【作者】 刘畅；

【导师】 屈福政；

【作者基本信息】 大连理工大学 ， 机械设计及理论， 2012， 博士

【摘要】 土压平衡盾构机是国家基础建设、资源开发和国防建设急需的重大技术装备,被广泛用于地铁隧道、越江隧道、铁路隧道等工程建设中。密封舱压力平衡控制是土压平衡盾构核心技术之一,直接影响着隧道开挖面的稳定性、施工安全和效率、能量消耗等。但由于对密封舱压力测点观测值与开挖面支护压力之间的映射关系认识不清,难以为密封舱压力平衡控制提供合理、准确的依据,给盾构设计、施工、控制带来了极大的困难,严重地阻碍了土压平衡盾构机的国产化进程。针对这一问题,本文采用模型实验、土工试验、数值模拟技术相结合的方法,研究了密封舱压力分布规律和密封舱压力传递特性,给出了密封舱等效压力的定义与计算方法,提出了密封舱压力测点优化布置方法,为密封舱压力平衡控制提供理论依据。本文以Φ6.28m土压平衡盾构作为设计原型,搭建密封舱压力控制实验台,并进行实验台模拟真实的密封舱压力分布规律的可行性实验。通过在不同改性砂土中进行实验可以发现,实验台密封舱竖直和水平压力分布与工程中的密封舱压力分布规律一致,表明实验台可以模拟改性砂土流动过程,能为密封舱内压力场数值模拟方法的有效性验证提供详实的数据。在搭建密封舱压力控制实验台的基础上,通过模型实验验证离散元法模拟密封舱压力场的有效性。依据改性砂土的三轴实验数据,采取基于遗传神经网络的反演方法获取改性砂土等效离散元模型参数。通过反演得到的接触模型参数预测的三轴实验结果与实测数据基本一致,表明接触模型能够模拟改性砂土颗粒间的力学行为,反演方法是可行的和正确的。在此基础上,以密封舱压力控制实验台为原型,进行密封舱压力场离散元数值模拟研究。数值模拟结果与实测结果具有较好的一致性,说明离散元仿真模型是有效的,为进一步的密封舱压力传递特性研究和测点布置优化奠定了基础。基于离散元数值模拟方法,本文研究了密封舱压力传递特性,提出开挖面与密封舱隔板间的压力差计算公式。采用数值模拟方法研究沈阳某地铁标段施工的Φ6.28m土压平衡盾构密封舱压力传递特性,通过施工数据验证了密封舱压力传递特性是可以用于指导施工的。同时,通过改变密封舱几何模型和边界条件,研究了密封舱长度、隧道埋深、刀盘开口对密封舱压力传递特性的影响。结果表明密封舱长度、隧道埋深对开挖面与隔板间的压力差的影响很小,但是随着刀盘开口率的增大,开挖面与隔板间的压力差反而降低,两者成二次函数曲线关系,为密封舱压力的设定提供了理论依据。为了获得较为精确的密封舱压力控制依据,本文提出密封舱等效压力的概念与加权计算方法,建立密封舱压力测点布置优化的数学模型,给出了密封舱压力测点优化布置方法。以Φ6.28m土压平衡盾构为研究对象,基于密封舱压力数值模拟数据,采用模糊聚类分析与判别分析相结合的方法进行了压力测点布置优化研究。通过对比密封舱等效压力误差可以发现,加权算法获得的密封舱等效压力是准确的,密封舱压力测点优化布置方法是可行的,为土压平衡盾构机设计、密封舱压力控制提供理论基础。最后,对下一步的研究工作进行了展望和规划。更多还原

【Abstract】 The earth pressure balance shield (EPBS) is the important technical equipment for infrastructure projects, resource development and national defence. It has been widely applied in metro tunnel, crossing-river tunnel, railway tunnel and so on. The pressure balance control of working chamber is one of the core technologies. It directly influences on stability of tunnel face, safety and efficiency of tunneling construction, energy consumption and so on. However, due to lack of understanding on mapping relationship between observed values of pressure measurement points of working chamber and support pressure of tunnel face, it is difficult to supply reasonable and exact basis for pressure balance control of working chamber. This condition causes difficulties for design, construction and control of EPBS. Thus localization process of EPBS is hindered seriously. Aiming at this problem, in this work, by adopting the method of combining model experiment with geotechnical test and numerical simulation technique, pressure distribution law and pressure transfer characteristic of working chamber are studied, definition and calculation method of equivalent pressure of working chamber are presented, at the same time, optimal arrangement of pressure measurement points in working chamber is put forward. These works should provide theoretical basis for pressure balance control of working chamber.By adopting6.28m diameter EPBS as design prototype, The experiment table of pressure control of working chamber has been set up, and then feasibility test is carried through to simulate pressure distribution law of actual working chamber on this experiment table. Through experimentizing in different kinds of conditioned sand, we can find out that pressure distribution of vertical and horizontal direction of working chamber is consistent with pressure distribution law in engineering. This condition indicates that experiment table can simulate flowing process of conditioned sand and it also can provide exhaustive and real data for verifying validity of simulation method on pressure field of working chamber.Based on model experiment, validity of simulating pressure field of working chamber is verified through discrete element method (DEM). According to triaxial test data of conditioned sand, inversion method which is based upon back-propagation (BP) network and gentic algorithm is adopted to obtain equivalent parameters of discrete element model of conditioned sand. By back analyzing, contact model parameters are obtained. The triaxial test result which is predicted by these parameters is basically consistent with actual measured data. It indicates that contact model can simulate mechanical behaviour of particles of conditioned sand, and inversion method is feasible and correct. On this basis, by adopting experiment table of pressure control of working chamber as prototype, research of DEM on pressure field of working chamber is carried out. The results of the numerical simulation are better consistent with actual measured results. This shows that simulation model of DEM is impactful. It lays the foundation for farther reaserch on pressure transfer characteristic and optimal arrangement of measurement points of working chamber.The calculation formula of pressure difference between tunnel face and bulkhead of working chamber are presented. The pressure transfer characteristic of working chamber of6.28m diameter EPBS employed in a certain project of metro is studied by adopting numerical simulation method, and construction data verifies that the pressure transfer characteristic of working chamber can be used to guide construction. At the same time, through changing geometric model and boundary condition of working chamber, impact on pressure transfer characteristic of working chamber by length of working chamber, tunnel depth and cutter head open ratio is studied. The results show that length of working chamber and tunnel depth have little effect on pressure difference between tunnel face and bulkhead. However, with cutter head open ratio increases, instead, the pressure difference reduces. There is quadratic function curve relation between the both. This provides theoretics basis for pressure setting of working chamber.The definition and calculation method of equivalent pressure of working chamber are presented, and mathematic model of optimal arrangement of pressure measurement points is established, at the same time, optimal arrangement method of measurement points is presented. By selecting6.28m diameter EPBS as study object, according to data of pressure numerical simulation of working chamber, the study on optimal arrangement of pressure measurement points is carried through by using the method of combining fuzzy clustering analysis with discriminant analysis. Through contrasting equivalent pressure error of working chamber, we can find out that equivalent pressure obtained by weighted algorithm is more exact and optimal arrangement method of pressure measurement points is feasible. It should give a theoretical basis to design of EPBS and pressure balance control of working chamber.Finally, some suggestions for further research are given in this thesis.更多还原