成都地铁17号线卵漂石地层水文地质特征及空间分布规律

文章以地铁17号线一期工程为依托工程,针对成都富水卵漂石地层,采用地质调查测绘、探井、钻孔等方法,对成都砂卵石岩土体工程特性及分布规律进行研究,分析得出温江区域漂石含量较大,粒径多集中在20～40 cm,且局部地段富集,采用盾构法施工应充分考虑不均匀分布的高强度、大粒径漂石的影响,从而为该地区隧道的设计与施工提供地质依据。     

大粒径卵砾石地层盾构刀盘选型及适应性评价

大粒径卵砾石地层是北京地铁修建过程中开挖难度最大的地层之一,给土压平衡盾构施工造成了一系列的难题。刀盘是土压平衡盾构的重要构件之一,合理的刀盘结构型式是大粒径卵砾石地层土压平衡盾构高效、可靠运行的前提。为了找出适用于大粒径卵砾石地层的刀盘结构型式,以北京地铁九号线盾构工程为背景,开展大粒径卵砾石地层土压平衡盾构开挖原型试验,基于"北京地铁盾构施工实时管理系统"和"北京地铁建设安全风险技术管理体系"收集盾构关键施工参数,以现场掘进试验数据有基础,对盾构掘进效能、盾构关键参数地层适应性及刀具磨损情况进行了对比研究。研究结果表明:1)大粒径砂卵石地层辐条式刀盘适应性更好,掘进效率更高,对刀具的磨损控制更为有利;2)辐条式刀盘可适当增大开口率至55%~65%;3)大粒径卵砾石地层,辐条式刀盘比面板式土压力控制更加稳定;提高盾构掘进速度的同时,应注意盾构土压力的控制,合理的盾构推进速度应为20~60mm/min。     

土压平衡盾构遭遇孤石、漂石的处理方法

以山西中部引黄工程盾构施工区间为例,就其在掘进过程中突遇未探明的孤石、大直径漂石,造成了盾构卡机无法继续推进以及在原有盾构机选型和刀具配置均不能适用于坚硬孤石地层的情况,采用“地震散射+物探验证”的探测方法确定了孤石、漂石的位置,通过对比后选用了潜孔钻机密打孔的方式将孤石、漂石打成筛状。同时,通过更换刀具也增强了盾构刀盘对该种复合地层的适用性。运用上述处理方法后,盾构机顺利通过了孤石、漂石段,使隧道成功贯通。通过对比分析地震散射探测报告与验证取芯数据,证明了地震散射技术探测孤石、漂石分布状态和位置的有效性;通过对比盾构恢复推进前后的各项参数,证明了潜孔钻机密打孔是一种效率高、成本低、风险低的孤石、漂石处理方法,该方法也可为类似工程提供参考。     

高强度基岩爆破预处理泥水盾构掘进特征研究

泥水盾构在高强度基岩地层中掘进,盾构自身刀具无法有效破岩,采用基岩爆破预处理的控制钻爆法能严格控制破碎碴块体量,提高刀具破岩能力,但盾构施工过程中,掘进参数与岩石之间关系非常复杂。以台山核电站取水隧道为背景,对现场获得的工作数据进行挖掘,分析基岩爆破前后地层中盾构刀盘推力、刀盘扭矩及掘进速度的参数的选用特点。在此基础上,引入参数转换量FPI、TPI指数及比能进行研究,研究表明,未经处理基岩地层,岩石强度过高,刀盘推力先达到最大值,但切深很浅,扭矩很难发挥最大能力;经爆破处理后,基岩岩体受到不同程度破碎,盾构机推力及扭矩能有效发挥其功能,掘进效能提高。因此,在盾构机的工作负荷范围内,应依据基岩岩体破碎效果,调整刀盘推力和扭矩,使之更好地适应地层,力争达到高效安全的掘进目的。     

