量和总铁(TFe₂O₃)含量明显高于其他类型土壤。研究区内不同类型土壤的DGT-Se明显不同,与土壤Se含量分布相反。相关性分析表明土壤DGT-Se与Se含量、TFe₂O₃含量、S含量、有机质含量、pH值、Al₂O₃含量显著相关,受理化性质影响导致不同类型土壤中DGT-Se的差异。水稻根系土壤DGT-Se与水稻籽实Se含量显著正相关,用DGT可以较好地表达水稻-根系土系统中土壤Se的生物有效性。基于DGT技术评估预测区域尺度农业土壤有效Se含量时,需充分考虑土壤类型及其理化性质。  相似文献   

塔里木盆地台盆区寒武系盖层评价及对油气盖层有利区的优选          下载免费PDF全文

季天愚  杨威  武雪琼  蒲仁海  李德江  刘满仓  缪卫东  苏楠  叶颖 《中国地质》2022,49(2):369-382

【研究目的】塔里木盆地台盆区中寒武统发育大面积的膏盐岩、膏质泥岩和膏质云岩地层,探讨该套地层的油气封盖能力和展布可为塔里木盆地寒武系盐下领域的勘探提供依据。【研究方法】对4口井的44个岩心样品进行镜下薄片、物性参数和突破压力测试。通过建立各参数之间的关系,定量地对研究区中寒武统不同岩性岩石的封盖能力进行评价;结合二维地震和14口钻井资料对研究区中寒武统膏盐岩、膏质泥岩和膏质云岩地层的厚度进行研究;最终综合研究区中寒武统微观和宏观的评价结果,并以实际钻井的勘探情况作为约束,建立针对该研究区盖层封盖能力的综合评价方式。【研究结果】研究结果认为膏盐岩相比膏质泥岩与膏质云岩具有更好的封盖能力,但断裂和石膏的埋藏地质条件会影响盖层的封盖能力。其中阿瓦提凹陷、塔中隆起北部、满西低凸起南部以及巴楚隆起中北部膏盐岩盖层厚度较大,以巴楚隆起北部为中心,膏盐岩厚度向四周呈不规则状递减,环绕状分布。【结论】认为阿瓦提凹陷、满西低凸起西部和南部、塔中隆起北部和西部,以及塔北隆起中部为盖层发育的有利区。  相似文献   

Effects of elevated CO2 concentration on CH4 and N2O emissions from paddy fields: A meta-analysis     

Haiyang YU  Tianyu WANG  Qiong HUANG  Kaifu SONG  Guangbin ZHANG  Jing MA  Hua XU 《中国科学:地球科学(英文版)》2022,65(1):96-106

The inevitable rise of atmospheric CO₂ concentration plays an important role in regulating the carbon(C)and nitrogen(N)cycling in the rice-cropping system.Elucidating the effects of elevated CO₂ concentration(ECO₂)on CH₄ and N₂O emissions from paddy fields is essential for evaluating agricultural production in response to global climate change.In this study,we conducted a global meta-analysis to assess the overall effect of ECO₂ on CH₄ and N₂O emissions from paddy fields,aiming at providing a guideline for sustainable C and N management in paddy fields under future climate conditions.The results showed that,overall,ECO₂ significantly increased CH₄ emissions from rice fields by 23%(P<0.05),but reduced N₂O emissions by 22%(P<0.05).With a long duration(>10 yr)of ECO₂ ,ECO₂ significantly reduced CH₄ and N₂O emissions from paddy fields by 27%and 53%,respectively(P<0.05).Along with the increasing levels of ECO₂ ,the stimulating effect of ECO₂ on CH₄ emissions showed a trend of"weakening firstly and then strengthening",while its effect on N₂O emissions changed from stimulation to inhibition.Agronomy managements(e.g.,N application rates,straw incorporations,water regimes,and rice cultivars)affected the effects of ECO₂ on CH₄ and N₂O emissions from paddy fields.With no or half amount of straw incorporation,ECO₂ increased CH₄ emissions by 27% or 49%(P<0.05)from paddy fields,respectively,while non-significant effects on CH₄ emissions from paddy fields were observed under full straw incorporation.With the increasing amount of straw incorporation,the reductions in N₂O emissions from paddy fields were enhanced by ECO₂.Compared with a continuous flooding regime,intermittent irrigation weakened the promoted effect on CH₄ emissions but stimulated the inhibited effect on N₂O emissions from paddy fields under ECO₂.Therefore,under the future condition of ECO₂,it is recommended to adopt the appropriate agricultural management measures,such as combining straw incorporation and intermittent irrigation,and optimizing N application and using rice cultivars of high-yield with lower emissions.In addition,it is necessary to conduct comprehensive studies at multiscale,with multi-factor,and by multi-method to effectively reduce the uncertainty of quantifying the response of CH₄ and N₂O emissions from paddy fields to future ECO₂ .  相似文献   

