| Our country is a mountainous country.With the development of economy,the country vigorously develops the transportation infrastructure construction.The tunnel works play an important role in crossing the mountains.However,many tunnels are located in high-latitude and high-altitude cold regions.When the groundwater is relatively abundant,it is prone to frost damage,threatening the stability of the tunnel structure and the safety of moving vehicles,and causing harm to human life and property.Therefore,taking effective measures to prevent or reduce the occurrence of frost damage is a problem that needs to be solved in the cold regional tunnel.The study of frost heaving force in cold regional tunnel has important practical significance and wide development space.Through studying the tunnel with freezing injury,it is found that frost heaving force is the main cause of freezing injury.The study of frost heaving force mainly involves coupling temperature,stress and seepage field.This method has great difficulty in engineering application,and its engineering applicability is low.The temperature of the Huitougou Tunnel is low in winter,in order to prevent the occurrence of the damage,this paper adopts the method of field monitoring and laboratory test measured the relevant parameters,and then based on the elastic mechanics and elastic-plastic mechanics as the basis for the study of frost heaving force.Finally,the antifreeze measures in the Huitougou tunnel were studied.The conclusions are as follows:(1)Through field temperature monitoring,it is found that the temperature change trend of the surrounding rock of the tunnel is the same as that of the external temperature.With the increase of the radial depth,the variation amplitude decreases,and the temperature change of the surrounding rock lagged behind the change of the external temperature.The depth of the surrounding rock is about 2m.(2)Through the surrounding rock frost heave test,the strain process of rock first decreases and then increases,and finally tends to be stable.The frost heaving of rock is less affected by temperature.The lower the freezing temperature is,the shorter the time to reach the extreme value of rock strain.The linear frost heave rate of rock is 0.045%.(3)Based on the elasticity mechanics,the influence of the lining elastic modulus,freezing depth,frost heaving rate,and lining thickness on the frost heaving force was analyzed.The lining elastic modulus,freezing depth and frost-heaving rate have a great influence on the frost-heaving force,and the lining thickness has little effect on the frost-heaving force.The frost heaving force of the three sections of the Huitougou Tunnel is 1.89 MPa,0.74 MPa,and 0.47 MPa.(4)Based on elastic-plastic theory,the internal stress distribution of lining under the action of frost heaving force is analyzed.The location of larger internal compressive stress is mainly located in the upper part of the side wall and the middle part of the invert arch.The frost heaving force is pressure stress in the lower lining.With the increase of frost heaving force,the tensile stress in the lining is mainly located on the inside of the arch and the inside of the vault.(5)The anti freezing measures of the Huitougou tunnel were studied.According to the temperature monitoring data,the thickness of the tunnel insulation layer should be 5cm.The thickness and length of the insulation layer were calculated by numerical simulation software,the thickness of the insulation layer is 5cm,and the length is 200 m. |
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