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21.
根据昆仑山口西8.1级地震前后GPS测点的位移速率,用弹性模型公式计算了地壳应变参数.应变参量的变化表明,震前在地震区附近以压应变为主,应变速率较大.位移速率矢量显示出震前的震中地区相对周围为活动性较弱的“稳定”地区.地壳的形变和应变揭示出孕震体在挤压状态下积累了较高的应变势能.8.1级地震的同时期由于地壳释放了巨大的应变能而应变速率变化显著.计算结果表明,地震所产生的应变达到4.5×10-6以上.发震断裂带的平均左旋走滑量是3.31m(89°E~96°E). 相似文献
22.
研究了边界是参考椭球面的Laplace方程Dirichlet边值问题的求解,在O(ε4·T)精 度下给出了参考椭球界面上扰动重力位Dirichlet外问题的积分解式. 该结果理论上优于目 前常用的球近似下的积分解式,从而为研究物理大地测量中边值问题的求解提供了新的依据 相似文献
23.
John M. Logan 《Environmental Geology》2004,46(3-4):456-467
Studies of marble panels from the exterior of two buildings document the processes leading to bowing of the material. Bowing of panels is most extensive in those areas that are exposed to direct or reflected thermal energy. The thermal anisotropic behavior of calcite results in grain-boundary separation, grain sliding and microfracturing. The resulting loss of strength is one factor leading to bowing. The development of bows further reduces the panel strength as the outer portions elongate by inelastic deformation mechanisms. Laboratory experiments cycling marble samples for over 200 cycles at three temperatures up to 107°C above room conditions show similar strength losses as the natural situation. The second factor contributing to the bowing process is the release of residual elastic strain. The strain is in part stored in the marble from its geologic history, but may also be accumulated during thermal cycling due to the properties of calcite. Marble panels have been found to bow when stored outside, but not attached to any framework, indicating that the release of residual strain is a critical factor in producing the bows. 相似文献
24.
Shear deformation of hot pressed plagioclase–olivine aggregates was studied in the presence and absence of mineral reaction. Experiments were performed at 900 °C, 1500 MPa, and a constant shear strain rate of 5×10−5 s−1 in a solid medium apparatus. Whether the mineral reaction between plagioclase and olivine takes place or not is controlled by choosing the appropriate plagioclase composition; labradorite (An60) does not react, anorthite (An92) does. Labradorite–olivine aggregates deformed without reaction are very strong and show strain hardening throughout the experiment. Syndeformational reaction between olivine and anorthite causes a pronounced strain weakening. The reaction produces fine-grained opx–cpx–spinel aggregates, which accommodate a large fraction of the finite strain. Deformation and reaction are localised within a 0.5-mm-wide sample. Three representative samples were analysed for their fabric anisotropy R* and shape-preferred orientation α* (fabric angle with the shear plane) using the autocorrelation function (ACF). Fabric anisotropy can be calibrated to quantify strain variations across the sheared samples. In the deformed and reacted anorthite–olivine aggregate, there is a strong correlation between reaction progress and strain; regions of large shear strain correspond to regions of maximum reaction progress. Within the sample, the derived strain rate variations range up to almost one order of magnitude. 相似文献
25.
钟业勋 《武汉大学学报(信息科学版)》2004,29(1):29-33
给出了地理空间的数学定义 ,推导了制图区域、地图投影、制图物体及其在椭球面和地图平面上的定位等概念 ,揭示了同一平面位置上可以依制图目的的不同而分别表示多种事物的性质或量值的基本原理 ,阐释了对同一制图区域进行多专题制图的客观条件和物理基础。 相似文献
26.
Z. Nadenik 《Studia Geophysica et Geodaetica》2005,49(3):277-288
In modern geodesy the triaxial ellipsoid as a generalisation of the ellipsoid of revolution has a significant position in studying the figure of the Earth. Lame surfaces represent a generalisation of the triaxial ellipsoid. The following paragraphs are devoted to curvatures of the Lame surfaces. 相似文献
27.
