研究目的: 由于非饱和土的复杂性，目前非饱和土理论还不完善，尚未形成成熟的非饱和土固结理论和沉降计算方法。地基沉降已成为高速铁路客运专线路基的主要控制因素之一，在掌握非饱和土物理力学特性基础上，揭示非饱和土地基沉降特性，对于在其上修建高速铁路客运专线根据工期情况选择更加合理、经济的地基处理措施具有重要意义。
研究结论: 胶济客专非饱和粉质黏土、粉土饱和度一般在 46% ～ 80%; 路堤在填筑期可完成总沉降的75% 以上，经过 3 ～ 5 个月的放置，可完成总沉降的 90% 左右; 非饱和土应力 － 应变、应变 － 时间关系均符合双曲线模型，沉降预测推荐双曲线法; 非饱和土地基上一般地段修建有砟轨道客运专线地基不处理，修建无砟轨道客运专线只对地基浅层 5 ～8 m 采用复合地基处理，对于高填方及过渡段加大复合地基处理深度。
Research purposes: Now the theory on the unsaturated soil is imperfect，and the consolidation theory and settlement calculating method for the unsaturated soil are not mature because of the complexity of the unsaturated soil．The subgrade settlement becomes one of important control factors of passenger dedicated line，so it is very important to know the physical mechanics characteristics of the unsaturated soil and it is very significant to reveal the settlement characteristics of unsaturated soil subgrade for selection of more reasonable and economic treatment way for the unsaturated soil subgrade of passenger dedicated line．
Research conclusions: The saturations of unsaturated silty clay and floury soil along the Qingdao － Jinan Railway are between 46% ～ 80% ． The embankment settlement during construction period can be above 75 percent of the total settlement and about 90 percent of the total settlement after 3 to 5 months． The stress － strain curve and the strain － time curve tally with the hyperbolic model，and hyperbolic method is recommended to predict the settlement of the subgrade． It is unnecessary to treat the unsaturated soil subgrade of the ballast track of passenger dedicated line． It is necessary to conduct the treatment to the shallowness from 5 m to 8 m of the subgrade of ballastless track of passenger dedicated line． The treating depth should increase for the high filling and transition sections of the ballastless track of passenger dedicated line．
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