围压对 TBM 滚刀破岩影响机制研究

穿越高大山体的隧道TBM施工不可避免地会遇到高地应力问题,研究地应力对TBM滚刀破岩机制和掘进效率的影响具有重大的工程价值和科学意义。通过理论分析和UDEC数值模拟技术对围压作用下滚刀破岩模式进行研究,发现围压对滚刀破岩过程影响比较复杂:围压对粉碎区深度和裂纹扩展区内滚刀作用方向的裂纹扩展起到抑制作用;而对围压作用方向的裂纹扩展有促进作用,表现为边裂纹的扩展范围会更大,扩展路径会更加平直,发展更加迅速,滚刀间岩片的形成更加容易。TBM现场掘进试验表明,地应力越高,围压作用越明显,TBM破岩更加容易,掘进效率会更高。从TBM滚刀作用下岩片形成的难易程度角度考虑,理论分析、数值模拟和TBM现场掘进试验都表明围压作用促进TBM滚刀破岩。     

围压对TBM滚刀破岩影响的数值模拟研究

采用一种新的无网格数值计算方法—广义粒子动力学法(GPD),研究了水平方向围压为0,5,10,15,20 MPa条件下,全断面隧道掘进机(TBM)滚刀的破岩过程及破岩模式,分析了围压对岩体可掘性的影响.得到:①围压的存在抑制中央裂纹的扩展;②随着围压的增加,赫兹裂纹的扩展方向发生偏转,与水平面的夹角变小;③相同贯入度下,随着围压的增加,滚刀法向力及其掘进指数均增加.利用GPD法分析了锦屏二级水电站隧道施工中,含节理的岩层中高地应力对TBM滚刀破岩的影响,成功模拟出高地应力下节理岩体的板裂化现象,得到高地应力能够使岩体产生板裂化促进滚刀破岩.     

贯入度与刀间距对TBM滚刀破岩推力的影响

针对目前盾构机在硬岩地层施工中经常遇到刀具选型、掘进速度慢及参数设定不确定等难题,本文以施工现场高硬度凝灰岩为岩样,进行了推力与贯入度和刀间距与破岩推力的试验。研究盾构两种常规滚刀的刀间距、掘进转速及贯入度的关系,为类似硬岩盾构施工提供试验基础和参考。     

多滚刀破岩时磨损状态对刀具破岩力的影响分析

在TBM掘进过程中,滚刀作为主要的破岩工具不可避免地会发生各式各样的磨损,但关于滚刀磨损后滚刀群中各滚刀受力特性变化的研究仍较为缺乏.通过ABAQUS软件对三滚刀顺序切削破岩过程进行模拟,对不同位置滚刀发生磨损后滚刀群中各滚刀的受力情况展开分析.结果表明,当三滚刀按顺序破岩时,首先进行切削的滚刀垂直力与滚动力越大,后进...     

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。     

复合岩体的TBM破岩机理数值模拟

为了指导TBM刀盘刀具的研制和不同地质条件下刀盘刀具的选型,TBM破岩机理的研究成为核心。在TBM滚刀的作用下,岩体中裂纹的生成、扩展和连接规律是深刻理解TBM破岩机理的前提,因此,TBM滚刀破岩机理的研究具有重要的工程应用价值。目前,TBM滚刀破岩机理的研究主要集中在单一岩体中,但在TBM施工过程中会遇到各种复杂的地质条件。笔者采用离散元方法,研究了复合岩体的破岩机理,复合岩体中岩片的形成不同于单一岩体,其裂纹的最终连接是由起裂于复合岩体交界面上的微裂纹的扩展,将两滚刀之间的赫兹裂纹连接,最终形成岩片。因此,在一定情况下复合岩体更有利于TBM隧道施工。     

基于HJC模型的盾构滚刀破岩能力研究及应用

为探明适用于济南地区不同地层条件下的盾构滚刀,文中基于HJC模型采用LS-DYNA对济南地铁R2线某盾构区间所选用的两种滚刀进行了动力学分析.结果表明刃宽为25mm的平刃滚刀适用于贯入度较大的施工条件,刃宽为22mm的圆刃滚刀在小贯入度情况下破岩效率更高.     

