有关工程方面的外文文献翻译

A convection-conduction model for analysis of the freeze-thaw

conditions in the surrounding rock wall of a

tunnel in permafrost regions

HE Chunxiong(何春雄)，

(State Key Laboratory of Frozen Soil Engineering, Lanzhou Institute of Glaciology and

Geocryology,

Chinese Academy of Sciences, Lanzhou 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 and

Geocryology

Chinese Academy of Sciences, Lanzhou 730000, China)

Received February 8, 1999

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 3754.78-3 801.23 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; Lh 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= 1013.25-0.1088 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 ρμν=. 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 No.2 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 0.025.Since 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.

4Prediction 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/m 3.Since 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 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[)(2

s 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%C0on 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 calculatefrom 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 ).

4 .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.

4 .3 Preliminary conclusion

Based on the initial-boundary conditions and thermal parameters mentioned above, we obtain the following preliminary conclusions:

1)The yearly-average temperature on the surface wall of the tunnel is approximately equal to the air 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=0.0216 W/m℃，FBT with depth of 0.085 m and heat conductivity λ=0.0517W/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

何春雄吴紫汪朱林楠

（中国科学院寒区旱区环境与工程研究所冻土工程国家重点实验室）

（华南理工大学应用数学系）

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3754.78~3801.23 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 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=-0.10C 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。

2.1 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=1013.25-0.1088H 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ρμν= 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-6.4C 0，年变化振幅分别为18.9C 0和17.6C 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0.025.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0.2C 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。

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。

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1.6C 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10.4C 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

λ，FBT厚0.085 m，

0216

=

.0?

m

W0

/

导热系数C

λ后，在距进出曰200 m的范围内，开通运营后第3 .0?

=

0517

/

m

W0

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。

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forced concrete structure reinforced with an overviewRein Since the reform and opening up, with the national economy's rapid and sustained development of a reinforced concrete structure built, reinforced with the development of technology has been great. Therefore, to promote the use of advanced technology reinforced connecting to improve project quality and speed up the pace of construction, improve labor productivity, reduce costs, and is of great significance. Reinforced steel bars connecting technologies can be divided into two broad categories linking welding machinery and steel. There are six types of welding steel welding methods, and some apply to the prefabricated plant, and some apply to the construction site, some of both apply. There are three types of machinery commonly used reinforcement linking method primarily applicable to the construction site. Ways has its own characteristics and different application, and in the continuous development and improvement. In actual production, should be based on specific conditions of work, working environment and technical requirements, the choice of suitable methods to achieve the best overall efficiency. 1、steel mechanical link 1.1 radial squeeze link Will be a steel sleeve in two sets to the highly-reinforced Department with superhigh pressure hydraulic equipment (squeeze tongs) along steel sleeve radial squeeze steel casing, in squeezing out tongs squeeze pressure role of a steel sleeve plasticity deformation closely integrated with reinforced through reinforced steel sleeve and Wang Liang's Position will be two solid steel bars linked Characteristic: Connect intensity to be high, performance reliable, can bear high stress draw and pigeonhole the load and tired load repeatedly.

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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

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,

土木工程外文文献及翻译

Original Article Impact of crack width on bond: confined and unconfine d rebar David https://www.sodocs.net/doc/eb14370251.html,w1, Denglei Tang2, Thoma s K. C.Molyneaux3 and Rebecca Gravina3 (1)School of the Built Environment, Heriot Watt University, Edinburgh, EH14 4AS, UK (2)VicRoads, Melbourne, VIC, Australia (3)School of Civil, Environmental and Chemical Engineering, RMIT University, Melbourne, VIC, 3000, Australia David W. Law Email: https://www.sodocs.net/doc/eb14370251.html,w@https://www.sodocs.net/doc/eb14370251.html, Received: 14January2010Accepted: 14Decemb er2010Published online: 23December2010 Abstract This paper reports the results of a research project comp aring the effect of surface crack width and degree of corrosi on on the bond strength of confined and unconfined deforme d 12 and 16mm mild steel reinforcing bars. The corrosion was induced by chloride contamination of the concrete and

土木工程外文翻译参考3篇

学校 毕业设计（论文）附件 外文文献翻译 学号： xxxxx 姓名： xxx 所在系别： xxxxx 专业班级： xxx 指导教师： xxxx 原文标题： Building construction concrete crack of prevention and processing 2012年月日 .

