【作者】 蒙晓莲；

【导师】 施仲衡； 张弥；

【作者基本信息】 北京交通大学 ， 道路与铁道工程， 2011， 博士

【摘要】 摘要：为了更好地满足线网规划、工程建设和运营的需要,广州市率先在国内采用了直线电机运载系统。与传统的运载系统相比,直线电机驱动地铁系统具有优良的动力性能和爬坡能力,线路的最大坡度可达80‰,最小曲线半径可以减小到80m。然而,直线电机驱动地铁系统带来选线灵活,减少隧道埋深,降低工程造价等众多优点的同时,也为其区间隧道的建设带来了一些新的挑战和问题,如开挖面的稳定问题、盾尾间隙的增大问题等。本论文以广州地铁4、5号线直线电机盾构隧道工程为背景,针对直线电机隧道大坡度和小曲线半径的显著特性,采用理论分析、数值计算、现场实测对比分析等方法,对小半径、大坡度线路条件下盾构隧道施工开挖面稳定性和管片受力相关问题进行了研究探讨。(1)以极限平衡理论为基础,考虑线路纵向坡度,引入Lagrange乘子,将土压力问题以变分学观点来描述,借助于极限平衡变分法以及求解问题的几何关系,将主动土压力和被动土压力的泛函极值问题转化为普通函数的极值问题,研究了盾构隧道施工工作面土体极限主动土压力和极限被动土压力的计算问题,分析了隧道周边土体参数对盾构开挖面支护压力的影响,讨论了不同条件下支护压力作用点位置的变化情况,进一步探讨了盾构迎坡掘进对开挖面极限支护压力的影响。(2)采用数值模拟计算方法,结合现场实际工程施工情况,研究了大坡度条件下盾构隧道施工工作面及周边地层的位移和应力的变化规律,分析了隧道纵坡大小对隧道周边地层不同方向的位移、洞周收敛位移、开挖面附近主应力、塑性区等的影响,并进一步探讨了盾构土仓压力、盾尾注浆效果等对地层变形及受力状态的影响。(3)采用ANSYS和FLAC3D联合建模进行计算的方法,对小曲线半径条件下盾构隧道施工引起的周边地层的受力和变形规律进行了研究,分析了曲线半径、不对称推力,盾尾注浆效果等因素对小半径盾构隧道施工的影响,同时探讨了曲线隧道盾尾间隙的计算方法,并按照现场实际施工的统计数据确定盾构的不对称推力,保证了计算结果的可靠性。(4)采用地层—结构计算模式,对大坡度、小曲线半径条件下盾构隧道管片衬砌的受力特征进行了研究,进一步分析了曲线半径、注浆方式、纵坡大小等对管片受力状态的影响。(5)从曲线段盾构掘进机的组成和掘进施工的特点出发,探讨了小半径条件下盾构隧道的轴线控制技术,隧道施工整体向外侧倾斜的控制技术等,提出合理的推力和掘进速度是盾构隧道施工安全的重要保证,通过工程实例分析,验证了小曲线半径条件下盾构隧道施工是能够保证安全的。更多还原

【Abstract】 ABSTRACT:To better meet the needs of network planning, project construction and operation, the liner motor traction transportation system is first adopted in Guangzhou City of China. Compared with the traditional traction transportation system, the linear motor-driven subway system has an excellent dynamic performance and grade ability, which means the greatest gradient of line can reach 80‰and the minimum radius can be reduced to 80m. Although the linear motor-driven subway system has a lot of advantages such as flexible election of line, reducing depth of tunnel, lowering project cost.etc, it also brought some new challenges and problems for its running tunnel construction, such as the stability of excavation face, the increasing gap of shield tail, and so on.This paper has a study and discussion on problems related with the Impact of Big gradient and curve in small radius on the stability of shield tunneling excavation face and the stress of segment through theoretical analysis, numerical calculation, on-site measure and comparative analysis, and so on, which takes Guangzhou Metro Line 4 and 5 with large gradient and curve in small radius shield tunnel project as background, aiming at distinct features of the linear motor-driven tunnel with large gradient and curve in small radius.(1) Based on the limit equilibrium theory, longitudinal gradient,and introducing the lagrange multipliers, the problem of soil pressure is described as calculus of variations view, which converts the functional extreme value problem of passive and active earth pressure into the extreme issues of general function through the limit equilibrium variation law and the geometric relations of solving problem. It makes a study of the calculation problems of the limit active earth pressure and limit passive earth pressure on the soil of the shield tunneling excavation face, analyzes the impact of soil parameters surrounding tunnels on the support pressure of the excavation face, discusses the position change of action point of support pressure under different conditions, and further explores the impact of the prop-setting grade construction method against to limit support pressure on excavation face.(2) By means of numerical simulation method, and in light of the actual on-site construction, the variation laws of stress and displacement of excavation face and surrounding stratums in shield tunneling under the condition of large gradient are studied in this paper, which analyzes the impact of the size of longitudinal slope on the displacement of surrounding stratums in different direction, convergence displacement, principle stress around excavation face, plastic zone,etc, and further explores the impact of pressure of the soil chamber and grouting effect in shield tail on the situation of stratums deformation and stress.(3) By ANSYS and FLAC3D joint modeling and calculating, this paper is to study the variation laws of stress and deformation of surrounding stratums induced by shield tunneling construction under the condition of curve in small radius, and to analyzes the impact of curve radius, asymmetrical thrust, grouting effect in shield tail on the construction of shield tunneling with small radius. At the same time, how to calculate the gap of shield tail in curve tunnel is discussed and the reliability of its result can be ensured by the asymmetrical thrust which is accordance with the construction site statistics.(4) By the stratum--structural calculation mode, the mechanic characteristics of shield tunneling segment lining under the condition of curve in small radius are studied in this paper, as well as the impact of curve radius, grouting method, size of longitudinal slope,etc. on the stress state of segment.(5) Based on the components of shield tunneling machine used in curved segment and the characteristics of tunneling construction, this paper is to discuss the axis controlling technologies under the conditions of small radius and overall lateral tilt during tunnel construction, and it points out that the reasonable thrust and driving speed are important elements to guarantee construction safety in shield tunneling. Finally,it is tested and verified through case study that it is safe to carry on shield tunneling under the conditions of small radius.更多还原