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| Research on Concrete of Cast-in-place Pile for Permafrost Zone in Qinghai-Tibet Plateau and Its Countermeasures |
| SHI Ren-jun, PAN Ting-yu, LIU Mei-ru, ZHANG Wan |
| China Academy of Railway Sciences, Beijing 100081, China |
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Abstract Research purposes: The countermeasures were proposed to the technical difficulties in strength and durability of concrete, and disturbance on frozen-soil structure by thermal transmission while building bridge span structure by adopting cast-in-place concrete pile in construction of railway and highway in permafrost zone in Qinghai-Tibet Plateau.
Research methods: The research, indoor simulation test, site exposure test and tests for the pile foundations in Qing-shui River and Kunlun Mountain's port were done for the durability's damage of concrete of bridge foundation on Qinghai-Tibet Highway.
Research results: The hardening strength of concrete of pile foundation in permafrost on Qinghai-Tibet Highway couldn’t arrive at the design grade because the concrete had been in negative temperature for long term. The main reason for durability damage was freezing-thawing damage caused by alternation of positive and negative temperatures frequently, and it was found no corruption damage by surfate. The start temperature of concrete and heat of hydration made frozen-soil structure damaged in interface. The frozen soil could return to its original frozen status for long time later.
Research conclusions: The moderate-heat early-strength concrete made from air-leading water-reducing agent or early-strength air-leading water-reducing agent could meet the requirements for the strength and durability of cast-in-place concrete pile and the stability of frozen soil structure. It was necessary to note the anti-freezing agent probably had negative effect on the stability of frozen soil structure in interface and environment protection.
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Received: 14 December 2005
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2006, Vol. 23 
