地质灾害隐患应急避险场所适宜性初步评价          下载免费PDF全文

丁桂伶  赵忠海  翟淑花  赵越 《中国地质灾害与防治学报》2014,25(4):97-100

地质灾害应急避险场所不仅在灾中或灾后能为灾民提供一个临时安置或生存场所,而且更是社会整合其有限资源开展防灾减灾工作的平台。本文结合北京市地质灾害应急避险现状及特征,提出了地质灾害隐患应急避险场所的概念、适宜性评价原则及标准。  相似文献   

边坡稳定强度折减有限元分析中的若干问题讨论   总被引：12，自引：1，他引：11  

万少石  年廷凯  蒋景彩  栾茂田 《岩土力学》2010,31(7):2283-2288

强度折减有限元法在边坡稳定性分析中得到了广泛应用,但仍存在一些问题未能很好地解决。首先探讨了不同单元类型对边坡稳定安全系数计算精度的影响,指出采用三角形二阶单元,能够较好地模拟土坡的渐近破坏过程,且相对网格大小控制在0.1～0.15之间时能获得较精确的解;其次讨论了边坡失稳的4个判据问题,指出在合理网格大小区间内,有限元强度折减至土坡破坏时,先后出现塑性区贯通、等效塑性应变带贯通、位移陡增与数值计算不收敛等4种表征,以此分别作为边坡失稳判据,所得到的安全系数具有较好的一致性;最后讨论了边坡破坏时滑动面深浅、滑出点位置与坡体材料的黏聚力、内摩擦角及坡角间的关系,指出黏聚力越大、内摩擦角越小或坡度越小,滑动面越深,且滑出点越远离坡脚。  相似文献   

河流健康及其指标   总被引：1，自引：0，他引：1  

刘昌明  刘晓燕 《地理学报(英文版)》2009,19(1):3-11

Based on the author’s practice in river harnessing, this paper defines that a healthy river is a river whose social and natural functions can be balanced or compromised in terms of the socio-economic, ecological and environmental values associated with the river. The environmental values of river systems should be judged according to the following criteria: the signal of a healthy river should be associated with favorable riverbed, acceptable water quality, sustainable river ecosystem and compatible runoff. The river health criterion should reflect the river’s natural function status which includes the riverbed, water quality, river ecosystem and runoff. But, the variety and quantity would be different for different rivers depending on different natural features and social background. The standards to be adopted for a healthy river should be determined according to the requirements for maintaining river’s normal natural functions and the extent whether the social and natural functions could perform in a balanced way, and also the standards adopted should be adjusted according to the change of the given conditions. The key factor of river health is the enough and clean flow. The authors stressed that human activities would hurt the river health which include excessive water diversion and excessive power generation from the river, improper regulation of flood and sediment, and over discharge of sewage into the river and over change in fish habitat. Taking the Yellow River as a case, this paper also discussed the method to identify what are the standards of a healthy river as well as environmental flows. Foundation: Chinese National Research Program, No.2006BAB06B; National Key Basic Research Development Program of China “973”, No.G1999043601 Author: Liu Changming, Academician  相似文献   

基底先存构造对裂陷盆地断层形成和演化的控制作用规律          下载免费PDF全文

童亨茂聂金英  孟令箭张红波 李晓宁 《地学前缘》2009,16(4):97-104

针对基底先存构造对裂陷盆地断层控制作用研究中存在的问题,应用脆性断裂新理论--“不协调性准则”来阐述、分析裂陷盆地基底先存构造控制断层形成和演化的力学机理,确定基底先存构造活动性的变化规律,探讨并初步确定基底先存构造对裂陷盆地断层形成和演化的控制作用具有如下规律: (1)先存构造(特别是先存断裂)优先活动,这是基底先存构造能控制沉积盆地断层形成和演化的根本原因。(2)先存构造对盆地断层控制作用的强度决定于其活动性,它由先存构造的产状、力学性质和应力状态决定,可以用先存构造活动性系数(fAS)来定量描述。(3)受基底先存断裂控制的断层发育的位置和延伸方向(走向)、形成次序、继承性特征,以及分布规模等都表现出显著的规律性。(4)与伸展方向垂直,且与σ1夹角为45°-(/2)的基底先存断裂对断层的控制作用最强;随着走向与伸展方向的夹角α逐渐变小,以及倾角偏离45°+(/2),对断层的控制作用就逐渐减小。(5)基底先存断裂的规模越大,对断层的控制作用就越强;受大规模基底先存断裂控制的断层往往构成裂陷盆地的构造格架。(6)随着薄弱带抗剪强度的减小,基底先存薄弱带发生破裂的可能性不断增大,对断层的控制作用不断增强;而相对基底先存断裂而言,其影响程度则相对偏弱。上述认识可以为裂陷盆地地震资料的构造解释提供理论模型,为裂陷盆地断裂系统的形成和演化的深入研究提供理论指导。  相似文献   

