A Connectivity Index for Discrete Fracture Networks     

C. Xu  P. A. Dowd  K. V. Mardia  R. J. Fowell 《Mathematical Geology》2006,38(5):611-634

Connectivity is an important measure for assessing flow transport in rock, especially through fractures. In this paper, rock fracture systems are modelled by a discrete fracture model simulated by a marked point process. A connectivity index is then introduced to quantify the connectivity between any two points in space. Monte Carlo simulation is used to evaluate the connectivity index for stationary cases and relationships between the connectivity index and the parameters of the discrete fracture model are analysed. The average number of intersections per fracture, X_f, and the fracture intensity, P12 (P32), are calculated and the relationships between these parameters and the connectivity index are investigated, concluding that X_f is the more suitable parameter for the classification of rock mass flow properties. The relationships between the connectivity index and the percolation state of the fractured medium are also discussed. An edge correction is briefly discussed and a practical example is used to demonstrate the method of computing the connectivity index.  相似文献   

A geochronological approach to understanding the role of solar activity on Holocene glacier length variability in the Swiss Alps   总被引：3，自引：0，他引：3  

Anne Hormes  Jürg Beer  Christian Schlüchter 《Geografiska Annaler: Series A, Physical Geography》2006,88(4):281-294

We present a radiocarbon data set of 71 samples of wood and peat material that melted out or sheared out from underneath eight presentday mid‐latitude glaciers in the Central Swiss Alps. Results indicated that in the past several glaciers have been repeatedly less extensive than they were in the 1990s. The periods when glaciers had a smaller volume and shorter length persisted between 320 and 2500 years. This data set provides greater insight into glacier variability than previously possible, especially for the early and middle Holocene. The radiocarbon‐dated periods defined with less extensive glaciers coincide with periods of reduced radio‐production, pointing to a connection between solar activity and glacier melting processes. Measured long‐term series of glacier length variations show significant correlation with the total solar irradiance. Incoming solar irradiance and changing albedo can account for a direct forcing of the glacier mass balances. Long‐term investigations of atmospheric processes that are in interaction with changing solar activity are needed in order to understand the feedback mechanisms with glacier mass balances.  相似文献   

Retrieval of stratospheric O3 and NO2 vertical profiles using zenith scattered light observations     

G. S. Meena  C. S. Bhosale  D. B. Jadhav 《Journal of Earth System Science》2006,115(3):333-347

Daily zenith scattered light intensity observations were carried out in the morning twilight hours using home-made UV-visible spectrometer over the tropical station Pune (18‡31′, 73‡51′) for the years 2000–2003. These observations are obtained in the spectral range 462–498 nm for the solar zenith angles (SZAs) varying from 87‡ to 91.5‡. An algorithm has been developed to retrieve vertical profiles of ozone (O₃) and nitrogen dioxide (NO₂) from ground-based measurements using the Chahine iteration method. This retrieval method has been checked using measured and recalculated slant column densities (SCDs) and they are found to be well matching. O₃ and NO₂ vertical profiles have been retrieved using a set of their air mass factors (AMFs) and SCDs measured over a range of 87–91.5‡ SZA during the morning. The vertical profiles obtained by this method are compared with Umkehr profiles and ozonesondes and they are found to be in good agreement. The bulk of the column density is found near layer 20–25 km. Daily total column densities (TCDs) of O₃ and NO₂ along with their stratospheric and tropospheric counterparts are derived using their vertical profiles for the period 2000–2003. The total column, stratospheric column and tropospheric column amounts of both trace gases are found to be maximum in summer and minimum in the winter season. Increasing trend is found in column density of NO₂ in stratospheric, tropospheric and surface layers, but no trend is observed in O₃ columns for above layers during the period 2000–2003  相似文献   

采矿引起的边坡倾倒滑移变形机理与变形安全性分析研究—以抚顺西露天矿边坡为例   总被引：1，自引：0，他引：1  

申力  纪玉石  刘大勇  祖国林  刘晶辉 《中国地质灾害与防治学报》2006,17(3):63-68

在矿山开发、水电建设过程中倾倒变形问题日渐突出。倾倒变形边坡一般具有反倾边坡结构,变形的过程和机理比较复杂、涉及的变形岩体范围较大、危害严重。论文以抚顺西露天矿边坡为例,通过岩体位移监测资料的跟踪分析、底面摩擦模拟试验,以岩体力学、松散介质力学原理为理论基础,探讨了采矿影响下边坡倾倒滑移体的变形机理,分析认为采矿引起的倾倒滑移变形问题是在特定的地质构造和采矿工程条件下产生的,并提出了岩体变形安全性分析方法。通过工程实例,验证了方法的实用性,并针对实际问题提出了变形整治对策。  相似文献   

洪山预测区煤层赋存的可能性分析     

尚洪田 《中国煤田地质》2006,18(4):25-26,52

分析了洪山预测区西部洪山岩体地质特征及其向外围扩散的范围和程度，研究了北掌勘查区和焦窑煤矿两邻区煤层受岩浆岩影响的程度，认为洪山岩体对预测区煤系及煤层赋存的影响较小，岩体外围仍有煤系赋存。为下一步找煤指明了方向。  相似文献   

