Crack damage investigation of paved highway embankment in the Tibetan Plateau permafrost environments

Field surveys focusing on the crack damages in paved embankment of the Qinghai-Tibet Highway were carried out at 17 sections. Some severe cracks were found in the road embankment constructed on the permafrost ground affecting the smooth operation of the highway. Road orientation, thaw settlement, crack width and length were measured at the typical crack sections. Besides, embankment slope surface temperatures were monitored at two road sections, and the temperature difference as high as 10 degrees C was observed in the cold winter time. Three scenarios were employed in the numerical modeling to assess the impact of climate warming, embankment slope surface temperature, and embankment itself on the underlying permafrost evolution process. Thereafter, a method was introduced to obtain the thaw settlement of the road embankment according to the simulated thawing front depth. The results indicate that the thaw settlement difference across the road embankment width is the main cause results in the crack damages. This uneven thaw settlement can be amplified due to the presence of the original ground slope. Additionally, climate warming intensified the underlying permafrost degradation and accelerated the thawing front penetrating into the subgrade permafrost. In summary, road orientation, original ground slope, climate warming, and underlying permafrost type are major but not the sole causes for the crack damages of the paved embankment in the Tibetan permafrost environments. It is recommended that steep slope and ice-rich permafrost ground should be avoided in the early design of the highway embankment.