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1.
为分析寒区渠基黏土热参数的随机分布特征及概率分布模型,以寒区渠基黏土的导热系数为样本,结合经典分布拟合法、多项式逼近法、最大熵法和正态信息扩散法,分别对寒区渠基黏土热参数的概率分布规律进行了研究。首先通过分析热参数的离散性,并比较概率分布曲线、拟合检验值和累计概率分布值,对不同方法描述热参数随机性的优劣进行了评价;然后,基于寒区渠基黏土热学参数对温度的敏感性,提出了一个可以达到理想拟合精度的寒区渠基黏土热参数概率推断的区间取值标准。研究结果表明：寒区渠基黏土的热参数具有随机变量的特征;正态信息扩散法可以描述热参数样本的随机波动性;在4种方法中,正态信息扩散法的拟合精度最高。使用3.5σ法,将[μ-3.5σ,μ+3.5σ]（μ为随机变量的均值,σ为标准差）作为概率函数推断时的取值区间,同时考虑偏度的影响,可使得累计概率值达到1.000 0的精度,能够较准确地推断热参数的概率分布函数。 相似文献
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基于区域地震台网的数字化波形资料,使用ISOLA方法对2019年5月18日吉林松原M5.1地震进行矩张量反演,研究地震的震源机制,并且收集了地震序列中ML2.5以上地震的震源机制解,采用FMSI（focal mechanism stress inversion）方法反演震中区构造应力场。结果显示：松原M5.1地震的矩震级为4.9,矩心深度为6 km,双力偶分量为91.5%,主压应力P轴方位角、倾角分别为76°和3°,主张应力T轴方位角、倾角分别为166°和16°,震源机制解显示典型的构造地震特征;震中区构造应力场理论应力轴σ1方位角、倾伏角分别为88.0°和0.9°,σ2方位角、倾伏角分别为178.2°和9.6°,σ3方位角、倾伏角分别为352.5°和80.4°,这一结果与区域构造应力场一致。推断认为区域构造应力场触发了2019年松原M5.1地震活动,地震震源机制解的北西向节面与震中区附近的第二松花江断裂现今活动性质完全一致,认为第二松花断裂可能是松原M5.1地震的发震断层。 相似文献
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采用刚性滑块构建两种圆形隧道失稳环向开挖面破坏模式,利用编制的非线性规划程序求解隧道失稳环向开挖面支护力系数σT /c（σT为均布支护荷载,c为有效黏聚力）最优上限解及地层破坏模式,揭示地层参数对隧道稳定性的影响,提出简单实用的极限支护力简化公式。研究结果表明：不排水条件下,当隧道埋深比H/D（H为埋深,D为隧道直径）和重度系数γD/c（γ 为重度）较小时,破坏区域主要集中在隧道中上部,随着H/D和γD/c增大,滑移线起始位置沿着隧道轮廓逐渐向隧道底部扩展,破坏区域向水平方向扩展。排水条件下,地层破坏模式主要有3种。当内摩擦角ϕ 和γD/c较大时,随着剪胀系数的减小,极限支护力和地层破坏范围变化较大,甚至可能引起破坏模式的改变。针对不同深度提出的极限支护力简化公式可快速获得隧道环向开挖面极限支护力。 相似文献
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以美国怀俄明州钠基（MX80）膨润土为研究对象,采用热探针法测定碱−热环境下MX80膨润土的导热系数,探讨了温度、碱液强度和干密度对试样导热系数λ的影响规律,并选择部分试样进行了X射线衍射（X-ray diffraction,简称XRD）和扫描电镜（scanning electron microscope,简称SEM）试验,揭示了碱−热环境下MX80膨润土导热性能演变的微观机制。试验结果表明：MX80膨润土的导热系数λ随碱液含量和干密度的递增而增大;在不同碱液含量条件下,膨润土的导热系数均随温度升高而增大,且碱液含量越高,导热系数的温度效应越显著;干密度较小时,膨润土导热系数λ随温度升高而增大的影响越明显,主要原因是温度促进了试样内部的水汽潜热传输;同一温度和干密度条件下,热传导系数λ随着碱液pH值的升高而降低6,且pH值越高,则λ降幅越明显,主要原因是强碱溶液腐蚀了膨润土的蒙脱石成分,减少了试样内石英含量,增大了膨润土试样的孔隙率,进而降低了膨润土导热系数,这与测试试样的XRD和SEM结果相吻合。 相似文献
