Acta Geotechnica - Structured granular materials exhibit strongly anisotropic mechanical behaviours resulting from the directional properties of their microstructural components such as grain... 相似文献
The dependence of rock behavior on the deformation rate is still not well understood. In salt rock, the fundamental mechanisms that drive the accumulation of irreversible deformation, the reduction of stiffness, and the development of hysteresis during cyclic loading are usually attributed to intracrystalline plasticity and diffusion. We hypothesize that at low pressure and low temperature, the rate‐dependent behavior of salt rock is governed by water‐assisted diffusion along grain boundaries. Accordingly, a chemo‐mechanical homogenization framework is proposed in which the representative elementary volume (REV) is viewed as a homogeneous polycrystalline matrix that contains sliding grain‐boundary cracks. The slip is related to the mass of salt ions that diffuse along the crack surface. The relationship between fluid inclusion‐scale and REV‐scale stresses and strains is established by using the Mori–Tanaka homogenization scheme. It is noted from the model that a lower strain rate and a larger number of sliding cracks enhance stiffness reduction and hysteresis. Thinner sliding cracks (i.e., thinner brine films) promote stiffness reduction and accelerate stress redistributions. The larger the volume fraction of the crack inclusions, the larger the REV deformation and the larger the hysteresis. Results presented in this study shed light on the mechanical behavior of salt rock that is pertinent to the design of geological storage facilities that undergo cyclic unloading, which could help optimize the energy production cycle with low carbon emissions. 相似文献
Rockbolts can be regarded as a permanent support structure for underground engineering. However, the coupled rheological mechanism between rockbolts and rock mass remain poorly understood. In this research, the rock mass supported with discretely mechanically or frictionally coupled rockbolts with the point load model was investigated. At first, the elastic solutions of the coupling model were solved. Subsequently, the viscoelastic analytical solutions were acquired by applying the Laplace inverse transforms. Finally, the effect of viscosity coefficients and supporting parameters on the coupling model rheological behavior were explored. The results indicated that the angle of rockbolts support has a greater influence on the radial stress and tangential stress of the rock mass in the elastic state, but has little influence on the rheological state. Moreover, the roof, the interface between the left wall and right wall should be supported strengthen; the viscosity coefficient has little influence on the radial stress and tangential stress in the rheological state and has a negative correlation with the radial displacement. In order to limit the displacement in the rheological state of the rock mass, we choose the rockbolts with a large viscosity coefficient.
The association between mineralisation and hydrocarbons in sedimentary basins is widely recognised, but the nature and significance of their relationships are not fully understood. This paper provides an example of metalliferous brines injecting into a palaeo‐oil–gas reservoir to form a world‐class Zn–Pb deposit (Jinding, China). Petrographic and microthermometric studies of oil inclusions and PVT simulations suggest that oil and gas were charged in a shallow (<1300 m) environment before mineralisation. This environment favoured bacterial sulphate reduction (BSR), which produced large amounts of H2S that accumulated in the gas cap. Forceful injection of hot brines penetrated the oil zone to reach the H2S‐rich gas cap and precipitated sulphide ores. Individual fluid injection events were short‐lived, and the reservoir was only partly and briefly heated to beyond the bacterial survival temperature. Episodic injection of metalliferous brines and sustained supply of H2S through BSR resulted in the formation of a large Zn–Pb deposit. 相似文献
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