土木外文翻译原文和译文
A convection-conduction model for analysis of the
freeze-thaw
conditions in the surrounding rock wall of a
tunnel in permafrost regions
Abstract
Based on the analyses of fundamental meteorological and hydrogeological conditions at the site of a tunnel in the cold regions, a combined convection-conduction model for air flow in the tunnel and temperature field in the surrounding has been constructed. Using the 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 air-temperature relationship between the temperature on the surface of the tunnel 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 regions, convective heat exchange and conduction, freeze-thaw.
A number of highway and railway tunnels have been constructed in the permafrost regions and their neighboring areas in China. Since the hydrological and thermal conditions changed after a tunnel was excavated，the surrounding wall rock materials 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 .Hence it is urgent to predict the freeze-thaw conditions in the surrounding rock materials and provide a basis for the design，construction and
maintenance of new tunnels in cold regions.
Many tunnels，constructed in cold regions or their neighbouring areas，pass through the part beneath the permafrost base .After a tunnel is excavated，the 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 coefficients 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 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 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 the 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 model，and simulate the 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.
Mathematical model
In order to construct an appropriate model, we need the in situ fundamental conditions as a ba-sis .Here we use the conditions at the scene of the Dabanshan Tunnel. The Dabanshan Tunnel is lo-toted on the highway from Xining to Zhangye, south of the Datong River, at an elevation of 801.23 m, with a length of 1 530 m and an alignment from southwest to northeast. The tunnel runs from the southwest to the
northeast.
Since the monthly-average air temperature is beneath 0`}C for eight months at the tunnel site each year and the construction would last for several years，the surrounding rock materials would become cooler during 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 dominant wind direction is 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 exit，the air flow in the tunnel would also be from the exit to entry .Additionally，since the wind speed at the tunnel site is low，we could consider that the air flow would be principally laminar.
Based on the reasons mentioned，we simplify the tunnel to a round tube，and consider that the
air flow and temperature are symmetrical about the axis of the tunnel，Ignoring the influence of the air temperature on the speed of air flow, we obtain the following equation:
where t ，x ，r are the time ，axial and radial coordinates; U ，V are axial and radial wind speeds; T is temperature; p is the effective pressure(that is ，air pressure divided by air density); v is the kinematic viscosity of air; a is the thermal conductivity of air; L is the length of the tunnel; R is the equivalent radius of the tunnel section; D is the length of time after the tunnel construction;，
f S (t), u S (t) are frozen and thawed parts in the surroundin
g rock materials respectively; f λ,u λand f C ,u C are thermal conductivities and volumetric thermal capacities in frozen and thawed parts respectively; X= (x , r)，ξ(t) is phase change front; L
h is heat latent of freezing water; and To is critical freezing temperature of rock ( here we assume To= -0.1℃).
2 used for solving the model
Equation(1)shows flow. We first solve those concerning temperature at 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 equations every time elapse.
2. 1 Procedure used for solving the continuity and momentum equations Since the first three equations in(1) are not independent we derive the second equation by x
and the third equation by r. After preliminary calculation we obtain the following elliptic equation concerning the effective pressure p:
Then we solve equations in(1) using the following procedures:
(i ) Assume the values for U0，V0;
( ii ) substituting U0，V0 into eq. (2)，and solving (2)，we obtain p0;
(iii) solving the first and second equations of(1)，we obtain U0，V1;
(iv) solving the first and third equations of(1)，we obtain U2，V2;
(v) calculating the momentum-average of U1，v1 and U2，v2，we obtain the new U0，V0;
then 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 p0，U0 and V0 as the initial values for the next elapse and solve those equations concerning the temperature..
2 .2 Entire method used for solving the energy equations
As mentioned previously ，the temperature field of the surrounding rock and the air flow affect each other. Thus the surface of the tunnel wall is both the boundary 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 temperature 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 equations based on the fact that at the tunnel wall surface both temperatures are equal .We should bear in mind the phase change while solving those equations concerning the temperature of the surrounding rock ，and the convection while solving those equations concerning the temperature of the air flow, and we only need to smooth those relative parameters at the tunnel wall surface .The solving methods for the equations with the phase change are the same as in reference [3].
2.3 Determination of thermal parameters and initial and boundary
conditions
2.3.1 Determination of the thermal parameters. Using p= H ，we calculate
air pressure p at elevation H and calculate the air density ρ using formula GT
P =ρ, where T is the yearly-average absolute air temperature ，
and G is the humidity constant of air. Letting P C be the thermal capacity with fixed pressure, λ the thermal conductivity ，
and μ the dynamic viscosity of air flow, we calculate the thermal conductivity and kinematic viscosity using the formulas ρλ
P C =ａ and ρ
μν=. The thermal parameters of the surrounding rock are determined from the tunnel site.
2 .3.2 Determination of the initial and boundary conditions .Choose the observed monthly average wind speed at the entry and exit as boundary conditions of wind speed ，and choose the relative effective pressure p=0 at the exit ( that is ，the entry of the dominant wind trend) and ]5[22/)/1(v d kL p ?+= on the section of entry ( that is ，the exit of the dominant wind trend )，where k is the coefficient of resistance along the tunnel wall, d = 2R ，and v is the axial average speed. We approximate T varying by the sine law according to the data observed at the scene and provide a suitable boundary value based on the position of the permafrost base and the geothermal gradient of the thaw rock materials beneath the permafrost base.
