振动沉管碎石桩复合地基综合检测若干值得研究的岩土工程问题     

赵法锁  杜纪民 《地球科学与环境学报》1993,(Z2)

近年来,振动沉管碎石挤密桩在处理饱和黄土地基方面得到了相当广泛的应用。本文通过对西安市某工程振动沉管碎石桩复合地基的综合检测,提出几个值得研究的岩土工程问题。  相似文献   

青年科学基金助推地理学研究创新与综合   总被引：1，自引：1，他引：0  

范闻捷  高锡章  冷疏影 《地理科学进展》2018,37(4):451-464

本文以国家自然科学基金委员会地理学科1987-2016年青年科学基金资助项目为研究对象,采用文献计量分析方法,从地理学科的4个分支学科：自然地理、人文地理、地理信息、环境地理出发,通过分析关键词词频在不同时段的变化特点、与同时期面上项目申请书关键词词频进行对比等方法,追寻不同分支学科青年科学基金的研究特点,分析各分支学科的青年科学基金选题的演变规律。以此为依据,筛选了7个有代表性的关键词,分析这些关键词所代表前沿研究方向,和青年科学基金选题变化情况,并根据后续资助情况分析学科发展过程中青年人才梯队的成长过程,追寻青年科学基金在地理学科发展和人才培养中的作用。研究表明,自1987年以来,青年科学基金选题一直处于地球表层自然环境和人文经济的格局与过程研究的最前沿,技术创新是青年科学基金最主要的源动力,研究不断向定量化发展;青年科学基金的研究选题也逐渐拓展,走向综合;同时持续推动地理学科研队伍的成长。对于地理科学的技术和理论创新的助推作用显著。  相似文献   

基于复合指数模型的DMSP/OLS夜间灯光影像饱和校正方法     

许文鑫  梁娟珠 《地球信息科学学报》2020,22(11):2227-2237

由于OLS传感器航行过程中增益记录和交叉定标的缺失,使得DMSP夜光影像在城市中心出现过度饱和等问题,因此探讨灯光数据去饱和方法在人类活动强度评估和城市时空演化分析等方面具有重要意义。为了解决这一难题,有学者提出使用NDVI修正饱和灯光数据的VANUI指数,为研究灯光数据去饱和提供了简单便捷的思路,然而该指数在部分城市中较难有明显的校正效果。本文在VANUI指数思想的基础上,顾及到人口密度随着郊区到城市中心距离的增加呈现指数型增长,提出了基于复合指数模型校正夜间灯光指数CEANI,为人类活动强度评价等研究提供更准确的结果。研究表明:① 与VANUI相比,CEANI在刻画城市内部饱和区域特征时具有更好的细节,较好地凸显城市内部空间异质性;② 在25组随机样本的相关对比中,CEANI（R²mean=0.79）与辐射定标产品比VANUI（R²mean=0.68）具有更高的相关性;③ 三大城市群中CEANI与常住人口的R²分别为0.767、0.676和0.841,比VANUI（R²分别为0.640、0.553和0.775）分别提高了0.127、0.123、0.066,相较于VANUI,CEANI与常住人口具有更强的相关性,对于人口指标的估算能力更强。  相似文献   

中国政治地理学研究进展——基于国家科学基金资助的分析   总被引：3，自引：1，他引：2  

安宁  梁邦兴 《地理科学进展》2017,36(12):1463-1474

国家科学基金(国家自然科学基金和国家社会科学基金的统称)研究立项课题旨在探究重大现实问题以及学科前沿发展,在很大程度上反映了相关学科研究的进展和整体水平。通过分析近20年来中国国家自然科学基金和社会科学基金对政治地理相关议题的资助,以及受资助人在该时期对相关议题的科研情况,得出以下结论：①2011年以来,国内政治地理学逐渐被认可和关注,并呈现出以北京、广州、昆明和上海研究机构为辐射中心的地理特征;②国内政治地理研究重点为边境与边界、环境政治、领土(主权和安全)、行政区划和管治、尺度和空间、社会和文化政治等六大议题;③国内政治地理研究日渐与国际接轨,但行政区划和管治等是独特的研究。整体而言,随着国家科学基金对政治地理研究支持力度的加大,期望能瞄准国际研究前沿和国内需求,建构符合中国国情的政治地理学学科体系。  相似文献   

研究地基液化的新方法   总被引：5，自引：0，他引：5  

王新德 《江苏地质》1997,21(1):43-46

介绍一种研究地基液化的新方法，利用地震时可能液化的土层的地面加速度，地下钻孔加速度及孔隙水压力方面的连续资料，通过计算处理，先后获得土层的水平位移反应，平均剪应变和有效应力，在此基础上，对平均剪应力－应变和有效应力路径历史作出评价，由此获得地震振动时有关地基液化过程的直接和有价值的资料。  相似文献   