建筑施工混凝土裂缝的预防与处理1 摘要 混凝土的裂缝问题是一个普遍存在而又难于解决的工程实际问题，本文对混凝土工程中常见的一些裂缝问题进行了探讨分析，并针对具体情况提出了一些预防、处理措施。 关键词：混凝土裂缝预防处理 前言 混凝土是一种由砂石骨料、水泥、水及其他外加材料混合而形成的非均质脆性材料。由于混凝土施工和本身变形、约束等一系列问题，硬化成型的混凝土中存在着众多的微孔隙、气穴和微裂缝，正是由于这些初始缺陷的存在才使混凝土呈现出一些非均质的特性。微裂缝通常是一种无害裂缝，对混凝土的承重、防渗及其他一些使用功能不产生危害。但是在混凝土受到荷载、温差等作用之后，微裂缝就会不断的扩展和连通，最终形成我们肉眼可见的宏观裂缝，也就是混凝土工程中常说的裂缝。 混凝土建筑和构件通常都是带缝工作的，由于裂缝的存在和发展通常会使内部的钢筋等材料产生腐蚀，降低钢筋混凝土材料的承载能力、耐久性及抗渗能力，影响建筑物的外观、使用寿命，严重者将会威胁到人们的生命和财产安全。很多工程的失事都是由于裂缝的不稳定发展所致。近代科学研究和大量的混凝土工程实践证明，在混凝土工程中裂缝问题是不可避免的，在一定的范围内也是可以接受的，只是要采取有效的措施将其危害程度控制在一定的范围之内。钢筋混凝土规范也明确规定：有些结构在所处的不同条件下，允许存在一定宽度的裂缝。但在施工中应尽量采取有效措施控制裂缝产生，使结构尽可能不出现裂缝或尽量减少裂缝的数量和宽度，尤其要尽量避免有害裂缝的出现，从而确保工程质量。 混凝土裂缝产生的原因很多，有变形引起的裂缝：如温度变化、收缩、膨胀、不均匀沉陷等原因引起的裂缝；有外载作用引起的裂缝；有养护环境不当和化学作用引起的裂缝等等。在实际工程中要区别对待，根据实际情况解决问题。 混凝土工程中常见裂缝及预防: 1.干缩裂缝及预防 干缩裂缝多出现在混凝土养护结束后的一段时间或是混凝土浇筑完毕后的一周左右。水泥浆中水分的蒸发会产生干缩，且这种收缩是不可逆的。干缩裂缝的产生主要是由于混凝土内外水分蒸发程度不同而导致变形不同的结果：混凝土受外部条件的影响，表面水分损失过快，变形较大，内部湿度变化较小变形较小，较大的表面干缩变形受到混凝土内部约束，产生较大拉应力而产生裂缝。相对湿度越低，水泥浆体干缩越大，干缩裂缝越易产 1原文出处及作者：《加拿大土木工程学报》

建筑外文文献及翻译

外文原文 Study on Human Resource Allocation in Multi-Project Based on the Priority and the Cost of Projects Lin Jingjing , Zhou Guohua SchoolofEconomics and management, Southwest Jiao tong University ,610031 ,China Abstract----This paper put forward the a ffecting factors of project’s priority. which is introduced into a multi-objective optimization model for human resource allocation in multi-project environment . The objectives of the model were the minimum cost loss due to the delay of the time limit of the projects and the minimum delay of the project with the highest priority .Then a Genetic Algorithm to solve the model was introduced. Finally, a numerical example was used to testify the feasibility of the model and the algorithm. Index Terms—Genetic Algorithm, Human Resource Allocation, Multi-project’s project’s priority . 1.INTRODUCTION More and more enterprises are facing the challenge of multi-project management, which has been the focus among researches on project management. In multi-project environment ,the share are competition of resources such as capital , time and human resources often occur .Therefore , it’s critical to schedule projects in order to satisfy the different resource demands and to shorten the projects’ duration time with resources constrained ,as in [1].For many enterprises ,the human resources are the most precious asset .So enterprises should reasonably and effectively allocate each resource , especially the human resource ,in order to shorten the time and cost of projects and to increase the benefits .Some literatures have

