瓦斯突出地球物理场的响应特征     

吕绍林  何继善  李舟波 《吉林大学学报(地球科学版)》2000,30(1):71-75

研究了瓦斯突出地球物理场的电磁波和弹性波响应特征,其响应是构成瓦斯突出地球物理场的介质条件所表现出来的。关键层应力墙瓦斯突出机理认为,瓦斯突出煤层由关键层和伴随层构成。关键层和伴随层在空间的分布规律和相互作用体现在物理场的差异上,把关键层（或瓦斯突出煤体）作为地球物理场中的异常体进行研究是可以利用地球物理方法识别的。突出地球物理场响应特征的研究为从地球物理研究瓦斯突出预测理论和方法提供了科学思路。  相似文献   

Spatial distribution and bonding forms of heavy metals in sediments along the middle course of the River Elbe (km 287ċ390)     

Andrea van der Veen  Corinna Ahlers  Dieter W. Zachmann  Kurt Friese 《洁净——土壤、空气、水》2006,34(3):214-222

Sediments of eight groyne fields along the middle course of the River Elbe (river km 287?390) were geochemically studied. The 78 sediment samples were analysed for pH and grain size distribution. The grain size fraction < 2 μm was used for mineralogical and chemical analysis: semiquantitative clay mineral analysis; total element content (Al, Ca, Fe, K, Mn, Cd, Cr, Cu, Ni, Pb, Zn), total inorganic and organic C, and bonding form fractionation with a six‐step sequential chemical extraction. The latter was performed on selected samples (n = 32). The sediments along the Elbe's course are still contaminated with heavy metals far above the local geogenic background level. An enrichment factor of more than 15 was calculated for zinc. Cr and Ni are the elements with the lowest enrichment. The bonding form analysis of selected heavy metals shows a dominance of relatively immobile bonding forms, e. g. the moderately reducible and the residual fraction, which implies a relative low mobility potential. Only Zn poses a higher potential threat to the environment, since it has a higher percentage of the first three extracted phases: adsorbed, carbonate, and easily reducible fraction.  相似文献   

豫西南泥湖多金属矿田铅锌矿地质特征与成因研究   总被引：10，自引：2，他引：10  

吕文德  赵春和  孙卫志  燕建设 《矿产与地质》2006,20(3):219-226

豫西南泥湖地区具有闻名于世界的特大型钼矿,通过近几年国土资源大调查工作,在南泥湖钼矿外围发现了矽卡岩型和中低温热液充填型铅-锌矿床,它们成环带状分布于南泥湖钼矿外围。文章重点论述了矽卡岩型和中低温热液充填成因的脉状铅-锌矿地质特征,并对其成因进行了研究,研究认为,上述三者均属于燕山期岩浆期后热液充填、交代成因的多金属矿床,并认为,不同类型矿床既存在一定的差别,同时在时、空上又具有一定的内在联系,共同构成了一个与燕山期中酸性小岩体有关的成矿系列。  相似文献   

Velocity distribution in a gradually accelerating free surface flow     

Shu-Qing Yang  Wei-Lin Xu  Guo-Liang Yu   《Advances in water resources》2006,29(12):1969-1980

This study investigates the interaction of the vertical velocity v and the streamwise velocity u in a gradually accelerating flow. The analytical result shows that the momentum of uv driven by the mean velocities in a non-uniform flow is not negligible. This additional momentum directly results in the concave profiles of Reynolds shear stress in gradually accelerating flows, a departure from the expected linear profile. Consequently, this momentum causes the maximum velocity to be located below the free surface, i.e., the dip-phenomenon. This paper investigated the interactions of the Reynolds shear stress, non-zero vertical velocity and dip-phenomenon, it is found that the non-zero vertical velocity causes the dip-phenomenon. The approach is tested using the experimental data of Song and others, and good agreements between the predicted and measured velocity profiles have been achieved.  相似文献   

Steady- and transient-state inversion in hydrogeology by successive flux estimation     

Philippe Pasquier  Denis Marcotte 《Advances in water resources》2006,29(12):1934-1952

A calibration method to solve the groundwater inverse problem under steady- and transient-state conditions is presented. The method compares kriged and numerical head field gradients to modify hydraulic conductivity without the use of non-linear optimization techniques. The process is repeated iteratively until a close match with piezometric data is reached. The approach includes a damping factor to avoid divergence and oscillation of the solution in areas of low hydraulic gradient and a weighting factor to account for temporal head variation in transient simulations. The efficiency of the method in terms of computing time and calibration results is demonstrated with a synthetic field. It is shown that the proposed method provides parameter fields that reproduce both hydraulic conductivity and piezometric data in few forward model solutions. Stochastic numerical experiments are conducted to evaluate the sensitivity of the method to the damping function and to the head field estimation errors.  相似文献   

地形对水平岩层自重成因地应力场的影响     

陶波  伍法权  郭改梅 《煤田地质与勘探》2006,34(1):34-37

通过极坐标系下的艾里应力函数法,求解出在集中力作用下水平岩层中各应力分量。山体对其下伏岩层可作为分布载荷,对集中力作用下水平岩层中各应力分量积分,便求得山体对下伏水平岩层的附加应力。已有研究成果表明,当由外载引起的附加应力小于由重力引起的静止侧压力的20%时,则可以不考虑外载的影响,这样便导出了地形对自重应力影响深度所满足的函数关系式。此外,本文举例说明了如何求得地形对水平均质各向同性水平岩层的自重应力场的影响深度。  相似文献   

Effect of water stress on ecosystem photosynthesis and respiration of a Leymus chinensis steppe in Inner Mongolia     

