土建專業(yè)畢業(yè)設(shè)計外文翻譯--孔隙水壓力作用下土坡的極限分析-文庫吧
2025-04-17 14:38 本頁面
【正文】 ven the so called “rigorous” solutions can be regarded as rigorous in a strict mechanical sense. In limitequilibrium, the equilibrium equations are not satisfied for every point in the soil mass. Additionally, the flow rule is not satisfied in typical assumed slip surface, nor are the patibility condition and prefailure constitutive relationship. Limit analysis takes advantage of the upperand lowerbound theorems of plasticity theory to bound the rigorous solution to a stability problem from below and above. Limit analysis solutions are rigorous in the sense that the stress field associated with a lowerbound solution is in equilibrium with imposed loads at every point in the soil mass, while the velocity field associated with an upperbound solution is patible with imposed displacements. In simple terms, under lowerbound loadings, collapse is not in progress, but it may be imminent if the lower bound coincides with the true solution lies can be narrowed down by finding the highest possible lowerbound solution and the lowest possible upperbound solution. For slope stability analysis, the solution is in terms of either a critical slope height or a collapse loading applied on some portion of the slope boundary, for given soil properties and/or given slope geometry. In the past, for slope stability applications, most research concentrated on the upperbound method. This is due to the fact that the construction of proper statically admissible stress fields for finding lowerbound solutions is a difficult task. Most previous work was based on total stresses. For effective stress analysis, it is necessary to calculate porewater pressures. In the limitequilibrium method, porewater pressures are estimated from groundwater conditions simulated by defining a phreatic surface, and possibly a flow , or by a porewater pressure ratio. Similar methods can be used to specify porewater pressure for limit analysis. The effects of porewater pressure have been considered in some studies focusing on calculation of upperbound solutions to the slope stability problem. Miller and Hamilton examined two types of failure mechanism: (1) rigid body rotation。 and (2) a bination of rigid rotation and continuous deformation. Porewater pressure was assumed to be hydrostatic beneath a parabolic free water surface. Although their calculations led to correct answers, the physical interpretation of their calculation of energy dissipation, where the porewater pressures were considered as internal forces and had the effect of reducing internal energy dissipation for a given collapse mechanism, has been disputed. Porewater pressures may also be regarded as external force. In a study by Michalowski, rigid body rotation along a logspiral failure surface was assumed, and porewater pressure was calculated using the porewater pressure ratio ru=u/ǐz, where u=porewater pressure, ǐ=total unit weight of soil, and z=depth of the point below the soil surface. It was showed that the porewater pressure has no influence on the analysis when the internal friction angle is equal to zero, which validates the use of total stress analysis with Φ =0. In another study, Michalowski followed the same approach, except for the use of failure surface with different shapes to incorporate the effect of porewater pressure on upperbound analy
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