The annual meeting of the Chinese Academy of Sciences 2nd-term Program, ‘Action in the Western China’ on the ‘Dynamics of the engineering safety and long-term foundation stability of the Qinghai-Tibet Railway and the feasibility study on the construction techniques for high-grade highways’, was held in Lanzhou, China on 13 January 2010. Professor Wei Ma, the Program Director and also the Vice-President of the Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, reported the major accomplishments of the program in 2009. Academician Guodong Cheng, and Professors Bojie Fu, Ming’an Shao, Tao Wang, and Yongjian Ding attended the meeting as the members of the Advisory Committee. Director Tieqing Huang and Dr. Tao Zhao from the Department of National Land Management, Bureau of Natural Resources and Environments, Chinese Academy of Sciences also participated in the meeting.In addition, Professors Qingbai Wu, Qihao Yu and Yuanming Lai, and Associate Professor Zhizhong Sun, the project leads in the program, presented the major progress in each subproject.

Since the initiation in July 2008, the program has been focusing on the dynamic changes of the permafrost foundation stability during the operation period of the National Key Project ‘Qinghai-Tibet Railway’and on the key scientific and technological problems associated with thebuildingof high-grade highways. It aims at establishing the long-term monitoring systems for the Qinghai-Tibet Railway, and at assessing and predicting the long-term effectiveness of the various measures for cooling the railbed foundations soils under the design principle of permafrost protection and the stability of the railbed foundation under the dynamic loads. The program also has an objective to set up an integrated suite of theories and methodologies for building the high-grade highways in the permafrost regions through the experimental research.

After one year of hard work, fruitful results have been obtained. The long-term monitoring systems for ensuring the engineering safety of the Qinghai-Tibet Railway in the permafrost regions have been elaborated and improved, and the preliminary database for the monitoring projects have been established. The investigation results for the deformation damage to the railbed and subgrades in the permafrost regions along the Qinghai-Tibet Highway indicate that the subsidence of foundation soils at the transition segments is closely related to the south and north ends of the bridges, orientations of the side protective slopes, embankment heights, permafrost types based on the ice contents, ground temperatures, railbed configurations, and engineering geological conditions.

Additionally, the dynamics of ground temperatures in the blocks and ordinary railbeds for the Qinghai-Tibet Railway was analyzed on the basis of the field measurements for years. It was concluded that either in stable zone of cold permafrost or in the very unstable zone of warm (>-1°C) permafrost, the U-shaped blocks railbed has a better cooling effect and a resultant higher foundation stability in comparison with that of blocks embankment; the overall cooling effect of the block railbed was closely related to the mean annual ground temperatures--the lower the ground temperature, the better the cooling effect. Although the railbed consisting of block layers has insulating and cooling effects, they are limited one way or another. In particular, it cannot maintain the long-term stability of the railbed foundation soils of the wider roadway by protecting the underlying permafrost. The cooling effect and subsequent capability of maintaining the long-term stability of foundation soils could be significantly enhanced after the addition of the airducts over the block layers. Therefore, the synthetic roadbed combining the airducts and the block layers was recommended for protecting the foundation engineering for the wide, high-grade highways.