中国西北地区干旱气象灾害监测预警与减灾技术研究进展及其展望   总被引：18，自引：1，他引：17  

张强  姚玉璧  李耀辉  罗哲贤  张存杰  李栋梁  王润元  王劲松  陈添宇 《地球科学进展》2015,30(2):196-211

干旱灾害是制约中国西北地区社会经济发展、农业生产和生态文明建设的重要自然灾害,而且随着气候变暖西北地区极端干旱事件发生频率和强度均呈增加趋势,影响不断加重。"中国西北干旱气象灾害监测预警及减灾技术研究"成果是在数十个国家级科研项目的支持下,经过过去20年的理论研究和应用技术开发所取得的一系列创新性成果。该成果对西北干旱形成机理及重大干旱事件发生、发展的规律取得了新认识,尤其是发现了形成西北干旱环流模态的4种主要物理途径;研制了西北干旱预测的新指标、干旱监测的新指数及监测农田蒸散的新设备,明显提高了干旱监测准确性和针对性;提出了山地云物理气象学新理论,研发了水源涵养型国家重点生态功能区——祁连山空中云水资源开发利用技术;发现了干旱半干旱区陆面水分输送和循环的新规律,揭示了绿洲自我维持的物理机制;认识了干旱气候变化对农业生态系统影响的新特征,建立了旱作农业对干旱灾害的响应关系;开发了旱区覆膜保墒、集雨补灌、垄沟栽培、适宜播期等应对气候变化的减灾技术,为西北实施种植制度、农业布局及结构调整和农业气候资源高效利用提供了科学方案。该成果的完成提升了中国干旱防灾减灾技术水平,培养了中国干旱气象科技队伍,推进了西北地区干旱气象业务服务能力,对西北地区社会经济发展、农业现代化和生态文明建设等方面起到了重要的促进作用。在此基础上,展望了西北地区干旱气象科学研究中迫切需要、有可能突破的主要领域。  相似文献   

黄土中圆形抗拔锚板基础承载力分析          下载免费PDF全文

胡建芳  李论基  史盛  赵天宇  杨钦明 《探矿工程》2020,47(9):52-56

在三维状态下运用极限平衡理论,对黄土中圆形抗拔锚板基础在受到垂直于板面荷载作用下的承载力进行理论分析,该理论研究考虑了锚板在上拔过程中板周土体的破裂方程、破裂面上的正应力和剪应力、埋深率等影响因素。理论公式计算结果表明：抗拔锚板承载力系数随着锚板埋深的增加而增大,并且当深度达到一定值时,承载力系数将达到其极限值;当埋深率h/D=1~2之间时,上覆土重对承载力系数影响较小;当h/D=4时,土体和锚板之间的吸力对承载力系数的影响大于锚板上覆土重;当h/D>4时,上覆土重对锚板抗拔承载力起着决定作用。理论计算公式与已有学者的试验结果进行对比表明提出的模型理论计算结果和其他学者的试验结果有良好的一致性,验证了该理论的正确性,为工程中抗拔锚板的设计提供了有价值的参考。  相似文献   

近46年重庆地区气温变化特征分析   总被引：1，自引：0，他引：1  

刘晓冉  程炳岩  张天宇  周浩  杨宝钢 《高原山地气象研究》2009,29(1):39-43

利用1961~2006年期间重庆地区的气温资料,对重庆气温变化的特征进行分析。结果表明:近46年,重庆年平均、年平均最高气温都经历了先降温后升温的过程,而且前期1961~1985年的降温趋势和后期1986~2006年的升温趋势都很显著,均通过了0.01的显著性水平检验。而年平均最低气温近46年的整体上升趋势明显,通过了0.01的显著性水平检验。对于重庆平均气温和平均最高气温,在前期降温过程中,春季和夏季的下降趋势显著;而在后期的升温过程中,春季和秋季的增温趋势显著。   相似文献