Study on the lateral thermal disturbances of three parallel embankments on permafrost along the Gonghe-Yushu Engineering Corridor in China

Abstract

The mutual thermal disturbance of built structures along narrow permafrost engineering corridors has become an evident influencing factor on the thermal stability of frozen soil engineering. To analyse the mutual thermal disturbance of the built structures along a permafrost engineering corridor in the Qinghai-Tibet Plateau, three parallel permafrost embankments (along the G214 Highway and the first- and second-stage projects of the Gonghe-Yushu Highway in the Gonghe-Yushu Engineering Corridor) were chosen as the research sites. These three highways were built at different times following different standards; thus, complicated lateral thermal disturbances occurred among the three parallel embankments. The embankment distress investigations, typical section drilling, and ground temperature observations were used for analysis. Then, the thermal distress and service status were analyzed under the mutual thermal disturbances of the three embankments. The continuous wave settlements and inclination deformations were relatively developed due to the remarkable mutual thermal disturbances from the shorter distances among the three embankments. Moreover, missing or poor drainage systems further aggravated the mutual thermal disturbances. The monitored data revealed that the transverse thermal disturbances weakened the cooling effects of several special structures to a certain degree; these structures included the ventiduct embankments and crushed-rock embankments. A thermal disturbance simulation model for the three parallel permafrost embankments was proposed and included the assignment of the general influence, core influence, and severe influence zones of the thermal disturbance. The computed results showed that the general influence zones and core influence zones under the three embankments were linked together after 3 and 10 years of construction, respectively, on the Gonghe-Yushu Highway. After 50 years, a vast thermal influence area almost 100 m wide and 20 m deep would form under the three embankments. The thermal disturbances at different distances between embankments were also analyzed using this model; the distances between G214 and the first-phase project of the Gonghe-Yushu Highway were inferred to be more than 15 m and 20 m between the first- and second-phase projects of the Gonghe-Yushu Highway, respectively.