【作者】 谭贤君；

【导师】 陈卫忠；

【作者基本信息】 中国科学院研究生院（武汉岩土力学研究所） ， 岩土工程， 2010， 博士

【摘要】 本文紧密结合高海拔寒区隧道工程建设中岩石冻融破坏及防寒保温领域的国际前沿科学问题,以建设西藏“扎墨”公路(连接中国唯一不通公路的县：墨脱县)的控制性工程——嘎隆拉隧道工程为依托。紧紧围绕“寒区隧道围岩冻胀破坏机理及其防寒保温技术”这一主题,以“通风条件下寒区隧道温度-渗流-应力-损伤(THMD)耦合机理”为理论基础,通过室内试验、理论分析、数值模拟以及现场监测等方法,对涉及该课题的相关理论模型和应用技术进行了全方位、多角度的研究,建立了高海拔寒区隧道冻胀力作用下隧道的结构稳定性评价方法和合理防寒保温措施。这些研究成果一方面深化了寒区隧道围岩冻胀机理的理论基础,填补了寒区隧道在通风条件下围岩THMD耦合理论的空白；另一方面,为寒区隧道支护结构的优化和合理防寒保温措施的建立做了开拓性的工作,取得了一系列的成果,具体来讲,主要包括以下几个方面：(1)建立了适用于低温相变岩体的温度-渗流耦合控制方程,提出了计算低温相变岩土类材料导热系数的新方法根据冻融条件下岩体水分运动和热量迁移的基本规律,基于连续介质力学、热力学以及分凝势理论,建立了低温相变岩体温度-渗流耦合控制方程,该耦合方程不仅包括了热传导、相变潜热和渗流速度对温度分布的影响,而且考虑了由Soret效应、分凝势引起的孔隙水流动对渗流速度以及渗透压力分布的影响,实现了温度场和渗流场的双向全耦合。并将研究成果与Mizoguchi等人著名的温度-渗流耦合室内试验进行了同等条件下的对比分析,有力地证明了该耦合模型的正确性和参数取值方法的合理性。同时,对本耦合模型中涉及到的水-热力学参数进行系统的归纳和总结,特别针对现有3种常用的计算岩土体导热系数方法的不足,从随机混合模型(RMM)理念出发,结合岩土类材料的本身特点(多孔隙,0℃以下还存在未冻水等),提出了计算低温相变岩土类材料导热系数的新方法,并通过与Mizoguchi等人的试验数据进行对比,验证了新方法的可行性。该模型既丰富和发展了现有的低温相变岩体的温度-渗流耦合模型,又为岩体“导热系数”这一重要热力学参数的取值方法提供了新的思路。(2)建立了考虑空气温度和湿度影响的隧道风流场湍流模型,探讨了隧道内风流场与围岩热量交换规律借助流体力学、传热学和空气动力学的基本原理与方法,在适当引入地铁通风和建筑节能方面研究成果的基础上,推导出考虑空气温度和湿度影响的风流场湍流模型,对现有的湍流数值模拟方法和围岩与风温热交换规律进行了深入的分析和探讨,并应用上述研究成果,数值模拟了Baly等人采用缩尺模型对室内空气混合对流进行的试验研究,通过与试验结果及Zhang等人数值模拟结果的比较,证明了本文推导的风流场模型及其采用的湍流数值模拟方法的优越性。在此基础上,采用数值分析方法探讨了空气的温度、湿度以及风速的大小对围岩温度场的影响,研究结果表明：风温和风速是影响围岩温度场的最主要的两个因素,相比之下,空气湿度对温度场的影响较小。该模型既深化了寒区隧道围岩温度场的研究水平,填补了国内外寒区隧道研究在该领域的空白,也可应用于地铁通风、火灾模拟、建筑节能和室内环境等领域的通风数值计算。(3)提出了考虑岩石冻融影响的损伤因子,建立了能够反映西藏嘎隆拉隧道围岩应力-应变关系的冻融损伤本构模型通过对西藏嘎隆拉隧道现场岩样进行系统的冻融试验和单轴、三轴压缩试验,全面分析了该类岩石在经历不同冻融次数、不同受力状态条件下的破坏形式、强度特性、变形特性和冻融劣化特征,研究结果表明：单轴条件下岩石破坏形式以劈裂破坏为主,三轴条件下以剪切破坏为主；强度随冻融次数增加而减小；应力峰值对应的轴向应变值随着围压和冻融次数的增加而增加。在此基础上,提出了考虑岩石冻融影响的损伤因子,建立了能够反映西藏嘎隆拉隧道围岩应力-应变关系的冻融损伤本构模型。该模型反映了岩石在多次冻融循环过程中的损伤特点,为进一步揭示工程岩体冻融损伤机理奠定了基础。(4)建立了通风条件下寒区隧道温度-渗流-应力-损伤(THMD)耦合模型考虑体积应变对围岩温度场和渗流场的影响,温度梯度、渗透压力和冻胀压力对围岩应力场的影响,建立了通风条件下寒区隧道THMD耦合模型。该模型除了包括传统三场耦合条件下的能量方程、质量守恒方程和平衡方程三大基本方程外,还根据寒区隧道的工程实际,添加了考虑隧道内空气湿度、风速和风温影响的风流场湍流模型方程组。在此基础上,数值仿真了某寒区管道工程的冻胀过程,通过与现场的实测结果对比表明：该模型能很好的反映围岩体由于负温所产生的冻胀现象。该模型是在THM三场耦合框架内,对寒区隧道复杂通风条件下围岩冻胀机理的一次崭新探索,使得THM耦合研究更接近隧道工程实际。(5)研制了一种高性能泡沫混凝土,通过试验研究了其保温性能和冻融劣化规律,通过数值分析研究了其在寒区隧道中的保温效果针对寒区隧道的特点,在对泡沫混凝土产品及其研究现状进行充分调研的基础上,比选出闭孔珍珠岩、聚丙烯纤维等9种材料作为本次高性能泡沫混凝土研制的基本原料；采用正交试验方法,研究了各种原材料对泡沫混凝土的密度、吸水率、抗压强度、劈裂抗拉强度等一系列基本性能的影响,试验结果显示：泡沫、闭孔珍珠岩和纤维含量是影响泡沫混凝土各项性能的最主要的几个因素。并根据正交试验的结果,优选出一种泡沫混凝土配方,重点对其保温性能和冻融特性进行研究,开发出兼具轻质、保温、抗冻、抗裂和抗震等功能,特别适合于寒区工程保温层及抗震层使用的泡沫混凝土。在此基础上,通过数值分析研究了其在寒区隧道中的保温效果。该产品的研制,使寒区隧道保温设计与抗震融为一体、两者兼得。(6)结合西藏嘎隆拉隧道的工程实际,设计并实施了多项现场试验,研制了隧道远程无线监测及健康诊断系统针对西藏嘎隆拉隧道地处喜马拉雅断裂带、海拔高、气温低、雨量极其丰富、进出口两端气候截然不同等特点,在隧道现场埋设了一大批监测仪器：温度传感器、渗压计、土压力盒、钢筋计、混凝土应变计和地震动加速度计；并借助移动通信GPRS技术,研制了远程无线健康诊断系统,实时监测隧道围岩和结构的温度分布、地下水渗流特征以及结构受力状况。该项研究工作,解决了传统监测方法无法在自然环境极其恶劣条件下开展、很难定时定量采集数据和长期监测需要花费大量人力、物力的难题。不仅为嘎隆拉隧道的施工与维护提供了决策依据,为寒区隧道积累了大量宝贵的技术数据,也为类似寒区隧道工程的长期监测与稳定性预测提供了新的方法。(7)确定了嘎隆拉隧道防寒保温材料的类型、厚度、安装位置和设防长度,得到了极端气候条件下嘎隆拉隧道围岩冻胀力大小,并对其在长期冻融循环荷载作用下的稳定性进行了分析利用前面得到的理论和试验研究成果,研究了隧道进出口端保温材料的类型、厚度、安装位置和设防长度对防寒保温效果的影响,分析了极端气候条件下嘎隆拉隧道围岩冻胀力的特征,并对隧道在长期冻融循环荷载作用下的稳定性进行了探讨。研究结果表明：1)在嘎隆拉隧道进口端600m、出口端400m范围内,二衬表面敷设6cm厚的聚酚醛保温材料,可以有效的防止嘎隆拉隧道衬砌和围岩发生冻融破坏；21极端气候条件下隧道围岩的最大冻胀力达到了1.6MPa；3)冻融循环对隧道衬砌受力影响较大。该项研究工作,既回答了隧道设计和现场施工人员所关心的几个主要问题,又使得本文前面得到的理论和试验研究成果接受了实践的检验。更多还原