掘进机刀盘滚刀间距对北山花岗岩破岩效率的影响实验研究

掘进机（TBM）开挖隧道过程中,其刀盘上滚刀间距设计的合适与否关系着破岩效率的高低。由于岩石非均匀、非连续、各项异性的特性,使用数值模拟方法研究滚刀破岩过程存在局限性。现场掘进实验主要是针对特定的掘进机做出机械运行参数优化,无法研究不同刀间距对破岩的影响。全尺寸滚刀破岩实验可以人为调整刀间距,且实验中采用大体积岩石可以避免尺寸效应的影响,因此受到了广泛的关注。采用北京工业大学自制的机械破岩试验平台,安装17英寸（432 mm）盘形滚刀,选取尺寸为1000 mm×1000 mm×600 mm的北山完整花岗岩试样,进行了5组刀间距的线性切割试验。实验中采集滚刀三向力,分层收集岩片且对其进行称重。对不同刀间距作用下的平均法向力、平均滚动力和比能进行了分析研究。当贯入度较小时,刀间距对平均法向力和平均滚动力的影响都不明显,随着贯入度的增加,刀间距对平均法向力和平均滚动力的影响增加。对于所有的刀间距而言,增加贯入度会产生更多的岩片,但并不一定会提高破岩效率,对于北山花岗岩而言,当刀间距与贯入度的比值为30左右时,比能值最低,此时破岩效率最高。     

盾构盘形滚刀不同刀间距下破岩仿真研究

在考虑滚刀实际几何形状、滚刀与岩石的非线性材料特性基础上,建立了盾构机滚刀挤压破岩有限元三维模型,求解中对模型的特性参数、边界条件及时间步长等进行设置,以适用盾构机滚刀与岩石相互作用过程中的动态仿真或瞬态破岩,并对仿真结果进行对比分析。并得到双刃滚刀在破岩相互作用中刀具受力和岩石破碎规律,为以后盾构刀具在刀盘上优化配置提供了参考。     

评价岩石脆性指标对滚刀破岩效率的影响

 脆性是岩石重要的力学性质之一。岩石脆性与滚刀破岩效率密切相关,但目前还没有统一的用于评价滚刀破岩效率的岩石脆性指标。总结现有的35种脆性指标,将其分为基于强度、应变、应变能、硬度、莫尔包络线、特殊试验和其他等7种类型。为研究岩石脆性与滚刀破岩效率之间的关系,通过滚刀贯入试验,引入归一化比能概念,提出表征岩石脆性的新指标,重点研究基于强度和贯入试验的脆性指标与归一化比能之间的关系。试验结果表明：(1) 滚刀更难贯入高强度岩石;(2) 脆性指标B2和B4与归一化比能之间呈强烈的指数函数关系,随着脆性的增高,归一化比能降低,滚刀破岩效率增高,应优先选用脆性指标B2来评价滚刀破岩效率,其次是脆性指标B4;(3) 将单轴抗压强度约20 MPa定义为单轴抗压强度过渡值,滚刀不适宜切削单轴抗压强度小于20 MPa的软岩。试验结果对评价滚刀破岩效率时岩石脆性指标的选取具有一定的指导意义。     

Numerical modeling of the effects of joint orientation on rock fragmentation by TBM cutters

The performance of tunnel boring machines (TBM) highly depends on the fragmentation efficiency of the cutters. Many geological factors can influence the rock fragmentation process. In this study, a series of two dimension numerical modeling were performed using the discrete element method (DEM) to explore the effect of joint orientation on rock fragmentation by a TBM cutter. Results show that the joint orientation can significantly influence the crack initiation and propagation as well as the fragmentation pattern, and hence affect the penetration rate of the TBM. Such observations are also noted by laboratory and site studies. It also indicates that discontinuum-based DEM has the potential in simulating rock indentation and fragmentation by TBM cutters when rock joints are taken into consideration.     

TBM自重对围岩变形影响的数值模拟研究

为研究双护盾全断面隧道掘进机(TBM)自重对围岩变形的影响,基于FLAC3D有限差分软件,通过改变隧道的埋深与围岩条件,建立3种工况数值模型,并对每个工况分别进行了考虑TBM自重与不考虑其自重的数值模拟,以对比各种工况下有无TBM自重作用的隧道围岩纵向位移曲线(LDP曲线);研究了TBM自重对围岩变形的影响。模拟结果表明,TBM自重可抑制隧道围岩的径向位移,并随着开挖隧道的围岩等级升高、埋深变浅,其自重对围岩变形的影响越大,且与不考虑TBM自重的围岩变形相比,边墙洞壁的径向位移减小率最大,仰拱与拱顶次之。这些认识对研究TBM与围岩的相互作用和预测卡机有重要意义。     

Effect of replacing disc cutters with chisel tools on performance of a TBM in difficult ground conditions

