ANALYSIS ON DYNAMIC RESPONSE OF THAWING-SOIL ROADBED UNDER TRAIN MOVING LOAD

The Qinghai-Tibet railway runs through the permafrost, and the temperature change has effected on the roadbed. In order to ascertain the effect of the train moving load on the thawing soil roadbed, using the dynamic parameters of the warm permafrost obtained from experiments, combining with the soil dynamics theory and finite element method, the time-displacement curve of the surface stress of the thawing roadbed to the vertical displacement under the train moving load is calculated and discussed, comparing with that of the frozen roadbed. The results show that, the stress are different for different roadbeds under the same train moving load; the effect of the train moving load on the thawing soil focus on the region within 15m beneath the surface of the roadbed; the stress attenuates obviously with the depth from the surface to the 5m depth beneath the surface at the center of the roadbed, being the obvious effect region of the train moving load to the roadbed; the train moving load is easy to induce plastic deformation of the thawing soil.