【Abstract】 Combining with the international frontier issues on freeze-thaw damage, cold-proof and thermal insulation in the construction of tunnel engineering in cold region with high altitude, Galongla tunnel which is an important part of Za-mo highway in Tibet is studied in this paper. The mechanism of frost heave for rock tunnel and related insulation technology are studied. The thermo-hydro-mechanical-damage (THMD) coupled model of rock tunnel in cold region under the ventilation condition is established. Researches on the related theoretic model and application technology are done with laboratory test, theoretic analysis, numerical simulation and field measurements. A method is proposed to do the stability analysis of tunnel in cold region with high altitude under frost heaving force and the related reasonable cold-proof measure is presented. There are two significances. Firstly, the THMD coupled model of tunnel in cold region under the ventilation condition is established, which is a theoretic extension of mechanism of frost heave for rock tunnel in cold region. Secondly, a pioneering work is done on the optimum design for tunnel support structure in cold region and the establishment for reasonable cold-proof measures. The conclusions of this study are list as follows.(1) The controlling equations for thermo-hydro coupled model of low-temperature rock mass considering phase change are established and a new method is proposed for calculation of thermal conductivity coefficient of geotechnical material considering the phase change under low temperature.According to the basic law of water flow and heat transfer in rock mass under freezing-thawing condition, the controlling equations for thermo-hydro (TH) coupled model of low-temperature rock mass considering phase change are established based on the theories of continuum mechanics, thermodynamics and segregation potential. These equations include not only the effect of heat conductivity, latent heat of phase change and the seepage velocity on temperature distribution but also the effect of water flow in pore resulted by Soret effect and segregation potential on seepage velocity and seepage pressure distribution. And the total bi-directional coupling between seepage field and temperature field is realized. Compared with the famous TH coupling laboratory test conducted by Mizoguchi et. al., the presented TH coupled model is verified and the reasonability of determination of related material parameters are proved. Meanwhile, the systematic summarizations are done to the related thermodynamic parameters for the TH coupled model. For geotechnical material, there are many pores and the unfrozen water still exists when the temperature is below 0℃. Combining with the above characteristic and aiming at the shortage of the three current methods for calculating the heat conductivity coefficient of geotechnical material, a new method is proposed to calculate the heat conductivity coefficient of geotechnical material with low-temperature considering phase change based on random mixed model (RMM). Through the comparison with Mizoguchi’s experiment results, the new method is verified.This model is an extension of the current HM coupled of low-temperature rock mass considering phase change, and provides a new method to determine the heat conductivity coefficient of rock mass.(2) Considering the effects of air temperature and humidity, the turbulence model of air-flow field in tunnel is established and the heat exchange law between surrounding rock and air-flow field in tunnel is studied.Based on the theories and methods of hydrodynamics, heat-transfer and aerodynamics, some researches on ventilation in subway and building energy efficiency are lead in to establish the turbulence model of air-flow field considering the effects of air temperature and humidity. Based analysis of current research on turbulence numerical simulation method and heat exchange law between air and surrounding rock, the proposed turbulence model is adopted and a numerical simulation for Baly’s laboratory experiment on mixed convection with reduced scale model is done. Comparing