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71.
高温高压下水的剪切粘滞度的平衡分子动力学计算 总被引:3,自引:1,他引:2
本项工作用TIP4P模型对水分子进行了平衡分子动力学模拟。根据Green-Kubo理论,计算了温度从652K到814K,密度从0.5360g/cm3到0.8638g/cm3六个不同温度和密度水的剪切粘滞度,并和实验值进行了对比。在所计算的温度和密度范围,平衡分子动力学计算结果与实验值的平均绝对值差别为15%,好于使用非平衡分子动力学方法获得的粘滞度值。平衡分子动力学的方法将是获得地学中高温高压下流体输运性质的重要途径。 相似文献
72.
The Taparko gold deposit, located in the eastern branch of the Proterozoic Birimian Bouroum-Yalogo greenstone belt (Burkina
Faso) consists of a network of quartz veins developed in a N 170° trending shear zone (250 m wide, 4 km long) superimposed
on the regional Birimian structural pattern. The quartz vein network is composed of: (a) a dominant array of quartz veins
(type 1), parallel to the shear zone and comprising strongly deformed dark quartz exhibiting foliation, layering, ribbon,
tension gashes, etc.; (b) oblique and subparallel related veins (type 2) of gray to white weakly deformed quartz crosscutting
the dominant quartz veins resulting in breccia structures; and (c) shallow dipping veins (type 3), cross-cutting veins types
1 and 2 and filled by undeformed white buck structure quartz. Cross-cutting relationships and different quartz types in different
veins and within individual veins imply a concomitant filling of the veins during the progressive deformation. Initial sinistral
transcurrent shearing evolved with time to sinistral reverse shearing. Metallic minerals occur only in type 1 and 2 veins
and were deposited in two stages, with native gold being related to second stage sulfides. Gold (and chalcopyrite) precipitated
preferentially upon the surfaces of fractured pyrite grains in low-pressure sites (pressure shadow zones) around and/or within
the sulfide grains (along subsequently annealed fractures). The formation of the South Taparko deposit can be divided into
a succession of events: (a) during the first event, N 170°-directed sinistral transcurrent shearing resulted in a N 20° mylonitic
foliation and fractured rock which allowed H2O-, CO2- and SiO2-rich fluids to circulate and deposit quartz with buck texture; (b) during the second event, type 1 quartz was strongly deformed
and type 2 veins formed with sigmoidal shapes as viewed on a horizontal plane; and (c) during the third event, the sinistral
transcurrent shearing evolved to sinistral reverse shearing and the deformation style evolved correspondingly from ductile
to brittle-ductile. During the last phase of deformation gold nucleated and deposited in low-pressure zones.
Received: 9 July 1997 / Accepted: 23 March 1998 相似文献
73.
74.
J. Bhattacharjee 《Ocean Engineering》2009,36(11):831-841
In the present study, the effect of shear current on the propagation of flexural gravity waves is analyzed under the assumptions of linearized shallow-water theory. Explicit expressions for the reflection and transmission coefficients associated with flexural gravity wave scattering by a step discontinuity in both water depth and current speed are derived. Further, trapping and scattering of flexural gravity waves by a jet-like shear current with a top-hat profile are examined and certain limiting conditions for the waves to exist are derived. The effects of change in water depth, current speed, incident wavelength and the angle of incidence on the group and phase velocities as well as on the reflection and transmission characteristics are analyzed through different numerical results. 相似文献
75.
Drag partition measurements were made in the atmospheric inertial sublayer for six roughness configurations made up of solid
elements in staggered arrays of different roughness densities. The roughness was in the form of a patch within a large open
area and in the shape of an equilateral triangle with 60 m long sides. Measurements were obtained of the total shear stress
(τ) acting on the surfaces, the surface shear stress on the ground between the elements (τS) and the drag force on the elements for each roughness array. The measurements indicated that τS quickly reduced near the leading edge of the roughness compared with τ, and a τS minimum occurs at a normalized distance (x/h, where h is element height) of
(downwind of the roughness leading edge is negative), then recovers to a relatively stable value. The location of the minimum
appears to scale with element height and not roughness density. The force on the elements decreases exponentially with normalized
downwind distance and this rate of change scales with the roughness density, with the rate of change increasing as roughness
density increases. Average τS : τ values for the six roughness surfaces scale predictably as a function of roughness density and in accordance with a shear
stress partitioning model. The shear stress partitioning model performed very well in predicting the amount of surface shear
stress, given knowledge of the stated input parameters for these patches of roughness. As the shear stress partitioning relationship
within the roughness appears to come into equilibrium faster for smaller roughness element sizes it would also appear the
shear stress partitioning model can be applied with confidence for smaller patches of smaller roughness elements than those
used in this experiment. 相似文献
76.
新山金矿属构造剪切带控制的典型金矿床,产于中元古界昆阳群美党组(Pt2m)中部变质石英砂板岩中。规模大、品位富、易采易选。矿区构造——含金剪切带与土壤地球化学金异常,是寻找该类金矿的重要标志。 相似文献
77.
