【作者】 丁祖德；

【导师】 彭立敏； 施成华；

【作者基本信息】 中南大学 ， 土木工程， 2012， 博士

【摘要】 随着我国高速铁路建设的快速发展,必然会出现越来越多穿越软弱地层的高速铁路隧道。为了满足高速列车运行的高标准,对隧道底部基岩的动力稳定性和衬砌结构的安全性提出了更高的要求,高速铁路隧道结构动力学问题日益突出。本文针对高速铁路隧道建设中亟需解决的软岩条件下隧道动力学问题,依托国家重点基础研究发展计划973项目(2011CB013802)、国家自然科学基金项目(50808176)和铁道部科技开发计划项目(2008G031-17),采用理论分析、室内试验以及数值计算相结合的方法,系统地研究了列车振动荷载作用下高速铁路隧道基底软岩的动力响应、损伤特性和动变形累积过程及发展规律,深入分析了基底状况对高速铁路隧道衬砌结构受力特性及长期性能的影响。主要研究内容与成果如下：(1)基于弹塑性理论和损伤理论,建立了混凝土和软岩的损伤演化方程,将损伤引入到双曲线型Drucker-Prager准则中,构建了考虑混凝土和软岩刚度下降和强度劣化的弹塑性损伤模型,推导了相应的本构积分算法迭代格式,利用ABAQUS有限元软件的UMAT子程序完成了模型的程序开发,并结合已有的试验结果验证了模型的有效性。(2)研制了能考虑地下水渗流和动载耦合作用的围岩循环三轴试验系统,通过多工况的软岩、软基岩与混凝土构件的循环三轴试验,确定了其累积变形规律及不同因素的影响程度,建立了列车振动荷载长期作用下的软岩塑性累积变形预测模型。试验结果表明：富水软岩不可逆变形随着动应力、静偏应力的提高而增大；随着加载频率的降低而增大；随着围压的增大而变大；地下水条件以及基底状况对软岩的动变形特性影响显著。(3)采用开发的混凝土和软岩弹塑性损伤模型,系统地探讨了隧道底部基岩在不同行车速度和隧道底部结构型式下的动力响应、动力损伤分布特征及发展规律。结果表明：隧道列车振动的影响深度约为基底以下5m范围。行车速度的改变对隧道底部基岩加速度的影响最大,增加仰拱厚度的减振效果不如改变仰拱矢跨比的效果明显；仰拱厚度的改变对基岩动应力的影响最大；随着仰拱矢跨比的减小,结构逐渐变得扁平,致使基岩动应力和损伤值增大。(4)针对高速铁路隧道V级围岩及富水地段,系统分析了高速铁路隧道地基长期累积变形问题。研究得出：隧道地基的累积变形随着列车运行速度的增加有所增大,随着仰拱矢跨比和仰拱厚度的增大而逐渐减小。基底围岩是否积水软化对隧道的长期累积变形影响显著。本文中计算的各种行车速度、仰拱矢跨比和仰拱厚度下,高速铁路隧道地基工后沉降能满足高速列车长期运营对无碴轨道平顺度的要求。(5)采用动力有限元计算,研究了隧道底部基岩软化和基底脱空对隧道结构受力状态的影响；在分析损伤累积理论的基础上,提出了一种幂函数形式的非线性损伤累积准则,预测了高速铁路隧道衬砌结构的疲劳寿命,量化了基底状况对衬砌结构长期性能的影响程度和发展趋势,提出了改善高速铁路隧道使用寿命的措施。更多还原

【Abstract】 With the rapid development of high-speed railway construction in China, more and more high-speed railway tunnels which cross through soft ground are currently being built. In order to meet the high standards of high-speed trains running in the tunnel, more and more requirements were set for the dynamic stability of the bottom bedrock and the safety of the lining structure of the tunnel. Therefore, the dynamics of the high-speed railway tunnel structure have become increasingly prominent.According to the dynamical problems of the high-speed railway tunnel in soft rock conditions, the dynamic response, damage characteristics and the process of dynamic strain and the law of cumulative plastic deformation of the base soft rock are investigated by using methods as theoretical analysis, laboratory test and numerical calculation. The influence of the bed situation on the force status and the long-term performance of railway tunnel lining structure are further studied in this dissertation. The dissertation is granted from the Major State Basic Research Development Program of China(NO:2011CB013802), the National Natural Science Foundation of China(NO:50808176), and the Science and Technology Development Plan Project of the Ministry of Railways. The main research contents and conclusions are as follows:(1) Based on the elastoplastic damage theory, the damage equations of concrete and soft rock are established, and the damage evolution equations are derived respectively. By introducing the damage variables into the hyperbolic Drucker-Prager criteria, the elastoplastic damage models are constructed which can be taken into account the stiffness and strength degradation of concrete and soft rock. The constitutive integration algorithm of the damage models is derived, and the program development of the models is completed by using the UMAT subroutine in ABQUS finite element software. Comparing with the results of previous tests, effectiveness of the proposed models is verified. (2) A soft rock cyclic triaxial testing system is developed which can be considered the impact of confining pressure and groundwater seepage, the dynamic deformation tests of soft rock with the influence of dynamic stress, static deviator stress, vibration frequency, confining pressure and groundwater are carried out by using this system. The laws of dynamic strain of water-rich soft rock and the influence degree of various factors on the accumulative deformation are obtained, and the accumulated plastic strain prediction model has been established. The cumulative deformation law of the composite member with soft rock and concrete is studied by the dynamic tests under different combination state.The test results show that the irreversible deformation of soft rock increases with the increasing of dynamic stress, static deviator stress and confining pressure, reduces with the increasing the vibration frequency. It is affected significantly with the changing of the underground water condition and the bed situation.(3) Dynamic responses and damage characteristics of bedrock are analyzed systemically in different conditions, such as the train running speed, the types of tunnel base structure and so on.The results show that the influence depth caused by train vibration in tunnel is about5m below the basement. Compared dynamic stress response with acceleration response, the changes of train speed has most influence on bedrock acceleration, and the changes of invert arch thickness on dynamic stress. Changing the invert arch rise-span ratio is more efficiency than increasing the thickness of invert arch in the way of reducing vibration effect.(4) Taking the high-speed railway tunnel in V class surrounding rock in water-abundant ground as the research object, the long-term cumulative deformation behavior of the tunnel in soft bedrock is analyzed with the cumulative plastic strain prediction model.It can be concluded that the cumulative deformation of tunnel foundation has been increased with the increasing of train speed, the decreasing of invert arch rise-span ratio and thickness. It is affected significantly when the bedrock softening. The calculation results also indicate that long-term settlement of tunnel in soft bedrock is enough to meet the requirements of the smoothness of ballastless track.(5) The influence of the bed situation on the force status of railway tunnel structure is studied by using dynamic numerical method. Meanwhile, based on the damage cumulative theory, a power-type equation of the non-linear damage cumulative criteria is proposed to predict the fatigue life of high-speed railway tunnel structures in different condition. The influence of the bed situation on the long-term performance and development trends of the tunnel structure is further analyzed. And then, some effective measures are put forward to improve the life of tunnel.更多还原