不同时期水库地震活动主要影响因素讨论以三峡库区微震活动为例     

蒋海昆  宋金  贾若  曲均浩  陈亚男 《地震》2014,34(1):13-23

结合微震活动的流体作用强度检测及孔隙压扩散模拟,讨论了三峡库区不同时期微震活动的主要影响因素。以2008年9月蓄水季为界划分前、后期,前期流体渗透导致的孔隙压力增加,使裂隙或断层面强度降低,是库区微震活动的主要影响因素,这一时期微震频次及ETAS模型参数μ值有起伏地缓慢增大,与库水位加卸载过程关系不明显; 后期由于流体渗透引起的孔隙压力变化趋于零,在新的流体平衡条件下,库水位加卸载过程所导致的裂隙或断层面上的应力变化,成为库区微震活动的主要影响因素,这一时期微震频次及μ值显示出与水位变化明显的关联特征。库区小震震源深度的时间变化支持上述观点。在此基础上,进一步讨论了水库“诱发”和水库“触发”地震的力学差异,认为前者主要缘于流体渗透导致的裂隙或断层面强度的“主动”降低,后者则主要与库水加卸载所导致的裂隙或断层面上应力增强有关。进一步推论认为,流体对小地震“诱发”、“触发”皆可能发生,但中强地震缘于流体“诱发”的可能性非常小,对水库区发生的中强地震,流体仅可能对处于临界状态的断层系统起到“触发”作用。  相似文献   

Numerical simulation of sea water intrusion near Beihai, China   总被引：6，自引：0，他引：6  

X. Zhou  M. Chen  X. Ju  X. Ning  J. Wang 《Environmental Geology》2000,40(1-2):223-233

 A leaky aquifer system occurs in the coastal plain near Beihai, China. Seawater intrusion into the confined aquifer took place along the northern coast. Chloride concentrations at some observation wells increased steadily from 1988 and were at their peak in 1993. A quasi-three-dimensional element model has been developed to simulate the spatial and temporal evolution of hydraulic heads and chloride concentrations of the groundwater near the northern coast. The simulation model was based on the transition zone approach, which requires simultaneous solution of the governing water flow and solute transport equations. An irregular grid of a quadrangle was used to discretize the flow domain. Various aquifer parameters were verified with the numerical model in order to obtain satisfactory matches between computed values and observed data from an investigation. Three pumpage schemes were designed to use the calibrated model for prediction of future changes in water levels and chloride concentrations in groundwater in the study area. Results show that seawater intrusion would worsen in the confined aquifer if the current rates of groundwater pumpage continue. The alternative, to eliminate pumpage in the intruded area and to moderate pumpage rates from water supply wells far from the seashore, may limit seawater intrusion significantly and is considered attractive in the area. Received: 27 September 1999 · Accepted: 27 December 1999  相似文献   

赣北上二叠统多重地层划分研究   总被引：2，自引：0，他引：2  

覃兆松 《江西地质》2000,14(4):241-250

在开展赣西１∶５万区调中,对上石炭统至下侏罗统开展了岩石地层、层序地层、生物地层、生态地层、年代地层及旋回地层和同位素地层研究,本文即是部分成果的总结。依据岩石特征,将赣北上二叠统分为６个岩石地层区,并创竹亭组代表其深水相沉积。依据七宝山、枣木两剖面资料,进行了生物地层、生态地层及年代地层划分,提出长兴阶顶界位于青龙组底部、底界位于长兴组下部的结论,并对吴家坪阶底界的优选点进行了探讨。通过生态地层  相似文献   

Optimal Groundwater Development in Coastal Aquifers Near Beihai, China   总被引：1，自引：0，他引：1  

Zhou Xun Chen Mingyou Wan Li Department of Water Resources  Environmental Engineering  China University of Geosciences  Beijing  China Wang Juping Ning Xuesheng Beihai Institute of Hydrogeology  Engineering Geology  Mineral Resour 《中国地质大学学报(英文版)》2000,11(3)

INTRODUCTIONThe city of Beihai,located on the south coast ofGuangxi,China,relies heavily on groundwater for its potablewater supply and agricultural irrigation.With rapid increasein population (for instance,from 134 0 0 0 in 1987to 47930 0in1995 ) and in developm ent program s,the demand for freshwater has been growing. Approxim ately 170 0 0 0 m3/ d ofgroundwater has been pumped from the productive coastalaquifers in recent years.Contamination of the fresh water inthe coastal aquifers b…  相似文献   

Ground deformation in a viscoelastic medium composed of a layer overlying a half-space: a comparison between point and extended sources     

Arnau Folch  José Fernández  John B. Rundle  & Joan Martí 《Geophysical Journal International》2000,140(1):37-50

We obtain and compare analytical and numerical solutions for ground displacement caused by an overpressurized magma chamber placed in a linear viscoelastic medium composed of a layer over a half-space. Different parameters such as size, depth and shape of the chamber, crustal rheology and topography are considered and discussed. Numerical solutions for an axisymmetric extended source are computed using a finite element method (FEM). Analytical solutions for a point source are obtained using the dislocation theory and the propagator matrix technique. In both cases, the elastic solutions are used together with the correspondence principle of linear viscoelasticity to obtain the solution in the Laplace transform domain. Viscoelastic solutions in the time domain are derived inverting the Laplace transform using the Prony series method. The differences between the results allow us to constrain the applicability of the point source and the flat surface hypothesis, which are usually implicitly assumed when analytical solutions are derived. The effect of the topography is also considered. The results obtained show that neglecting the topographic effects may, in some cases, introduce an error greater than that implicit in the point-source hypothesis. Therefore, for an adequate modelling and interpretation of the time-dependent displacements, topography must be considered.  相似文献   

