Study On Temperature Field And Plan Of The Heat Presearvation And Insulation Layer On The Extra-Long Highway Tunnel In High Attitude And Cold Zones

In order to solve the problem of anti-freezedamage for highway tunnel construction in high attitude and cold zones, based on the design of extra-long highway tunnel under construction in our countryat present--the national highway No. 317 Zhegushan Tunnel, the anti-freeze datum in tunnel engineering from domestic and abroad is investigated and analyzed in this paper, the temperature field of the tunnel structure and rock mass is measured in field; according to the statistical analysis of temperature test datum during about 1 year, this paper concludes regularity of temperature field of the environ -ment temperature in tunnel zone tunnel structure and rock mass ; from this, the anti-freeze plan is determined to be placing heat preservation and insulation layer on the secondary line surface.Through taking sample of typical surrounding rock mass of the tunnel in field and measurement of thermophysical parameters of sample in laboratory, thermophysical characters of rock mass is obtained. Based on this ,the method of calculation the thickness of heat preservation and insulation material is proposed through syntheti -cally analyzing the rule of temperature field in tunnel structure and surrounding rock mass. The finite element models of the temperature field of the section of normal burying depth and shallow burying depth are set up respecting by using two-dimensional steady and two -dimensional unsteady state heat conduction and the effect of the warmkeeping with the different thickness of heat preservation and insulation material is studied by numerical simulation in the paper. Besides this, the result datum of the normal burying depth and one of the normal burying depth by one-dimensional steady heat conduction approximate calculation method is compared in this paper.On the basis of the above result, three field test plans with the different thickness and material characteristics of the different heat preservation and insulation layer is put forward, the thickness of theheat preservation and insulation material is verified by numerical simulation analysis, and some suggestion on operational plan of the heat preservation and insulation layer in future is also proposed.