含砾粗砂岩地层双模盾构土压模式渣土改良技术

为了进一步提高双模盾构土压掘进模式对含砾粗砂岩地层的适应性,依托广州地铁7号线二期工程洪圣沙站-裕丰围站区间项目开展了渣土改良技术研究。首先优选渣土改良剂并测定其性能,然后根据二次改良试验结果提出合理的渣土改良参数,并通过实际应用效果验证了渣土改良参数的合理性。采用优选的改良参数时,刀盘扭矩系数和螺机扭矩系数均有所减小,有利于盾构掘进,但是由于刀具破岩效率受渣土改良影响较小,地层贯入指数变化较小。     

关于北京地铁复合地层盾构选型的分析

北京地铁9号线6标盾构隧道穿越地层为第三系强风化～中等风化粘土岩、砾岩及卵砾、圆砾层,局部为粉质粘土、细砂层。在隧道范围内随机分布有大粒径卵石和漂石,区间隧道大部分处于潜水层中,且需穿越310m宽的玉渊潭东湖。本文根据北京地区的各种情况对盾构机选型问题进行探讨。     

复杂地层地铁盾构施工技术研究

随着城市经济的高速发展,越来越多的城市都将地下交通网线作为解决交通拥挤的最为有效的手段,这亦使地铁盾构法施工在不断普及和高速发展的同时面临更大的挑战.盾构法施工将向大深度、急曲线、长距离、大直径的趋势发展，尤其是对含有较大漂石、砂卵石、砾石等河口沉积地层中的盾构隧道施工,将带来盾构机压力平衡、壁后注浆及纠偏、土体位移及地表沉降控制等困难,以及刀具磨损快等一系列技术和理论问题.     

砂卵石地层泥水盾构掘进地表沉降规律及影响因素研究

兰州地铁1号线迎门滩站—马滩站区间隧道首次在兰州粗粒径砂卵石地层中采用泥水平衡盾构法掘进,该区间全程穿越富水粗粒径砂卵石地层,需在富水砂卵石地层下穿黄河,地下水压力大,施工环境复杂,地表沉降控制难度大。以该区间泥水盾构掘进为研究对象,对泥水平衡盾构掘进引起的地表沉降规律进行理论及现场实测分析,结合盾构掘进参数的控制方式,分析此类粗粒径砂卵石地层掘进控制与地表沉降的关系。     

软硬不均地层盾构滚刀受力特性研究

针对软硬不均地层条件下,盾构刀具异常损坏严重的问题,基于理论分析,结合开展滚刀软硬不均地层破岩机理实验的方法,探索软硬不均地层条件下滚刀受力特性。从刀具受力变化规律入手,以优化刀具受力状态为目标,从定性的角度,指导软硬不均地层条件下盾构刀盘转速、推进速度等参数的选择,以提高刀具使用寿命,减少刀具因受力冲击而造成的异常损坏。     

大直径土压平衡盾构在复杂地层中的应用

以都江堰至四姑娘山山地轨道交通土建1标项目的都江堰站至永丰站地下区间和永丰站至蒲阳站区间为工程背景，针对土压平衡盾构穿越高富水、大粒径砂卵石复杂地层进行研究，论述盾构的选型，分析掘进过程中存在的刀盘磨损严重、刀具更换困难、扭矩过大等实际问题，得出相关规律，采取针对性优化措施，从而使得刀盘结构对富水大粒径砂卵石地层的适应性更强，减少换刀频次，提高施工效率，大幅度降低施工成本，为类似地层的盾构施工提供一定的借鉴和指导。     

Analysis on the damage behavior of mixed ground during TBM cutting process

Accurate prediction of rock cutting forces of disc cutters is especially significant for the design and construction of tunnel boring machine (TBM). Through the analysis of motion trajectory of TBM disc cutters, a three-dimensional model of rock breaking process of disc cutters is established. In terms of the rock strain which is resulted from the interaction between disc cutters and rock during the process of rock breaking, a three-dimensional cutting forces model is proposed with disc cutters set at certain parameters and in certain sizes. Subsequently, the equation of contacting forces between rock and disc cutter is derived. Moreover, a new method has been presented for the study of the rock breaking theory of the disc cutter and it also provides guidance for the design and application of TBM in tunnel excavation. The three-dimensional model for the rock breaking mechanism is used for predicting the cutting force for the situation of mixed ground.The damage field and the rock failure zone induced by disc cutter for mixed ground are also discussed in this study. In detail, the rock damage zones are divided into two parts, one is the left damage field which located in the outside of disc cutter. The other is the right damage field which located in the outside of disc cutter. The influence of the rock ground dip on the rock failure zone was also studied by parameter analysis.     

