完整版有关隧道方面外文文献与翻译.docx

1、完整版有关隧道方面外文文献与翻译A convection-conduction model for analysis of the freeze-thawconditions in the surrounding rock wall of atunnel in permafrost regionsHE Chunxiong （何春雄）,（State Key Laboratory of Frozen Soil Engineering, Lanzhou Institute of Glaciology andGeocryology,Chinese Academy of Sciences, Lanzho

2、u 730000, China; Department of Applied Mathematics,South China University of Technology, Guangzhou 510640, China）WU Ziwang （吴紫汪）and ZHU Linnan （朱林楠）（State key Laboratory of Frozen Soil Engineering, Lanzhou Institute of Glaciology andGeocryologyChinese Academy of Sciences, Lanzhou 730000, China）Recei

3、ved February 8, 1999AbstractBased on the an alyses of fun dame ntal meteorological and hydrogeological con ditions at the site of a tunnel in the cold regi ons, a combined convection-c on duction model for air flow in the tunnel and temperature field in the surrounding has been constructed. Using th

4、e model, the air temperature distribution in the Xiluoqi No. 2 Tunnel has been simulated numerically. The simulated results are in agreement with the data observed. Then, based on the in situ conditions of sir temperature, atmospheric pressure, wind force, hydrogeology and engineering geology, the a

5、ir temperature relati on ship betwee n the temperature on the surface of the tun nel wall and the air temperature at the entry and exit of the tunnel has been obtained, and the freeze-thaw conditions at the Dabanshan Tunnel which is now under construction is predicted.Keywords: tunnel in cold region

6、s, convective heat exchange and conduction, freeze thaw.A number of highway and railway tunnels have been constructed in the permafrostregions and their neighboring areas in China. Since the hydrological and thermal conditions changed after a tunnel was excavated, the surrounding wall rock materials

7、 often froze, the frost heaving caused damage to the liner layers and seeping water froze into ice diamonds, which seriously interfered with the communication and transportation. Similar problems of the freezing damage in the tunnels also appeared in other countries like Russia, Norway and Japan .He

8、nce it is urgent to predict the freeze- thaw conditions in the surrounding rock materials and provide a basis for the design, construction and maintenanee of new tunnels in cold regions.Many tunnels, constructed in cold regions or their neighbouring area, s pass through the part beneath the permafro

9、st base .After a tunnel is excavat, edthe original thermodynamical conditions in the surroundings are and thaw destroyed and replaced mainly by the air connections without the heat radiation, the conditions determined principally by the temperature and velocity of air flow in the tunnel , the coeffi

10、cients of convective heat transfer on the tunnel wall, and the geothermal heat. In order to analyze and predict the freeze and thaw conditions of the surrounding wall rock of a tunnel, presuming the axial variations of air flow temperature and the coefficients of convective heat transfer, Lunardini

11、discussed the freeze and thaw conditions by the approximate formulae obtained by Sham-sundar in study of freezing outside a circular tube with axial variations of coolant temperature We simulated the temperature conditions on the surface of a tunnel wall varying similarly to the periodic changes of

12、the outside air temperature .In fact, the temperatures of the air and the surrounding wall rock material affect each other so we cannot find the temperature variations of the air flow in advance; furthermore, it is difficult to quantify the coefficient of convective heat exchange at the surface of t

13、he tunnel wall Therefore it is not practicable to define the temperature on the surface of the tunnel wall according to the outside air temperature .In this paper, we combine the air flow convective heat ex-change and heat conduction in the surrounding rock material into one mode, I and simulate the

14、 freeze-thaw conditions of the surrounding rock material based on the in situ conditions of air temperature, atmospheric pressure, wind force at the entry and exit of the tunnel, and the conditions of hydrogeology and engineering geology. MathematicalmodelIn order to con struct an appropriate model,

15、 we n eed the in situ fun damental conditions as a ba-sis .Here we use the conditions at the scene of the Dabanshan Tunnel. The Dabanshan Turin el is lo-toted on the highway from Xining to Zhangye, south of the Datong River, at an elevation of 3754.78-3 801.23 m, with a length of 1 530 m and an alig

16、nment from southwest to northeast. The tunnel runs from the southwest to the northeast.Since the mon thly-average air temperature is ben eath OC for eight mon ths at the tunnel site each year and the construction would last for several years, the surrounding rock materials would become cooler during

