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101.
隧道围岩分类的层次类比系统方法 总被引:1,自引:0,他引:1
吕小平 《水文地质工程地质》1993,20(4):10-13
在本文中,把围岩分类的因素分为3种。第一种为大的地质环境,它主要包括地层、构造、地形等;第二种为围岩的小环境,它包括岩体结构、结构面的发育情况、地下水的分布等;第三种为围岩的物理、力学、水理以及埋深等具体参数。这3种因素从大到小形成一个层次递阶关系,下层元素是上层元素的具体表现,上层元素对下层元素产生影响。把用这种层次关系表征的典型工点集合,作为一个工程地质评价模型的基础。按典型工点的稳定性进行排序或进行聚类分析,再把新工点的稳定性权重与典型工点的稳定性权重序列或相似序列比较,找出新工点在典型工点序列中的相当位置,这样就可根据与新工点相近的典型工点围岩类别以及施工、支护等成功的设计参数或经验教训作为新工点的设计参数。 相似文献
102.
IntroductionAfteramoderateorstronger(Ms25.0)earthquake,themosturgentworkofthedivisionforearthquakemonitoringandpredictionistodetermineitstimeoforigin,hypocentrallocation(longitude,latitudeanddepth)andmagnitudeandtojudgethetrendofseismicregimedevelopmentassoonaspossible.Ingeneralcases,whenanearthquakewithMS25.0insideChinaoraonewithMS26.0inneighboringareasofChinahasoccurred,theEarthquakeBulletinofChineseSeismologicalNetworkcanprovidedeterminationoftheorigintime,hypocentrallocation(longitude,… 相似文献
103.
The status of the ecological environment and a proposed protection strategy in Sanya Bay,Hainan Island,China 总被引:8,自引:0,他引:8
Huang L Tan Y Song X Huang X Wang H Zhang S Dong J Chen R 《Marine pollution bulletin》2003,47(1-6):180-186
Sanya Bay encompasses a high diversity of natural habitats, ranging from coral reefs, rocky and sandy shores and mudflats to mangroves. Seasonal physicochemical and biological investigations were conducted from 1998 to 1999 and again in April 2000. Water-related environmental quality in Sanya Bay is in good condition. The levels of dissolved oxygen, nitrogen, phosphorus and heavy metals are within the first class of National Seawater Quality Standards for China. Annual mean values of chlorophyll a of 0.93 mg m(-3) and phytoplankton primary productivity of 440.8 mgC m(-2)d(-1), respectively, were found in the waters, both of which show a significant correlation with inorganic nitrogen. A mean new productivity of 144.6 mgC m(-2) d(-1) was recorded in summer. Sanya Bay is rich in natural resources and biodiversity with 235 species of phytoplankton and 129 species of zooplankton identified in the survey. The annual mean abundance of phytoplankton and zooplankton were 1564 x 10 cells m(-3) and 121 individuals m(-3), respectively, with an annual mean zooplankton biomass of 129 mg m(-3). A total of 243 species of fish were sampled in the survey including many of high economic value. Three hundred and eighty-four species of benthos in 121 families were found by mud sampling and trawling. The average biomass of benthic organisms was 11.55 gm(-2), with a density of 31 individuals m(-2). Molluscs were the dominant group, followed by crustaceans; coelenterates exhibited the lowest biomass. One hundred and twenty-six species from 48 families of intertidal organisms were collected by frame sampling, with a mean annual biomass of 644.7 gm(-2) and average density of 816 individuals m(-2). The highest biomass of 1673.5 gm(-2) was collected in a coral reef region, while the highest density of 1219 individuals m(-2) occurred in a mangrove region. The coastline is characterized by coral reefs that accounts for 30% of the total coastline length in the bay, so coral reefs are a key ecosystem that are important for maintaining the regional marine resources and biodiversity. We need to pay much more attention to such diverse marine resources to maintain the integrity and function of these coastal ecosystems. 相似文献
104.
Basic characteristics of active tectonics of China 总被引:84,自引:8,他引:76
Active tectonics is inferred to all the structures which have been active since the late Pleisto-cene, 100—120 ka B.P., are still active recently, and will be active in a certain time period in the future, such as active faults, active folds, active basi… 相似文献
105.
全球化、跨国公司投资与地区发展关系研究进展 总被引:5,自引:1,他引:4
近年来,全球化力量成为影响区域经济发展及其空间格局演变的主要因素之一。在未来相当长一个时期内,全球化因素影响的深度与广度都将进一步扩展。随着经济活动全球化的发展,学术界有相当多的研究关注全球化、跨国公司投资及其社会经济影响。本文分别从国家、区域和企业三个不同的层面及全球化与区域发展互动的角度对现有的关于全球化、跨国公司投资与地区发展的相关研究进行总结和评述。 相似文献
106.
近44 a中国冬夏气温变率及其对区域变暖性的影响 总被引:6,自引:2,他引:4
利用近44a中国85个测站冬夏季逐日平均、最高和最低气温序列,研究冬夏季温度季节变率及其时空演变特征,探讨其对区域变暖稳定性的影响。结果表明:冬季,除高原、西南、东北以外的中国大部分地区,温度的季节变率存在显著下降趋势,是近期变暖的稳定区,其中变暖最为稳定、显著的区域是西北、华北地区,东北北部虽变暖幅度很大,但稳定性最差;夏季,长江中下游及其江南地区温度变率存在显著上升趋势,20世纪70年代后年际变幅明显增大,表明该地区80年代降温的稳定性差。 相似文献
107.
The response of gobi surfaces to the near-surface air flow can be characterized quantitatively by drag coefficients. By using wind tunnel tests, an attempt is made to define the relationship between the drag coefficients of gobi surfaces and gravel size and coverage. It is concluded that the drag coefficients of gobi surfaces tend to be constants when gravel coverage is over 40%-50%. Consequently, we think that the gobi deflation planes expanding vastly in the arid Northwestern China are aerodynamically stable, at least not the supplying sources of current dust storms, and therefore the emphasis on dust storm control should be paid on the so-called "earth gobi" that has low gravel coverage. The prediction model for drag coefficients of gobi surfaces has been developed by regressing drag coefficients on gravel size and coverage, the predicted results are in reasonably good agreement with wind tunnel results (R 2 = 0.94). The change of drag coefficients with gravel friction Reynolds number implies that the development extent of drag effect increases with gravel size and coverage. 相似文献
108.
距离和坐标方位角计算的简易方法 总被引:3,自引:0,他引:3
提出一种更简便、实用的距离和坐标方位角同时计算的新方法,编写两种不同型号的常用计算器程序。 相似文献
109.
110.
Jacques Hinderer 《中国科学D辑(英文版)》2006,49(12):1259-1269
New generation superconducting gravimeters (SGs), which have been demonstrated to be better than the best seismometers STS-1 at frequencies below 1 mHz, can be accepted as the quietest vertical seismometers for observation of long-period earth free oscillations. Wavelet filtering with narrow band-pass frequency response as shown in this paper is very helpful in removing at- mospheric pressure effects from on gravity records in long-period seismic mode frequency bands. The processing of high quality SG records after the great Sumatra earthquake (Dec. 26, 2004) with wavelet filtering leads to clear observations of all coupled toroidal modes below 1.5 mHz except these for 0T5, 0T7 and 1T1; moreover 1T2 and 1T3 are, for the first time, unambiguously revealed in the vertical components of the free oscillations. The three well-resolved splitting singlets of overtones 2S1 are observed from a single SG record for the first time. 相似文献