青蔵鉄路の永久凍土対策
アラスカなどの極地地域での永久凍土が溶け出して地面がずれる問題は中国の青蔵鉄路でも例外ではない。青蔵鉄路は半分の線路が永久凍土を通っており，今世紀中にチベット高原での気温上昇が予測されている。エンジニアは問題の対策として砕いた岩を使って永久凍土を冷やすという簡単で確立された方法を使っている。砕いた岩は夏には熱の吸収を最小限に抑え，冬には熱の放出を促す効果を持つ。
"Tingun Zhang, a researcher at the US National Snow and Ice Data Center in Boulder, Colorado, reported at the AGU on the particular challenge slumping ground presents to the construction of the Qinghai-Xizang railroad across Tibet, perhaps the most ambitious permafrost-zone project since the Trans-Alaskan pipeline.
Nearly half the railroad will lie across permafrost, and temperatures in the region are expected to rise during this century.
Engineers are using a simple - and long established - trick of cooling the permafrost with crushed rock. Rocks minimise heat intake in summer and promote heat loss in winter.
It is the first time a large-scale project is using the crushed-rock method as its primary solution, according to Dr Zhang."
