Study On Mechanism And Techniques Of Tunneling Grouting In Freezing-Thawing Condition

The seepage of water is one of the main reasons that freezing damage occurs in permafrost regions tunnel.Grouting is a direct and effective way of controlling seepage. However, because of the frost heaving force , ring of permafrost, the durability of material and the temperature field ,grouting in freezing-thawing condition becomes more difficult. The study is based on grouting in Kunlunshan tunnel, taking grouting mechanism and grouting techniques in freezing-thawing condition as the study object, and combining the indoor experiment with outdoor experiment. The main contents include:1 , Based on the basic property of soil freezing and soil freezing and melting ,this paper discussed the damage characters of surrounding rocks and lining of tunnel , and showed grouting mechanism in freezing-thawing condition.2, Grouting in the freezing-thawing condition requires more for grouting techniques, and especially grouting material must wear well and have maneuverability in low temperature.In this study, much experiment of resisting low temperature and physical mechanics is carried out for cement and chemic grouting materials. By contrast and analysis qualified grouting material is selected. Then it is made better through practical construction and is used in broad construction reaching the ideal effect.3 , Construction condition and characters of surrounding rocks are greatly different in freezing-thawing condition and normal temperature. This study establish practical grouting techniques in freezing-thawing condition,including grouting method and some correlative parameter(grouting pressure, grouting hole space, hole mode and standard of ending grouting etc.).4, Combined with practical condition of Kunlunshang tunnel, experiment was put into practice in the spot and validated. It turned out to be good water-proof effect, and the seepage is almost avoided.5 , Throu gh the above research, the paper puts forward that the tunneling grouting in the freezing-thawing condition should follow the principle of plugging dominantly and treating synthetically.