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排序方式: 共有115条查询结果,搜索用时 19 毫秒
1.
Wenzhong Zhu John J. Hughes Nenad Bicanic Chris J. Pearce 《Materials Characterization》2007,58(11-12):1189
This paper reports a study to assess nanoindentation mapping of mechanical properties of cement paste and natural rocks. Initial work seems to show that mechanical property mapping by nanoindentation is feasible and can be related to microscopic information. Further work is however required on the effect of indent size and spacing. Such a testing technique can be very useful for materials with different phases to study the intrinsic properties of each component, and also the interaction and properties of the interfacial regions of different phases. The values of Young's modulus and hardness of the individual mineral phases were also determined by statistically analysing a large number of experimental data. 相似文献
2.
集群是目前高性能计算机系统主要的解决方案。随着集群规模的扩大。也出现了不易安装与管理、故障率高、缺乏方便的并行程序开发调试环境等问题。本文在集群安装软件包Rocks的基础上。结合Xen虚拟化技术构建了一个高性能虚拟集群,从而简化了集群的组建与管理,并提高了系统可靠性与容错性能及并行程序开发效率。 相似文献
3.
This paper presents the poromechanics/poroelastic analytical solution for stress and pore pressure fields induced by the action of drilling and/or the pressurization of an inclined/horizontal wellbore in fractured fluid-saturated porous media, or naturally fractured fluid-saturated rock formations. The model which is developed within the framework of the coupled processes in the dual-porosity/dual-permeability approach accounts for coupled isothermal fluid flow and rock/fractures deformation. The solution to the inclined/horizontal wellbore problem is derived for a wellbore drilled in an infinite naturally fractured poroelastic medium, subjected to three-dimensional in situ state of stress and pore pressure. The dual-porosity analytical solution is first reduced to the limiting single-porosity case and verified against an existing single-porosity solution. A comparison between single-porosity and dual-porosity poroelastic results is conducted and displayed in this work. Finally, wellbore stability analyses have been carried out to demonstrate possible applications of the solution. 相似文献
4.
5.
G. Suresh Kumar 《Canadian Metallurgical Quarterly》2009,135(1):1-7
Diffusive mass transfer between fracture and matrix accompanied with sorption significantly influences the efficiency of natural attenuation in hard rocks. While these processes have extensively been studied in a fractured formation, limited information exists on the sorption nonlinearity. For this purpose, a numerical model is developed that couples matrix diffusion and nonlinear sorption at the scale of a single fracture using the dual-porosity concept. The study is limited to a constant continuous solute source boundary condition. The influence of both favorable and unfavorable sorption intensities on solute mobility is investigated using the method of spatial moments. The differing capacities of available sorption sites between fracture surfaces at the fracture-matrix interface and the solid grain surfaces within the rock matrix result in a slower migration of solutes along the fracture, and a larger amount of diffusive mass transfer away from the high permeability fracture. 相似文献
6.
Sheng-hong Chen Weiming Wang Hui-feng Zheng Isam Shahrour 《Canadian Metallurgical Quarterly》2010,136(12):1610-1617
The seismic stability analysis of rock slope is implemented using a block element method (BEM) in this paper. Based on the formulations of the matrices of stiffness, mass, and damping, the dynamic governing equation for the rock block system is established. The Wilson method is used to solve the dynamic governing equation, and the viscoelastic artificial boundary condition is introduced to treat the unbound domain problem. The proposed method is applied to the seismic stability analysis of the intake slope in a hydropower project, from which the dynamic safety factors of key block element combinations during earthquake and their dynamic amplification factors of acceleration are evaluated. 相似文献
7.