复杂岩石地层盾构掘进效能影响因素分析

基于现场掘进试验和岩石点荷载强度试验,对泥岩、砂岩交互地层条件下泥水盾构的掘进效能及其影响因素进行研究.利用现场采集的数据,运用回归分析的方法,主要分析盾构掘进效能与岩石强度、刀盘推力及刀盘扭矩的关系.研究成果表明,岩石强度越高,刀盘每转切深和掘进速率就越低,二者呈幂函数曲线关系;随着刀盘推力的增大,切深呈幂函数关系增加;而随着刀盘切深的增加,刀盘扭矩则呈线性增加.对比两种地层的掘进特性,相对而言,泥岩地层掘进效能较高,但需要较大的扭矩,而在砂岩地层掘进需要较大的推力才能获得理想的掘进效能.     

盾构隧道施工盘形滚刀推力分布规律研究

 盾构掘进时,刀盘由油缸推压到工作面上,滚刀与岩石之间产生相互作用。为研究各滚刀推力分布规律,分析影响滚刀与岩石相互作用的影响因素,指出掘进过程中滚刀推力分布主要与岩石刚度有关。假设滚刀与岩石弹性点接触,建立刀盘与岩石相互作用的三维弹性支点力学模型并进行了简化,运用有限元方法对其进行分析与比较。研究表明,刀盘上各滚刀的推力分布并不均匀,滚刀布置稀少处的推力较高,面刀推力均比边刀推力高出40%～60%。相同的刀盘形式,滚刀布置方式不同,其推力分布差异较大。最后,运用蒙特卡罗有限元方法,分析岩石刚度变化对滚刀推力分布的影响,岩石越软,滚刀推力分布越均匀;反之,滚刀推力分布的均匀性越差。在硬地层中掘进时,个别推力高的滚刀磨损严重,换刀频繁,影响了施工进度。因此,该部位的滚刀布置值得进一步研究。     

富水砂卵石地层地铁盾构施工若干问题及对策

成都地铁工程大规模穿越市域富水砂卵石地层,该地层具有地下水位高、卵漂石含量高和卵石强度高等“三高”特点。一号线前期大量出现刀盘刀具磨耗严重、换刀频繁、带压换刀失效、刀盘结泥饼等现象,严重制约了盾构的掘进效率。在回顾成都地铁一号线一期工程前期盾构选型和施工的若干问题的基础上,提出并总结了富水砂卵石地层盾构选型和配置的一些具体对策,包括:树立“排出为主,破碎为辅”的地层处治理念,调整刀盘和螺旋出土器的结构型式、刀盘开口率、刀具布置型式,改进同步注浆浆液配比,优化泡沫系统和搅拌系统,改进碴土改良系统等。成都地铁一号线一期工程中后期以及二号线一期工程的施工实践表明:以上调整是有效的,盾构换刀距离和盾构施工平均月进度都获得了显著提高。     

Theoretical prediction of wear of disc cutters in tunnel boring machine and its application

Predicting the cutter consumption and the exact time to replace the worn-out cutters in tunneling projects constructed with tunnel boring machine (TBM) is always a challenging issue. In this paper, we focus on the analyses of cutter motion in the rock breaking process and trajectory of rock breaking point on the cutter edge in rocks. The analytical expressions of the length of face along which the breaking point moves and the length of spiral trajectory of the maximum penetration point are derived. Through observation of rock breaking process of disc cutters as well as analysis of disc rock interaction, the following concepts are proposed: the arc length theory of predicting wear extent of inner and center cutters, and the spiral theory of predicting wear extent of gage and transition cutters. Data obtained from 5621 m-long Qinling tunnel reveal that among 39 disc cutters, the relative errors between cumulatively predicted and measured wear values for nine cutters are larger than 20%, while approximately 76.9% of total cutters have the relative errors less than 20%. The proposed method could offer a new attempt to predict the disc cutter's wear extent and changing time.     

