【作者】 王振飞；

【导师】 张顶立；

【作者基本信息】 北京交通大学 ， 地下工程， 2014， 博士

【摘要】 针对北京砂卵石地层大直径泥水加压平衡盾构适应性这一重要课题,采用颗粒离散元模拟、理论分析、室内试验及现场实测相结合的研究方法,对砂卵石地层中的盾构选型、盾构开挖面失稳破坏特征及影响因素、泥浆特性及其作用、盾构施工对周边环境的影响和盾构刀盘刀具的适应性等关键问题进行了系统研究,取得的主要成果如下：(1)采用PFC2D双轴数值试验及室内土工三轴试验得到了颗粒流细观参数与砂卵石土体宏观参数c、φ的关系,进而通过颗粒离散元模拟分析,揭示了盾构隧道开挖面及地层土体滑移和破坏的渐进性变化特征,描述了土颗粒的位移场演化规律,给出了土颗粒摩擦系数与地层变形之间的动态关系,在此基础上,系统阐述了泥水加压平衡盾构开挖面稳定性的基本原理。(2)在开挖面上形成良好的泥膜,对于维持开挖面稳定具有重要的作用,其中,泥膜厚度与强度对开挖面稳定影响最大,一定厚度和强度的泥膜是保证开挖面稳定的重要条件。基于泥浆作用原理,通过大量的泥浆试验,提出了适于北京砂卵石地层大直径泥水盾构的泥浆相对密度、粘度等特性参数；从渗透距离、极限渗流量、孔隙水压力以及泥膜抗渗性4个方面对3种类型泥浆的作用效果进行了分析评价,并对其适应性进行了分析。(3)现场实测数据表明,科学的刀盘刀具配置、合适的泥浆特性参数及合理的掘进参数条件下,泥水盾构对北京砂卵石地层具有良好的适应性,盾构施工引起的地层变形能够满足安全和环境影响控制的要求；基于实测数据和理论分析,建立了盾构掘进参数与地层变形之间的关系,论证了带压进仓换刀的安全性及其对周边环境的影响程度。(4)为了使大直径泥水盾构对北京砂卵石地层具有更好的适应性,提出了滚刀、撕裂刀、切刀等长短刀具的合理化及立体化配置方案,对致密砂卵石地层的刀盘刀具配置方案进行了专门设计；基于实测数据,比较分析了单刃滚刀与双刃滚刀的平均磨损系数,进而提出了砂卵石地层掘进过程中的刀具更换原则：每100-120m进行一次带压进仓检查并对磨损较大的刀具进行更换,每230-300m设置一个停机加固点进行刀具更换。更多还原

【Abstract】 In this paper, the adaptability of large-diameter slurry shield to Beijing sand and gravel soils was studied systematically and exhaustively through DEM simulation, theoretical analysis, laboratory test and field measurement. Based on this project, features and influenc factors of tunnel face instability, parameters determination of mud fluid properties, influences of shield tunnelling on neighboring environment, and adaptability of cutterhead were systematically studied, respectively. The main results are as follows:(1)The relationships between micro-parameters of PFC2D and macro-parameters c and φ of sand and gravel soils were obtained by means of PFC2D biaxial numerical tests and soil tri-axial tests indoor. Then the PFC numerical simulations (DEM) were conducted to obtain progressivity variation features of slide and failure in tunnel face and surrounding soils. The evolution laws of displacement field and dynamic relationships between friction coefficient of soils and ground deformation were also obtained. And on this basis, the fundamental principles of stability of tunnel face were stated systematically.(2) Forming fine filter cake on the excavation face is significantly important to maintain stability of the shield tunnel face. Thickness and adhesive strength of the filter cake are the most important factors. Filter cake with certain thickness and adhesive strength on the excavation face is vital to ensure stability of the excavation face. Through numerous slurry tests, based on action principle, the characteristic parameter which is applicable to large-diameter slurry shield to Beijing sand and gravel soils were proposed such as relative density and viscosity. In this paper, the effect and adaptability of3types of slurry were analyzed and evaluated from4aspects, including penetration distance, limit seepage flow, pore-water pressure and mud film impermeability.(3) According to field data, the slurry shield was of fine adaptability to Beijing sand and gravel soils, on the conditions of scientific configuration of cutter head, appropriate slurry parametersand reasonable tunneling parameters. Ground deformation caused by shield tunnelling can meet the safety and control requirements of environmental impact. Based on the field data and theoretical analysis, the relationship between the shield tunneling parameters and ground deformation were established. Moreover, the safety of change tools under compressed air condition and the impact on the surrounding environment were demonstrated.(4) In order to make large-diameter slurry shield has better adaptability to Beijing sand and gravel soils, the configuration of cutter head and cutter tool was designed specially. And a scheme in which disc cutters, ripper, scrape and other tools of different size were configurated rationally and three-dimensionally was put forward. Based on the field data, a comparative analysis about average wear coefficient between single-edged disc cutter and double-edged disc cutter was made, and then the principles of tool replacement during tunneling process for sand and gravel soils were put forward, which contain check inside the chamber under compressed air condition once every100～120m and replace badly worn tools; set a reinforced stop point every230～300m to change cutting tools.更多还原