《中国科学D辑(英文版)》2006,(Z2)

Many studies on global climate have forecast major changes in the amounts and spatial patterns of precipitation that may significantly affect temperate grasslands in arid and semi-arid regions. As a part of ChinaFLUX, eddy covariance flux measurements were made at a semi-arid Leymus chinensis steppe in Inner Mongolia, China during 2003-2004 to quantify the response of carbon exchange to environmental changes. Results showed that gross ecosystem production (FGEP) and ecosystem respiration (Reco) of the steppe were significantly depressed by water stress due to lack of precipitation during the growing season. Temperature was the dominant factor affecting FGEP and Reco in 2003, whereas soil moisture imposed a significant influence on both Reco and FGEP in 2004. Under wet conditions, Reco showed an exponentially increasing trend with temperature (Q10 = 2.0), but an apparent reduction in the value of Reco and its temperature sensitivity were observed during the periods of water stress (Q10=1.6). Both heat and water stress can cause decrease in FGEP. The sea-sonality of ecosystem carbon exchange was strongly correlated with the variation of precipitation. With less precipitation in 2003, the steppe sequestrated carbon in June and July, and went into a senescence in early August due to water stress. As compared to 2003, the severe drought during the spring of 2004 delayed the growth of the steppe until late June, and the steppe became a CO2 sink from early July until mid-September, with ample precipitation in August. The semi-arid steppe released a total of 9.7 g C·m-2 from May 16 to the end of September 2003, whereas the net carbon budget during the same period in 2004 was close to zero. Long-term measurements over various grasslands are needed to quantify carbon balance in temperate grasslands.  相似文献   

大厂矿田长坡矿床深部区叠瓦状构造控矿特征及找矿前景分析   总被引：2，自引：0，他引：2  

李春平  吴德成  蔡明海 《矿产与地质》2006,20(6):623-627

长坡矿床深部区是近年来在大厂长坡矿区深部取得了较好找矿效果的一个勘查靶区,新发现了77-1号、77-2号、75-1号、115号等多个锡多金属矿体,这些矿体均赋存于大厂断裂F1及其下盘F1-1、F3、F5组成的叠瓦状构造中,锡多金属矿体呈似层状、脉状产出,这些新发现展示了良好的找矿前景。文章在研究该勘查区矿床特征及叠瓦状构造控矿特征的基础上,结合井中物探、化探资料,对该区的找矿远景和找矿方向进行了探讨。  相似文献   

长白山区图们江流域新生代火山岩的岩石化学研究   总被引：5，自引：3，他引：5  

王团华  樊祺诚孙谦  谌宏伟李霓 《岩石学报》2006,22(6):1481-1490

图们江流域新生代火山岩以溢流式喷发为特征，其主要岩石类型以拉斑玄武岩为主，含少量玄武质粗安岩、碱性玄武岩、玄武质安山岩和粗面玄武岩。根据图们江流域火山岩的Mg#（Mg#=100Mg^2＋／（Mg^2＋＋Fe^2＋））值多数≤60，Ni含量〈100μg／g和主、微量元素地球化学特征综合表明，形成火山岩的岩浆不是原始岩浆，它们是原始岩浆在上地幔经历了橄榄石、辉石分离结晶作用后形成的以拉斑玄武岩为主，包括碱性玄武岩和粗面玄武岩等演化岩浆，结晶分异作用是岩浆演化过程的主要控制因素。拉斑玄武质岩浆在上升过程中发生了不同程度的壳源物质同化混染作用，发生在上地壳遭受较大程度混染的岩浆K2O含量明显偏高（〉2．6％），形成玄武质粗安岩。  相似文献   

巴姆地震变形场和应力场：Ⅱ．用FEPG有限元方法求解   总被引：2，自引：0，他引：2  

罗扬施旭  赵永红 《岩石学报》2006,22(9):2375-2380

本文利用 FEPG 有限元程序对2003年12月的巴姆地震变形场和应力场进行了模拟计算。2003年12月26日,巴姆地区发生6.6级地震。Nakamura、Suzuki 等人利用余震资料和地震破坏程度的分布图分析了余震震中的统计分布形式,得到了此次地震的发震断层是巴姆断层以西大约5km 的 Arg-e-Bam 隐伏断层的结论。凌勇等人从差分干涉雷达(D-InSAR)出发,得到了此次地震的同震干涉条纹和雷达视线方向的位移场,并从雷达干涉的相干图上确定了发震断层的痕迹。他们还利用 Okada 程序模拟计算了此次地震的位移场,模拟计算的结果与 D-InSAR 测量的位移场比较符合。Okada 程序从断层的位错为出发点进行计算,从运动学角度对此次地震变形场和应力场进行研究;本文从动力学的角度出发,研究远场区域边界的应力状态以及断层的物性参数的变化对巴姆地震形变场的影响,将各种计算结果进行对比的同时也和前人的结果相比较。本文计算中采用了凌勇等人的断层参数,即 Arg-e-Bam 隐伏断层为近南北走向,向东倾斜,近直立的倾角,右旋走滑,其(Strike,dip,slip)为(175°,80°,173°)。断层未延伸到地表,自地面以下1km 处往下延伸16km 的宽度,断层长度为20km。对断层的杨氏模量、泊松比、断层附近区域的边界受力大小、两个主应力的比例以及主应力的方向的改变对计算结果的影响做了讨论。最后通过上述几组计算结果建立了一个与前人结果较为符合的巴姆地震参数模型。通过计算,一方面揭示了应力状态和物性参数的影响,另一方面也说明 Arg-e-Bam 隐伏断层是此次地震的发震断层这一结论是可信的。  相似文献