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1.
基于拖带坐标法建立了岩层大变形的一维非线性微分方程,然后用解析与数值方法研究了变刚度、可伸缩岩层在侧向压力及自重作用下的分叉特性,初步揭示了褶皱岩层初始挠曲的形成机理。 相似文献
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Four types of soft-sediment folds of distinct geometry can be recognized in the upper part of the Talchir Formation (Lower Permian) of Jharia Basin, India. These folds, on systematic examination, indicate some events of progressive deformation. Experimental study reveals that if a layered stack of clay and overlying sand is allowed to flow slowly down a slope, differential velocity due to viscosity contrast leads to the deformation of the rheologic interface. The sharp planar contact gradually becomes wavy leading to the development of round-hinged folds involving sediments adjacent to it. With the advancement of the flow these folds gradually become overturned with the rotation of the axial plane in the direction of flow. Computer simulation suggests that progressive deformation of these folds by simple shearing may lead to the formation of tight isoclinal folds, which on dislocation along intrastratal normal faults may lead to the development of rootless isoclinal folds. The sheath folds observed in the studied section also indicate accentuation of the curved hinge due to simple shearing. The spatial distribution of these fold types in conjunction with the inferred direction of progressive deformation indicate basinward translation of the slump slice. If the same stack of sediments rapidly flows down the slope, the waveform generated at the interface quickly breaks in the form of roll-up recumbent fold due to Kelvin–Helmholtz instability. 相似文献
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Q. J. Huggett A. K. Cooper M. L. Somers A. R. Stubbs 《Marine Geophysical Researches》1992,14(1):47-63
GLORIA side-scan sonographs from the Bering Sea Basin show a complex pattern of interference fringes sub-parallel to the ship's track. Surveys along the same trackline made in 1986 and 1987 show nearly identical patterns. It is concluded from this that the interference patterns are caused by features in the shallow subsurface rather than in the water column. The fringes are interpreted as a thin-layer interference effect that occurs when some of the sound reaching the seafloor passes through it and is reflected off a subsurface layer. The backscattered sound interferes (constructively or desctructively) with the reflected sound. Constructive/destructive interference occurs when the difference in the length of the two soundpaths is a whole/half multiple of GLORIA's 25 cm wavelength. Thus as range from the ship increases, sound moves in and out of phase causing bands of greater and lesser intensity on the GLORIA sonograph. Fluctuations (or wiggles) of the fringes on the GLORIA sonographs relate to changes in layer thickness. In principle, a simple three dimensional image of the subsurface layer may be obtained using GLORIA and bathymetric data from adjacent (parallel) ship's tracks. These patterns have also been identified in images from two other systems; SeaMARC II (12 kHz) long-range sonar, and TOBI (30 kHz) deep-towed sonar. In these, and other cases world-wide, the fringes do not appear with the same persistence as those seen in the Bering Sea. 相似文献
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小直径组合桩的波浪力实验分析 总被引:2,自引:1,他引:2
本文给出小直径孤立桩、两个桩和2×2个桩的波浪作用力实验结果。在波浪水槽中以0°,45°,90°三个波浪方向测量了各桩所受的纵向力和横向力,文中讨论了组合桩之间的干扰效应,给出了干扰系数随KC数和桩距的变化。 相似文献
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C.H.K. Williamson 《Applied Ocean Research》1985,7(3):124-127
The present brief paper is intended to show that the fluid forces on a small cylinder can be considerably magnified when it is in the flow field of a larger cylinder. Two cylinders of unequal diameter are oscillated in a tank of fluid, and the lift and in-line forces on the smaller cylinder are measured when the pair of cylinders is placed at various orientations and spacings. 相似文献
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从区域构造入手,对单侯井田构造进行分析,认为井田内断层发育以走向NW—NE、落差≤5m的小型正断层为主,且主要分布于大中型构造的两侧.特别是在其弧形转折带附近往往形成“羽”状雁列的小断层密集带。断层垂向上多分布于4—7号煤层之间的厚煤层发育区,其严重破坏了煤层的连续及完整性,是影响煤层开采的最主要因素之一。井田褶皱构造相对不发育,以短轴小型背、向斜为主,均属缓波状褶曲,对煤层的开采无影响或影响较小。根据井田地质构造发育程度,对其进行预测及分区评价:井田东部为强烈的构造挤压带,以发育走向NW-近EW—NE向的大型逆掩断层为特点,构造最复杂;井田西北部是相对较轻微的构造挤压带,以发育走向NE向的逆断层为特征,构造较复杂;井田南部以发育近SN或NNW向正断层为主,构造相对简单。评价结果对矿井设计及采区与工作面布置有一定的指导作用。 相似文献
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基于天池煤矿地质勘探资料,结合区域构造背景研究了矿井地质构造特征及形成机制。天池煤矿构造属简单构造,地层总体呈走向北东、倾向北西的单斜构造,矿井内褶皱发育程度较低,断层以正断层为主,其次为低角度逆掩断层。陷落柱分布较为杂乱,成群出现,常见于褶皱轴部。自三叠纪末期开始一直受到区域构造活动的控制作用,印支期受SN向的挤压,形成了一些近EW向的构造;燕山期经历两期NWW--SEE向挤压使井田内地层及煤层主体呈NE走向;喜山早期的NE—SW向挤压,导致NE向断层的性质发生转变;上新世开始表现为区域上的伸展作用。 相似文献