塔北地区寒武系白云岩储层裂缝充填特征与有效性     

彭军  林攀  夏青松  李斌  韩浩东 《地球科学与环境学报》2019,(1):40-53

塔里木盆地寒武系白云岩储层具有年代老、埋深大、成岩作用强烈的特征,原生孔隙几乎被破坏殆尽,有效裂缝的发育程度是决定储层优劣的关键因素。根据岩芯描述、薄片鉴定、FMI成像测井、扫描电镜、阴极发光、电子探针以及流体包裹体分析等研究手段,开展了塔里木盆地北部地区(简称"塔北地区")寒武系白云岩储层的裂缝充填特征及有效性分析。塔北地区整体裂缝发育,天山南地区与塔河地区裂缝在产状、线密度、形态以及充填特征上存在差异。天山南地区裂缝线密度与有效性均低于塔河地区,充填矿物主要为自形白云石与石英,其次为方解石、石膏与黄铁矿。充填白云石分为3期,对应的温度区间分别为70℃～90℃、90℃～110℃及110℃以上,均为地层内的成岩流体成因;充填石英分两期,第一期为黏土矿物转化蚀变形成,第二期可能为热液成因。塔河地区裂缝线密度高,有效性较好,溶蚀作用发育,是有利的勘探地区,其充填物以热液矿物组合形式出现,主要为方解石,其次为石膏、鞍状白云石、黏土矿物、沥青等,重晶石以交代白云石的形式出现。充填方解石分为4期,对应的温度区间分别为70℃～100℃、100℃～130℃、130℃～180℃及180℃以上,前3期充填为不同埋深时期地层内成岩流体成因,最后一期充填为自下部运移而来的高温热液流体成因。  相似文献   

Performance of pile-restrained flexible floating breakwaters     

Ioanna Diamantoulaki  Demos C. Angelides  George D. Manolis 《Applied Ocean Research》2008,30(4):243-255

The overall performance of pile-restrained flexible floating breakwaters is investigated under the action of linear monochromatic incident waves in the frequency domain. The aforementioned floating breakwaters undergo only vertical structural deflections along their length and are held in place by means of vertical piles. The total number of degrees of freedom equals the six conventional body modes, when the breakwater moves as a rigid body, plus the extra bending modes. These bending modes are introduced to represent the structural deflections of the floating breakwater and are described by the Bernoulli–Euler flexible beam equation. The number of bending modes introduced is determined through an appropriate iterative procedure. The hydrostatic coefficients corresponding to the bending modes are also derived. The numerical analysis of the flexible floating breakwaters is based on a three-dimensional hydrodynamic formulation of the floating body. A parametric study is carried out for a wide range of structural stiffness parameters and wave headings, to investigate their effect on the performance of flexible floating breakwaters. Moreover, this performance is compared with that of the corresponding pile-restrained rigid floating breakwater. Results indicated that the degree of structural stiffness and the wave heading strongly affect the performance of flexible floating breakwaters. The existence of an “optimum” value of structural stiffness is demonstrated for the entire wave frequency range.  相似文献   

Three-dimensional analysis of the screening effectiveness of hollow pile barriers for foundation-induced vertical vibration   总被引：2，自引：0，他引：2  

Pei-hsun Tsai  Zheng-yi Feng  Tin-lon Jen 《Computers and Geotechnics》2008,35(3):489-499

The study applies the three-dimensional boundary element method in frequency domain to investigate the screening effectiveness of circular piles in a row for a massless square foundation subject to harmonic vertical loading. Four types of piles were studied: steel pipe piles, concrete hollow piles, concrete solid piles and timber piles. A parametric study was undertaken to examine the effects of pile dimensions, operational frequency, and source distance on the screening effectiveness. The results showed that screening effectiveness of steel pipe piles is generally better than that of solid piles, and that a concrete hollow pile barrier can be ineffective due to its stiffness. The influence of pile length on screening effectiveness is more significant than that of pile spacing and the distance between the vibrating foundation and the pile barrier.  相似文献   

