北京西山变玄武岩裂隙发育规律及含水特征     

沈继方  史毅虹 《地球科学》1985,(1)

全文论述三个方面:(1)对比不同剖面熔岩层单层厚度的统计特征值,确定其频率分布均为对数正态型式;根据内部结构构造将每一熔岩层划分为四个亚层。(2)讨论了裂隙的成因类型、分布特征及其控制因素。指出:同时发育有构造裂隙和成岩裂隙,但以前者为主;不同构造盆地中的裂隙参数与熔岩层厚度具相反的线性相关关系,分别反映了构造裂隙和成岩裂隙的分布特征。(3)将所有裂隙分为四级储容—渗透空间,提出了两种类型的含水系统模型及其渗流特征。  相似文献   

利用联合反演技术进行反射地震的波速成象   总被引：5，自引：0，他引：5       下载免费PDF全文

杨文采  焦富光 《地球物理学报》1987,30(6):617-627

本文介绍了根据反射地震数据进行波速成象的一种方法,其基础为多种反演技术的综合。由于要求的波速图象C（x,z）具有间断性,除利用走时数据T（x,t）外,在地层比较水平的情况下,还利用了均方根速度V（x,t）和统计子波W（t）的数据来成象。计算机层析成象过程分为三步:首先重做速度分析,取得与初次反射走时一致的均方根速度数据;然后用反射走时与均方根速度联合反演对应分析道的层速度和界面深度;最后由联合反演结果和反射面走时求波速图象函数的数字化版。文中还给出了波速成象方法在我国西北某沉积盆地上的应用及验证结果。  相似文献   

A sequence of seismic activity in the Kanto area precursory to the 1923 Kanto earthquake     

Mitiyasu Ohnaka 《Pure and Applied Geophysics》1984,122(6):848-862

The Kanto earthquake (M=7.9) that occurred along the Sagami Trough in the Sagami Bay on 1 September 1923 was one of the most disastrous earthquakes in Japanese history. The Kanto area includes Metropolitan Tokyo and Yokohama which are densely populated, and hence it has been a matter of great concern, from the viewpoints of earthquake prediction and disaster prevention, whether or not the 1923 Kanto earthquake was preceded by precursory seismicity. A study using the most complete lists of earthquakes catalogued recently by Utsu and the Japan Meteorological Agency reveals that seismic activity in the Kanto area was appreciably higher before and after the Kanto earthquake, and that the Kanto earthquake was preceded by a sequence of anomalous seismic activity, quiescence, and foreshocks. Such higher activity before and after the Kanto earthquake is contrasted with low seismicity during the recent 30-year period. A model is proposed to explain the precursory seismic activity, subsequent quiescence, and foreshocks for the Kanto earthquake. In the model, the transition from precursory seismic activity to quiescence is ascribed to time-dependent fracture due to stress-aided corrosion. Foreshocks are related to an acceleration of premonitory slip shortly before the mainshock slip.  相似文献   

Model-free estimation of fracture aperture with neural networks     

Marek Kacewicz 《Mathematical Geology》1994,26(8):985-994

The feedforward backpropagation technique provides a model-free estimation with neural networks. The algorithm was used to estimate fracture aperture of natural fractures in three dimensional space. A three-layer neural network with at least 5 nodes in a hidden layer was trained on a data set consisting of formation imaging microscanner logs (FMS)from horizontal boreholes. Sensitivity studies were performed to account for the rate of learning convergence, convergence to local error minima, etc. Among the factors contributing mostly to the overall good or bad performance of the network, the following are worth mentioning: number of data points, data spacing, and data variability. It is shown that a smoothing operation applied to aperture data along the wellbore often helps to reduce disorientation of the network and to switch from oscillations or chaotic jumps to convergence.  相似文献   

4.8 – 20 μm Imaging of orion BN/KL: II. A new look at luminosity sources and the role of IRc2     

Daniel Y. Gezari  Dana E. Backman 《Experimental Astronomy》1994,3(1-4):45-52

We have reconsidered the energetics of the BN/KL infrared complex, using array images at nine wavelengths between 4.8 and 20 m, and find a much lower luminosity for IRc2 than the generally accepted value. The new observations resolve larcsec structure throughout the region, including several new compact sources within a few arcsec of IRc2 and significant details imaged in the 9.7 m silicate feature. Together with other recent work, the results suggest that luminous stars associated with three compact HII regions found within BN/KL, rather than IRc2, may be the more significant luminosity sources for the complex.  相似文献   

瞬变电磁电阻率成像法探测岩体渗漏通道的研究及应用   总被引：2，自引：0，他引：2  

薛云峰  孙晓暾  孙雅芳 《水文地质工程地质》2004,31(3):96-98

本文利用等效代换的方法建立计算瞬变电磁响应的概念及方法,通过视电阻率和视深度的计算,进行实测剖面的二维电阻率成像,并利用该成像技术探测某水库岩体集中渗漏通道,获得良好的效果。  相似文献   

