Study On The Regular Of Temperature Spread And Technology To Resistance Frozen During The Construction Of Highway Tunnel Located Cold Region

Tunnels in cold region are always located in high altitude ares.There are always some forst damages during operating by low temperature and large temperature difference between day and night.Those damages pose a threat to the safety for operation of the tunnel.By the same time,there are some forst damages can be appear during the construction of tunnel in the winter.When the tunnel constructed in the winter.Study the characteristics of temperature changing,the temperature propagation characteristics of surrounding rock,the affecting factors,mechanical characteristics and measures of rssistance forst damages by means of researching information,studying theoretical,field test and numerical simulation.And get the following main conclusions:(1)Based on the field test results about Baima tunnel,get the regular of temperature changes between outside and inside of the tunnel;The change and distribution of temperature influence on surrounding rock and lining by construction ventilation during winter construction.The change and distribution of temperature influence on surrounding rock and lining by casting lining.(2)Based on the results of numerical simulation.lt find that the regular are close between inside tunnel and outside tunnel.But,with distance become more far from the exit of duct,the air temperature changed more gentlely.The surrounding rock temperature become lower with the temperature lower of outside.At the same time,the sensitivity of temperature bocome lower with the deep of surrounding rock.The temperature in the same cross section distribute as subsider.The temperature change similarity between surrounding rock of outermost layer about 0.5m and the exit of duct for those surrounding rock without the second line.(3)Through the numerical simulation to explore the cold regions tunnel during construction period influencing factors of temperature and the propagation law of surrounding rock,they have the same effect when you improve the duct speed,increase the temperature difference between the suroounding rock and outside and shorten of excavation.The temperature reduce to stability with the deeper of surrounding rock in the same cross section.The temperature bocome lower with the closer to the duct exit in the same vertical section.The gradient of the influenced region and subsider increase more.(4)For those rock with second lining,temperature influence depth are same,and the depth increase with the increase of duce velocity.The influence depth firstly increased and then decreased with temperature increase of surrounding rock,.but The influence depth decrease with temperature increase of outside or longer of excabation.But for those rock without second linging,the influence depth doesn't change with the change of duct velocity,The influence depth increased with temperature increase of surrounding rock,.but the influence depth decrease with temperature increase of outside or longer of excabation.but the influence depth is depper when the rock without lining.(5)it is directly to control the temperature difference or install the insulation layer to avoid forst damages during construction period.The insulation layer can decrease the contact between the air and ling or rock effectivly,so the influence depth behind the insulation decrease sharply.At the same time,the level of maximum stress on the lining decrease 23.56%,the vertical of maximum stress on the lining decrease 5.25%,.The maximum stress on the lining decrease 10.44%.Aso the cnvcergence deformation decrease,expecially for crown settlement.