在湿陷黄土地区修建客运专线如何满足修建过程中以及工后沉降的要求，同时提高路基结构的抗渗性能，是该地区客运专线路基工程的关键技术。提出侧向约束防渗的路基结构新形式，研究了湿陷性黄土地基侧向约束防渗路基结构的防渗效果。采用灰土挤密桩和水泥土挤密桩作为侧向约束防渗结构，通过室内模型试验，针对不同桩体填料及桩间距，测试地基中不同位置及深度处地基土含水率的变化，对比分析后得出，与天然地基相比，设置挤密桩显著提高了地基的侧向防渗能力，且随着桩间距的减小，地基土含水率增长速率逐渐减小，即渗流速度减缓，防渗效果越好。对比试验中两种挤密桩复合地基，水泥土挤密桩侧向防渗效果优于灰土挤密桩，研究成果可供同类工程参考。

How to meet the settlement requirements both within construction process and post-construction and to improve impermeability of embankment is a key technology in building the passenger dedicated line in collapsible loess area. On the basis of the subgrade structure with lateral-constraint and seepage control, the effects of lateral-constraint and seepage structure in high speed railway subgrade on improving the seepage property of foundation soil in collapsible loess area are researched. Lime-soil compaction pile and cement-soil compaction pile with different pile spacing are adopted as lateral seepage control structure for indoor model test. According to different fillings of compaction piles and pile spacing, the change of moisture content of the foundation soil in different position and depth is measured. It is concluded by comparative analysis that setting compaction piles has a significant effect on the lateral seepage control compared with natural foundation. And with the spacing decreasing, the change of moisture content of the foundation soil decreases gradually, which means the slower the flowing speed, the better seepage control effect. In terms of the two kinds of compaction piles mentioned above, cement-soil compaction pile has a better effect on seepage control than lime-soil compaction pile. The research results can provide a reference for similar projects.