青岛地区粉质粘土动力特性及其与地铁隧道结构动响应研究

发布时间：2018-06-16 22:39

本文选题：青岛地铁 + 隧道　；参考：《青岛理工大学》2014年硕士论文

【摘要】：近十多年来,随着城市化进程的加快,城市人口、城市交通地域规划和城市生态环境都面临巨大的压力。在大力改善地面交通的同时,城市地下空间的开发和利用已成为众所关心的热点。本文以青岛正在兴建的地铁为研究对象。青岛地铁在地下穿越不同的地质土层，其中拟建的地铁一号线在城阳区出现穿越第四系上更新统冲洪积粉质粘土层（Q3al+pl）段。我们通过对青岛第四系冲洪积粉质粘土进行室内动三轴试验，研究其动力特性。在试验得到第四系上更新统冲洪积粉质粘土相应动参数的基础上，对青岛地区穿越第四系上更新统冲洪积粉质粘土地质类型的三种不同形状地铁隧道,应用ANSYS软件对其进行动响应分析。主要研究内容及其研究成果有： 1.青岛地区第四系上更新统冲洪积粉质粘土动力特性的研究。对青岛地铁线路下的第四系上更新统冲洪积粉质粘土进行室内动三轴试验，得到该土的动应力-应变关系、动弹性模量与围压的关系、动剪切模量与动剪应变的关系、初始动弹性模量Ed0的取值范围、起始动剪切模量Gd0和最大动剪应力y与轴向固结应力的关系、阻尼比与轴向固结应力的关系及阻尼比的取值范围等一系列动力特性规律。具体研究成果有： (1)青岛标准层序第十一层第四系上更新统冲洪积粉质粘土的动应力-应变关系符合双曲线模型，并且动弹性模量的倒数1/Ed和动应变d之间近似为直线关系，得到不同围压下1/Ed和d的拟合直线关系式。 (2)土的动弹性模量随动应变的增大而减小，，随围压的增大而增大。土的动剪切模量随动剪应变的增大而减小。得到初始动弹模Ed0的取值范围为31-48MPa。 (3)发现土的起始动剪切模量Gd0和最大动剪应力y与轴向固结应力间均有良好的幂函数关系，并通过试验数据拟合得到幂函数关系式：Gd0=1.19(Kc3c)0.483，y=1.304(Kc3c)0.582。 (4)固结围压3和固结比Kc对阻尼比的影响较小,阻尼比随剪应变γd的增大而逐渐减小，且当γd接近0.002时阻尼比稳定于0.01。 2.介绍动力有限元法分析地下结构动力问题的理论和模拟计算步骤以及ANSYS基于有限元理论的弹塑性DP模型。 3.确定列车振动荷载。根据前人经验和现有研究成果用人工激励函数来模拟列车振动荷载，得到列车振动荷载随时间变化的时程曲线。 4.在大型通用有限元分析软件ANSYS上建立三种不同形状隧道结构动力有限元模型，应用粉质粘土动力特性试验结果和青岛地铁1号线勘察资料，对隧道体系从开挖到施加车辆振动荷载进行数值模拟，得到隧道结构的内力和动响应。通过对隧道内力和动响应的分析得出以下结论： (1)在粉质粘土层中，圆形地铁隧道受力最合理，建议拟建的地铁1号线穿越粉质粘土层隧道采用圆形衬砌，应用盾构技术。 (2)列车振动荷载作用下，不同形状的衬砌动响应内力变化较小，所以列车振动荷载并不是影响隧道结构稳定与安全性的主要因素。
[Abstract]:In the last more than 10 years, with the acceleration of urbanization process, urban population, urban transportation regional planning and urban ecological environment are facing enormous pressure. While improving the ground traffic, the development and utilization of urban underground space has become a hot topic of concern. This paper takes the subway being built in Qingdao as the research object. The Qingdao subway is the research object. In the underground crossing different geological soil layers, the proposed Metro Line 1 appears in the Quaternary upper Pleistocene alluvial silty clay layer (Q3al+pl) section in Chengyang area. Through the laboratory dynamic three axis test of the Quaternary flushing silty clay in Qingdao, the dynamic characteristics of the quaternary system are studied. On the basis of the corresponding dynamic parameters of the clay, the response analysis of three different shapes of subway tunnels of the Quaternary upper Pleistocene alluvial silty clay in the Qingdao area was analyzed by ANSYS software. The main research content and the research results were as follows:
1. study on the dynamic characteristics of the alluvial silty clay in the Quaternary upper Pleistocene in the Qingdao area. The dynamic stress-strain relationship of the Quaternary upper Pleistocene silty clay under the Qingdao subway line was tested, and the relationship between the dynamic stress and strain, the relationship between the dynamic elastic modulus and the confining pressure, the relationship between the dynamic shear modulus and the dynamic shear strain, and the initial dynamic elasticity were obtained. The range of the value of the modulus Ed0, the relationship between the initial dynamic shear modulus Gd0 and the maximum dynamic shear stress y and the axial consolidation stress, the relationship between the damping ratio and the axial consolidation stress and the range of the damping ratio, and so on. The specific research results are as follows:
(1) the dynamic stress-strain relationship of the alluvial silty clay in the upper Pleistocene of the eleventh layer of the Qingdao standard sequence is in accordance with the hyperbolic model, and the reciprocal 1/Ed of the dynamic elastic modulus and the dynamic strain D are approximately linear, and the fitting linear relation of 1/Ed and D under different confining pressures is obtained.
(2) the dynamic elastic modulus of the soil decreases with the increase of the dynamic strain, and increases with the increase of the confining pressure. The dynamic shear modulus of the soil decreases with the increase of the dynamic shear strain. The range of the initial dynamic elastic modulus Ed0 is 31-48MPa.
(3) it is found that the initial dynamic shear modulus Gd0 and the maximum dynamic shear stress y have a good power function relation between the axial consolidation stress and the axial consolidation stress, and the power function formula is obtained by fitting the experimental data: Gd0=1.19 (Kc3c) 0.483, y=1.304 (Kc3c) 0.582.
(4) the influence of the consolidation confining pressure 3 and the consolidation ratio Kc on the damping ratio is smaller, and the damping ratio decreases gradually with the increase of shear strain gamma D, and the damping ratio is stable when the gamma D is close to 0.002.
2. introduce the theoretical and simulation steps of dynamic finite element method to analyze the dynamic problems of underground structures and the elasto-plastic DP model of ANSYS based on finite element theory.
3. the vibration load of the train is determined. According to the previous experience and the existing research results, the artificial excitation function is used to simulate the train vibration load, and the time history curve of the train vibration load changes with time is obtained.
4. the dynamic finite element model of three different shape tunnel structures is established on the large general finite element analysis software ANSYS. The dynamic characteristics test results of the silty clay and the survey data of the Qingdao subway line 1 are used to simulate the tunnel system from excavation to the vibration load of the vehicle, and the internal force and dynamic response of the tunnel structure are obtained. The following conclusions can be drawn from the analysis of tunnel internal force and dynamic response.
(1) in the silty clay layer, the force of the circular subway tunnel is most reasonable. It is suggested that the proposed subway line 1 pass through the circular lining in the tunnel of the silty clay layer and apply the shield technology.
(2) under the action of the vibration load of the train, the internal force of the dynamic response of the lining of different shapes is less, so the vibration load of the train is not the main factor affecting the stability and safety of the tunnel structure.
【学位授予单位】：青岛理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U231.1;U452.11

【相似文献】