S. C. Tarantino M. Zema F. Maglia M. C. Domeneghetti M. A. Carpenter 《Physics and Chemistry of Minerals》2005,32(8-9):568-577
A suite of (Mn1-x
Fe
x
)Nb2O6 (x=0, 0.05, 0.25, 0.50, 0.75, 1) columbite samples has been prepared by solid-state reaction from oxides. X-ray diffraction
and spectroscopic investigations have been carried out in order to gain different perspectives on how the solid solution adapts
at different length scales to cation mixing. X-ray powder diffraction and powder absorption IR spectroscopy data are presented.
The powder diffraction data show that there is no significant excess volume of mixing on the Fe–Mn columbite join. All the
unit-cell parameters decrease linearly as a function of increasing Fe content. Substitution of Fe2+ for the larger Mn2+ cation causes a decrease in the volume of the A polyhedron, which also becomes more regular with respect to both bond-length
and edge-length distortion parameters. No significant variation of the B site has been observed. Wavenumber shifts of the
IR peaks nearly all vary linearly with composition, consistent with linear variations of the lattice parameters. Line broadening
has been quantified by autocorrelation analysis of the IR spectra. This is interpreted as suggesting that there is some element
of local strain or positional disorder at the length scale of second or third nearest neighbours around sites occupied by
Fe. 相似文献
28.
The development of subgrain misorientations with strain in dry synthetic NaCl measured using EBSD 总被引:1,自引:0,他引:1
The development of subgrain boundary misorientations with strain in dry, synthetic NaCl polycrystals, deformed at elevated temperature, has been investigated using electron backscattered diffraction (EBSD). At low natural strains, up to 0.5, average misorientations of subgrain boundaries increase with strain and a power law relationship exists between strain and average misorientations. The average misorientations are strongly influenced by grain orientation, suggesting that the misorientation–strain relationship may also be texture dependent in materials with high plastic anisotropy, like NaCl. A slight grain size dependency of the average misorientations was observed. The results indicate that with suitable calibration, average subgrain boundary misorientations may offer a method for estimating the strain accommodated by dislocation creep in NaCl and thus perhaps in other geological materials, although current theories for polycrystalline plasticity imply that misorientations may also depend on stress in some situations. 相似文献
29.
不同的GNSS采用的坐标系定义几乎相近,但参考椭球及其坐标实现不同,这将影响多GNSS融合导航定位效果。根据各GNSS坐标系所采用参考椭球的基本常数,计算比较了不同坐标系参考椭球参数的差异;导出了相应的正常重力公式,比较了这些正常重力公式确定的正常重力值差异;最后分别从坐标系统的定义与实现两个方面分析了其对定位结果的影响。结果表明:1)GPS(BDS)与Galileo和GLONASS所使用的参考椭球引起正常重力差约为0.15和0.30 mgal;2)GPS与BDS,Galileo及GLONASS所使用参考椭球引起纬度分量最大差异约为0.1 mm,3 cm和3 cm,高程分量约为0.1 mm,0.5 m和1 m;3)各GNSS所使用坐标框架间转换参数引起的坐标变化达到厘米级。 相似文献
30.
The Ribeira Belt (Brazil) is a Neoproterozoic collisional-related feature that was located in a south-central position in West Gondwana. We present quantitative data on finite strain, flow vorticity and deformation temperatures for the Curitiba Terrane, a major segment of the southern Ribeira Belt. Six deformation phases (D1-D6) related with crustal thickening and exhumation were recognized. D1 and D2-related microstructures are preserved exclusively within porphyroblasts, in part grown during stages of high-pressure (∼9–12 kbar) isobaric heating after crustal thickening. D3 phase was active from peak metamorphism attained in contrasting crustal levels (810–400 °C), to the early stage of exhumation (500–400 °C), as indicated by petrological, microstructural and quartz c-axis fabric evidence. Kinematic vorticity results indicate that the SL3 mylonitic fabric resulted from a simple shear-dominated deformation related with westward thrusting. North-verging overturned D4 folds with E-W-trending subhorizontal axes derived from a pure shear-dominated deformation. Regional D5 open folds with subvertical axes and NNE-SSW-trending traces were produced by indentation tectonics. D6 phase comprises retrograde orogen-parallel transcurrent shear zones related with scape tectonics. Geochronological data indicate that D3-D6 phases occurred between 584 and 580 Ma, suggesting a fast exhumation rate of ∼8 mm/year for the deepest rocks from the southern Ribeira Belt. 相似文献