with the experiment results and numerical results from Ma et.al., the proposed turbulence model is verified and its advantages are presented. Based on the above studies, the numerical analysis is done to study the effects of air temperature, air humidity and air speed on temperature distribution of surrounding rock in tunnel. It is concluded that:air temperature and air speed are two important factors which significantly affect the temperature distribution of surrounding rock in tunnel. In contrast, the effect of air humidity on temperature field is much smaller.The turbulence model is an extension research on temperature field of surrounding rock in tunnel in cold region and can be applied to the related ventilation numerical simulation such as ventilation of subway, fire modeling, building energy efficiency, indoor environment and so on.(3) A damage factor is proposed to consider the freezing-thawing effect in rock and the damage constitutive model considering the freezing-thawing is presented to describe the stress-strain relationship of surrounding rock for Galongla tunnel in Tibet.The freezing-thawing laboratory test, uniaxial compression test and triaxial compression test are done with the samples from Galongla tunnel in Tibet. The failure forms, strength, deformation and degradation characteristics of rock under different freezing-thawing condition are analyzed. It is concluded that:the main failure form of rock under uniaxial compression is splitting failure and that under triaxial compression is shear failure. The strength decreases with the increasing of numbers of freezing-thawing. The axial strain corresponding to the peak stress increases with the increasing of confining pressure and numbers of freezing-thawing. Based on the above researches, a damage factor is proposed to consider the freezing-thawing effect in rock and the damage constitutive model considering the freezing-thawing is presented to describe the stress-strain relationship of surrounding rock for Galongla tunnel in Tibet.With this model, the damage characteristic of rock in the process of freezing-thawing is described and a foundation is provided to reveal the mechanism of freezing-thawing damage for engineering rock mass.(4) The THMD coupled model for tunnel in cold region under ventilation is established.The THMD coupled model for tunnel in cold region under ventilation is established, considering the effect of volume strain on temperature and seepage field of surrounding rock and the effect of temperature gradient, seepage pressure and frost heave pressure on mechanical field. Besides three traditional controlling equations for THM coupling (energy conservation equation, mass conservation equation and balance equation), there are turbulence equations considering the effects of air temperature, air humidity and air speed in tunnel in the proposed model. Based on the above study, a numerical simulation is done to model the frost heave process of a pipeline engineering in cold region. Compared with the field measurements, it is concluded that:the frost heave phenomenon caused by temperature variation in surrounding rock can be described well and truly with the proposed model.Based on the THM coupled theory, the proposed model is a new exploration on mechanism of frost heave of rock in tunnel in cold region under complex ventilation condition. And this model is much closer to the actual situation for tunnel engineering in cold region.