3 A simulated example
Using the model and the solving method mentioned above ，we simulate the varying law of the air temperature in the tunnel along with the temperature at the entry and exit of the Xiluoqi Tunnel .We observe that the simulated results are close to the data observed[6].
The Xiluoqi No .2 Tunnel is located on the Nongling railway in northeastern China and passes through the part beneath the permafrost base .It has a length of 1 160 m running from the northwest to the southeast, with the entry of the tunnel in the northwest ，and the elevation is about 700 m. The dominant wind direction in the tunnel is from northwest to southeast, with a maximum monthly-average speed of 3 m/s and a minimum monthly-average speed of 1 .7 m/s . Based on the data observed ，we
approximate the varying sine law of air temperature at the entry and exit with yearly averages of -5℃，-6.4℃ and amplitudes of 18.9℃ and 17.6℃respectively. The equivalent diameter is 5 .8m，and the resistant coefficient along the tunnel wall is the effect of the thermal parameter of the surrounding rock on the air flow is much smaller than that of wind speed，pressure and temperature at the entry and exit，we refer to the data observed in the Dabanshan Tunnel for the thermal parameters.
Figure 1 shows the simulated yearly-average air temperature inside and at the entry and exit of the tunnel compared with the data observed .We observe that the difference is less than 0 .2 `C from the entry to exit.
Figure 2 shows a comparison of the simulated and observed monthly-average air temperature in-side (distance greater than 100 m from the entry and exit) the tunnel. We observe that the principal law is almost the same，and the main reason for the difference is the errors that came from approximating the varying sine law at the entry and exit; especially , the maximum monthly-average air temperature of 1979 was not for July but for August.
. Comparison of simulated and observed air temperature in Xiluoqi Tunnel in ,simulated values;2,observed values
comparison of simulated and observed air temperature inside
The Xiluoqi Tunnel in ,simulated values;2,observed values
4 Prediction of the freeze-thaw conditions for the Dabanshan Tunnel 4 .1 Thermal parameter and initial and boundary conditions
Using the elevation of 3 800 m and the yearly-average air temperature of -3℃, we calculate the air density p=0 .774 kg/3 steam exists In the air, we choose the thermal capacity with a fixed pressure of air ),./(8744.10C kg kJ C p = heat conductivity )./(100.202C m W -?=λ and
and the dynamic viscosity )../(10218.96s m kg -?=μ After calculation we obtain the thermal diffusivity a= 1 .3788s m /1025-? and the kinematic viscosity ，s m /1019.125-?=ν .
Considering that the section of automobiles is much smaller than that of the tunnel and the auto-mobiles pass through the tunnel at a low speed ，we ignore the piston effects ，coming from the movement of automobiles ，in the diffusion of the air.
We consider the rock as a whole component and choose the dry volumetric cavity 3/2400m kg d =λ,content of water and unfrozen water W=3% and W=1%, and the thermal conductivity c m W o u ./9.1=λ,c m W o f ./0.2=λ,heat capacity
c kg kJ C o V ./8.0= an
d d u f W w C γ?++=1)128.48.0(,d u u W
w C γ?++=1)128.48.0( According to the data observed at the tunnel site ，the maximum monthly-average wind speed is about 3 .5 m/s ，and the minimum monthly-average wind speed is about 2 .5 m/s .We approximate the wind speed at the entry and exit as )/](5.2)7(028.0[)(2s m t t v +-?=, where t is in month. The initial wind speed in the tunnel is set to be
.0),,0(),)(1(),,0(2=-=r x V R r U r x U a The initial and boundary values of temperature T are set to be
where f(x) is the distance from the vault to the permafrost base ，and
R0=25 m is the radius of do-main of solution T. We assume that the geothermal gradient is 3%，the yearly-average air temperature outside tunnel the is A=-3C 0，and the amplitude is B=12C 0.
As for the boundary of R=Ro ，we first solve the equations considering R=Ro as the first type of boundary; that is we assume that T=f(x) 3%C 0on R=Ro. We find that, after one year, the heat flow trend will have changed in the range of radius between 5 and 25m in the surrounding rock.. Considering that the rock will be cooler hereafter and it will be affected yet by geothermal heat, we appoximately assume that the boundary R=Ro is the second type of boundary; that is ，we assume that the gradient value ，obtained from the calculation up to the end of the first year after excavation under the first type of boundary value, is the gradient on R=Ro of T.
Considering the surrounding rock to be cooler during the period of construction ，we calculate
from January and iterate some elapses of time under the same boundary. Then we let the boundary
values vary and solve the equations step by step(it can be proved that the solution will not depend on the choice of initial values after many time elapses ).
1)The yearly-average temperature on the surface wall of the tunnel is approximately equal to the ai4 .2 Calculated results
Figures 3 and 4 show the variations of the monthly-average temperatures on the surface of the tunnel wall along with the variations at the entry and exit .Figs .5 and 6 show the year when permafrost begins to form and the maximum thawed depth after permafrost formed in different surrounding sections.
monthly-average temperature of the monthly-
On the surface of Dabanshan , average temperature on the surface The month,I=1,2,3,,,12 tunnel with that outside the tunnel.