Being a potential preferential way for water to flow, interfaces between host rock and engineered barriers are critical in the design of deep radioactive waste repositories. In case of cementitious materials, presence of water may lead to long term degradation by leaching. Such a phenomenon could impede the integrity of the confinement by its effect on the hydro-mechanical properties of the interface. Recent experimental results from Buzzi et al. [8] have evidenced some effects of leaching on the hydro-mechanical behavior of rock–concrete interfaces for one leaching time. This paper intends to investigate the influence of leaching on the mechanical behavior of rock–mortar interfaces by means of numerical simulations. These latter will be run for several leaching times to produce a better understanding of the phenomenon. For this purpose, a DEM approach has been developed to simulate the increase of the macro-porosity resulting from the leaching process. The implementation of the approach is first discussed. Then direct shear tests under constant normal stress are performed on a simple interface geometry and on a natural interface geometry. The results after Buzzi et al. [8] are corroborated by this research. 相似文献
78.
New structural data obtained on the Birimian terranes of the Kolia-Boboti sedimentary Basin, the eastern part of the Dialé-Daléma Supergroup in the Kédougou-Kéniéba inlier show two major phases of Eburnean compressional deformation: (1) a D1 phase of thrusting tectonics affected the Lower Birimian B1 tourmalinized sediments. This first tectonic phase is characterized by isoclinals overturned to recumbent folds P1 with N040° 20°NE trending axis, associated with axial plane schistosity S0S1 which is mainly transposed in the bedding; (2) a D2 phase of compressional (D2a) and transpressional (D2b) tectonics is responsible for the crossfolds P2a-P2b exhibiting curved axes. These P2 folds are associated with the major schistosity S2, north-south to SW-NE trending, mainly dipping to the south-east. The S2 schistosity is mostly displayed in the large shear zones corridors where it steeply dips locally toward the north-west. A north-west vergence thrusting phase (D2c) of flats and ramps, associated with reverse folds, represents the last Eburnean event. This geometrical feature is characteristic of a “positive flower structure”. These different Eburnean compressional phases are separated by extensional deformation which is characterized by sedimentary deposits and volcanic flows. 相似文献
79.
根据气象常规观测资料、湛江新一代天气雷达资料、CFL-08风廓线雷达资料及卫星云图,分析2012年4月20日粤西沿海特大暴雨的天气环流形势、能量场、对流不稳定度、水汽输送和辐合辐散等环境特征及物理量场特征。结果表明:这次暴雨过程粤西地区共经历两次强降水过程,分别是受飑线系统、以及高空槽和低空切变影响;西南低空急流的出现有利于粤西暴雨的形成、维持和发展;暴雨过程粤西上空垂直累积液水含量达25~30g/m2;暴雨期间风向随高度明显逆转,有冷平流输送;约2.0 km高度以下低空急流的下传和增强与暴雨的产生有密切关系;短时间内多普勒天气雷达的速度回波低层辐合区域远远大于辐散区域是可能产生强降水的标志。 相似文献
80.
The La Peña alkaline complex (LPC) of Miocene age (18–19 Ma) lies on the eastern front of the Precordillera (32°41ʹ34ʺS, 68°59ʹ48″W, 1400–2900 m a.s.l.), 30 km northwest of Mendoza city, Argentina. It is a subcircular massif of 19 km2 and 5 km in diameter, intruded in the metasedimentary sequence of the Villavicencio Formation of Silurian-Devonian age. It is the result of integration of multiple pulses derived from one or more deep magma chambers, which form a suite of silicate rocks grouped into: a clinopyroxenite body, a central syenite facies with a large breccia zone at the contact with the clinopyroxenite, bodies of malignite, trachyte and syenite porphyry necks, and a system of radial and annular dikes of different compositions. Its subcircular geometry and dike system distribution are frequent features of intraplate plutons or plutons emplaced in post-orogenic settings. These morphostructural features characterize numerous alkaline complexes worldwide and denote the importance of magmatic pressures that cause doming with radial and annular fracturing, in a brittle country rock. However, in the LPC, the attitude of the internal fabric of plutonic and subvolcanic units and the preferential layout of dikes match the NW–SE extensional fractures widely distributed in the host rock. This feature indicates a strong tectonic control linked to the structure that facilitate space for emplacement, corresponding to the brittle shear zone parallel to the N–S stratigraphy of the country rock. Shearing produced a system of discontinuities, with a K fractal fracture pattern, given by the combination of Riedel (R), anti-Riedel (R′), (P) and extensional (T) fracture systems, responsible for the control of melt migration by the opening of various fracture branches, but particularly through the NW–SE (T) fractures. Five different pulses would have ascent, (1) an initial one from which cumulate clinopyroxenite was formed, (2) a phase of mafic composition represented by dikes cross-cutting the clinopyroxenite, (3) a malignite facies that causes a small breccia in the clinopyroxenite, (4) a central syenite facies that develops breccias at the contact with the clinopyroxenite and, finally, (5) porphyry necks and a system of radial dikes intruding all units. At the moment of the emplacement different mechanisms would have acted, they summarized in: 1) opening of discontinuities synchronous to the magma circulation as the principal mechanism for formation of dikes and conduits; 2) stoping processes, that play an important role in the development of the breccia zone and enabling an efficient transference of material during the emplacement of the syenitic magma and 3) shear-related deformation (regional stress), affected the internal fabric of the facies, causing intracrystalline deformation and submagmatic flow, which is very evident in the central syenite intrusive. The kinematic analysis of shear planes allows proposing that emplacement of the LPC took place in a transtensive regime, which would have occurred in the back-arc of the Andes orogen, during a long period spanning from Miocene to the present, of the compressive deformation responsible, westward and at the same latitude, for the development of the Aconcagua fold and thrust belt. 相似文献