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τ-p变换是一种经典的函数投影变换方法,在地震数据处理中有着广泛的应用,可以根据地震数据射线参数的差异,实现信噪分离、地震道插值、平面波分解等。但是,由于τ-p变换的精度和分辨率受到相应数学反问题的限制,在保证较高变换精度的前提下,τ-p变换计算速度的加快,以及相应滤波算子的设计等都值得研究。本文提出了基于径向道变换的τ-p变换方法和基于斜率分解的τ-p变换方法,阐明了两种方法的基本原理并与常规τ-p变换方法进行对比。基于径向道变换的τ-p变换方法利用快速Fourier变换和径向道变换,能有效减少τ-p变换的耗时;基于斜率分解的τ-p变换方法运用斜率分解算法,能进行高分辨率τ-p变换,并且提供冗余变换维度（τ-x-p域）,使滤波器算子的设计更灵活。数值实验结果表明,两种实现方法分别在计算速度和重构精度上优于传统τ-p变换算法。通过面波噪声压制的实际数据处理和比较,证明本文提出的两种τ-p变换实现方法可以为实际处理提供更加有效和灵活的实施方案。 相似文献
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前哨林场大地构造上位于大兴安岭北段额尔古纳地块北部的漠河前陆盆地边缘。本文研究了大兴安岭漠河前哨林场侵入岩的岩相学、年代学及岩石地球化学特征,探讨了研究区内侵入岩的形成时代、岩石成因及其构造环境。LA-ICP-MS锆石U-Pb定年结果表明,花岗岩形成于199.9~199.3 Ma、辉长岩形成于（201.8±2.6） Ma,即研究区内的花岗岩、辉长岩均形成于晚三叠世—早侏罗世。岩石地球化学研究表明：花岗岩的w（SiO2）为63.22%~70.10%,w（Al2O3）为12.43%~14.36%,里特曼指数（σ）为0.74~1.65,属高钾钙碱性系列岩石,具有较低的Mg#值（平均值为39.43）,w（TFeO）为2.80%~4.41%,w（CaO）为1.47%~3.38%,轻重稀土分馏明显,富集轻稀土,亏损重稀土,δEu为0.48~0.84,富集Rb、Ta、K、La、Nd、Zr、Ti等元素,相对亏损Th、U、Sr、P、Eu等元素;辉长岩的w（SiO2）为51.42%~51.98%,w（Al2O3）为17.24%~17.73%,里特曼指数（σ）为3.00~3.53,属高钾钙碱性系列岩石,具有较高的Mg#值（平均值为51.07）,w（TFeO）为9.06%~9.14%,w（CaO）为5.81%~6.69%,重稀土分馏不明显,δEu为0.86~0.98,富集Rb、Ta、Nb、Nd等元素,相对亏损Th、U、P、Eu等元素。上述岩石地球化学特征表明,花岗岩为辉长岩结晶分异的产物,原始岩浆起源于地幔,并受地壳物质的混染改造。研究区侵入岩形成于造山阶段挤压环境,是蒙古—鄂霍茨克洋俯冲碰撞的产物。 相似文献
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古河道对于重现古气候、古生态环境变化有着重要的意义。极化合成孔径雷达（SAR）数据以散射矩阵的形式记录了地物的后向散射信息,能有效地识别隐伏的古河道信息。本文以古河道发育的松嫩平原西部作为研究区域,选取Sentinel-1双极化数据（VV-VH）作为数据源,通过VV-VH双极化模式下的H/α分解处理,构建了由散射熵H与散射角α构成的二维H/α平面。依据雷达波在古河道充填沉积物中发生体散射以及在古河床底界面发生二次散射,并且体散射功率大于二次散射功率,确定了古河道散射类型属于H/α平面上的高熵多次散射。结合此特征与Sentinel-2影像,最终对研究区内的古河道信息进行了提取。研究表明,通过VV-VH双极化模式下的H/α分解方式可以提取到在Sentinel-2影像上无明显特征的古河道信息。 相似文献
10.