1,inner temperature on the surface ;2,outside air temperature
year when permafrost maximum thawed depth after
Begins to from in different permafrost formed in different years Sections of the surrounding
rock
4 .3 Preliminary conclusion
Based on the initial-boundary conditions and thermal parameters mentioned above, we obtain the following preliminary conclusions: r temperature at the entry and exit. It is warmer during the cold season and cooler during the warm season in the internal part (more than 100 m from the entry and exit) of the tunnel than at the entry and exit . Fig .1 shows that the internal monthly-average temperature on the surface of the tunnel wall is 1.2℃ higher in January, February and December, 1℃higher in March and October, and 1 .6℃ lower in June and August, and 2qC lower in July than the air temperature at the entry and exit. In other
months the infernal temperature on the surface of the tunnel wall approximately equals the air temperature at the entry and exit.
2) Since it is affected by the geothermal heat in the internal surrounding section，especially in the central part, the internal amplitude of the yearly-average temperature on the surface of the tunnel wall decreases and is 1 .6℃ lower than that at the entry and exit.
3 ) Under the conditions that the surrounding rock is compact , without a great amount of under-ground water, and using a thermal insulating layer(as designed PU with depth of 0.05 m and heat conductivity λ= W/m℃，FBT with depth of 0.085 m and heat conductivity λ=m℃)，in the third year after tunnel construction，the surrounding rock will begin to form permafrost in the range of 200 m from the entry and exit .In the first and the second year after construction, the surrounding rock will begin to form permafrost in the range of 40 and 100m from the entry and exit respectively .In the central part，more than 200m from the entry and exit, permafrost will begin to form in the eighth year. Near the center of the tunnel，permafrost will appear in the 14-15th years. During the first and second years after permafrost formed，the maximum of annual thawed depth is large (especially in the central part of the surrounding rock section) and thereafter it decreases every year. The maximum of annual thawed depth will be stable until the 19-20th years and will remain in s range of 2-3 m.
4) If permafrost forms entirely in the surrounding rock，the permafrost will provide a water-isolating layer and be favourable for communication and transportation .However, in the process of construction，we found a lot of underground water in some sections of the surrounding rock .It will permanently exist in those sections，seeping out water and resulting in freezing damage to the liner layer. Further work will be reported elsewhere.
严寒地区隧道围岩冻融状况分析的导热与对流换热模型摘要
通过对严寒地区隧道现场基本气象条件的分析，建立了隧道内空气与围岩对流换热及固体导热的综合模型;用此模型对大兴安岭西罗奇2号隧道的洞内气温分布进行了模拟计算，结果与实测值基本一致;分析预报了正在开凿的祁连山区大坂山隧道开通运营后洞内温度及围岩冻结、融化状况.
关键词严寒地区隧道导热与对流换热冻结与融化
在我国多年冻土分布及邻近地区，修筑了公路和铁路隧道几十座.由于隧道开通后洞内水热条件的变化;，普遍引起洞内围岩冻结，造成对衬砌层的冻胀破坏以及洞内渗水冻结成冰凌等，严重影响了正常交通.类似隧道冻害问题同样出现在其他国家（苏联、挪威、日本等)的寒冷地区.如何预测分析隧道开挖后围岩的冻结状况，为严寒地区隧道建设的设计、施工及维护提供依据，这是一个亟待解决的重要课题.
在多年冻土及其临近地区修筑的隧道，多数除进出口部分外从多年冻土下限以下岩层穿
过.隧道贯通后，围岩内原有的稳定热力学条件遭到破坏，代之以阻断热辐射、开放通风对流为特征的新的热力系统.隧道开通运营后，围岩的冻融特性将主要由流经洞内的气流的温度、速度、气—固交界面的换热以及地热梯度所确定.为分析预测隧道开通后围岩的冻融特性，Lu-nardini借用Shamsundar研究圆形制冷管周围土体冻融特性时所得的近似公式，讨论过围岩的冻融特性.我们也曾就壁面温度随气温周期性变化的情况，分析计算了隧道围岩的温度场[3].但实际情况下，围岩与气体的温度场相互作用，隧道内气体温度的变化规律无法预先知道，加之洞壁表面的换热系数在技术上很难测定，从而由气温的变化确定壁面温度的变化难以实现.本文通过气一固祸合的办法，把气体、固体的换热和导热作为整体来处理，从洞口气温、风速和空气湿度、压力及围岩的水热物理参数等基本数据出发，计算出围岩的温度场.
1数学模型
为确定合适的数学模型，须以现场的基本情况为依据.这里我们以青海祁连山区大坂山公路隧道的基本情况为背景来加以说明.大坂山隧道位于西宁一张业公路大河以南，海拔~3801.23 m，全长1530 m ,隧道近西南—东北走向.