冲绳海槽玄武岩中中酸性残余熔体研究及其岩石学意义   总被引：1，自引：0，他引：1  

陈小明  王汝成赵明 倪培赵广涛  李巍然 《岩石学报》2005,21(1):158-168

与洋壳有关的酸性岩由于对了解幔源岩浆的演化以及判别古老蛇绿岩套及其构造位置的重要意义而倍受岩石学家和构造地质学家的关注。本对发现于冲绳海槽玄武岩基质中的中酸性到酸性残余熔体进行了详细研究，它们提供了幔源玄武岩浆结晶分异形成酸性岩浆的直接证据。在细小的基质矿物间分布有一种玻璃质的残余熔体，其成分随距冷凝边距离(L)的增加而越来越酸性。在SiO2对Na2O K2O图解上，残余熔体的投影点从玄武岩到英安岩均有分布，反映了一个连续的演化系列。在AFM图解上，残余熔体表现出与Thingmuli火山岩系列类似的拉斑玄武岩系列的演化趋势。我们的研究表明：残余熔体的演化受结晶分异作用控制。在早期结晶阶段，辉石的结晶起主导作用，结果造成残余熔体中SiO2、Al2O3，Na2O的迅速增加，FeO、MgO、CaO迅速降低。在晚期结晶阶段，斜长石成为主导结晶相，导致残余熔体中Al2O3，Na2O的迅速消减。Al2O3、Na2O从增加到降低的转变出现在SiO2=62％左右。在L=27．5mm处，85～90％的基质岩浆已发生了结晶作用，导致残余熔体中SiO2含量达到69～70％，而且此处还新出现了一种富FeTi的氧化物。该玄武岩中残余熔体和基质矿物的成分及演化特征分别与Thingmuli火山岩系列中酸性端元的组成相似，在也佐证了Thingmuli火山岩系列是幔源岩浆结晶分异的产物.  相似文献   

湖北省巴东县黄土坡滑坡深部变形防治方案探讨   总被引：1，自引：0，他引：1  

江鸿彬 《中国地质灾害与防治学报》2005,16(1):53-56,60

文章根据几年来从事黄土坡滑坡区的勘查、可研及现场工程管理的认识，从滑坡分布特征、物质构成、稳定研究、变形特征等方面对滑坡进行研究。针对该滑坡厚度巨大，滑体强度高，近期深部变形较明显的实情，作者以库仑定律为基础，提出采用岩土加固治理滑坡区深部滑移的初步治理方案。  相似文献   

引黄水在北大港水库蓄存期水质咸化的研究   总被引：10，自引：0，他引：10       下载免费PDF全文

赵文玉  王启山  吴国平  吴立波  孙增峰  郑力燕 《水科学进展》2005,16(6):763-766

依据引黄水在北大港水库蓄存期水质咸化的事实以及传质理论,定性地分析了引黄水水质咸化的主要原因,包括盐碱土传质作用、蒸发浓缩作用以及风的扰动加速传质作用等.在北大港水库旁修建了一个模拟试验水池,进行了现场模拟试验研究.依据水量平衡和氯离子总量平衡的原理,分别定量地计算了传质作用和蒸发浓缩作用对水质咸化影响的比重.结果表明,在模拟水池蓄水后的30 d内,传质作用对水质咸化影响的比重有随时间增加而增长的趋势;30 d后,传质作用对水质咸化影响的比重稳定在80%,蒸发浓缩作用对水质咸化影响的比重稳定在20%,说明导致水质咸化的最主要因素是盐碱土传质作用.  相似文献   

旋转流地转适应过程与能量转换规律     

Fang Juan  Wu Rongsheng 《大气科学进展》2002,19(5):845-854

利用一维线性浅水模式从一个比较普遍的角度对地转适应过程中能量转换的特点进行分析。中首先考虑了两类不同的初始不平衡流的适应问题。一个是Gill所采用的质量不平衡模型，即初始场是静止的，只有水面扰动；另一个是Rossby中所考虑的动量不平衡模型，其初始不平衡流中只有风场的扰动，对这两个模型的适应过程而言，一个显的 特点就是能量转换率始终不会大于1／2或小于0，即适应过程中有位（动）能的释放和向动（位）能的转换，但释放出的能量最多只有其中的一半可以保留在最后的平衡场中。另外，本对任意初始不平衡流适应过程中的能量学特征也进行了分析，指出对于偏差场（相对于一定基本态）的动能和位能而言，上述能量转换关系依然成立。  相似文献   

柯树背岩体的元素地球化学特征及其成矿意义   总被引：1，自引：0，他引：1  

胡恭任  陈培荣等 《地质与勘探》2002,38(6):25-29

对柯树背岩体的岩石化学，稀土元素，微量元素及铀金成矿元素进行了系统的研究。研究结果表明：柯树背岩体F9大断裂（鹰潭－安远深大断裂）以东部分（东体）与F9大断裂以西部分（西体）在稀土分布模式，微量元素，铀金成矿元素及矿化特征上存在很大的差别，东体与寨背岩体类似，为同熔系列花岗岩，对铀成矿不利；西体为重熔再生岩浆成因的改造型花岗岩，对铀成矿有利，具有良好的成矿远景。  相似文献