Friction coefficient and stress–strain on a soil-buried box culvert jacking in highway construction

Abstract

In this article, the factors affecting the friction coefficient between a box culvert’s sidewalls and surrounding soil and the box culvert’s mechanical behavior during the jacking process in construction were studied with an engineering example in Guangdong province, China. First, the principal factors that affected changes in the friction coefficient and its law were analyzed with self-development model testing. Second, in combination with 3D finite element simulation, both the stress and strain laws of a box culvert’s different parts were studied by considering changes in jacking distance, soil thickness, and drag reduction material. The results showed that with increasing jacking distance, both the curves of stress and strain on the roof and floor with jacking distance exhibited an “armchair” shape, while the web had a “trapezoid” shape as the box culvert was jacked into the subgrade. Both the thickness and characteristics of the cover soil on top of the box culvert had an essential influence on the stress and strain values of the box culvert’s structure. Water content’s effect on the friction coefficient decreased gradually when the water content exceeded its plastic limit. The optimal ratio of cement slurry to soil was approximately 1:4 in the project. It is also suggested that a paraffin and engine oil mixture can be used as a drag reduction material when jacking a box culvert.