由于大坂山地区隧道施工现场平均气温为负温的时间每年约长8个月，加之施工时间持续数年，围岩在施土过程中己经预冷，所以隧道开通运营后，洞内气体流动的形态主要由进出口的主导风速所确定，而受洞内围岩地温与洞外气温的温度压差的影响较小；冬季祁连山区盛行西北风，气流将从隧道出曰流向进口端，夏季虽然祁连山区盛行东偏南风，但考虑到洞口两端气压差、温度压差以及进出口地形等因素，洞内气流仍将由出口北端流向进口端.另外，由于现场年平均风速不大，可以认为洞内气体将以层流为主
基于以上基本情况，我们将隧道简化成圆筒，并认为气流、温度等关十隧道
中心线轴对称，忽略气体温度的变化对其流速的影响，可有如下的方程:
其中t 为时间，x 为轴向坐标，r 为径向坐标;U, V 分别为轴向和径向速度，T 为温度，P 为有效压力(即空气压力与空气密度之比少，V 为空气运动粘性系数，a 为空气的导温系数，L 为隧道长度，R 为隧道的当量半径，D 为时间长度)(t S f , )(t S u 分别为围岩的冻、融区域. f λ,u λ分别为冻、融状态下的热传导系数，f C ,u C 分别为冻、融状态下的体积热容量，
X=(x,r) , )(t ξ为冻、融相变界面,To 为岩石冻结临界温度(这里具体计算时取To=C 0，h L 为水的相变潜热.
2 求解过程
由方程(1)知，围岩的温度的高低不影响气体的流动速度，所以我们可先解出速度，再解温度.
连续性方程和动量方程的求解
由于方程((1)的前3个方程不是相互独立的，通过将动量方程分别对x 和r 求导，经整理
化简，我们得到关于压力P 的如下椭圆型方程:
于是，对方程(1)中的连续性方程和动量方程的求解，我们按如下步骤进行:
(1)设定速度0U ,0V ;
( 2)将0U ,0V 代入方程并求解，得0P
(3)联立方程(1)的第一个和第二个方程，解得一组解1U ,1V ;
(4)联立方程((1)的第一个和第三个方程，解得一组解2U ,2V ;
(5)对((3) ,(4)得到的速度进行动量平均,得新的0U ,0V 返回(2) ;
(6)按上述方法进行迭代，直到前后两次的速度值之差足够小.以0P ,0U ,0V 作为本时段
的解,下一时段求解时以此作为迭代初值.
2. 2 能量方程的整体解法
如前所述，围岩与空气的温度场相互作用，壁面既是气体温度场的边界，又是固体温度场的边界，壁面的温度值难以确定，我们无法分别独立地求解隧道内的气体温度场和围岩温度场.为克服这一困难，我们利用在洞壁表面上，固体温度等于气体温度这一事实，把隧道内气体的温度和围岩内固体的温度放在一起求解，这样壁面温度将作为末知量被解出来.只是需要注意两点:解流体温度场时不考虑相变和解固体温度时没有对流项;在洞壁表面上方程系数的光滑化.另外，带相变的温度场的算法与文献[3]相同.
2. 3热参数及初边值的确定
热参数的确定方法: 用p=计算出海拔高度为H 的隧道现场的大气 压强，再由GT
P =ρ计算出现场空气密度ρ，其中T 为现场大气的年平均绝对温度，G 为空气的气体常数.记定压比热为P C ,导热系数为λ，空气的动力粘性系数为μ.按ρλ
P C =ａ 和ρ
μν= 计算空气的导温系数和运动粘性系数.围岩的热物理参数则由现场采样测定.
初边值的确定方法:洞曰风速取为现场观测的各月平均风速.取卞导风进曰的相对有效
气压为0，主导风出口的气压则取为]5[22/)/1(v d kL p ?+=，这里k 为隧道内的沿程阻力系数，L 为隧道长度，d 为隧道端面的当量直径，ν为进口端面轴向平均速度.进出口气温年变化规律由现场观测资料，用正弦曲线拟合，围岩内计算区域的边界按现场多年冻土下限和地热梯度确定出适当的温度值或温度梯度. 3 计算实例
按以上所述的模型及计算方法，我们对大兴安岭西罗奇2号隧道内气温随洞曰外气温变化的规律进行了模拟计算验证，所得结果与实测值[6]相比较,基本规律一致.
西罗奇2号隧道是位十东北嫩林线的一座非多年冻土单线铁路隧道，全长1160 m ,隧道
近西北一东南向，高洞口位于西北向，冬季隧道主导风向为西北风.洞口海拔高度约为700 m ,
月平均最高风速约为3m/s,最低风速约为1.7m/s.根据现场观测资料，我们将进出口气温拟
合为年平均分别为-5C 0和C 0，年变化振幅分别为C 0和C 0的正弦曲线.隧道的当量直径为5.8 m,沿程阻力系数取为.由于围岩的热物理参数对计算洞内气温的影响
远比洞口的风速、压力及气温的影响小得多，我们这里参考使用了大坂山隧道的资料.
图1给出了洞口及洞内年平均气温的计算值与观测值比较的情况，从进口到出口，两值之差都小于C 0.
图2给出了洞内 (距进出口l00m 以上)月平均气温的计算值与观测值比较的情况，可以看出温度变化的基本规律完全一致，造成两值之差的主要原因是洞口气温年变化规律之正弦曲线的拟合误差，特别是1979年隧道现场月平均最高气温不是在7月份，而是在8月份.
