青藏高原北部铁路沿线移动冰丘的特征及其灾害效应

Migrating pingos and their hazard effects in the vicinity of the railway across the northern Tibetan Plateau.

青藏高原北部常年冻土地区部分断裂破碎带发育移动冰丘。青藏铁路沿线典型移动冰丘包括不冻泉活动断裂诱发移动冰丘、乌丽活动断裂诱发86道班移动冰丘、二道沟盆南断裂破碎带桥梁施工诱发雅玛尔河移动冰丘、断裂破碎带桥基施工诱发83道班移动冰丘和乌丽盆北断裂破碎带DK1202+668大桥中部桥墩施工诱发85道班移动冰丘。移动冰丘的形成演化与活动断裂、地下水运动、气温变化存在动力学成因联系,是青藏高原北部常年冻土地区内动力与外营力相互耦合的标志和产物。移动冰丘能够穿刺公路路基、拱曲破坏涵洞结构、导致桥梁墩台破裂和输油管道拱曲变形,产生显著的灾害效应,成为高寒环境地质灾害的重要类型。采用适当的工程措施,通过疏导、排放地下泉水,能够有效地防治移动冰丘及灾害效应。

Migrating pingos are developed in some fracture zones in permafrost areas of the northern Qinghai-Tibet Plateau. Those typical ones along the Qinghai-Tibet Railway include the migrating pingo induced by the Budongquan active fault, migration pingo induced by the Wuli active fault near the 86th highway maintenance station, Yamar River migrating pingo induced by construction of a bridge in a fi＇acture zone in south branch active faults of the Erdaogou basin, migrating pingo induced by construction of the bridge foundation in a fracture zone at the 83rd highway maintenance station and migrating pingo induced by construction of bridge piers in the central segment of the DK1202＋668 railway bridge in a fracture zone at the 85th highway maintenance station north of the Wuli basin. The formation and evolution of these migrating pingos have dynamic genetic relation to active faults, groundwater movement and temperature change. They are the marker and product of coupling of the internal and external agents in permafrost areas on the northern Qinghai-Tibet Plateau. The migrating pingos can pierce the foundation of the highway, arch up and destruct the culverts and cause breaking of bridge piers and arched deformation of oil pipelines, producing serious hazard effects on engineering works. They are an important type of geological hazard in the high-altitude and cold environment. Appropriate engineering measures such as drainage of underground springwater, can effectively help prevent and control migrating pingos and reduce geological hazards.