Reasonable Height of Roadway Embankment in Permafrost Regions

Abstract

Many researches and engineering practices about the Qinghai-Tibetan Highway have proved that the thermal stability of the roadbed is the key problem of the roadway stability in permafrost regions. Beginning with the concept of critical heights of roadway embankment in permafrost regions, the authors conducted an in-situ experiment along the Qinghai-Tibetan Railway and a series of numerical analysis about the reasonable heights of roadway embankment on the Qinghai-Tibetan Plateau. The main conclusions are as follows: (1) the in-situ experiment shows that the rise of permafrost table under the embankment is not in proportion to the increase of embankment height. When the embankment is higher than 4m, the rises of permafrost table decrease with increasing embankment height. (2) the numerical analysis illustrates that, under the condition of mean annual air temperatures (MAAT) at −3.0, −3.5, −4.0, −4.5°C, respectively, the minimum embankment heights for asphalt pavement should be 8.24, 5.32, 3.11, 1.67m, and the maximum embankment heights should be 2.79, 3.4, 3.71, 3.99m; otherwise, the minimum embankment heights for gravel pavement should be 1.84, 0.55, 0.42, 0.42m, and the maximum embankment heights should be 3.42, 3.90, 4.13, 4.39m. (3) the critical values of MAAT for the existence of the critical embankment heights are −3.9°C for asphalt pavement and −2.8°C for gravel pavement.