图1. 比较1979年在西罗奇周家山2号隧道仿真试验与观察的空气温度
.1、模拟值;2、观测值
图2。比较1979年在西罗奇周家山2号隧道的仿真试验与观察到的空气室内温度1、模拟值;2、观测值
4 对大坂山隧道洞内壁温及围岩冻结状况的分析预测
4. 1热参数及初边值
按大坂山隧道的高度值 3 800 m 和年平均气温-3C 0，我们算得空气密度3/774.0m kg =ρ；由于大气中含有水汽，我们将空气的定压比热取为[7] s m kJ C p ?=/8744.1导热系数C m W 02/100.2??=-λ，空气的动力粘性系数取为s m kg ??=-/10218.96μ,经计算，得出空气的导温系数s m a /103788.125-?=和运动粘性系数s m /1019.125-?=ν.
考虑到车体迎风面与隧道端面相比较小、车辆在隧道内行驶速度较慢等因素，我们这里忽略了车辆运行时所形成的活塞效应对气体扩散性能的影响.
岩体的导热系数皆按完好致密岩石的情况处理，取岩石的干容重3/2400m kg d =λ时，含水量和末冻水含量分别为W=3%和W=1 %，c m W o u ./9.1=λ,c m W o f ./0.2=λ岩石的比热取为C kg kJ C V 0./8.0=，d u f W w C γ?++=1)128.48.0(,d u u W
w C γ?++=1)128.48.0(. 另外，据有关资料，大坂山地区月平均最大风速约为3.5 m/s ，月平均最小大风速约为2.5m/s;我们将洞口风速拟合为)/](5.2)7(028.0[)(2s m t t v +-?=，这里t 为月份.
洞内风速初值为：.0),,0(),)(
1(),,0(2=-=r x V R
r U r x U a 这里取s m U a /0.3=.而将温度的初边值取为
这里记f (x)为多年冻土下限到隧道拱顶的距离，Ro = 25m 为求解区域的半径.地热梯度取为
3%，洞外天然年平均气温A=-3C 0，年气温变化振幅B=12C 0.
对于边界R = Ro ，我们先按第一类边值(到多年冻土下限的距离乘以 3 %)计算，发现一年后，在半径为5m 到25m 范围内围岩的热流方向己经发生转向.考虑到此后围岩会继续冷却，但在边界R=0R 上又受地热梯度的作用，我们近似
地将边界R= Ro作为第二类边界处理，即把由定边值计算一年后R=R。上的温度梯度作为该边界上的梯度值
考虑到围岩在施土过程中己经预冷，我们这里从几月份算起，在同一边值下进行迭代，直到该边值下的温度场基本稳定后，再令边值依正弦规律变化，逐时段进行求解(可以证明，很多时段后的解，将不依赖于初值的选择).
4. 2 计算结果
图3和图4给出了我们预测的隧道壁温随洞口气温变化的情况，图5和图6给出了我们
预测的不同部位围岩开始形成多年冻土的起始年份和多年冻土形成后围岩的年最大融化深度.
图3.大坂山隧道表面月均温度
图 4.比较隧道内表面和隧道外月均温
度。1，隧道内表面温度；2，隧道外空
气温度
图 5.在不同部位围岩形成冻土的起始年
份
图 6. 多年冻土形成后围岩的年最大融化
深度.
4. 3初步结论
对于大坂山隧道，按如上选取的参数及初边值进行计算，我们得出如下初步结论:
（1）洞内（距进出口100 m 以上）年平均壁温与洞外年平均气温基本相同，但洞内寒季较暖、暖季较凉.从图1可以看出，洞内壁温与洞外气温相比较，1，2 ，12月份高约
1. 2C 0 ,3 ,11月份高约1C 0,4 ,5 ,9和10月份基本相同，6月份和8月份低约C 0 ,7月份低约2C 0.
（2）由于隧道内部（距进出口100 m 以上，特别是靠中心地段）受地热作用较强，洞内平均壁温的年变化振幅降低.年平均壁面温度约为-3C 0，振幅约为C 0.
（3）就我们所考虑的完好致密岩石、没有大量地下水流动的情况，按现有设计铺设保温材料(PU 厚0.05m ，导热系数C m W 0/0216.0?=λ，FBT 厚0.085 m ，导热系数C m W 0/0517.0?=λ后，在距进出曰200 m 的范围内，开通运营后第3年就开始形成多年冻土，其中40 m 以内和100 m 以内在第一年和第二年就开始形成多年冻土;在距进出曰200 m 以上的中间段，开通运营8年后开始形成多年冻土，其中在距洞中心200 m 的范围内，14—15年后开始形成多年冻土.多年冻
土形成后的一两年内，年最大融化深度较大(尤其是中间段)，以后逐年减小，至19—20年后融化深度基本达到稳定，洞口段及中间段的融化深度都在2—3 m 的范围内.
(4)洞内若整体性形成多年冻土，这将成为一道隔水屏障，有利于车辆运行的安全，但在目前的施土中己发现有些部位有较丰富的地下水，因此很有可能在地下水溢出带中出现永久性融区，造成洞内渗水结冰病害，这个问题我们将在以后详细讨论.
