Numerical Analysis and Geo-Mechanism Study on the Subgrade Cracking Process Based on RFPA

Based on the typical highways widening approaches used in the process of expressway extension in China, the differential settlement and cracking mechanism in the pavement while widening unilaterally and bilaterally were studied using the FEM software RFPA. The results showed that the cracks initially appeared from the toe of side slope of the new foundation. As time went on, the settlement increased and cracks arised from the toe of side slope of the old foundation. Then these cracks propagated gradually and eventually formed a clear sliding surface, leading to glides along the interfaces between the old and new foundations. The interfaces were apt to be the potential gliding planes. If the embankment was higher, the global stability would be worse and the differential settlement would be larger. While the differential settlement and glide increased, the generated additional flexural-tensile stress and shear stress also increased progressively. The consequences were that the longitudinal cracks would appear in the foundation and further brought about the cracking of the asphalt pavement.