Tectonic geomorphology of the easternmost extension of the Gulf of Corinth (Beotia, Central Greece)   总被引：4，自引：2，他引：2  

Ioannis M. Tsodoulos  Ioannis K. Koukouvelas  Spyros Pavlides 《Tectonophysics》2008,453(1-4):211

The easternmost sector of the Gulf of Corinth, the Beotia area in Central Greece, is an area with active normal faults located between the two major rift structures of Central Greece, the Gulf of Corinth and the North Gulf of Evia. These active normal faults include WNW to E–W and NE to ENE-trending faults affect the landscape and generate basin and range topography within the Beotia. We study four normal fault zones and drainage basin geometry in the easternmost sector of the Gulf of Corinth to document the impact of active tectonics on the landscape evolution. Fault and drainage geometry are investigated based on detailed field mapping and high-resolution digital elevation models. Tectonic geomorphic analysis using several parameters of active tectonics provides information concerning the relative tectonic activity and fault growth. In order to detect areas of lateral stream migration that could indicate recent tectonic activity, the Transverse Topographic Symmetry Factor and the Asymmetry Factor are used to analyse drainage basin geometry in six large drainage basins and a drainage domain covering the study area. Our results show that vertical motions and tilting associated with normal faulting influence the drainage geometry and its development. Values of stream-gradient indices (S_L) are relatively high close to the fault traces of the studied fault zones suggesting high activity. Mountain-front sinuosity (S_mf) mean values along the fault zones ranges from 1.08 to 1.26. Valley floor width to valley height ratios (V_f) mean values along the studied fault zones range between 0.5 and 1.6. Drainage basin shape (B_S) mean values along the fault zones range from 1.08 to 3.54. All these geomorphic parameters and geomorphological data suggest that the analyzed normal faults are highly active. Lateral fault growth was likely produced by primarily eastward propagation, with the WNW to E–W trending faults being the relatively more active structures.  相似文献   

Geomorphic considerations for erosion prediction   总被引：9，自引：0，他引：9  

W. R. Osterkamp  T. J. Toy 《Environmental Geology》1997,29(3-4):152-157

 Current soil-erosion prediction technology addresses processes of rainsplash, overland-flow sediment transport, and rill erosion in small watersheds. The effects of factors determining sediment yield from larger-scale drainage basins, in which sediment movement is controlled by the combined small-scale processes and a complex set of channel and other basin-scale sediment-delivery processes, such as soil creep, bioturbation, and accelerated erosion due to denudation of vegetation, have been poorly evaluated. General suggestions are provided for the development of erosion-prediction technology at the geomorphic or drainage-basin scale based on the separation of sediment-yield data for channel and geomorphic processes from those of field-scale soil loss. An emerging technology must consider: (1) the effects on sediment yield of climate, geology and soils, topography, biotic interactions with other soil processes, and land-use practices; (2) all processes of sediment delivery to a channel system; and (3) the general tendency in most drainage basins for progressively greater sediment storage in the downstream direction. Received: 8 November 1995 · Accepted: 20 November 1995  相似文献   

海南省暖云烟炉设置及人工增雨作业条件分析     

何媛  黄彦彬  李春鸾  李光伟 《气象科技》2016,44(6):1043-1052

用地面烟炉开展人工增雨作业的关键环节是作业点附近的上升气流,利用海南省昌江霸王岭、东方玉龙山、乐东付光和五指山毛阳4个烟炉作业点附近的自动站和海口多普勒雷达资料并结合作业点地形特点对烟炉作业点布设条件和作业条件进行了分析,采用高斯模式对催化剂扩散情况进行了数值模拟。结果显示:这4个烟炉作业点均位于一定海拔的迎风坡,可利用上升气流将催化剂带入云中进行催化。综合利用NCEP/NCAR再分析资料、MICAPS资料和雷达数据确定作业时机,开展暖云烟炉人工增雨作业,增雨效果明显。  相似文献   

地貌素描在黄渤海海岸地貌研究中的应用     

徐小薇 《海洋科学进展》1996,(4)