方家沟地区二长花岗岩中锆石颗粒的晶体内部结构清晰,振荡生长环带发育和较高的Th/U比值（0.99~3.10）,反映了岩浆成因特征.LA-ICP-MS锆石U-Pb定年结果为（152.9±2.2）Ma.岩石SiO2含量73.06%~76.25%,里特曼指数（σ）2.51~2.63,具有高钾钙碱性特征,呈过铝质特点.ΣLREE/ΣHREE比值和（La/Yb）N比值分别为6.21~10.43和4.98~12.18,为轻稀土富集、重稀土亏损型.δEu值0.52~0.72,为中弱亏损.以上特征表明方家沟岩体为过铝质高分异I型花岗岩.其成因可能是由于造山后的拉张环境使得地壳减薄,促使软流圈的物质上涌和幔源岩浆的底侵作用,导致地壳的温度升高,减压熔融形成二长花岗岩. 相似文献
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In this paper an experimental study was planned on rock mass model with three joint sets under triaxial and true-triaxial
stress states to assess the influence of joint geometry and stress ratios on deformational behaviour of rock mass. The physical
models were composed of three continuous orthogonal joint sets in which joint set-I was inclined at angle θ=0°, 20°, 40°,
60°, 80° and 90° with x-axis, joint set-II was produced at staggering s=0.5 and joint set-III was kept always vertical. Thus, rock mass models with medium interlocked smooth joints (ϕ
j
=36.8°) were simulated under true triaxial compression (σ1>σ2>σ3). Modulus of rock mass shows anisotropy with joint inclination θ which diminishes with increase in σ2/σ3 ratio. The rock mass at θ=60° shows the highest modulus enhancement (599.9%) whereas it is minimum (32.3%) at θ=90°. Further
two empirical expressions for estimation of deformation modulus were suggested based on experimental results, which were developed
by incorporating two basic concepts, e.g. Janbu’s coefficients and joint factor, J
f. 相似文献
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Turbidity currents and pyroclastic density currents may originate as stratified flows or develop stratification during propagation. Analogue, density‐stratified laboratory currents are described, using layers of salt solutions with different concentrations and depths to create the initial vertical stratification. The evolving structure of the flow depends on the distribution of the driving buoyancy between the layers, B* (proportional to the layer volumes and densities), and their density ratio, ρ*. When the lower layer contains more salt than the upper layer, and so has a greater proportion of the driving buoyancy (B* < 0·5), this layer can run ahead leading to streamwise or longitudinal stratification (ρ*→0), or the layers can mix to produce a homogeneous current (ρ*→1). If the upper layer contains more salt and thus buoyancy (B* > 0·5), this layer travels to the nose of the current by mixing into the back of the head along the body/wake density interface to produce a homogeneous flow (ρ*→1) or overtaking, leading to streamwise stratification (ρ*→0). Timescales describing the mixing between the layers and the streamwise separation of the layers are used to understand these flow behaviours and are in accordance with the experimental observations. Distance–time measurements of the flow front show that strongly stratified flows initially travel faster than weakly stratified flows but, during their later stages, they travel more slowly. In natural flows that are stratified in concentration and grain size, internal features, such as stepwise grading, gradual upward fining and reverse grading, could be produced depending on B* and ρ*. Stratification may also be expected to affect interactions with topography and overall fan architecture. 相似文献
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地质体是在地壳演化中形成的,它是建造和构造形变的综合体。断裂化的地质体在较晚期构造力或工程载荷作用下沿已存在的断裂发生形变和位移的现象被称为迭加断裂,其形成过程即是迭加断裂作用。 本文以莫尔-库仑理论为基楚,探讨断裂发育与迭加断裂作用、构造应力场的关系,并对地质构造研究中的“断裂继承”,“断裂复活”进行定量的探讨。研究过程中承谷德振老师指导和鼓励,于此表示衷心的感谢。 相似文献