自由面对滚刀破岩机制影响的数值模拟研究

为了研究自由面对滚刀破岩机理的影响,运用UDEC方法建立了滚刀贯切岩石的二维数值系列模型,对TBM滚刀破岩过程进行了仿真。分析表明：在合理的刀间距和贯人度情况下,破碎坑自由面的存在使裂纹扩展能耗降低,裂纹密度增大,起裂方式增多,容易实现体积破碎,提高滚刀破岩效率。     

不同围压条件下TBM刀具破岩模式的数值研究

为了研究不同围压条件下TBM刀具在掘进施工过程中的破岩机理,基于2-D离散单元法,利用UDEC仿真软件建立了双把TBM刀具侵入岩石的仿真模型。在此基础上设计了一组数值试验,成功地模拟出了不同围压条件以及不同刀间距下岩石裂纹生成,扩展和岩石破碎的全过程。仿真结果表明：TBM刀具作用下岩石存在四种基本的破碎模式,它们的出现与围压以及刀间距有关;破碎模式对刀具的破岩效率,岩石破碎块度均有影响;随着围压的增加,最优刀间距增大,但围压超过一定值后,最优刀间距反而减小。     

Opening the excavation chamber of the large-diameter size slurry shield: A case study in Nanjing Yangtze River Tunnel in China

Shield tunnel construction in a dense strata often encounters malfunction of shield-tunneling machine or abrasion of cutters. Accessing to an excavation chamber under compressed air is a main method to repair and replace worn cutters. And many safety issues such as stability of the excavation face were involved. However, the face stability due to opening an excavation chamber was not fully studied. To overcome this shortcoming, face support scheme and stability analysis were presented in a case history of opening the pressure chamber for a large-diameter (up to 14.93 m) slurry shield tunnel constructed underneath Nanjing Yangtze River. Since most of the damaged cutters were distributed along the edge of cutting wheel, only top 3 m of tunnel face within the chamber needed to be supported by compressed air, and remaining area would also to be supported by slurry pressure. A series of simple primary laboratory tests were carried out to design an optimum slurries mixing scheme to support the tunnel face as accessing to the pressure chamber in the project. The face stability was analyzed in terms of the pressure equilibrium (i.e., internal and external pressures) as well as three-dimensional numerical analysis by adopting properties of soils and filter cakes from laboratory tests. By injecting lower density slurry into the sand to form a stable infiltration zone, followed by using higher density slurry to create a filter cake at tunnel face, compressed air-support system could ensure face stability during maintenance of cutter wheel. The success of applying the mixed slurry and compressed air-support scheme in this project is valuable to shield tunnel constructions in similar ground conditions.     

简单复合岩体中TBM多滚刀破岩机理离散元分析

采用引入考虑胶结尺寸的微观接触模型的PFC^2D离散元软件,对全断面岩石掘进机（TBM）盘形滚刀作用下简单形式的复合岩体破岩机理进行数值模拟研究。进行了单滚刀、双滚刀和三滚刀作用下的复合岩体破碎过程的模拟。模拟结果表明：滚刀破岩过程可以分为三个阶段：加载阶段、卸载阶段和残余跃进阶段。通过双滚刀和三滚刀侵入复合岩体的推力-侵深曲线分析,软岩上的滚刀比硬岩上的滚刀进入各阶段稍慢,略有滞后;不同滚刀间的峰值法向推力相差较大,易造成滚刀磨损。对于花岗岩-绿片岩复合岩体,破岩时接触力链被岩体分界面分割,硬岩区胶结破坏数目较多,双滚刀、三滚刀侵入时易形成贯通裂缝;破岩效率由大到小为双滚刀效率、三滚刀效率、单滚刀效率,而且双滚刀能够将效率提高一倍左右。