(5) A high-performance foamed concrete is designed. Its insulation properties and degradation characteristics under freezing-thawing are studied through laboratory test and the numerical analysis is done to study the insulation effect in tunnel in cold region.Aiming at the characteristics of tunnel in cold region and based on the investigation of foamed concrete products,9 types of material are chosen to be the basic materials of the designed foamed concrete such as obturator perlite, polypropylene fibers and so on. With the orthogonal test, the effect of each basic material on performance of foamed concrete is studied. The results show that the contents of foam, obturator perlite and polypropylene fibers are the main factors which affect each characteristics of foamed concrete. According to the orthogonal test results, the optimal formula is established to make up a high-performance foamed concrete. Its insulation property and degradation characteristics under freezing-thawing are studied particularly. The experimental results show that this foamed concrete is suitable for application to the insulation layer and anti-seismic layer in engineering in cold region which has the characteristics of lightweight, cold-proof, crack resistance and anti-seismic. Based on the above research, the insulation effect in tunnel in cold region is studied by numerical simulation.With this foamed concrete, the design of insulation and anti-seismic of tunnel in cold region are integrated together.(6) Combining with the Galongla tunnel engineering in Tibet, many field tests are done and a remote wireless monitor and health diagnose system in tunnel is presented.There are many characteristics in Galongla tunnel which locates at the Himalaya fault zone in Tibet, such as high altitude, low temperature, large rainfall and different climate at the entrance and exit of tunnel. Aiming at those characteristics, many monitoring equipments are installed in situ such as temperature sensor, osmometer, pressure cell, steel bar meter, concrete strain gauge and Seismic accelerometer. With GPRS technology, a remote wireless health diagnose system is designed to monitor the temperature distribution, underground water seepage and stress status of structure and surrounding rock in tunnel.With this monitor system, the measurements can be done under any severe environment condition and cost less resources compared with those traditional monitor methods. The basis is provided for construction and maintenance of Galongla tunnel and many precious technical data are provided for tunnel in cold region. A new method is proposed for stability prediction and long-term monitor of tunnel engineering in cold region.(7) Aiming at Galongla tunnel, the material type, depth, location and length for cold-proof and insulation are determined and the frost heave force of surrounding rock in an extreme climate is obtained. The stability analysis of tunnel under long-term freezing-thawing cycle is done.With the above theoretic and experimental results, the length of insulation material near the entrance and exit of tunnel and the frost heave force in an extreme climate in Galongla tunnel are studied. The stability analysis of tunnel under long-term freezing-thawing cycle is done. It is concluded that:1) 600m far from the entrance of tunnel and 400 m far from the exit of tunnel, the application of insulation material with a depth of 6cm at the surface of secondary lining can prevent the lining and surrounding rock from freezing-thawing damage effectively for Galongla tunnel.2) the frost heave force of surrounding rock of tunnel in an extreme climate reaches to 1.6MPa.With this part of work, the above theoretic and experimental results are applied to an actual projects and are verified.更多还原