Abstract: In engineering practice, problems of cracking of the channel-buried culverts on a soft soil foundation often appear as a result of unevenness in settlement and stress. Using a case study of the culvert project in Guangdong, this paper provides an analysis on the mechanics and causes for the cracking, based on field investigation, in-situ tests, and finite element simulations. This study reveals that the loads on the culvert depend on the effects of foundation treatment. If the foundation is much more rigid after treatment, the differential settlement between the pile and foundation soil will be relatively large and as a result, culvert load will also be larger than the weight load of soil columns. Without a full consideration, such a large load in this situation would exceed the bearing capacity of culvert structure, hence causing cracking. The results also indicate that for the culverts buried on a rigid pile composite foundation, a cushion layer could coordinate the distribution of stress, which is a significant guidance to the design of culverts on soft soil foundation. And on this basis, precautions against culvert cracking are suggested for similar projects.