Study On Frost Damage Grades And Its Prevention And Control Technologies In Cold Region Tunnel

Frost damage in cold region tunnels has been a outstanding issues in engineering. Based on a lot of related literature both abroad and domestic, the paper utilizes measured data of typical tunnel, analysing temperature distribution law of different types of cold region tunnels, researching the damage and failure and mechanical properties due freeing-thawing of shotcrete in cold area tunnel by using indoor test methods, dividing the frost resistance and fortified degrees of the new tunnel by comprehensive evaluation method, and partitioning the frost damage level degrees of existed tunnel by T-S fuzzy fault tree and event tree theory. In view of the frost resistance and fortified degrees of the new tunnel and the frost damage level degrees of existed tunnel, the paper lays down related freeze damage precautionary measures and regulation measures, which succeed in the application of engineering. Main research work and results are as follows:(1) By analysing measured data of typical tunnel which selected from permafrost region, local permafrost region and non-permafrost region, the paper summarizes temperature distribution law of different types of cold region tunnels.(2)In accordance with shotcrete freeing-thawing test results, the paper researches frost resistance durability of shotcrete by using indoor test methods. The results indicated that the relative durability Index of shotcrete is lower than concrete.(3) Using the average temperature of the coldest month, the freezing depth and the form of groundwater occurred and supplied and the situation of groundwater to thrust into tunnel as evaluation indexes, the paper partitions the frost resistance and fortified of the new tunnel to five degrees. Meanwhile, in order to easily divide the frost resistance and fortified degrees of cold region tunnels, the paper calculates temperature of tunnel located region by the kriging principle in spatial interpolation theory.(4) Based on T-S fuzzy fault tree and event tree theory, the paper sets up the tunnel frost damage tree and event tree. Taking advantage of standardizing action that Event Tree Analysis to results event class partition, the paper partitions the frost damage level of existed tunnel into five degrees.(5) In view of the frost resistance and fortified degrees of the new tunnel and the frost damage level degrees of existed tunnel, the paper lays down related freeze damage precautionary measures and policies and regulation measures, then applied to specific engineering. Application results shows that the division method of tunnel frost damage degree is feasible, and prevention and control measures for tunnel frost damage is expedient.112 figs,24 tabs,150 refs.