2001-2006年青藏铁路多年冻土区冻害调查与分析

多年冻土问题是青藏铁路建设面临的主要工程地质问题,2001年开始,随着铁路路基、桥梁等构筑物的建设施工,多年冻土环境发生了变化,从而影响到多年冻土的工程稳定性.通过对青藏铁路建设期间历年来寒季暖季的冻害现场调查,在2002年寒季调查中发现多年冻土区的路基出现裂缝;2003年寒季调查发现冰椎、冰幔、混凝土剥蚀、沙害等;2004年又发现边坡渗水、涵洞积冰等冻害;2005年寒季调查发现新生病害较少.通过现场分析和及时治理,逐步提出了多年冻土区的补强措施,制定了主动保护措施为主、被动保护措施为辅的综合性解决方案.在设计方面,增加了对多年冻土的认识,及时将调查情况反馈到设计中去,调整设计思路,转变设计理念,实现青藏铁路的动态设计理念.

Frost Damages in Permafrost Regions along the Qinghai-Tibet Railway in 2001-2006: Investigation and Analysis

Permafrost is a principal engineering-geological problem in the construction of Qinghai Tibet railway. Along with the construction of embankment, bridge etc., the permafrost Condition has been change since 2001, which may influence the permafrost stability. In this paper, the investi gations in winter and summer year by year are introduced. In 2002, crevices was discovered in embankments in permafrost regions by winter investigation; in 2003, ice-cone, ice-mantle, concrete erode, sand disaster etc. were discovered by winter investigation; in 2004, seepage from embankment, icing in culvert were discovered; in 2005, less damage to the railway was found. Then, the permafrost condition is analyzed based on the winter and summer investigations in the constructing period, the control measures against frost damages are put forward step by step, and a synthetical scheme, i.e., taking actively protecting permafrost as the principal measures, assisted with passively protecting permafrost, was suggested. With the deeply understanding the permafrost propertied, the applying the investigation results to the design of railway, improving the design method, and changing the design ideas, a new dynamic design was established for the Qinghai-Tibet railway.