Distribution Law Of Temperature Field And Research On Frost Heave Force Action On Tunnel Lining

With the rapid development of the national economy, the road transport services of china have been booming.Freeway tunnel as an important structure of freeway projects also ushered in the building boom of unprecedented scale. A series of freezing injury caused by cold environment will exert influence on the design and construction of the tunneling engineering in seasonal frozen region as well as the post-stage operation and management.It will cause great economical loss if we can not handle it properly.The original stable thermal state of the region will be disturbed after the excavation of the tunnel,and a new thermal state system with opening,ventilation, convection and no solar heat is formed.The surrounding rock behind the lining will generate a seasonal active ring of permafrost due to the seasonal climate variation.The water between the seasonal active ring of permafrost will pose repeated frost heave pressure to the lining which will lead to the damage of the lining structure and also accelerate the weathering of the surrounding rock.The increase of the surrounding rock fragmentation degrees will conversely provide favorable conditions for the frost heaving force growth ,therefore it will intensify the destroying effect simultaneously.The primary facing problems of the tunneling engineering in seasonal frozen region was as follows::â‘ the change of temperature in tunnel and surrounding rock is very large ,â‘¡because of the repeated freeze-thaw ,result in losing of strength .â‘¢tunnel lining layer will be subjected to frost heave loads .This makes it's important to study the distribution of temperature and the couple relationship between with seepage field and stress field ,also the change laws of surrounding rock .This paper bases on chisongbai tunnel ,according to local meteorological date ,uses Flac₃d software to establish three-dimensional model ,and combines the embedded language'fish', to compile dynamic temperature boundary conditions , and to dynamic change tunnel parameters with freeze-thaw environmental ,then to have a more real simulation of the process of frost heave . and this paper also summarizes the laws to freeze , compares the different between the case of tunnel freeze depth norm and the case of tunnel freeze depth with the insulation layer , compiles dynamic parameters in seepage model to couple calculation between temperature and seepage field .then to compare and analyse the impact of seepage field to deep freeze .The paper calculates freeze heave presser , the normal method is establishing the freeze depth ,then give special parameters to calculate freeze heave presser ,while this paper use the language embedded'fish'compiling dynamic parameters which changes with temperature changing ,then to calculate frost heave presser more real ,and discuss the affection of the surrounding rock parameters to frost heave pressure ,finally get some conclusion and results:1,the freeze depth in tunnel entrance is larger than it inner tunnel under the same conditions , the freeze depth develops rapidly in 1 to 5 years , while to be stability after 10 years .The freeze depth at the vault is smaller than it at the end of the arch , the freeze depth at arched feet is smallest .Insulation layer can effectively reduce tunnel freeze depth , because of the differences freeze depth between tunnel entrance and inner ,so it's obviously unreasonable to lay the same insulation layer all the tunnel , the paper advice to lay different thickness and kinds of insulation layer .2,The freeze depth which considers seepage field is smaller than it not consider , so seepage affects freeze depth obviously .3,Water with in tunnel rock will movie to the vault ,arched feet and the arch at the end under freezing.It's easily to leak when melts in spring.4,The frost heave pressure increase with the increase of tunnel lining thickness ,it's because increase tunnel lining thickness which equivalent to confirm the deformation of surround rock , so it can not only increase tunnel lining thickness ,but should take the form of variable cross-section design.The frost heave pressure increase with the increase of lining stiffness , so it's should be soft not rigid when only considering frost damage to design.5,The frost heave pressure obviously increase with the increase of frost heave rate of rock ,so there should be sufficient attention to the rate .The frost heave pressure is closely related to the physical and mechanical parameters surrounding rock , which increase with the increase of elastic modulus of surrounding rock ,which reduces with the increase of internal friction angle , increase with the increase of cohesion ,but frost heave rate impact most obviously .