地貌素描是地貌调查的一种重要方法，它能直观而又突出地表现典型地貌类型的特征形态和三维空间透视感。与摄影方法相比．地貌素描不受光线和摄影角度的限制，是外业摄影方法的一种补充手段。本文选取了作者多年来创作的部分典型海岸地貌素描图，较逼真地说明了海岸地质构造和地貌特点，阐述了地貌素描在海岸地貌调查中的作用。  相似文献   

Model Simulations of Carbon Sequestration in the Northwest Pacific by Direct Injection     

Katsumi?MatsumotoEmail author  Bryan?K.?Mignone 《Journal of Oceanography》2005,61(4):747-760

The direct disposal of CO₂ into the ocean interior represents a possible means to help mitigate rising levels of atmospheric CO₂. Here, we use three different versions of an ocean general circulation model (OGCM) to simulate the direct injection of liquid CO₂ near Tokyo. Our results confirm that direct injection can sequester large amounts of CO₂ from the atmosphere when disposal is made at sufficient depth (80–100% of the carbon injected at 3000 m remains in the ocean after 500 years) but show that the calculated efficiency is rather sensitive to the choice of physical model. Moreover, we show, for the first time in an OGCM and under a reasonable set of economic assumptions, that sequestration effectiveness is quite high for even shallow injections. However, the severe acidification that accompanies injection and the impossibility of effectively monitoring injected plumes argue against the large-scale viability of this technology. Our coarse-grid models show that injection at the rate of 0.1 Pg-C/yr lowers pH near the site of injection by as much as 0.7–1.0 pH-unit. Such pH anomalies would be much larger in more finely gridded models (and in reality) and have potential to severely harm deep-sea organisms. We also show that, after several hundred years, one would effectively need to survey the entire ocean in order to accurately verify the inventory of injected carbon. These results suggest that while retention may be sufficient to justify disposal costs, other practical problems will limit or at best delay widespread deployment of this technology.  相似文献   

Evaluating the effectiveness of road‐crossing drainage culverts in ephemeral streams     

C. Conesa‐García  R. García‐Lorenzo 《水文研究》2013,27(12):1781-1796

The present study proposes a method for evaluating the effectiveness of road‐crossing drainage culverts in ephemeral streams. This approach is focused on estimating the culvert capacity in road–stream crossings and the probable runoff generated on the road from hydrological thresholds associated with hydromorphological criteria. In particular, discharges at bankfull and flood‐prone stages have been used in combination with 2.5 and 100‐year peak discharges. Different hydraulic variables have been considered for calculating the discharge through culverts under these conditions (e.g. tailwater and headwater depth, inlet control, pipe roughness, pipe cross‐area and slope, pipe outlet velocity, critical water depth, and flow rate over the road). Geomorphological factors such as bed stability, bed load transport, and channel roughness have also been considered because of their potential for obstructing the drains in this type of channel. In addition, a potential obstruction index (PI_OBSTR) has been calculated, as a dependent parameter of the obstacle index (I_OBST) and the potential build‐up of coarse sediments (PB_CS). The study has been carried out on the Mediterranean coast in the region of Murcia (Spain), where there are numerous examples of road–stream crossings equipped with culverts in ephemeral channels that could cause highly dangerous situations for road traffic. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

热带雨林景观土壤测量采样深度与样品粒级试验研究——以加纳国雅卡锰金矿为例     

丁兆举 《地质与勘探》2021,57(3):554-562

加纳国雅卡锰金矿床位于著名的阿散蒂金矿带上。在该成矿带进行土壤测量采样深度、样品粒级试验以及方法技术的适应性和有效性研究,可为下一步开展大面积土壤地球化学测量提供技术依据,从而圈定可靠土壤地球化学异常。本文采用的工作方法为土壤垂向剖面法,选择有代表性的地段进行试验研究,结果显示在已知矿上方获得了明显的土壤地球化学异常。通过实验研究,选取土壤测量采样深度60～80 cm,截取样品粒级-4～+20目,获得了可靠、明显的土壤地球化学异常。研究证明该方法具有显著的地球化学找矿效果。  相似文献