考虑加载过程的真空预压轴对称解析解     

彭劼  董江平  宋恩润  洪雷 《岩土力学》2010,31(Z1):79-85

本文在砂井地基轴对称等应变方程的基础上,推导了真空预压荷载下的轴对称孔压、固结度解析解,该解析解利用函数模拟孔压在地表的初始条件,以考虑真空荷载的施加过程,解决了以往真空预压解孔压边界条件和初始条件在地表处的矛盾。同时也可考虑涂抹和井阻等因素,更加接近实际工程情况。通过例题与其他解答及数值解进行了验证、比较,证明了该解答的适用性,可进一步用于实际工程的设计计算。  相似文献   

河流砂岩地震储层预测中的几个问题   总被引：3，自引：1，他引：2  

崔永谦  邵龙义  谢建荣  胡建玲  杜维良  冯小英 《物探与化探》2010,34(1):54-58

河流砂岩是陆相盆地常见储层类型及油气储集有利场所。由于河流改道迁移频繁,河流相沉积常为砂、泥岩交互且岩性横向变化快,造成地震反射呈断续特征,利用常规地震资料进行砂、泥岩分辨和预测难度很大。笔者在分析河流砂岩地质特征和地球物理响应的基础上,研究和讨论了砂岩的精确标定、等时地层格架下的精细解释和地震属性提取,优选地震振幅类属性和分频处理预测薄层砂岩的平面展布,构建合理的地质模型,优选参数进行拟声波反演预测砂岩垂向分布及厚度变化等储层预测中的技术问题。通过实际应用和资料验证,采用技术方法合理,并取得了高精度的预测结果。  相似文献   

福建漳浦山门石英砂矿地质特征及成因探讨     

戴元毅 《福建地质》2010,29(2):111-114

山门石英砂矿主要贮存于长乐组海积层中,矿体近水平层状产出,主要受物质来源、地貌和水动力与新构造运动等条件控制,矿床成因类型属滨海堆积。区内石英砂资源量大且质优,成矿地质条件好。  相似文献   

地表几何形态对冲断带构造特征影响的物理模拟实验研究          下载免费PDF全文

谢玉华  赵坤  周建勋  王利  王雪芹 《沉积与特提斯地质》2010,30(1):89-92

设计了基底均匀的水平砂层单测挤压砂箱模型,包括水平砂层上无砂丘以及砂丘分别位于距左侧活动挡板5 cm、10 cm、15 cm、20 cm、25 cm、30 cm时的7组实验,通过实验着重对水平砂层在受单侧挤压时不同位置砂丘对冲断带的影响问题进行研究。实验结果表明,砂丘在不同位置时,冲断带的形成规模、几何形状都发生相应变化:砂丘距左侧活动挡板10～25 cm时,冲起构造发育,且冲断带的构造特征明显;而砂丘距左铡活动档板5 cm、30 cm时不发育冲起构造,主要发育逆冲断层。  相似文献   

Identification and definition of primary and reworked tephra in Late Glacial and Holocene marine shelf sediments off North Iceland     

Esther Ruth Gudmundsdóttir  Jón Eiríksson  Gudrún Larsen 《第四纪科学杂志》2011,26(6):589-602

Nine tephra layers in marine sediment cores (MD99‐2271 and MD99‐2275) from the North Icelandic shelf, spanning the Late Glacial and the Holocene, have been investigated to evaluate the effectiveness of methods to detect tephra layers in marine environments, to pinpoint the stratigraphic level of the time signal the tephra layers provide, and to discriminate between primary and reworked tephra layers in a marine environment. These nine tephra layers are the Borrobol‐like tephra, Vedde Ash, Askja S tephra, Saksunarvatn ash, and Hekla 5, Hekla 4, Hekla 3, Hekla 1104 and V1477 tephras. The methods used were visual inspection, magnetic susceptibility, X‐ray photography, mineralogical counts, grain size and morphological measurements, and microprobe analysis. The results demonstrate that grain size measurements and mineralogical counts are the most effective methods to detect tephra layers in this environment, revealing all nine tephra layers in question. Definition of the tephra layers revealed a 2–3 cm diffuse upper boundary in eight of the nine tephra layers and 2–3 cm diffuse lower boundary in two tephra layers. Using a multi‐parameter approach the stratigraphic position of a tephra layer was determined where the rate of change of the parameters tested was the greatest compared with background values below the tephra. The first attempt to use grain morphology to distinguish between primary and reworked tephra in a marine environment suggests that this method can be effective in verifying whether a tephra layer is primary or reworked. Morphological measurements and microprobe analyses in combination with other methods can be used to identify primary tephra layers securely. The study shows that there is a need to apply a combination of methods to detect, define (the time signal) and discriminate between primary and reworked tephra in marine environments. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