A summary of a research program covering a period of two years on the performance of a TBM in a very complex and difficult geology is presented in this study. The formations in the study area varied from alluvium, sludge, mudstone, shale and limestone to quartzite with strengths from soft to very hard. The dykes frequently intruded the sedimentary rocks resulting in different degrees of weathering and fracturing in the country rock causing tremendous delays in progress rate of the TBM. The disc cutters started cutting inefficiently in clayey medium strength ground with extreme water income, at where also excessive disc consumptions started due to insufficient friction between the disc cutters and very soft (sludgy) formation, and it was decided to replace all disc cutters with chisel tools (ripper, scraper). Before making this important decision that could affect totally the excavation efficiency and production rate, some theoretical estimations were performed using the Evans’ cutting theory after some modifications based on the previous experimental studies for relieved cutting mode and wear flat, front ridge and vee-bottom angles found in complex shapes of chisel tools to estimate deterministically the torque and thrust requirements of the TBM.Field measurements of the torque and thrust requirements of the TBM equipped with the chisel tools validated the theoretical considerations and the deterministic model used for predicting the performance. Statistical analysis indicated that the model could be used reliably for performance prediction. This study also gave a unique opportunity to compare the performance of disc cutters and chisel tools used on the same TBM at variety of grounds and to analyze the effect of replacing disc cutters with chisel tools on the performance of the TBM. The field measurements indicated that the chisel tools were superior to the disc cutters in especially soft to medium strength rocks.     

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.     

隧洞工程TBM法施工计算机模拟研究

TBM（全断面掘进机）在隧洞工程施工中得到了广泛的应用，把循环运行网络（Cyclic Operation Network）理论与计算机模拟技术相结合，可以对隧洞工程TBM法施工过程进行模拟，通过对多个施工方案模拟结果进行技术经济分析，可以得到最优的施工方案，从而提高工效、缩短工期、降低费用。     

TBM施工隧道超欠挖对围岩及支护结构影响分析

结合西安 -南京线桃花铺 1 #隧道采用隧道掘进机 (TBM)施工实践 ,运用有限元法 ,针对TBM施工隧道中常见的轴线偏移问题 ,定量分析了TBM施工隧道超欠挖对隧道围岩及支护结构的影响 ,得出的结论可供同类工程参考。     

浅埋单护盾TBM隧道施工地表变形规律研究

重庆轨道交通环线重庆西站-上桥站区间使用单护盾TBM进行施工,通过浅埋段时,因隧道拱顶穿越的基岩最小厚度已不足0.5 m,极可能会给工程带来极大安全隐患。按设计要求,对上覆土体进行旋喷桩加固与钻孔注浆加固。利用有限元数值软件ADINA建立该区段的精细有限元模型,并提出了适用单护盾TBM施工特点的数值模拟方法。数值计算结果不仅说明了表层土的加固是有效的且十分必要,并对单护盾TBM掘进过程的三个主要施工参数研究与对比分析,总结出工程浅埋段最优掘进参数。对比现场地表位移监测数据,总结得出该浅埋区间单护盾TBM隧道施工地表横向变形曲线高低肩的特点;另一方面也验证了数值模型的可用性与模拟方法的正确性,可为该区域其它地铁线路的施工提供借鉴与参考。     

Study on the influence of confining stress on TBM performance in granite rock by linear cutting test

Rock stress problems induced by overburden or anisotropic stresses are significant to the TBM tunneling. In this paper, the effect of different confining stressed conditions on TBM performance are investigated by using full-scale cutting tests with large intact granite specimens (1000 mm × 1000 mm × 600 mm). In these tests, the effects of confining stresses on the normal force, rolling force, the cutting coefficient and specific energy are analyzed. It is found that the confining stress has significant impact on the normal force and rolling force. Specifically, for the same cutting spacing and penetration depth, the normal force increases with increasing confining stress due to enhancement of the rock resistance strength; meanwhile the rolling force decreases gradually with increasing confining stress. The stress deviation between two confining directions affects the optimum penetration that corresponds to small specific energy. The results provide better understanding of the effect of confining stress on the TBM performance and also recommend some guidelines for TBM tunneling under stressed geological condition.     

自行走隧道掘进机施工引起地表沉降规律分析

通过水准测量对自行走隧道掘进机施工过程中地表变形进行了研究,结果表明：横向沉降槽曲线不完全符合Peck理论的正态分布,最大沉降点位于轴线上方。沉降变形集中发生在土体开挖而掘进机尚未到达掌子面时,环向增阻块对土体挤压造成地表轻微隆起。     

不同围压及切削顺序对TBM刀具破岩机理的影响

在综合考虑围压及刀具切削顺序的前提下,利用二维离散单元法建立双把TBM刀具切削节理不发育岩石的仿真模型,模拟出岩石裂纹的生产与扩展全过程。根据获得的裂纹扩展形态以及破碎块形成规则,总结归纳出四种典型破碎模式,并从刀具破岩效率、岩石裂纹扩展能力以及岩石破碎块度三个方面对刀具破岩机理进行进一步研究。仿真结果表明:随着围压的增加,刀具的破岩效率与裂纹扩展能力降低;同时加载方式下破岩效率比先后加载方式要大,而裂纹扩展能力则刚好相反;岩石破碎块度与破碎模式有关。