土建专业毕业设计外文翻译--孔隙水压力作用下土坡的极限分析(编辑修改稿)

土建专业毕业设计外文翻译--孔隙水压力作用下土坡的极限分析(编辑修改稿)内容摘要：

sis of slopes, the writers are not aware of any lowerbound limit analysis done in term of effective stresses. This is probably due to the increased in constructing statically admissible stress fields accounting also for the porewater pressures. The objectives of this paper are (1) present a finiteelement formulation in terms of effective stresses for limit analysis of soil slopes subjected to porewater pressures。 and (2) to check the accuracy of Bishop’s simplified method for slope stability analysis by paring Bishop’s solution with lowerand upperbound solution. The present study is an extension of previous research, where Bishop’s simplified limitequilibrium solutions are pared with lowerand upperbund solutions for simple slopes without considering the effect of porewater pressure. In the present paper, the effect of porewater pressure is considered in both lowerand upperbound limit analysis under planestrain conditions. Porewater pressures are accounted for by making modifications to the numerical algorithm for lowerand upperbound calculations using linear threenoded triangles developed by Sloan and Sloan and Kleeman. To model the stress field criterion, flow of linear equations in terms of nodal stresses and porewater pressures, or velocities, the problem of finding optimum lower and upperbound solutions can be set up as a linear programming problem. Lower and upperbound collapse loadings are calculated for several simple slope configurations and groundwater patterns, and the solutions are presented in the form of chart. LIMIT ANALYSIS WITH POREWATER PRESSURE Assumptions and Their implementation Limit analysis uses an idealized yield criterion and stressstrain relation: soil is assumed to follow perfect plasticity with an associated flow rule. The assumption of perfect plasticity expresses the possible states of stress in the form F( 39。 ij ) = 0 (1) Where F( 39。 ij ) = yield function。 and 39。 ij = effective stress tensor. Associated flow rule defines the plastic strain rate by assuming the yield function F to coincide with the plastic potential function G, from which the plastic strain rate pij can be obtained though 39。 39。 pij ij ijGF   （ 2） where  = nonnegative plastic multiplier rate that is positive only when plastic deformations occur. Eq. (2) is often referred to as the normality condition, which states that the direction of plastic strain rate is perpendicular to the yield surface. Perfect plasticity with an associated with very large displacements are of concern. In addition, theoretical studies show that the collapse loads for earth slopes, where soils are not heavily constrained, are quite insensitive to whether the flow rule is associated or nonassociated. Principle of Virtual Work Both the lowerand upper –bound theorems are based on the principle of virtual work. The virtual work equation is applicable, given the assumption of small deformations before collapse, and can be expressed as either 39。 ()A B A B A Bi i i i ij ijs V VABij ij ijVT v d S X v d V d Vp d V     （ 3） Or 39。 A B A B Bi i i i ij ijS V VT v dS X v dV dV   （ 4） Where AiT = boundary loadings。 AijX = body forces。