1外文文献翻译原文及译文汇总
华北电力大学科技学院 毕业设计（论文）附件 外文文献翻译 学号：121912020115姓名：彭钰钊 所在系别：动力工程系专业班级：测控技术与仪器12K1指导教师：李冰 原文标题：Infrared Remote Control System Abstract 2016 年 4 月 19 日
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土木工程类专业英文文献及翻译
PA VEMENT PROBLEMS CAUSED BY COLLAPSIBLE SUBGRADES By Sandra L. Houston,1 Associate Member, ASCE (Reviewed by the Highway Division) ABSTRACT: Problem subgrade materials consisting of collapsible soils are com- mon in arid environments, which have climatic conditions and depositional and weathering processes favorable to their formation. Included herein is a discussion of predictive techniques that use commonly available laboratory equipment and testing methods for obtaining reliable estimates of the volume change for these problem soils. A method for predicting relevant stresses and corresponding collapse strains for typical pavement subgrades is presented. Relatively simple methods of evaluating potential volume change, based on results of familiar laboratory tests, are used. INTRODUCTION When a soil is given free access to water, it may decrease in volume, increase in volume, or do nothing. A soil that increases in volume is called a swelling or expansive soil, and a soil that decreases in volume is called a collapsible soil. The amount of volume change that occurs depends on the soil type and structure, the initial soil density, the imposed stress state, and the degree and extent of wetting. Subgrade materials comprised of soils that change volume upon wetting have caused distress to highways since the be- ginning of the professional practice and have cost many millions of dollars in roadway repairs. The prediction of the volume changes that may occur in the field is the first step in making an economic decision for dealing with these problem subgrade materials. Each project will have different design considerations, economic con- straints, and risk factors that will have to be taken into account. However, with a reliable method for making volume change predictions, the best design relative to the subgrade soils becomes a matter of economic comparison, and a much more rational design approach may be made. For example, typical techniques for dealing with expansive clays include: (1) In situ treatments with substances such as lime, cement, or fly-ash; (2) seepage barriers and/ or drainage systems; or (3) a computing of the serviceability loss and a mod- ification of the design to "accept" the anticipated expansion. In order to make the most economical decision, the amount of volume change (especially non- uniform volume change) must be accurately estimated, and the degree of road roughness evaluated from these data. Similarly, alternative design techniques are available for any roadway problem. The emphasis here will be placed on presenting economical and simple methods for: (1) Determining whether the subgrade materials are collapsible; and (2) estimating the amount of volume change that is likely to occur in the 'Asst. Prof., Ctr. for Advanced Res. in Transp., Arizona State Univ., Tempe, AZ 85287. Note. Discussion open until April 1, 1989. To extend the closing date one month,
土木工程外文翻译
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土木外文翻译原文和译文
A convection-conduction model for analysis of the freeze-thaw conditions in the surrounding rock wall of a tunnel in permafrost regions Abstract Based on the analyses of fundamental meteorological and hydrogeological conditions at the site of a tunnel in the cold regions, a combined convection-conduction model for air flow in the tunnel and temperature field in the surrounding has been constructed. Using the 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 air-temperature relationship between the temperature on the surface of the tunnel 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 regions, convective heat exchange and conduction, freeze-thaw. A number of highway and railway tunnels have been constructed in the permafrost regions and their neighboring areas in China. Since the hydrological and thermal conditions changed after a tunnel was excavated，the surrounding wall rock materials 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 .Hence it is urgent to predict the freeze-thaw conditions in the surrounding rock materials and provide a basis for the design，construction and