17、 the construction We conclude that, after excavation, the pattern of air flow would depend mainly on the dominant wind speed at the entry and exit, and the effects of the temperature difference between the inside and outside of the tunnel would be very small . Since the domina nt wind di recti on is

18、 northeast at the tunnel site in winter, the air flow in the tunnel would go from the exit to the entry. Even though the dominant wind trend is southeastly in summer, considering the pressure difference, the temperature difference and the topography of the entry and exi, tthe air flow in the tunnel

19、would also be from the exit to entry Additi on ally, since the wind speed at the tunnel site is low, we could con sider that the air flow would be principally laminar.Based on the reasons mentione, dwe simplify the tunnel to a round tube, and consider that theair flow and temperature are symmetrical

20、 about the axis of the tunnel, Ignoring the influe nee of the air temperature on the speed of air flow, we obtai n the following equati on:ra (/ v a v 亠X + 7 亦at/ r/A u -z + (/ + dt %where t, x, r are the time, axial and radial coord in ates; U, V are axial and radial wind speeds; T is temperature;

21、p is the effective pressure(that,isair pressure divided by air den sity); v is the kin ematic viscosity of air; a is the thermal con ductivity of air; L is the len gth of the tunn el; R is the equivale nt radius of the tunnel secti on; D is the len gth of time after the tunnel con structi on;St (t),

22、 Su (t) are frozen and thawed parts in the surrounding rock materials respectively; f, uand Ct ,CU are thermal conductivities and volumetric thermalcapacities in frozen and thawed parts respectively; X= (x , r) , (t) is phase change front; Lh is heat late nt of freez ing water; and To is critical fr

23、eez ing temperature of rock (here we assume To= -0.1C).2used for sol ving the modelEquation( 1)shows flow. We first solve those concerning temperatureat that the temperature of the surrounding rock does not affect the speed of air equations concerning the speed of air flow, and then solve those equa

24、tions every time elapse. 2.1 Procedure used for sol ving the continu ity and mome ntum equati onsSince the first three equati ons in are not in depe ndent we derive the sec ond equati on by xand the third equation by r. After preliminary calculation we obtain the followingelliptic equation concernin

25、g the effective pressure p: Then we solve equatio ns in(1) using the follow ing procedures:(i)Assume the values for UO VO;(ii) substituting UO , VO into eq. (2), and solving (2), we obtain pO;(iii)solving the first and second equations of(1), we obtain UO, V1;(iv)solving the first and third equation

26、s of(1), we obtain U2, V2;(v)calculating the momentum-average of U1, v1 and U2, v2, we obtain the new UO, VO;the n return to (ii);(vi)iterating as above until the disparity of those solutions in two consecutive iterations is sufficiently small or is satisfied, we then take those values of pO UO and

27、VO as the in itial values for the n ext elapse and solve those equati ons concerning the temperature.2 .2 En tire method used for sol ving the en ergy equati onsAs mentioned previously, the temperature field of the surrounding rock and the air flow affect each other. Thus the surface of the tunnel w

28、all is both the boun dary of the temperature field in the surrounding rock and the boundary of the temperature field in air flow .Therefore , it is difficult to separately identify the temperature on the tunnel wall surface , and we cannot independently solve those equations concerning the temperatu

29、re of air flow and those equations concerning the temperature of the surrounding rock .In order to cope with this problem, we simultaneously solve the two groups of equati ons based on the fact that at the tunnel wall surface both temperatures are equal .We should bear in mind the phase cha nge whil

30、e sol ving those equati ons concerning the temperature of the surro unding rock a nd the convection while solvi ng those equations concerning the temperature of the air flow, and we only need to smooth those relative parameters at the tunnel wall surface .The solvi ng methods forthe equati ons with

31、the phase cha nge are the same as in ref ere nee 3.2.3 Determ in ati on of thermal parameters and in itial and boun dary con diti ons 2.3.1 Determination of the thermal parameters. Using p= 1013.25-0.1088 H , we calculateP air pressure p at elevati on H and calculate the air den sity using formula ,

32、where T is the yearly-average absolute air temperature and G is the humidity constant of air. Letting Cp be the thermal capacity with fixed pressure, the thermal con ductivity, and the dyn amic viscosity of air flow, we calculate the thermal con ductivity and of the surro unding rock are determ ined from the tunnel site.kinematic viscosity using the formulas a and .The thermal parametersCP2.3.2 Determ in ati on of the in itial and boun dary con diti ons .Choose the observed mon thly average wind speed at the entry and exit as boun dary con diti ons of wind speed