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421.
Influence of Water Pressure on the Stress State in Stopes with Cohesionless Backfill 总被引:2,自引:2,他引:0
The rapid increase of backfill use in underground mines requires a better understanding of the interaction between the fill
material and the surrounding rock mass. This is a fairly complex issue as backfill materials are weak compared to the rock
mass. This difference in the mechanical behavior induces a stress transfer along the contact area. Previous work conducted
on backfilled trenches and mining stopes has shown that basic arching theory can be used to estimate earth pressures in narrow,
vertical openings. In this regard, most existing solutions have been developed for dry backfills. However, in many cases,
water is present in mine stopes, so its effect should be assessed. In this paper, the authors present a solution to evaluate
the stress state in submerged or partially submerged backfilled stopes. The proposed analytical solution is validated against
numerical modeling results. 相似文献
422.
应用奇异非线性Dirichlet问题的上下解方法以及极大值原理,得到了一类奇异半线性Dirichlet问题正古典解的存在性,最后进一步给出解的正则性。 相似文献
423.
为了研究Navier-Stokes方程相关的三维轴对称驻点流系统的解,给出了一个积分方程系统,扩展了它的用途.并通过研究该积分方程系统的性质,在更广的范围内,利用这个系统的解,得出了与Navier-Stokes方程相关的三维轴对称驻点流系统的相似解.同时还改进了一个相似解的不存在性结果. 相似文献
424.
20世纪中期以来,麻山喀斯特山区随着周边社会环境的巨变,这些巨变冲击了麻山地区生态系统的脆弱环节,使麻山地区石漠化灾变日趋扩大。国家从20世纪60年代开始虽经多方救治,成效甚微。我们在对苗族生计方式的田野调查后发现,生息在这里的苗族积累有高效利用与精心维护喀斯特生态系统的经验和技能,发掘和利用苗族传统的地方性知识和技能,在石漠化灾变救治中具有不可替代的特殊价值。 相似文献
425.
Luca Cozzolino Renata Della Morte Carmine Covelli Giuseppe Del Giudice Domenico Pianese 《Advances in water resources》2011,34(11):1413-1426
Free-surface flows are usually modelled by means of the Shallow-water Equations: this system of hyperbolic equations exhibits a source term which is proportional to the product of the water depth by the bed slope, and which takes into account the effect of gravity onto fluid mass. Recently, much attention has been paid to the case in which bottom discontinuities are present in the physical domain to be represented: in this case, it is difficult to define the non-conservative product in the distributional sense. Here, the discontinuous-bottom Shallow-water Equations with hydrostatic pressure distribution at the bed step (Bernetti et al., 2006) are discussed in the context of the theory of Dal Maso et al. (1995) [9]; finally, a first-order numerical scheme is presented, which is consistent for regular solutions, and which is able to capture contact discontinuities at bottom steps. Numerous tests are presented to show the feasibility of the scheme and its ability to converge to the exact solution in the cases of smooth as well as discontinuous bed profiles. 相似文献
426.
Diapycnal mixing plays an important role in the ocean circulation.Internal waves are a kind of bridge relating the diapycnal mixing to external sources of mechanical energy.Difficulty in obtaining eigen solutions of internal waves over curved topography is a limitation for further theoretical study on the generation problem and scattering process.In this study,a kind of transform method is put forward to derive the eigen solutions of internal waves over subcritical topography in twodimensional and linear framework.The transform converts the curved topography in physical space to flat bottom in transform space while the governing equation of internal waves is still hyperbolic if proper transform function is selected.Thus,one can obtain eigen solutions of internal waves in the transform space.Several examples of transform functions,which convert the linear slope,the convex slope,and the concave slope to flat bottom,and the corresponding eigen solutions are illustrated.A method,using a polynomial to approximate the transform function and least squares method to estimate the undetermined coefficients in the polynomial,is introduced to calculate the approximate expression of the transform function for the given subcritical topography. 相似文献
427.
428.
The volumes and enthalpies of mixing, ΔV Mix and ΔH
Mix, of binary solid-solution aluminosilicate garnets have been studied by computer simulation. The use of “average atoms” to
simulate solid solution was found to give results that are considerably different from those obtained by calculating and averaging
over many configurations of cations at a given composition. Although we expect mineral properties calculated from model calculations
to be correct only on a qualitative rather than a quantitative scale, fair agreement with experiment was obtained where carefully
tested potential parameters were used. The results show that mixing behaviour in these materials is controlled by local strain
and relaxation effects resulting from the atomic size mismatch of the mixing divalent cations. In particular, ΔV
Mix and ΔH
Mix are shown to scale quadratically with the volume difference between the end members, and to vary essentially symmetrically
with composition, with a moderate dependence on the degree and nature of cation order. We conclude that computer modelling
should be useful in providing detailed qualitative information about the mixing properties of solid solutions, which can help
to better constrain and interpret experimental results.
Received: 8 March 2000 / Accepted: 1 October 2000 相似文献
429.
430.