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The problem of settlement of shallow foundations is among the most important ones in classical soil mechanics. And while for the settlement of flexible foundations elastic solutions are widely used, for rigid rectangular foundations where the actual contact pressure distribution is still unknown, the problem is approximated either analytically assuming a contact pressure distribution or semi‐empirically combining the theory of elasticity with experimental and/or numerical results. A third and often attractive choice is the use of simple empirical relationships or relevant tabulated values relating the elastic settlement of rigid foundations (ρR) with the settlement of the respective flexible foundations (e.g. at the center, ρCe). Reviewing the relathionships of this third approach, the author revealed serious lack of consesous between the various sources; for example, according to the literature, ρR ranges between 68 and 125% of ρCe, the time when it is well-known that ρR?<?ρCe. In this paper, comparison of the settlement of 210 rigid foundation cases derived from 3D elastic finite element analysis, with the settlement of the respective flexible foundations derived from the theory of elasticity, led to simple empirical relationships between ρR and ρCe as well as between ρR and ρAv (ρAv?=?average settlement of the flexible foundation) with coefficient of determination (R2) almost unity. The analysis showed that these relationships are largely independent of the aspect ratio of foundations and the thickness and Poisson’s ratio (ν) of the compressible medium, although separate relationships are given for ν?=?0.5, slightly increasing R2. Finally, a correction factor for foundation rigidity is given exploting the known linear relationship that exists between the relative stiffness factor of foundations and settlement.
相似文献16.
Günther Josef Redhammer Anatoliy Senyshyn Gerold Tippelt Clemens Pietzonka Georg Roth Georg Amthauer 《Physics and Chemistry of Minerals》2010,37(5):311-332
CoGeO3 was synthesized at 1,273 and 1,448 K using ceramic sintering techniques in the monoclinic and orthorhombic modification,
respectively. The two compounds were analysed by magnetic susceptibility measurements and neutron diffraction in order to
study magnetic ordering and spin structures at low temperature. The monoclinic form of CoGeO3 has C2/c symmetry and orders magnetically below 36 K with a small negative paramagnetic Curie temperature θ
P = −4.6 (2) K. The magnetic structure can be described with k = (1, 0, 0) in the magnetic space group C2′/c′ having a ferromagnetic spin arrangement within the chains of M1 sites, but a dominating antiferromagnetic coupling between
the chains. At the M1 sites the magnetic spins are aligned within the a–c plane forming an angle of 120° with the +a-axis and they are not parallel to the spins at M2. Here spins are also ferromagnetically coupled within, but antiferromagnetically
coupled between the M1/M2 site bands. The orthorhombic phase of CoGeO3 displays Pbca symmetry and transforms to an antiferromagnetically ordered state [θ
P = −18.6(2) K] below 33 K. The magnetic spin structure can be described with k = (0, 0, 0) in space group Pbca′ and it is similar to the one of the C2/c phase except that it is non-collinear in nature, i.e. there are components of the magnetic moment along all three crystallographic
axes. Small magneto-elastic coupling is observed in the orthorhombic phase. 相似文献
17.