Micromechanical Model for Simulating the Fracture Process of Rock   总被引：25，自引：3，他引：25  

W. C. Zhu  C. A. Tang 《Rock Mechanics and Rock Engineering》2004,37(1):25-56

Summary A micromechanical model is proposed to study the deformation and failure process of rock based on knowledge of heterogeneity of rock at the mesoscopic level. In this numerical model, the heterogeneity of rock at the mesoscopic level is considered by assuming the material properties in rock conform to the Weibull distribution. Elastic damage mechanics is used to describe the constitutive law of meso-level elements, the finite element method is employed as the basic stress analysis tool and the maximum tensile strain criterion as well as the Mohr-Coulomb criterion is utilized as the damage threshold. A simple method, similar to a smeared crack model, is used for tracing the crack propagation process and interaction of multiple cracks. Based on this model, a numerical simulation program named Rock Failure Process Analysis Code (RFPA) is developed. The influence of parameters that include the Weibull distribution parameters, constitutive parameters of meso-level elements and number of elements in the numerical model, are discussed in detail. It is shown that the homogeneity index is the most important factor to simulate material failure with this model. This model is able to capture the complete mechanical responses of rock, which includes the crack patterns associated with different loading stages and loading conditions, localization of deformation, stress redistribution and failure process. The numerical simulation of rock specimens under a variety of static loading conditions is presented, and the results compare well with experimental results.  相似文献   

Damage to Rocks and Cementitious Materials from Solid Impact     

A. W. Momber 《Rock Mechanics and Rock Engineering》2004,37(1):57-82

Summary The erosion of four rock types and two cementitious materials by solid particle impact is investigated. The experimental set-up used to perform the erosion tests is briefly described. The materials are eroded predominantly by intergranular and intercrystalline fracture. For the cementitious materials, the interface between cement matrix and aggregate is of decisive importance. The power exponents for the particle velocity are estimated and found to vary between 2.59 and 3.65. A statistical fracture model is derived to discuss deviations in the particle velocity power exponent. It is further shown that the experimental results of this study confirm the erosion model of Finnie and Oh (1966); an exception is schist which shows features of plastic deformation and radial cracking during the Hertzian indentation test.  相似文献   

Partial Crystallization of Mid-Ocean Ridge Basalts in the Crust and Mantle   总被引：2，自引：2，他引：2  

HERZBERG  CLAUDE 《Journal of Petrology》2004,45(12):2389-2405

Pressures at which partial crystallization occurs for mid-oceanridge basalts (MORB) have been examined by a new petrologicalmethod that is based on a parameterization of experimental datain the form of projections. Application to a global MORB glassdatabase shows that partial crystallization of olivine + plagioclase+ augite ranges from 1 atm to 1·0 GPa, in good agreementwith previous determinations, and that there are regional variationsthat generally correlate with spreading rate. MORB from fast-spreadingcenters display partial crystallization in the crust at ridgesegment centers and in both mantle and crust at ridge terminations.Fracture zones are likely to be regions where magma chambersare absent and where there is enhanced conductive cooling ofthe lithosphere at depth. MORB from slow-spreading centers displayprominent partial crystallization in the mantle, consistentwith models of enhanced conductive cooling of the lithosphereand the greater abundance of fracture zones through which theypass. In general, magmas that move through cold mantle experiencesome partial crystallization, whereas magmas that pass throughhot mantle may be comparatively unaffected. Estimated pressuresof partial crystallization indicate that the top of the partialmelting region is deeper than about 20–35 km below slow-spreadingcenters and some ridge segment terminations at fast-spreadingcenters. KEY WORDS: MORB; olivine gabbro; partial crystallization; partial melting; ridge segmentation; fracture zones; crust; mantle; lithosphere  相似文献   

塔河碳酸盐岩洞缝型油藏堵水效果评价方法初探   总被引：5，自引：0，他引：5  

谭承军  朱伟  马旭杰 《新疆地质》2004,22(1):94-97

总结了塔河油田碳酸盐岩洞缝型油藏的堵水工作．对堵水效果及其影响因素进行了探讨．认为堵水井储集体剖面类型、水淹特征及其类型、完井方式、投产方式对堵水效果有不同程度的影响：①大型洞穴型储集体堵水效果较其余储集体类型差．单一储集体剖面类型堵水效果较多重储集体剖面类型差：②底部出水型堵水效果明显好于其它出水类型．全井出水型堵水效果最差：⑨裸眼(直接)投产井堵水效果好于酸压(完井)投产井．最后就塔河油田超深碳酸盐岩洞缝型油藏的特点对行标SY／T5874—93的某些内容在操作上进行了讨论：建议统一机械堵水、化学堵水和复合堵水的有效期级别评价指标．并考虑降水幅度;措施有效率评价时应包含经济效益评价指标．针对油藏特点适当上提降水指标下限值;堵水增油量或有效期的计算应考虑堵前指标的动态变化趋势来综合确定。  相似文献