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

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