基于压汞法的冻融循环对土体孔隙特征影响的试验研究   总被引：13，自引：6，他引：7  

张英  邴慧 《冰川冻土》2015,37(1):169-174

冻融循环会改变土的微观结构, 孔隙特征的变化是其结构性发生改变的重要体现. 以青藏铁路沿线粉质黏土为研究对象, 借助压汞技术对不同冻融次数下重塑土样的孔隙特征进行了研究. 结果表明:土体孔隙特征分布曲线表现出明显的双峰特征, 据此可将土样的孔隙分为大孔和小孔两大类; 冻融循环次数对小孔隙的影响较小, 小孔隙直径和体积基本保持不变; 冻融循环次数对大孔隙的影响较大, 特别是孔径为20～40 μm的孔隙, 其直径和体积均随冻融次数的增加而增大. 试样的孔隙率随冻融次数的增加并无明显规律, 但总体的变化趋势是先增大后减小. 由孔隙分形维数计算结果可知, 冻融循环在改变土体孔隙结构的同时, 使孔隙内壁的粗糙程度及孔隙结构的复杂程度降低.  相似文献   

北秦岭弧后盆地俯冲消减与陆壳物质再循环——桃园岩体和黄岗杂岩体的地球化学证据   总被引：1，自引：0，他引：1  

张利  王林森  周炼 《地球科学》2001,26(1):18-24

对桐柏北部加里东期桃园岩体和黄岗杂岩体的地球化学研究表明, 桃园岩体形成于与洋壳消减作用有关的弧后盆地环境, 与二郎坪基性火山岩具有相同的岩浆来源.黄岗杂岩岩浆中含有一定比例的陆壳物质, 该物质来自俯冲板片上陆壳沉积物的再循环, 与二郎坪弧后盆地向北的俯冲消减有密切联系.   相似文献   

鄂尔多斯盆地延长组致密砂岩孔喉结构与油藏物性表征     

王付勇  程辉 《吉林大学学报(地球科学版)》2020,50(3):721-731

基于高压压汞和核磁共振测试方法,结合分形理论对鄂尔多斯盆地延长组致密砂岩孔喉结构与油藏物性进行了表征。采用毛管束模型和润湿相模型计算了高压压汞孔喉分形维数,利用核磁共振测试T₂谱分别计算了大孔、中孔、小孔以及总孔隙的分形维数;对各分形维数与油藏物性之间的关系进行了对比分析。研究表明：基于高压压汞曲线计算岩心分形维数时,相比于润湿相模型,毛管束模型计算得到的分形维数与油藏物性之间具有更好的相关性,随着分形维数增加,平均半径减小,孔喉结构非均质性增强,油藏物性变差。核磁总孔隙分形维数与油藏物性相关性较差,大孔和中孔的分形维数与油藏物性具有较好的相关性,其中随着大孔和中孔分形维数增加,岩心渗透率降低,油藏物性变差;与小孔相比,大孔和中孔的分形维数与油藏物性的相关性更强,表明致密砂岩储层物性主要受大孔和中孔控制,分形维数可以有效表征致密砂岩小孔、中孔和大孔对油藏物性的影响。  相似文献   

山西省中生代侵入岩新认识     

张玉生  李建荣  张诚  孙华  刘伟东  侯冬红  毛永栋  孙杰 《中国地质调查》2020,7(2):45-57

根据区域地质调查资料,对山西省中生代侵入岩进行分析研究,将其划分为3个岩浆系列: 碱性偏碱性系列、亚碱性(基性)中性—中酸性系列和A型花岗岩(酸性)系列。碱性偏碱性岩系列形成于后碰撞构造环境,亚碱性(基性)中性—中酸性岩系列为大陆边缘弧和大陆岛弧及后造山构造环境,A型花岗岩系列为板内大陆裂谷或与地幔热点(地幔羽)有关的构造环境,板块俯冲作用为其提供了热能和含水溶液。大地构造分区划分为华北陆块区构造岩浆省(Ⅰ级),其中包括3个岩浆带(Ⅱ级): 南兴蒙岩浆带、北秦岭岩浆带和华北东部岩浆带,每个岩浆带又可划分为2个岩浆亚带(2期岩浆作用)(Ⅲ级),各个岩浆亚带均具有板块俯冲造山带火成岩的特征和发育演化极性。该成果为解决板块构造登陆问题提供了借鉴。  相似文献   

琼东南盆地长昌凹陷火成岩侵入体对温度场及烃源岩成熟度的影响   总被引：4，自引：0，他引：4       下载免费PDF全文

唐晓音  张功成  梁建设  杨树春  饶松  胡圣标 《地球物理学报》2013,56(1):159-169

最新地震资料显示,琼东南盆地深水区长昌凹陷内部分布着多个火成岩侵入体,单个侵入体的面积可超过300 km²,高(厚)度约为10 km.本文基于有限元方法的二维剖面地温场模拟,分析了研究区位于同一条地震测线上的三个不同规模侵入体对温度场的影响,并结合热史恢复方法及Easy%Ro模型,定量评价了侵入体对距其2 km及5 km处人工井崖城组烃源岩有机质成熟度Ro的影响.结果表明,凹陷内火成岩侵入体对温度场有显著影响的时限不超过1 Ma,5 Ma以后影响非常微弱,10 Ma以后侵入体温度与围岩温度基本一致;侵入体对烃源岩有机质成熟度的影响随侵入体的规模、距侵入体的距离不同而不同,规模最大侵入体对距其2 km处崖城组烃源岩成熟度Ro的影响可达1.6%,而对距其5 km处的烃源岩成熟度影响较小.  相似文献