Abstract: In order to solve the problems of collapsibility and large deformation of highway loess roadbed, taking the project from Taiyangshan Development Zone to Pengyang (Ningxia-Gansu Border) of the Yin chuan-Kunming Express way as an example, based on the analysis of the engineering geological characteristics of collapsible loess roadbed in the field area, dynamic compaction method is applied to strengthen collapsible loess. Based on the static penetration test, the influence of the number of hits and the distance between ramming points on the reinforcement effect is evaluated. The combined method of field shallow plate load test and laboratory test is used to test the treated subgrade. The results show that when the number of tamping hits is 10, the strengthening strength and depth of soil are improved significantly. The strengthening point spacing has little effect on the strength of the center of the tamping point, and the strength of the other points increases with the decrease of the tamping point spacing. After treatment, the characteristic value of the loess subgrade bearing capacity increases between 96.3% and 128.8%, and the load settlement curve presents two stages of nonlinear accelerated deformation stage and failure stage, with no obvious proportion limit. The compressive modulus of treated loess increases by 40% on average, and the distribution of compressive modulus is relatively uniform in the sampling depth range, with the compressive modulus ranging from 12 to 16 MPa.

Key words: Yinchuan to Kunming Expressway, collapsible loess, engineering geological characteristics, subgrade treatment, modulus of compression

摘要： 为解决高速公路黄土路基的湿陷性和大变形问题,以银昆高速太阳山开发区至彭阳(宁甘界)项目为例,在分析场区湿陷性黄土路基的工程地质特性基础上,运用强夯法对湿陷性黄土进行加固,基于静力触探试验评价了夯点击数和夯点间距对加固效果的影响,并运用现场浅层平板载荷试验和室内试验相结合的方法对处理后的路基进行测试。测试表明,夯点击数为10击时,土体加固强度和深度提升较为明显,加固点间距对于夯点中心位置的强度影响不大,其余位置的强度随夯点间距的减小而增大;处理后的黄土路基承载力特征值提升幅度为96.3%~128.8%,荷载沉降曲线呈现非线性加速变形阶段、破坏阶段的2阶段变化,无明显比例界限;处理后黄土的压缩模量平均提升幅度为40%,且在取样深度范围内压缩模量分布较为均匀,压缩模量为12～16MPa。

关键词: 银昆高速, 湿陷性黄土, 工程地质特征, 路基处理, 压缩模量