Oceanographic Research Vessel Sharing Plan—A Significant Creation of the National Natural Science Foundation of China     

Ge Renfeng  Shi Maochong 《地球科学进展》2016,31(4):428-435

To settle the difficulties of the shortage of oceanographic research vessels in our country, the National Natural Science Foundation Committee of China founded Oceanographic Research Vessel Sharing Plan in 2009. It is aimed at enhancing efficiency and optimization of the vessel resources,and coordinating the use demands of vessels for the different foundation projects and the efficient use of the research vessels. We have summarized the achievements made in the Plan from 2010 to 2014, as well as the use system of the research vessels sharing, the specific operating mode ,the organization and the management framework of the Plan. In the end, we put forward our suggestions on the improvement of the Plan after the primary analysis of the present situation of the sharing of the survey data and the existing problems.  相似文献   

Exploration on compound water circulation system to solve water resources problems of North China Plain     

LIU Ji-chao  SHI Jian-sheng  GAO Ye-xin  REN Zhan-bing 《地下水科学与工程》2016,4(3):229-237

In order to solve water resources problems in the North China Plain, this paper explored human-nature compound water circulation system from three aspects including urban flood control, surface drainage and saline water in the central and eastern of the North China Plain. Results show that: (1) The technical methods have achieved zero increase in rainwater runoff in urban areas, (2) surface drainage depletion problems can be solved through abandoned water and river water separation method, (3) and technical method through promoting rainwater infiltration would be used to solve problem of saline water in the central and eastern parts. This research provides a new perspective to the ultimate solutions to water resources problems in the North China Plain, and a fresh research direction for the development of hydro-geological science.  相似文献   

Identification of soil–structure interaction effect in base-isolated bridges from earthquake records     

M. T. A. Chaudhary  M. Ab  Y. Fujino 《Soil Dynamics and Earthquake Engineering》2001,21(8):713-725

Identification of system parameters with the help of records made on base-isolated bridge during earthquakes provides an excellent opportunity to study the performance of the various components of such bridge systems. Using a two-stage system identification methodology for non-classically damped systems, modal and structural parameters of four base-isolated bridges are reliably identified using acceleration data recorded during 18 earthquakes. Physical stiffness of reinforced concrete columns, dynamic properties of soil and foundation impedance are found by available theoretical models in conjunction with pertinent information from the recorded accelerographs. Soil–structure interaction (SSI) effect in these bridges is examined by comparing the identified and physical stiffness of the sub-structure components. It is found that SSI is relatively pronounced in bridges founded in weaker soils and is more strongly related to the ratio of pier flexural stiffness and horizontal foundation stiffness than soil shear modulus, G_s, alone. However, substantial reduction in G_s is observed for moderate seismic excitation and this effect should be taken into account while computing foundation impedance.  相似文献   

宜昌市城区工程地质研究     

金明信 《中国煤田地质》1994,6(3):56-64

本文对宜昌河段河谷的演变，各级阶地发育特征进行了研究和论述，归纳了宜昌城区目前在建设工程地质和环境地质中存在的十一种问题及处理方法。通过研究区内地基土的评价。对有关问题提出探讨和建议。  相似文献   

Centrifuge modeling of load-deformation behavior of rocking shallow foundations   总被引：4，自引：0，他引：4  

Sivapalan Gajan  Bruce L. Kutter  Justin D. Phalen  Tara C. Hutchinson  Geoff R. Martin 《Soil Dynamics and Earthquake Engineering》2005,25(7-10):773-783

Shallow foundations supporting building structures might be loaded well into their nonlinear range during intense earthquake loading. The nonlinearity of the soil may act as an energy dissipation mechanism, potentially reducing shaking demands exerted on the building. This nonlinearity, however, may result in permanent deformations that also cause damage to the building. Five series of tests on a large centrifuge, including 40 models of shear wall footings, were performed to study the nonlinear load-deformation characteristics during cyclic and earthquake loading. Footing dimensions, depth of embedment, wall weight, initial static vertical factor of safety, soil density, and soil type (dry sand and saturated clay) were systematically varied. The moment capacity was not observed to degrade with cycling, but due to the deformed shape of the footing–soil interface and uplift associated with large rotations, stiffness degradation was observed. Permanent deformations beneath the footing continue to accumulate with the number of cycles of loading, though the rate of accumulation of settlement decreases as the footing embeds itself.  相似文献