中文摘要：

针对路堤填土自重作用下的平面应变天然软土地基，基于能合理反映中间主应力效应的广义SMP准则，同时考虑地基软土的侧压力系数和固结程度，建立了软土地基临界荷载与路堤临界填土高度的解析公式，并给出公式适用条件，最后结合M-C准则解答探讨了各参数的影响特性。经与文献结果比较，验证了解析公式的正确性及所给公式适用条件的必要性。参数分析表明：固结度、侧压力系数、黏聚力及内摩擦角对路堤临界填土高度的影响均很显著，不应盲目选定固结度为0或100％进行计算；M-C准则的结果偏保守，考虑中间主应力所得解答的最小侧压力系数更小、公式适用范围更广；应原位测定地基软土的真实侧压力系数，并充分考虑其抗剪强度参数的变异性。

英文摘要：

For the natural soft ground with plane strain under the self-weight of embankment filling, analytical formulae for both the critical load of soft ground and the critical filling height of embankment are proposed based on the generalized spatially mobilized plane （SMP） criterion with reasonable consideration of the intermediate principal stress. The lateral pressure coefficient and consolidation degree of soft ground are also taken into account, and more applicable conditions of the obtained analytical formulae are provided. Finally, the parametric studies combined with the results of Mohr-Coulomb （M-C） criterion are discussed. By comparing with the results of the existing literatures, these analytical formulae are validated, and the necessity of given applicable conditions is highlighted. It is found that all the effects of consolidation degree, lateral pressure coefficient, cohesion and inner friction angle on the critical filling height of embankment are very significant and the consolidation degree should not be blindly adopted as 0 or 100%. The results of M-C criterion are conservative, whereas the minimum lateral pressure coefficient of the proposed formulae is smaller due to the effect of the intermediate principal stress, and thus its application range is wider. The real lateral pressure coefficient of soft ground should be determined by in-situ tests, and the variability of its strength parameters should be fully considered.