建筑外文文献及翻译

建筑外文文献及翻译

外文原文 Study on Human Resource Allocation in Multi-Project Based on the Priority and the Cost of Projects Lin Jingjing , Zhou Guohua SchoolofEconomics and management, Southwest Jiao tong University ,610031 ,China Abstract -- This paper put forward the affecting factors of project 'prsiority. which is introduced into a multi-objective optimization model for human resource allocation in multi-project environment . The objectives of the model were the minimum cost loss due to the delay of the time limit of the projects and the minimum delay of the project with the highest priority .Then a Genetic Algorithm to solve the model was introduced. Finally, a numerical example was used to testify the feasibility of the model and the algorithm. Index Terms —Genetic Algorithm, Human Resource Allocation, Multi- project 's project 's priority . 1.INTRODUCTION More and more enterprises are facing the challenge of multi-project management, which has been the focus among researches on project management. In multi-project environment ,the share are competition of resources such as capital , time and human resources often occur .Therefore , it 'csritical to schedule projects in order to satisfy the different resource demands and to shorten the projects 'duration time with resources constrained ,as in [1].For many enterprises ,the human resources are the most precious asset .So enterprises should reasonably and effectively allocate each resource , especially the human resource ,in order to shorten the time and cost of projects and to increase the benefits .Some literatures have discussed the resource allocation problem in multi-project environment with resources constrained. Reference [1] designed an iterative algorithm and proposed a mathematical model of the resource-constrained multi-project scheduling .Based on work breakdown structure (WBS) and Dantzig-Wolfe decomposition method ,a feasible multi-project planning method was illustrated , as in [2] . References [3,4] discussed the resource-constrained project scheduling based on Branch Delimitation method .Reference [5] put forward the framework of human resource allocation in multi-project in Long-

土木工程类外文文献翻译

外文文献翻译 1 中文翻译 1.1钢筋混凝土 素混凝土是由水泥、水、细骨料、粗骨料（碎石或；卵石）、空气，通常还有其他外加剂等经过凝固硬化而成。将可塑的混凝土拌合物注入到模板内，并将其捣实，然后进行养护，以加速水泥与水的水化反应，最后获得硬化的混凝土。其最终制成品具有较高的抗压强度和较低的抗拉强度。其抗拉强度约为抗压强度的十分之一。因此，截面的受拉区必须配置抗拉钢筋和抗剪钢筋以增加钢筋混凝土构件中较弱的受拉区的强度。 由于钢筋混凝土截面在均质性上与标准的木材或钢的截面存在着差异，因此，需要对结构设计的基本原理进行修改。将钢筋混凝土这种非均质截面的两种组成部分按一定比例适当布置，可以最好的利用这两种材料。这一要求是可以达到的。因混凝土由配料搅拌成湿拌合物，经过振捣并凝固硬化，可以做成任何一种需要的形状。如果拌制混凝土的各种材料配合比恰当，则混凝土制成品的强度较高，经久耐用，配置钢筋后，可以作为任何结构体系的主要构件。 浇筑混凝土所需要的技术取决于即将浇筑的构件类型，诸如：柱、梁、墙、板、基础，大体积混凝土水坝或者继续延长已浇筑完毕并且已经凝固的混凝土等。对于梁、柱、墙等构件，当模板清理干净后应该在其上涂油，钢筋表面的锈及其他有害物质也应该被清除干净。浇筑基础前，应将坑底土夯实并用水浸湿6英寸，以免土壤从新浇的混凝土中吸收水分。一般情况下，除使用混凝土泵浇筑外，混凝土都应在水平方向分层浇筑，并使用插入式或表面式高频电动振捣器捣实。必须记住，过分的振捣将导致骨料离析和混凝土泌浆等现象，因而是有害的。 水泥的水化作用发生在有水分存在，而且气温在50°F以上的条件下。为了保证水泥的水化作用得以进行，必须具备上述条件。如果干燥过快则会出现表面裂缝，这将有损与混凝土的强度，同时也会影响到水泥水化作用的充分进行。 设计钢筋混凝土构件时显然需要处理大量的参数，诸如宽度、高度等几何尺寸，配筋的面积，钢筋的应变和混凝土的应变，钢筋的应力等等。因此，在选择混凝土截面时需要进行试算并作调整，根据施工现场条件、混凝土原材料的供应情况、业主提出的特殊要求、对建筑和净空高度的要求、所用的设计规范以及建筑物周围环