The Research On Antifreezing Mechanism And Antifreezing Measures In Cold Regional Tunnels

With the development of economy, tunnels now are more frequently constructed in cold regions than ever. As is clearly known, special conditions in alpine regions affect the construction and design of tunnels badly. Given the difficult tasks that temperature testing costs of tunnels in alpine regions are tremendous and temperature testing can only be achieved after construction of tunnels, this article is to resolve them by fluent numerical simulation which not only saves the costs, but also provides basis for tunnel design. Right in accordance with the acquaintances above and features of tunnels in alpine regions, this article is to research on settinglength of warm antifreeze of tunnels in cold regions under low temperature with consideration of surrounding rocks, lining structures and drainage ditches in numerical simulation. At first, it takes Nan Shan Tunnel such a typical practice as an example to research on setting length of thermal insulation of drainage ditches, and then extends to those in southwest and northeast which will provide initial judgment data. At last, it takes Ba Sumu Tunnel as an example to research on cold-proof measures such as insulation curtains and layers. Primary works that have been done include:(1) Setting length of thermal insulation of drainage ditches in Nan Shan Tunnel: Setting length of warm antifreeze of drainage ditches in Nan Shan Tunnel is obtained by analyzing with numerical simulation. In this report the result is1400m-1500m。(2) Setting length of warm antifreeze of drainage ditches in32different kinds of tunnels which locate in southwest and northeast is calculated in terms of their sectional area, total length of tunnel and their maximum buried depth. Thus, a general form of it is delivered on basis of that in32kinds of tunnels. We get the general formula in the southwest:z＝(1560.30-0.02x+2.83×10-4x2+485.10y)/(1+4.93×10-3x-0.158y), In the Northeast: z=(455416.95+3032.26x-4.80x2+0.002x3-87800.39y)/(1+0.28x-00003x2+265.15y-41.63y2) Wherein, z is a side groove of the tunnel winterization length, x is the maximum depth of the tunnel, y is the length of the tunnel.(3) The study on the Insulation measures which include the analysis of the thermal insulation curtain for tunnel construction and analysis of insulation for the anti-frost heaving of surrounding rock. Insulation curtain on concrete construction or construction staff efficiency has important significance, and insulation can effectively prevent frost heaving damage of the surrounding rock.