辽宁省义县大铁厂地区金钼矿地质特征与找矿标志     

曲亚财  王红领 《火山地质与矿产》2012,(2):101-103

辽宁省义县大铁厂地区金钼矿床为浅成中一高温热液石英脉型,受韧性剪切构造和岩浆活动控制,本文在详细研究了矿床地质及地球物理化学特征基础上,总结了该矿床的主要控矿因素并归纳了主要找矿标志,为进一步在该区找矿指明了方向。  相似文献   

Seismic fragility assessment of RC frame structure designed according to modern Chinese code for seismic design of buildings   总被引：1，自引：0，他引：1  

S.Tesfamariam  S.F.Stiemer 《地震工程与工程振动(英文版)》2012,11(3):331-342

Following several damaging earthquakes in China,research has been devoted to find the causes of the collapse of reinforced concrete(RC) building sand studying the vulnerability of existing buildings.The Chinese Code for Seismic Design of Buildings(CCSDB) has evolved over time,however,there is still reported earthquake induced damage of newly designed RC buildings.Thus,to investigate modern Chinese seismic design code,three low-,mid-and high-rise RC frames were designed according to the 2010 CCSDB and the corresponding vulnerability curves were derived by computing a probabilistic seismic demand model(PSDM).The PSDM was computed by carrying out nonlinear time history analysis using thirty ground motions obtained from the Pacific Earthquake Engineering Research Center.Finally,the PSDM was used to generate fragility curves for immediate occupancy,significant damage,and collapse prevention damage levels.Results of the vulnerability assessment indicate that the seismic demands on the three different frames designed according to the 2010 CCSDB meet the seismic requirements and are almost in the same safety level.  相似文献   

城市抗震设防标准的优化     

管友海  冯启民  王耀 《地震》2010,30(4):82-88

本文提出了城市抗震设防标准的优化方法, 该方法利用了建筑结构的易损性分析理论, 初始造价与设防烈度的关系, 地震设防时增加的经济投入与设防烈度的关系, 地震经济损失与设防烈度的关系等, 根据抗震设防增加的经济投入与地震经济损失之和最小的模型得到经济最优设防烈度, 并以按经济最优烈度设防时地震中的人员伤亡率小于社会可接受地震人员死亡率为限制条件, 求得最优设防烈度。  相似文献   

A new method in determining potential region of precipitation enhancement above coastal land     

Yilin Wang  Wei Wu 《中国海洋大学学报(英文版)》2010,9(4):309-316

To ensure the effectiveness of the operation of artificial precipitation enhancement, a potential region for the operation should be determined in advance.As cloud microphysical measurements needed for the determination of the potential region of cloud seeding are not available before the operation of routine precipitation enhancement, a new method based on the growth process of ice crystal is put forward for determining the potential region using the numerical weather prediction model output.The ice supersaturation, accumulated water vapor within minus temperature layer (≥9 mm), and upward water vapor transportation are adopted as criteria to determine the potential time, height and region of cloud seeding, and the real-time radar images are applied to make decisions on the seeding commanding.The criteria and Doppler radar images are studied in a case of precipitation enhancement characterized by significant water vapor supply from the north part of a tropical cyclone in the northwest Pacific, which shows that the ocean plays a crucial role in the advection transportation of water vapor to the potential region of the coastal area.The study presents a new method to determine the potential region of precipitation enhancement using macro-physical quantities under ice crystal growth environment.The method possesses a clear physical significance and can be readily applied with the required and easily predicted parameters.  相似文献   

矽卡岩矿床的研究现状   总被引：11，自引：0，他引：11  

黄华盛 《地学前缘》1994,1(3):0-0

本文评述了矽卡岩矿床类型划分、矽卡岩形成的物理化学条件、成矿流体以及矿物成分与矿化关系的某些进展。镁矽卡岩形成于各种深度,而钙矽卡岩则形成于较浅和较低温的环境;限制矽卡岩形成的主要参数是ＣＯ＿２、深度以及岩浆期后诸元素的活度（如Ｍｇ￣（２＋）、Ｃａ￣（２＋）…）、ｐＨ和Ｅ＿ｈ值。当前已应用非平衡热力学去研究矽卡岩成岩成矿过程。接触交代带中存在两种流体,一种来自岩浆,另一种是天水循环来源;同位素资料提供水／岩反应的信息,而Ｓ、Ｐｂ、Ｓｒ等同位素资料提供矿质来源的标志。矽卡岩矿物如辉石、石榴石的化学成分与矿化关系密切,可以指示矿化类型。文中总结了矽卡岩型金矿特点,其蹄、铋矿物及退化蚀变是重要的找矿标志。含矿流体及成矿动力学是今后研究的重要方向。  相似文献   

大横路钴铜矿床控矿因素及找矿标志     

任启武  薛剑波  王丽梅  李德洪  苏伟华 《吉林地质》2005,24(4):26-31

大横路钴铜矿床主要产于老岭群大栗子组第二岩性段内.其控矿因素主要有地层、褶皱和断裂、变质作用及岩浆活动.找矿标志主要为老岭群大栗子组含炭岩系、矿化蚀变（硅化、孔雀石化、褐铁矿化、黄铜矿化）、区域化探及土壤异常（Co、Cu、Ni、Pb、Zn、Ag等组合异常）、老岭群大栗子组中的中基性脉岩等.  相似文献