【作者】 黄娟；

【导师】 彭立敏；

【作者基本信息】 中南大学 ， 桥梁与隧道工程， 2010， 博士

【摘要】 针对目前国内外对高速铁路隧道结构动力响应研究相对滞后,特别是对列车动载作用下隧道结构的损伤特性和疲劳性能研究严重不足的现状,本文以国家自然科学基金项目(50778178)为依托,以我国现行设计的典型双线高速铁路隧道结构为研究对象,采用理论分析、数值计算和模型试验的研究方法,系统地研究了衬砌结构在列车振动荷载作用下的动力响应和损伤特性,量化了衬砌结构的损伤程度,深入探讨了高速铁路隧道衬砌结构的疲劳寿命和破坏机理,为我国高速铁路隧道的合理设计与施工提供了重要参考依据。主要研究内容与成果如下：(1)在已有损伤模型的基础上,分别建立考虑初始损伤效应的混凝土单轴拉、压应力损伤方程及损伤演化方程,提出了拉、压应力损伤的具体组合模式,通过定义由拉、压应力损伤组成的双标量损伤变量来描述混凝土的材料特性；并将双标量损伤变量引入到经典的Drucker-Prager屈服准则中,采用非关联流动法则建立了混凝土材料的弹塑性损伤本构模型。(2)根据建立的混凝土弹塑性损伤本构模型,给出了损伤本构模型具体的数值算法和计算流程,包括弹性预测、塑性修正、损伤修正及应力修正；编制了混凝土弹塑性损伤本构模型的相应计算程序,并利用有限差分软件FLAC5.0所提供的二次开发程序接口实现了混凝土弹塑性损伤本构模型的数值分析程序化；采用开发的损伤本构模型对前人完成的混凝土试件疲劳破坏试验进行数值模拟,通过对比分析验证了模型的有效性,为损伤本构模型的实际工程应用奠定了基础。(3)针对我国现行设计的Ⅳ级、V级围岩条件下的双线高速铁路隧道标准断面(非加强型),采用开发的损伤本构模型系统地研究了衬砌结构的动力响应和损伤特性；根据提出的隧道结构振动评价标准,对衬砌结构在列车振动荷载作用下的动力响应进行了评价分析。结果表明：衬砌结构的动力损伤演化过程与其动力响应时程相对应；衬砌结构的动力响应和损伤量随列车速度的提高而增大；围岩条件对衬砌结构(特别是仰拱部位)的动力响应和动力损伤影响较为显著；衬砌动力损伤与初始损伤状态密切相关,初始损伤越大,列车振动引起的动力损伤越大,即结构新增损伤量越大。(4)采用模型试验研究手段,对V级围岩条件下的高速铁路隧道底部结构进行了三种加载频率(即列车速度)下的动力模型试验,重点分析了仰拱结构的受力特点以及仰拱动应力、动应变、动力系数、轨面累积沉降与加载频率(即车速)、加载次数之间的变化规律。试验结果表明：仰拱底部的环向应力和纵向应力主要表现为拉应力,环向应力较纵向应力大；仰拱动力系数存在方向性,仰拱环向动力系数明显较纵向动力系数大；仰拱各向应力、动力系数以及轨面累积沉降均随加载频率(即列车速度)的提高而增大；仰拱动应变、轨面累积沉降与振动作用次数大致存在对数增长关系。(5)基于数值分析和动力模型试验的研究成果,分别采用混凝土弯曲抗拉S-N疲劳方程和Miner线性疲劳累积损伤理论对高速铁路隧道衬砌结构的疲劳寿命进行了预测分析。预测结果表明：在本文计算条件下和预估的高速列车车流量条件下,Ⅳ级围岩条件下的高速铁路隧道结构满足基准期内(100年)的抗疲劳要求。对于V级围岩,当列车以300km/h的车速运行时,衬砌结构尚不满足抗疲劳要求。(6)从损伤累积理论的角度,对高速铁路隧道结构的累积疲劳破损机理进行分析,指出了引起隧道结构累积疲劳破损的主要因素,并提出了提高隧道结构使用寿命的具体措施。更多还原

【Abstract】 More and more high-speed railway tunnels are being built in our country, while the research on dynamic responses of high-speed railway tunnels is relatively lagging behind, especially the study on dynamic damage and fatigue properties of high-speed railway tunnels. In response to this shortage of research, this dissertation, supported by the National natural Science Foundation Project of China (NO.550778178), studies dynamic responses and damage characteristics of current double-track high-speed railway tunnels systematically by using methods such as theoretical analysis, numerical calculation and model test. The damage of linings is quantified and the analysis on fatigue life of high-speed railway tunnels, together with their damage mechanisms, is carried on. The main research contents and conclusions are as follows:(1) Based on the exiting damage models, the damage equations considering initial damage of concrete under uniaxial tensile stress state and uniacial compressive stress state are established respectively. Then a double-scalar damage variable combined with a tensile damage variable and a compressive damage variable is presented to describe the damage properties of concrete. By introducing the defined double-scalar damage variable into Drucker-Prager yield criterion, an elastoplastic damage constitutive model is proposed with a non-associated flow rule.(2) Specific numerical algorithm and calculation flow processes including elastic guesses, plastic corrections, damage modification and stress correction are designed for the proposed model. Corresponding calculation program is compiled as well. By means of the interface of finite difference software FLAC5.0, redevelopment is carried out to program the damage model. Through comparing the results of previous tests with their numerical results by applying the redeveloped damage model, effectiveness of the proposed model is verified.(3) Taking the current double-track high-speed railway tunnels (general type) inⅣorⅤclass surrounding rocks as research objects, dynamic responses and damage characteristics of linings are studied systemically with the redeveloped damage model. The results show that:the development process of dynamic damage coincides with the time history of dynamic responses; responses and damage of linings are significantly influenced by surrounding rock conditions and increase as train speed increases; dynamic damage of linings is closely related to the initial damage. The more initial damage, the more dynamic damage that caused by train vibration. (4) According to Similarity Theory, dynamic model tests under different loading frequencies, namely train speed, are designed and performed for bottom structures of high-speed railway tunnels. Not only are the stress characteristics, dynamic coefficient, dynamic strain of inverts and accumulative vertical displacement of rails emphatically analyzed, their relation with loading frequency and loading cycles are also discussed in details. The test results show that:the bottom of inverts is mainly in a tensile stress state and the circumferential stress is higher than the longitudinal stress; the circumferential dynamic coefficient is also larger than the longitudinal one; the stress, dynamic coefficient of inverts and accumulative displacement of rails increase as loading frequency and loading cycles increase. Furthermore, dynamic strain and accumulative displacement are logarithmically related to loading cycles.(5) On the basis of numerical and model test results, tensile fatigue equations from S-N curves of concrete and Miner linear damage cumulative theory are adopted to predict the life of high-speed railway tunnels. The calculation results indicate that under the given calculation conditions along with the estimated vehicle flow in this dissertation, the anti-fatigue performance of tunnel structures designed for IV class surrounding rocks is enough to meet the stability requirement during design reference period(100 years). But that forⅣclass surrounding rocks is not enough to meet requirement, if trains run through tunnels at a speed of 300km/h.(6) In terms of damage cumulative theory, the fatigue damage mechanisms of high-speed railway tunnel structures is explained in details. The main factors (those have great influence on the fatigue life of tunnels) are listed. Then, some effective measures to improve the serve life of high-speed railway tunnel structures are emphasized.更多还原