Analysis of DNAPL infiltration in a medium with a low-permeable lens     

M.J. de Neef  J. Molenaar 《Computational Geosciences》1997,1(2):191-214

In this paper we study the infiltration of DNAPL in a porous medium containing a single low-permeable lens. Our aim is to determine whether or not DNAPL infiltrates into the lens. A key role is played by the capillary pressure: DNAPL cannot infiltrate into the lens unless the capillary pressure exceeds the entry pressure of the lens. In the model this is reflected by an interface condition, the extended capillary pressure condition. To derive analytical approximations we first consider a steady-state DNAPL plume in a homogeneous medium. This results in an estimate of the DNAPL plume width as a function of depth, and an asymptotic solution for small saturations. Assuming that the extent of the lens is much larger than the width of the unperturbed DNAPL plume in the homogeneous medium, we derive an explicit criterion for DNAPL infiltration into the lens in terms of a critical inflow rate. A numerical algorithm is presented in which the extended capillary pressure condition is incorporated. The numerical and analytical results show good qualitative agreement. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

PDC钻头切削齿受力随布齿密度变化关系研究   总被引：1，自引：0，他引：1  

罗超  王镇泉 《地质与勘探》1997,33(4):60-63

采用不同布齿方式的３个ＰＤＣ切削齿同步连续切削转动的岩石为模拟井底钻头切削齿实际工作状态，用切削岩石时相同的布齿参数切削砂轮来磨损切削以模拟切削的以模拟切削齿磨状态，试验研究了不同磨损程度的切削齿受力与布齿密度的关系。  相似文献   

提高地方地震台网地震速报水平初探     

王登伟  管勇  马付红 《四川地震》2004,(2):12-15,20

总结了西昌遥测地震台网地震速报处理技术经验，针对地方台网地震速报中常出现的地震参数误差提出了改进思路。  相似文献   

Seasonal and Diurnal Variation of Surface Ozone and a Preliminary Analysis of Exceedance of its Critical Levels at a Semi-arid Site in India   总被引：1，自引：0，他引：1  

Gur Sumiran Satsangi  A. Lakhani  P. R. Kulshrestha  A. Taneja 《Journal of Atmospheric Chemistry》2004,47(3):271-286

The mixing ratios of surface O₃ were measured at St. John's College, Agra, an urban and traffic influenced area for the period of 2000–2002. The monthly averaged O₃ mixing ratios ranged between 8 to 40 ppb with an annual average of 21 ppb. Strong diurnal and seasonal variations in O₃ mixing ratios were observed throughout the year except for monsoon season. The mixing ratios of O₃ follow the surface temperature cycle and solar radiation (r = 0.72 and r = 0.65 with temperature and solar radiation, respectively). Concentrations were higher with winds associated with NE and NW direction indicating the impact of pollution sources on surface O₃ concentration. Exceedance of ozone critical level was calculated using the AOT 40 index and found to be 840 ppb.h and 2430 ppb.h for summer and winter seasons, respectively. The present O₃ exposures are lower than the critical level of O₃ and suggest that the present level of O₃ does not have any impact on reduction in crop yields.  相似文献   

多年冻土地区砂砾路面路堤临界高度数值分析     

张明义  赖远明  张建明  齐吉琳 《冰川冻土》2004,26(Z1):76-82

In permafrost regions of Qinghai-Tibetan Plateau, the critical embankment height must be considered in the process of the construction of highway, especially for the global climatic warming. In this paper, the two-dimensional numerical analysis for the critical embankment height (for gravel road surface and coarse-grained soil) has been performed by using thefinite element method. In the calculation, we think that the service life of the construction is at least 50 years. The mean annual air temperatures applied to the calculation model are -6.5 ℃, -6.0 ℃, -5.5 ℃, -5.0 ℃, -4.5 ℃ and -4.0 ℃, respectively, and the value of temperature rise are taken as 1.10℃ in the coming 50 years. The minimum embankment heights derived from the analysis are 0.85 m, 0.92 m, 1.01 m, 1.18 m, 1.60 m and 2.66 m for the different mean annual air temperatures and the maximum embankment heights are 7.68 m,7.55 m, 7.34 m, 7.00 m, 6.45 m and 5.85m, accordingly. On condition that the service life of embankment is 50 years, the critical value of the mean annual air temperature is -3.5 ℃. Namely, in the areas where the mean annual air temperature is higher than -3.5 ℃, the critical embankment height does not exist.  相似文献   

水泥土桩单桩荷载传递及临界桩长研究   总被引：7，自引：0，他引：7  

吴雄志 《岩土力学》2004,25(9):1491-1494

将克拉夫-邓肯模型作为传递函数，对水泥土桩荷载传递规律及临界桩长进行了研究，描述了桩周摩阻力的分布及发展规律，并详细讨论了临界桩长的确定标准及各种因素对临界桩长的影响。结果表明，该方法是可行的，该方法同样适用于其它形式的柔性桩。  相似文献   

区域滑坡泥石流灾害预警理论与方法研究   总被引：39，自引：4，他引：39  

刘传正 《水文地质工程地质》2004,31(3):1-6

根据数年来的调查观测研究和工作实践,提出了滑坡泥石流灾害的预警分类体系,包括按物理参量划分的空间、时间与强度预警和按诱发因素参量划分的气象、地震与人类活动预警以及多参数、多因素共同作用下的综合预警。初步创建了区域性滑坡泥石流灾害暴发的两种预警理论方法,一种是基于临界过程降雨量判据图的预警方法;另一种是基于GIS的地质环境空间分析预警理论方法,通过计算预警区的滑坡泥石流灾害"发育度"、"潜势度"、"危险度"和"危害度"来实现。阐述了滑坡泥石流灾害预警的技术和行政工作程序,指出建立临界过程降雨量判据与地质环境空间分析相耦合的滑坡泥石流灾害预警理论方法是研究的新方向。  相似文献   

无地面控制GPS辅助光束法区域网平差   总被引：2，自引：4，他引：2  

袁修孝  朱武  武军郦  王瑞幺 《武汉大学学报(信息科学版)》2004,29(10):852-857

介绍了在WGS-84坐标系中进行GPS辅助光束法区域网平差的基本原理以及利用大地水准面拟合方法实施大地高与正常高的变换方法。利用新疆库尔勒地区1：25000和1：50000实际航摄资料验证了理论与程序实现的正确性。试验结果表明，无地面控制GPS辅助光束法区域网平差可用于中小比例尺测图的加密，在WGS-84坐标系中可以获得较高的点定位精度，而在国家80坐标系下，利用大地水；隹面拟合前后的GPS摄站坐标进行GPS辅助光束法区域网平差，加密精度没有明显差异。  相似文献   

基于灰关联分析的GPS高程拟合加权平均函数模型权函数优选   总被引：6，自引：0，他引：6  

邱斌  朱建军 《测绘信息与工程》2004,29(1):13-14

基于灰色系统理论的灰关联分析方法,提出了权函数的优选方法,实例分析表明其具有较好的实用价值.  相似文献   

Search for direct empirical spatial correlation signatures of the critical triggering earthquake model   总被引：1，自引：0，他引：1  

G. Ouillon  D. Sornette 《Geophysical Journal International》2004,157(3):1233-1246

  相似文献