Thermally induced volumetric changes in rock result in pore pressure variations, and lead to a coupling between the thermal and poromechanical processes. This paper examines the response of a fracture in porothermoelastic rock when subjected to stress, pore pressure, and temperature perturbations. The contribution of each mechanism to the temporal variation of fracture opening is studied to elucidate its effect. This is achieved by development and use of a transient displacement discontinuity (DD) boundary element method for porothermoelasticity. While the full range of the crack opening due to the applied loads is investigated with the porothermoelastic DD, the asymptotic crack opening is ascertained analytically. Good agreement is observed between the numerical and analytical calculations. The results of the study show that, as expected, an applied stress causes the fracture to open while a pore pressure loading reduces the fracture width (aperture). In contrast to the pore pressure effect, cooling of the crack surfaces increases the fracture aperture. It is found that the impact of cooling can be more significant when compared to that of hydraulic loading (i.e., an applied stress and pore pressure) and can cause significant permeability enhancement, particularly for injection/extraction operations that are carried out over a long period of time in geothermal reservoirs. 相似文献
8.
Structural Modifications of a Hard Deep Clayey Rock due to Hygro-Mechanical Solicitations 总被引:1,自引:0,他引:1
Wetting/drying tests including cycling effects were performed on an argillaceous deep rock coming from a Callovo–Oxfordian deposit in eastern France. Bulk volume and water content were measured in order to estimate the importance of physical changes. Then, mercury intrusion porosimetry (MIP) was performed on dry and moist samples in order to quantify the influence of hydraulic history on fracture. Results showed that shrinkage and swelling caused microcracks, which led to volume variations thus altering the structures of the rock. MIP tests performed on moist samples equilibrated with different hygrometric saline solutions allow unsaturated pores and classic water retention curves to be described so as to explain changes in the microstructure. 相似文献
9.
Three-Dimensional Hoek-Brown Strength Criterion for Rocks 总被引:5,自引:0,他引:5
A great number of rock strength criteria have been proposed over the past decades. Of these different strength criteria, the Hoek-Brown strength criterion has been used most widely, because: (1) it has been developed specifically for rock materials and rock masses; (2) its input parameters can be determined from routine unconfined compression tests, mineralogical examination, and discontinuity characterization; and (3) it has been applied for over 20?years by practitioners in rock engineering, and has been applied successfully to a wide range of intact and fractured rock types. The Hoek-Brown strength criterion, however, does not take account of the influence of the intermediate principal stress, although much evidence has been accumulating to indicate that the intermediate principal stress does influence the rock strength in many instances. In this paper, a three-dimensional (3D) version of the Hoek-Brown strength criterion has been proposed. The original Hoek-Brown strength criterion is just a two-dimensional (2D) version of the proposed 3D strength criterion. The 3D strength criterion not only inherits the advantages of the original Hoek-Brown strength criterion, but can take account of the influence of the intermediate principal stress. Polyaxial or true triaxial compression test data of intact rocks and jointed rock masses has been collected from the published literature and used to validate the proposed 3D Hoek-Brown strength criterion. Predictions of the proposed 3D Hoek-Brown strength criterion are in good agreement with the test data for a range of different rock types. The proposed 3D Hoek-Brown strength criterion is also compared with a simplified 3D Hoek-Brown strength criterion proposed by Pan and Hudson. The Pan-Hudson criterion cannot be considered a true 3D version of the Hoek-Brown criterion, because it does not reduce to the form of the original Hoek-Brown criterion at either triaxial or biaxial state. The Pan-Hudson criterion underpredicts the strength at the triaxial state, but overpredicts the strength at the biaxial state. 相似文献
10.
The purpose of this project was to evaluate mechanical properties of St. Peter sandstone by in situ testing, and to compare the field data with laboratory results. Direct shear tests were conducted to evaluate the strength-dilatancy behavior, and thin-section microscopy was used to help explain the significant friction angles associated with the material. St. Peter sandstone is nearly cohesionless, but it possesses a friction angle of 57–63° at low confinement. The large angle of internal friction at failure may be due to locking of sand particles or to postdepositional quartz overgrowths. Tests on pulverized densely packed sand and loosely packed sand were conducted in the same manner as the intact specimens and yielded friction angles of about 42 and 34°. Pressuremeter tests were performed in situ and the results were interpreted using an elasto-plastic analysis in terms of total stresses. By appropriate consideration of system stiffness, Young’s modulus was found to be about 0.5 GPa, slightly lower than the laboratory value, although unload-reload cycles were not attempted. Assuming associative behavior, the friction angle was estimated to be at least 56°. 相似文献