Mechanism And Processing Method Of The Bridge Disease In Alpine Permafrost Areas

Because of the high altitude Qinghai-Tibet Plateau, cold changeable weather, so the alpine permafrost that distribute in here is particularity and complexity. The surface active layer of permafrost changes with the seasons, melting and freezing. Below the surface is frozen soil layer, which is frozen year round. If the construction of roads or railways in such geological conditions that would result in the original condition of surface heat balance and ecological damage. Then it will produce bridge structures common diseases, such as freezing, thawing, and cracks.During the construction process, a lot of heat incoming foundation, which come from construction machinery and concrete pouring, it will cause permafrost in foundation melting and sinking, and then create the basis of pier subsiding and bridge superstructure deforming; When the years of frozen in foundation contains large quantities of ice and the temperature of frozen for many years is high, this phenomenon is more obvious; During the operational phase, due to the frequent effect of vehicle load, changing the heat balance of the surface in bridge region, which makes many years of frozen in the foundation produce frost heave and thawing settlement, even the bridge structure cracking. These factors will cause bridge structures instability in loads, especially with the rapid West economic development in recent years, the increase in road traffic and road overload in permafrost regions, resulting in bridge damage, direct impact on the security and service life of the bridges.Based on the above issues, this entry point of this paper is superposed the survey of dangerous bridge and culvert of Qinghai in 2007, and highway bridge status in Qinghai and investigation of the types of bridge diseases in G214 line. The bridge common problems are summarized in permafrost areas, primarily research are carried out in the following areas:(1) More comprehensive statistics and analysis within the disease status of highway are completed in alpine permafrost region of Qinghai Province;(2) Exploring the causes of bridge defects in the frigid permafrost region, disease mechanism and hazardless, etc;(3) The feasible measures to prevent bridge disease and the methods of disease treatment in plateau permafrost regions are summarized.