极限平衡理论在加筋土结构设计中应用的评述

为分析加筋土结构设计目前大都采用的极限平衡理论的保守问题, 在介绍国际上若干现行规范要点的基础上, 以国内外若干工程的实测资料说明这种保守的程度。还对加筋土结构的破坏模式和稳定校核的内容作了叙述, 建议从筋材本身的安全与加筋土结构整体稳定2方面进行稳定计算, 认为复合滑动面可能是结构稳定安全系数最小的滑动面, 该滑动面可能穿过筋材并沿筋材表面滑动。目前常用的所谓“外部稳定校核”、“内部稳定校核”等分析方法, 不可能找到整个结构所有可能的滑动面。最后对加筋土结构的合理设计方法提出了建议, 认为对结构物的应力应变分析是设计的最基本、最有用的资料, 但极限状态下结构物性状也需掌握, 因此最合理的是采用有限元分析法和极限平衡分析法相结合的设计方法。

Review on Limited Balance Theory Applied in the Design of Reinforced Soil Structures

The design of reinforced soil structure is mostly based on the Limited Equilibrium Theory (LET), which is somewhat conservative. In this paper, the conservatism in several international design codes or design guidelines are analyzed, and field measurement data from well working reinforced soil structures are listed to verify the degree of conservatism. Moreover, the failure modes (patterns) and stability analysis scenario for reinforced structures are described. Stability calculation is recommended to be conducted in terms of the stability of reinforcement material itself and the overall stability of reinforced soil structure. It is emphasized that as not all of the possible failure mechanisms were found from internal or external stability analysis, analysis on the compound slide surface which has possibly the minimum stability coefficient is necessary. It means that the designer has to consider all failure mechanisms: the compound slip surface might slide across the reinforcement and/or slide along the geosynthetics at each layer. So the stability calculation for the whole structure needs to be conducted without any distinction of internal or external. Finally, a reasonable design method (FEM + LEM) for reinforced soil structures is recommended. Stress-strain analysis is the most fundamental and useful data for design, but the performance of structure in limit state should also be taken into consideration.