毕业设计外文翻译附原文
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外文资料名称： Design and performance evaluation of vacuum cleaners using cyclone technology 外文资料出处：Korean J. Chem. Eng., 23(6), (用外文写) 925-930 (2006) 附件： 1.外文资料翻译译文 2.外文原文
应用旋风技术真空吸尘器的设计和性能介绍 吉尔泰金，洪城铱昌，宰瑾李， 刘链柱译 摘要：旋风型分离器技术用于真空吸尘器 - 轴向进流旋风和切向进气道流旋风有效地收集粉尘和降低压力降已被实验研究。优化设计等因素作为集尘效率，压降，并切成尺寸被粒度对应于分级收集的50％的效率进行了研究。颗粒切成大小降低入口面积，体直径，减小涡取景器直径的旋风。切向入口的双流量气旋具有良好的性能考虑的350毫米汞柱的低压降和为1.5μm的质量中位直径在1米3的流量的截止尺寸。一使用切向入口的双流量旋风吸尘器示出了势是一种有效的方法，用于收集在家庭中产生的粉尘。 摘要及关键词：吸尘器; 粉尘; 旋风分离器 引言 我们这个时代的很大一部分都花在了房子，工作场所，或其他建筑，因此，室内空间应该是既舒适情绪和卫生。但室内空气中含有超过室外空气因气密性的二次污染物，毒物，食品气味。这是通过使用产生在建筑中的新材料和设备。真空吸尘器为代表的家电去除有害物质从地板到地毯所用的商用真空吸尘器房子由纸过滤，预过滤器和排气过滤器通过洁净的空气排放到大气中。虽然真空吸尘器是方便在使用中，吸入压力下降说唱空转成比例地清洗的时间，以及纸过滤器也应定期更换，由于压力下降，气味和细菌通过纸过滤器内的残留粉尘。 图1示出了大气气溶胶的粒度分布通常是双峰形，在粗颗粒（>2.0微米）模式为主要的外部来源，如风吹尘，海盐喷雾，火山，从工厂直接排放和车辆废气排放，以及那些在细颗粒模式包括燃烧或光化学反应。表1显示模式，典型的大气航空的直径和质量浓度溶胶被许多研究者测量。精细模式在0.18?0.36 在5.7到25微米尺寸范围微米尺寸范围。质量浓度为2?205微克，可直接在大气气溶胶和 3.85至36.3μg/m3柴油气溶胶。
土木工程岩土类毕业设计外文翻译
姓名： 学号： 10447425 X X 大学 毕业设计（论文）外文翻译 （2014届） 外文题目Developments in excavation bracing systems 译文题目开挖工程支撑体系的发展 外文出处Tunnelling and Underground Space Technology 31 (2012) 107–116 学生XXX 学院XXXX 专业班级XXXXX 校内指导教师XXX 专业技术职务XXXXX 校外指导老师专业技术职务 二○一三年十二月
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土木工程外文翻译.doc
项目成本控制 一、引言 项目是企业形象的窗口和效益的源泉。随着市场竞争日趋激烈，工程质量、文明施工要求不断提高，材料价格波动起伏，以及其他种种不确定因素的影响，使得项目运作处于较为严峻的环境之中。由此可见项目的成本控制是贯穿在工程建设自招投标阶段直到竣工验收的全过程，它是企业全面成本管理的重要环节，必须在组织和控制措施上给于高度的重视，以期达到提高企业经济效益的目的。 二、概述 工程施工项目成本控制，指在项目成本在成本发生和形成过程中，对生产经营所消耗的人力资源、物资资源和费用开支，进行指导、监督、调节和限制，及时预防、发现和纠正偏差从而把各项费用控制在计划成本的预定目标之内，以达到保证企业生产经营效益的目的。 三、施工企业成本控制原则 施工企业的成本控制是以施工项目成本控制为中心，施工项目成本控制原则是企业成本管理的基础和核心，施工企业项目经理部在对项目施工过程进行成本控制时，必须遵循以下基本原则。 3.1 成本最低化原则。施工项目成本控制的根本目的，在于通过成本管理的各种手段，促进不断降低施工项目成本，以达到可能实现最低的目标成本的要求。在实行成本最低化原则时，应注意降低成本的可能性和合理的成本最低化。一方面挖掘各种降低成本的能力，使可能性变为现实；另一方面要从实际出发，制定通过主观努力可能达到合理的最低成本水平。 3.2 全面成本控制原则。全面成本管理是全企业、全员和全过程的管理，亦称“三全”管理。项目成本的全员控制有一个系统的实质性内容，包括各部门、各单位的责任网络和班组经济核算等等，应防止成本控制人人有责，人人不管。项目成本的全过程控制要求成本控制工作要随着项目施工进展的各个阶段连续 进行，既不能疏漏，又不能时紧时松，应使施工项目成本自始至终置于有效的控制之下。 3.3 动态控制原则。施工项目是一次性的，成本控制应强调项目的中间控制，即动态控制。因为施工准备阶段的成本控制只是根据施工组织设计的具体内容确
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英文原文： Building construction concrete crack of prevention and processing Abstract The crack problem of concrete is a widespread existence but again difficult in solve of engineering actual problem, this text carried on a study analysis to a little bit familiar crack problem in the concrete engineering, and aim at concrete the circumstance put forward some prevention, processing measure. Keyword:Concrete crack prevention processing Foreword Concrete's ising 1 kind is anticipate by the freestone bone, cement, water and other mixture but formation of the in addition material of quality brittleness not and all material.Because the concrete construction transform with oneself, control etc. a series problem, harden model of in the concrete existence numerous tiny hole, spirit cave and tiny crack, is exactly because these beginning start blemish of existence just make the concrete present one some not and all the characteristic of quality.The tiny crack is a kind of harmless crack and accept concrete heavy, defend Shen and a little bit other use function not a creation to endanger.But after the concrete be subjected to lotus carry, difference in temperature etc. function, tiny crack would continuously of expand with connect, end formation we can see without the
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土木工程外文文献翻译
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工程造价外文翻译(有出处)