漏斗式全沙排沙技术及其应用   总被引：9，自引：0，他引：9       下载免费PDF全文

周著  邱秀云  侯杰  王顺久 《水科学进展》2001,12(1):95-98

主要介绍了一种新型泥沙处理技术,即“漏斗式全沙排沙术”.该项技术既可以排除粗颗粒的推移质泥沙,也可以排除细颗粒的悬移质泥沙.对0.5mm以上的粗颗粒泥沙的截沙率为100%,对0.5mm以下细颗粒泥沙的截沙率为90%,排沙耗水量仅占渠道引水量的2%～5%.  相似文献   

关于风积砂地基扩展基础抗拔计算公式的探讨     

滕凯  周金柱  吴华 《岩土工程技术》2001,(2):69-72,91

利用风积砂地基抗拔室内模型试验资料，通过对抗拔土体破坏机理的全面分析，提出了土体形成极限承载力的三个受力过程，建立了扩展基础抗拔承载力计算的基本公式，与目前其它计算方法比较，成果精度提高很多倍，而且适用范围不受深宽比限制，便于推广应用。  相似文献   

新疆西昆仑地区干旱荒漠景观区域化探方法技术初步研究   总被引：12，自引：0，他引：12  

张华  杨少平  刘应汉  刘华忠 《新疆地质》2001,19(3):221-227

西昆仑地区地处中国风成沙的沉降区，与其它区相比较，风成沙粒级偏细。风成沙中主要颗粒成分为石英长石，但偏粗粒级混有一定比例近源岩屑；细粒级云母和暗色矿物颗粒增多，导致风成沙各粒级元素含量人布从粗粒至细粒级呈两头偏高，中间偏低的趋势。该区水系中普遍见风成沙掺入，水系沉积物从粗至细粒级石英长石颗粒逐渐增多，岩屑颗粒逐渐减少，石英长石主要来自风成沙。水系沉积物中，元素含量以80目级为界出现明显差异，－80目粒级元素含量明显受到风成沙干扰。因此，在该区开展区域化探采样粒级应为－10－＋80目粒级。奥依且克地区－10－＋80目和－80目两种粒级试点测量结果，表明－10－＋80目粒级的正确性。  相似文献   

Extended Self-Similarity in Geophysical and Geological Applications     

Vladimir I. Nikora  Derek G. Goring 《Mathematical Geology》2001,33(3):251-271

In this paper we demonstrate application of the Extended Self-Similarity (ESS) concept, recently developed in turbulence physics, for geological and geophysical phenomena. The theoretical background is discussed first and then the ESS properties in fluvial turbulence, sand wave dynamics, Martian topography, river morphometry, gravel-bed mobility, and atmospheric barometric pressure are explored. The main attention is paid to fluvial turbulence and sand waves, while other examples are presented to support the generality of the ESS concept in earth sciences. The results show that the ESS properties of the considered phenomena are remarkably similar to those reported for turbulence, in spite of different underlying mechanisms. This suggests that a general rule should exist which governs a wide class of complex natural phenomena.  相似文献   

Internal structure of a trough blowout, determined from migrated ground-penetrating radar profiles   总被引：2，自引：0，他引：2  

Adrian Neal  & Clive L. Roberts 《Sedimentology》2001,48(4):791-810

Ground‐penetrating radar (GPR) was used to investigate the relationship between the geomorphological development of a large aeolian trough blowout and the stratigraphy and internal sedimentary structure of its associated deposits. Although analogous, many of the data‐processing techniques routinely applied in seismic reflection are very rarely applied in GPR studies. In this study, a simple migration program was used that significantly enhanced the quality of GPR images from a large trough blowout at Raven Meols on the Sefton coast, northwest England. These improvements aided subsequent data interpretation, which was achieved through application of the principles of radar stratigraphy. GPR shows the pre‐blowout dunes to have a complex internal structure that suggests they were formed in the presence of at least a partial vegetation cover. Subsequent to stabilization of these dunes a thin soil developed. This dune soil forms an important radar sequence boundary and delineates a complex topography beneath the depositional lobe of the blowout. The internal structure of the depositional lobe of the blowout does not conform to a model of simple radial foreset deposition, as derived from contemporary process studies reported in the literature. Instead, the pattern of deposition has been extensively modified by the antecedent dune topography and by varying spatial and temporal exposure to important sand‐transporting winds that is partly controlled by interactions between the regional wind pattern and local dune morphology. Trough blowout deposits in coastal aeolian sedimentary sequences are likely to be recognized by the presence of laterally continuous packets of relatively high‐angle cross‐strata, which often display a spatially‐variable radial dip pattern that is only very poorly or partially developed. In addition, a soil, or other surface representing a significant hiatus in dune deposition, is likely to underlie the blowout deposits, the topography of which will show a clear relationship to the dip and orientation of the overlying cross‐strata.  相似文献