To estimate static and seismic active earth pressure (Pad) on a rigid retaining wall, numerical analyses using different step sizes have been carried out in this paper, based on the
modified Culmann line method by considering Coulomb’s planar rupture surface. Equivalent pseudo-static seismic forces are
considered in the analysis. A new concept of modified unit weight by considering ground surcharge is introduced under static
and seismic conditions. By numerical analysis, area of soil (A) has been estimated to obtain the ratio of A/A0 where A0 is θh2, θ is the angle between retaining structure and ground surface and h is the vertical height of the wall. This ratio remains constant for a particular type of soil and has been used to estimate
the maximum active earth pressure using force diagram. Results are provided in tabular form for easy calculation of the coefficient
of static and seismic active earth pressure. Present results by considering the new technique, compares well with the results
obtained by earlier researchers. 相似文献
18.
The orientation of the straight internal foliation Si within large ( 5 mm) garnet porphyroblasts has been measured relative to the orientation of the external foliation Se around a single antiform of 0.5 m wavelength, which folds the dominant regional foliation. The internal foliation is not constant in orientation, but varies consistently both with position around the fold and with the porphyroblast ellipticity. The dip of Si (hinge dip taken as zero) is consistently less than the dip of Se; it increases with increasing dip of Se and with increasing ellipticity of the porphyroblasts. Si effectively defines a fold with an opening angle greater than that in the external foliation. The opening angle of this fold in Si decreases with increasing porphyroblast ellipticity. The observed variation in the orientation of Si can be explained qualitatively by a flattened flexural flow model for fold development, as could be expected for folding of a pre-existing, strongly anisotropic foliation. The measurements clearly demonstrate that rotation of porphyroblasts relative to geographical co-ordinates did occur during the development of this fold and that a model based on the classical theories of rotation of stiff inclusions in a weaker viscous matrix is most appropriate. 相似文献
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Vojsava Gjoni Francesco Cozzoli Ilaria Rosati Alberto Basset 《Estuaries and Coasts》2017,40(4):1142-1158
Cross-community scaling relationships (CCSRs), which result from individual density scaling with average individual body size at guild and community levels, enable investigation of energy constraints at high levels of the ecological hierarchy. Here, we studied cross-community scaling relationships in benthic macroinvertebrate guilds in 15 Mediterranean and Black Sea lagoon ecosystems characterized by strong habitat heterogeneity and high energy density, using data already available in the LifeWatch-Italy data portal. The study sought to describe CCSR patterns in lagoon ecosystems, analyzing their variability across habitat and ecosystem types and evaluating the relative influence on individual body size, macroinvertebrate guild density, or both, of proxies of ecosystem properties, including physiographic characteristics and external disturbance, acting as potential drivers. Significant CCSRs were observed in benthic macroinvertebrate guilds in Mediterranean and Black Sea lagoons. They were characterized by high internal variability and slopes less negative than the metabolic scaling theory expectation (b = ?0.75), ranging between b = ?0.27 and b = ?0.50. Lagoon ecosystem typology, inter-lagoon variation, and ecosystem properties explained part of the variation in internal CCSRs, while habitat variation and intra-ecosystem habitat heterogeneity did not show any influence. CCSR intercepts expressing macroinvertebrate-specific densities showed patterns of variation that were consistent with those of proxies of ecosystem energetics and parsimony, such as eutrophication, chemical and physical disturbances, and openness. These relationships highlight the relevance of CCSRs, which enable inferences on the properties, functioning, and ecological status of ecosystems from simple analyses of community structure. 相似文献
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Kenya Ohgushi Yoshitaka Matsushita Nobuyoshi Miyajima Yoshio Katsuya Masahiko Tanaka Fujio Izumi Hirotada Gotou Yutaka Ueda Takehiko Yagi 《Physics and Chemistry of Minerals》2008,35(4):189-195
Structural, morphological, magnetic, and thermal properties have been investigated for a novel post-perovskite oxide CaPtO3 synthesized under high pressure. By comparing obtained structural parameters with those for known post-perovskite compounds,
we argue that the chemical bond has a strong covalent character. Precise measurements of the Langevin susceptibility χ
0
= −9.6 × 10−5 emu/mol and Debye temperature θ ∼ 470 K provide a good opportunity to confirm the reliability of first-principle calculations on predicting physical properties
of the Earth’s D” layer. 相似文献