【作者】 汤国璋；

【导师】 王星华；

【作者基本信息】 中南大学 ， 岩土工程， 2005， 博士

【摘要】 针对青藏铁路昆仑山隧道工程中的两个关键问题——多年冻土隧道工程的开挖与衬砌矛盾和昆仑山隧道渗漏水特征分析及相应的治理方案展开研究,首先介绍了工程背景,以热力学理论为基础,采用有限元技术对不同模型进行数值模拟;通过施工温度场监测,形成了昆仑山隧道工程开挖施工控制与预报系统;通过昆仑山隧道洞内排水沟流量测试、连通试验、地温及水位观测,阐明了昆仑山隧道渗漏水特征,同时也验证了移动边界计算模型的正确性,而移动边界计算模型的引入又从理论上解释了昆仑山隧道形成这种渗漏水特征的原因。 昆仑山隧道的开挖与衬砌: 1) 通过对昆仑山隧道自然环境特征分析,初步把握了昆仑山隧道工程的自然气温规律,为整个隧道工程的施工和研究提供了依据。 2) 通过对施工环境温度场的监测和数理统计分析,第一次提出了分区温度场适应不同工序作业的理念,解决了多年冻土隧道工程开挖与衬砌的矛盾,极大地改善了洞内的作业环境,且将施工对多年冻土环境的热扰动降到最低。 3) 根据昆仑山隧道工程实际情况建立有限元模型,对隧道不同开挖过程进行了数值模拟,以发现可能存在的稳定问题,从而选取了合理的隧道开挖方案。 4) 根据工程实际情况选取了瞬态传热分析有限元模型和边界条件,对围岩状态进行了数值模拟。结合施工安全的需要,将昆仑山隧道的开挖过程分为四个阶段,并在此基础上建立了第一个多年冻土隧道工程施工控制与预测系统,成功地指导了昆仑山隧道工程的开挖与衬砌施工。 昆仑山隧道渗漏水特征分析: 1) 重新定义了移动边界的概念,将其增加新的内涵,并提出了产生移动边界特征的充要条件,首次揭示了流动的热载体(水)对多年冻土热融蚀作用远远大于静态水对多年冻土的热融蚀作用的原因,为工程界进一步认识冻土提供了新的理论依据。 2) 根据移动边界的定义,建立了移动边界特征计算模型,并在通用商业有限元程序的基础上,编写了自开发模块,实现了移动边界特征计算程序化。讨论了具有移动边界特征的多年冻土(岩)融化速度的影响因素,更多还原

【Abstract】 Research on two key points of Kunlun mountain tunnel of Qinghai-Tibet railway, which are the contradiction of excavation and lining of tunneling in permafrost region and the analysis of water seepage from Kunlun mountain tunnel and corresponding treatment, has been done. The engineering project is introduced firstly. Finite element method (FEM) is applied to simulate different models on the basis of thermodynamic theory. The system of construction control and prediction for excavation of Kunlun mountain tunnel is built up by site-monitoring temperature of wall rock. The water seepage features are presented by tests of ditch flux of the tunnel and ground temperature and ground water table and connectivity, and the validity of computational model of moving boundary is verified at the same time. The application of the computational model of moving boundary theoretically explains why water seepage features of Kunlun mountain tunnel are formed. 1. Excavation and lining of Kunlun mountain tunnel1) The climate law around the tunnel is got for research and construction of the tunnel by analysis of the climate around the tunnel.2) The features of site temperature are got for the analysis of wall rock stability of a tunnel in permafrost region and choosing and controlling different temperature fields for excavation and lining of the tunnel by statistical analyses of climate and construction temperature at Kunlun mountain tunnel. The fractional temperature fields are presented firstly for different programs during construction of tunnel in permafrost region. So construction environment is greatly improved, and the disturbing of tunneling to permafrost is limited to minimum.3) The FEM is applied to simulate different excavation to find probable ground stability by the strength and deformation of wall rock on base of geologic feature and geohydrologic condition of Kunlun mountain tunnel, so a suitable excavating method is selected.4) A finite element model is selected to do a transient heat transfer analysis of wall rock on the base of Kunlun mountain tunnel. Construction process is divided by four phases for fulfilling construction safety. Then a system ofconstruction control and prediction is firstly established to guide construction of Kunlun mountain tunnel. There is no record of tunneling technique about it in permafrost region.2. Analysis of water seepage from Kunlun mountain tunnel1) Moving boundary is redefined, and the essential factors are presented. It is firstly discovered that the erosion of fluid flow to permafrost is far great than that of still water to permafrost. A new method is presented to further understand frozen soil.2) A suitable computational method is created to calculate a thawed depth with moving boundary property. Some programs are made on the basis of a popular finite element program to perform computing a thawing depth with moving boundary property. The factors influencing a thawing depth are discussed, and critical damping distance is the key factor. The program is used to simulate different models. The method theoretically explains the reason why the water seepage features of Kunlun mountain tunnel form.3) The relationship between water seepage distribution and topography is analyzed to find that one of water seepage features is that water seepage distributes under the valleys over the tunnel.4) It is testified by connectivity test that water seepage from the tunnel comes mainly from surface water of No.l and No.2 valleys, and seepage runoff exists between the tunnel and the bottom of two valleys.5) The results of analysis of ground temperature and geohydrologic condition of No.2 valley in Oct to Nov 2003 and Mar to May 2004 shows that an unfrozen ground water runoff exists between the tunnel and the bottom of No.2 valley along the valley at least, and that tunneling affects on permafrost around the tunnel to a certain extent.6) From the analysis of the relationship between water seepage distribution and topography of Kunlun mountain tunnel to the analysis of connectivity test, and the analysis of ground temperature and ground water table observation, the water seepage behaviors of the tunnel and fit treatments are presented.更多还原