预测高速公路建设项目最终的预算和时间 摘要 目的——本文的目的是开发模型来预测公路建设项目施工阶段最后的预算和持续的时间。 设计——测算收集告诉公路建设项目，在发展预测模型之前找出影响项目最终的预算和时间，研究内容是基于人工神经网络(ANN)的原理。与预测结果提出的方法进行比较,其精度从当前方法基于挣值。 结果——根据影响因素最后提出了预算和时间，基于人工神经网络的应用原理方法获得的预测结果比当前基于挣值法得到的结果更准确和稳定。 研究局限性/意义——因素影响最终的预算和时间可能不同,如果应用于其他国家,由于该项目数据收集的都是泰国的预测模型,因此,必须重新考虑更好的结果。 实际意义——这项研究为用于高速公路建设项目经理来预测项目最终的预算和时间提供了一个有用的工具，可为结果提供早期预算和进度延误的警告。 创意/价值——用ANN模型来预测最后的预算和时间的高速公路建设项目,开发利用项目数据反映出持续的和季节性周期数据, 在施工阶段可以提供更好的预测结果。 关键词：神经网、建筑业、预测、道路、泰国 文章类型：案例研究 前言 一个建设工程项普遍的目的是为了在时间和在预算内满足既定的质量要求和其他规格。为了实现这个目标,大量的工作在施工过程的管理必须提供且不能没有计划地做成本控制系统。一个控制系统定期收集实际成本和进度数据,然后对比与计划的时间表来衡量工作进展是否提前或落后时间表和强调潜在的问题(泰克兹,1993)。成本和时间是两个关键参数，在建设项目管理和相关参数的研究中扮演着重要的角色，不断提供适当的方法和
工具，使施工经理有效处理一个项目，以实现其在前期建设和在施工阶段的目标。在施工阶段,一个常见的问题要求各方参与一个项目，尤其是一个所有者,最终项目的预算到底是多少?或什么时候该项目能被完成？ 在跟踪和控制一个建设项目时，预测项目的性能是非常必要的。目前已经提出了几种方法,如基于挣值技术、模糊逻辑、社会判断理论和神经网络。将挣值法视为一个确定的方法，其一般假设，无论是性能效率可达至报告日期保持不变，或整个项目其余部分将计划超出申报日期（克里斯坦森，1992；弗莱明和坎普曼，2000 ；阿萨班尼，1999；维卡尔等人，2000）。然而，挣值法的基本概念在研究确定潜在的进度延误、成本和进度的差异成本超支的地区。吉布利（1985）利用平均每个成本帐户执行工作的实际成本，也称作单位收入的成本，其标准差来预测项目完工成本。各成本帐户每月的进度是一个平均平稳过程标准偏差，显示预测模型的可靠性，然而，接受的单位成本收益在每个报告期在变化。埃尔丁和休斯（1992）和阿萨班尼（1999）利用分解组成成本的结构来提高预测精度。迪克曼和Al-Tabtabai（1992）基于社会判断理论提出了一个方法，该方法在预测未来的基础上的一组线索，源于人的判断而不是从纯粹的数学算法。有经验的项目经理要求基于社会判断理论方法的使用得到满意的结果。Moselhi等人（2006）应用“模糊逻辑”来预测潜在的成本超支和对建设工程项目的进度延迟。该方法的结果在评估特定时间状态的项目和评价该项目的利润效率有作用。这有助于工程人员所完成的项目时间限制和监控项目预算。Kaastra和博伊德（1996）开发的“人工神经网络”,此网络作为一种有效的预测工具，可以利用过去“模式识别”工作和显示各种影响因素的关系，然后预测未来的发展趋势。罗威等人（2006）开发的成本回归模型能在项目的早期阶段估计建筑成本。总共有41个潜在的独立变量被确定，但只有四个变量：总建筑面积，持续时间，机械设备，和打桩，是线性成本的关键驱动因素，因为它们出现在所有的模型中。模型提出了进一步的洞察了施工成本和预测变量的各种关系。从模型得到的估计结果可以提供早期阶段的造价咨询（威廉姆斯（2003））——最终竞标利用回归模型预测的建设项目成本。 人工神经网络已被广泛用在不同的施工功能中，如估价、计划和产能预测。神经网络建设是Moselhi等人（1991）指出，由Hegazy（1998）开发了一个模型，该模型考虑了项目的外在特征，估计加拿大的公路建设成本： ·项目类型 ·项目范围
土木工程毕业设计外文翻译最终中英文
7 Rigid-Frame Structures A rigid-frame high-rise structure typically comprises parallel or orthogonally arranged bents consisting of columns and girders with moment resistant joints. Resistance to horizontal loading is provided by the bending resistance of the columns, girders, and joints. The continuity of the frame also contributes to resisting gravity loading, by reducing the moments in the girders. The advantages of a rigid frame are the simplicity and convenience of its rectangular form.Its unobstructed arrangement, clear of bracing members and structural walls, allows freedom internally for the layout and externally for the fenestration. Rig id frames are considered economical for buildings of up to' about 25 stories, above which their drift resistance is costly to control. If, however, a rigid frame is combined with shear walls or cores, the resulting structure is very much stiffer so that its height potential may extend up to 50 stories or more. A flat plate structure is very similar to a rigid frame, but with slabs replacing the girders As with a rigid frame, horizontal and vertical loadings are resisted in a flat plate structure by the flexural continuity between the vertical and horizontal components. As highly redundant structures, rigid frames are designed initially on the basis of approximate analyses, after which more rigorous analyses and checks can be made. The procedure may typically inc lude the following stages: 1. Estimation of gravity load forces in girders and columns by approximate method. 2. Preliminary estimate of member sizes based on gravity load forces with arbitrary increase in sizes to allow for horizontal loading. 3. Approximate allocation of horizontal loading to bents and preliminary analysis of member forces in bents. 4. Check on drift and adjustment of member sizes if necessary. 5. Check on strength of members for worst combination of gravity and horizontal loading, and adjustment of member sizes if necessary. 6. Computer analysis of total structure for more accurate check on member strengths and drift, with further adjustment of sizes where required. This stage may include the second-order P-Delta effects of gravity loading on the member forces and drift.. 7. Detailed design of members and connections.