Model tests on vibration characteristics of cutting subgrade of expansive soil of express railways under different service environments

In order to study the vibration characteristics of cutting subgrade by using semi-rigid water-proof structural layer, 1:1 large-scale model tests are carried out. The cyclic loads with frequency of 4 Hz and excitation of 100 thousand times are imposed on the subgrade model under three kinds of service environments (dry, raining and underground water rising). The results show that under the same cyclic loads, the influence of service environments on velocity and acceleration of cutting subgrade is significant, but they have not obvious influence on their attenuation law in the vertical direction. Compared to that under the dry working condition, the increasing range of velocity and acceleration on subgrade surface is respectively 35% and 20% under the raining service environment, and 45% and 23% under the underground water rising service environment.