赖远明 论文题目：寒区隧道温度场、渗流场和应力场耦合问题的非线性分析 作者简介：赖远明，男，1962年08月出生，1996年09月师从于中国科学院寒区旱区环境与工程研究所吴紫汪教授，于2000年01月获博士学位。
摘 要
在我国东北和西北地区有众多隧道，无论是大兴安岭地区的铁路隧道，还是高海拔的甘、青、新铁路和公路隧道，凡是年平均气温低于-1.0℃，都有不同程度的冻害，严重者常年有7～8个月不能使用，有的隧道甚至报废而全年不能使用。随着西部经济的开发，我国在寒冷地区的隧道数目将会增加。为研究解决隧道冻害机理，为设计提供理论依据，为病害整治提供方法措施，本文以青海大坂山隧道为模型，对寒区隧道进行了全方位多侧面的研究。这一研究填补了国内外在寒区隧道设计计算理论方面的空白，为寒区隧道规范的建立做了开拓性的工作。具体来讲，主要做了如下几个方面的研究工作：
在国内外，首次研究了渗流对隧道围岩温度场的影响，根据传热学和渗流理论，导出了温度场和渗流场耦合问题的控制微分方程，应用显热容法和伽辽金法导出了这一问题的有限元计算公式，根据大坂山的气温和围岩的热物理学参数，应用这一有限元公式和Crank—Nicolson格式，对不同围岩渗流系数下的隧道围岩温度场进行了数值模拟，研究了渗流对隧道温度场的影响规律。考察了安装保温层后，隧道围岩的冻融情况。研究结果表明围岩渗流对寒区工程的冻深影响很大，良好的保温层可以大大减小隧洞围岩的冻结深度。计算结果还表明，隧道运营后，随着时间的推移，隧道围岩将逐渐形成多年冻土。
应用摄动技术，研究了具有接近零度初始温度的圆形隧道的冻结规律，给出了这一问题的近似解析解。该解既可用于工程估算也可用来检验数值计算结果。
应用弹性—粘弹性相应原理，导出了隧道衬砌—正冻围岩—未冻围岩体系的冻胀力在拉氏像空间中的有关公式，推出了该公式的数值逆变换算式，算出了圆形隧道围岩冻胀力和衬砌的应力随时间变化的规律。已有的没有考虑冻胀因素的弹性理论计算结果比考虑冻胀因素的粘弹性结果小53.9%,这就是为什么以前的隧道理论计算认为是安全的隧道仍会出现裂缝的原因。
根据传热学，渗流理论和冻土力学提出了带相变的温度场、渗流场和应力场三场耦合问题的数学力学模型及其控制微分方程，应用伽辽金法导出了这一问题的有限元计算公式，并以大坂山隧道为模型，模拟了隧道开挖支护过程，然后在此基础上对寒区隧道在渗流体积力和冻土蠕变及体积冻胀荷载作用下隧道衬砌和围岩的应力场和温度场进行了数值模拟。分析了隧道在刚修好，经过一个冻融循环和５个冻融循环后，隧道衬砌的应力和变形。计算结果表明三场之间有较大的相互影响，特别是渗流场和应力场对寒区工程的冻深有很大的影响，冻胀力对隧道衬砌的应力影响非常大。
应用Mises屈服准则和冻土的工程蠕变理论，导出了冻土粘塑性本构关系，提出了冻土工程地震的计算方法，最后对寒区隧道在使用1年后和5年后的地震响应进行了弹粘塑性有限元分析，算例表明，寒区隧道衬砌和围岩的初应力和位移对其地震响应有很大的影响，在寒区隧道设计中应该充分考虑这些因数的影响。
根据青海省祁连山区的大坂山公路隧道处的气候条件，对该隧道围岩试样进行了冻融损伤的力学实验，并用CT对冻融前后的试样进行了检测，根据CT扫描结果分析了岩石冻融损伤的定性规律。
关键词：温度场，渗流场，应力场，耦合问题，地震响应和非线性分析。
Abstract
There are many tunnels in northeastern and
northwestern China. If only these tunnels are located in cold regions whose
yearly-average air temperature is below -1.0℃, both the railway tunnels located in DaXinAn
mountain area and the tunnels with high elevations in Gan, Qing, Xin Provinces
or District all have different degree of damage caused by frost action. Because
of this effect, some of the damaged tunnels can not be used for as much as 7-8
months a year. Some of them can not be used forever. With the economic
development in western China, the number of tunnels in cold regions in China
will be increased. In order to study the frost action mechanism of tunnels,
provide computational theory for design and eliminate the damage of heaving
frost to tunnels, in this paper, taking DaBan mountain tunnel in Qinghai
province as example, the cold-regions tunnels are studied from various aspects.
This study is worldwide first one in setting up computational theory of cold
regional tunnels. The pioneering work has been done for building the
construction code of cold regions tunnels. The following research work has been
done.
The governing differential equations of
the coupled problem of temperature and seepage fields with phase change are
derived from the theory of heat transfer and theory of seepage. The finite
element formulae of this problem are obtained from Galerkin's method. Taking
DaBan mountain tunnel as example, the effects of seepage and insulation on the
frozen depths have been investigated. The studied results indicate that the
influence of seepage on the frozen depth of cold regions engineering is large
and good insulation can largely decrease the frozen depth of rock surrounding
tunnels.
Using perturbative method, the research
of the freezing process of circular tunnel with initial temperature near 0 ℃
has been made. The approximate analytic solution to this problem is given. This
solution can be used in both engineering computation and the examination of
numerically calculated results.
The formulae of Laplace transform with
respect to time for frost forces of the liner-frozen surrounding rock-unfrozen
surrounding rock system are derived from the elastic-viscoelastic
correspondence principle. The variations of the frost forces and liner stresses
of cold regional tunnel versus time are obtained by the numerical inversion of
the Laplace transform.
The governing differential equations of
the coupled problem of temperature, seepage and stress fields are derived from
the theory of heat transfer, the theory of seepage and frozen soil mechanics.
The finite element formulae of this problem are obtained from Galerkin's
method. The excavating, lining and freezing-thawing processes of tunnel have
been modeled. The temperature and stress fields of tunnel lining and rock
surrounding tunnel at differential stages have been worked out. The calculated
results indicate that there are large interactions among these three fields.
Especially, the effect of seepage on temperature field is large and the
influence of frost action on stress field is large.
The visco-plastic constitutive equations
of frozen soil are given from the Von Mises yield criterion and the engineering
creep theory of frozen soil. The displacement and stress earthquake response of
cold regional tunnel at different periods has been computed. The calculated
results show that the effect of initial stresses on the stress response of
tunnel lining is very large.
The mechanical experiment of frost damage
to rocks surrounding the tunnel is made according to the meteorological data in
DaBan mountain area. The measurements for the samples before and after frost
damage are carried out by CT. Quantitative and qualitative results and laws of
rock frost damage are analyzed by means of CT scan.
Key words:
temperature field, seepage field, stress field, coupled problem, earthquake
response and nonlinear analysis.