A Closer Look at the Design of Cutterheads for Hard Rock Tunnel-Boring Machines

The success of a tunnel-boring machine （TBM） in a given project depends on the functionality of all components of the system, from the cutters to the backup system, and on the entire rolling stock. However, no part of the machine plays a more crucial role in the efficient operation of the machine than its cutterhead. The design of the cutterhead impacts the efficiency of cutting, the balance of the head, the life of the cutters, the maintenance of the main bearing/gearbox, and the effectiveness of the mucking along with its effects on the wear of the face and gage cutters/muck buckets. Overall, cutterhead design heavily impacts the rate of penetration （ROP）, rate of machine utilization （U）, and daffy advance rate （AR）. Although there has been some discussion in commonly available publications regarding disk cutters, cutting forces, and some design features of the head, there is limited literature on this subject because the design of cutter- heads is mainly handled by machine manufacturers. Most of the design process involves proprietary algorithms by the manufacturers, and despite recent attention on the subject, the design of rock TBMs has been somewhat of a mystery to most end-users. This paper is an attempt to demystify the basic concepts in design. Although it may not be sufficient for a full-fledged design by the readers, this paper allows engineers and contractors to understand the thought process in the design steps, what to Look for in a proper design, and the implications of the head design on machine operation and life cycle.

On the Loads for Strength Design of Cutterhead of Full Face Rock Tunnel Boring Machine

Cutterhead loads are the key mechanical parameters for the strength design of the full face hard rock tunnel boring machine(TBM).Due to the brittle rock-breaking mechanism,the excavation loads acting on cutters fluctuate strongly and show some randomness.The conventional method that using combinations of some special static loads to perform the strength design of TBM cutterhead may lead to strength failure during working practice.In this paper,a three-dimensional finite element model for coupled Cutterhead–Rock is developed to determine the cutterhead loads.Then the distribution characteristics and the influence factors of cutterhead loads are analyzed based on the numerical results.It is found that,as time changes,the normal and tangential forces acting on cutters and the total torque acting on the cutterhead approximately distribute log normally,while the total thrusts acting on the cutterhead approximately show a normal distribution.Furthermore,the statistical average values of cutterhead loads are proportional to the uniaxial compressive strength(UCS)of cutting rocks.The values also change with the penetration and the diameter of cutterhead following a power function.Based on these findings,we propose a three-parameter model for the mean of cutterhead loads and a method of generating the random cutter forces.Then the strength properties of a typical cutterhead are analyzed in detail using loads generated by the new method.The optimized cutterhead has been successfully applied in engineering.The method in this paper may provide a useful reference for the strength design of TBM cutterhead.

Numerical simulation of freezing effect and tool change of shield machine with a frozen cutterhead

A shield machine with freezing function is proposed in order to realize tool change operation at atmospheric pressure. Furthermore, the transformation project of freezing cutterhead and tool change maintenance method are put forward. Taking the shield construction of Huanxi Power Tunnel as an example, a numerical analysis of the freezing cutter head of the project was carried out. The results show that when the brine temperature is-25 °C, after 30 d of freezing, the thickness of the frozen wall can reach 0.67 m and the average temperature drops to-9.9 °C. When the brine temperature is-30 °C, after 50 d of freezing, the thickness of the frozen wall can reach 1.01 m and the average temperature drops to-12.4 °C. If the thickness of the frozen wall is 0.5 m and the average temperature is-10 °C, as the design index of the frozen wall, the brine temperature should be lower than-28 °C to meet the excavation requirements in 30 d. Analyzing the frozen wall stress under 0.5 m thickness and-10 °C average temperature condition, the tensile safety factor and compressive safety factor are both greater than 2 at the most dangerous position, which can meet the tool change requirements for shield construction.

A New System to Evaluate Comprehensive Performance of Hard-Rock Tunnel Boring Machine Cutterheads

The accurate performance evaluation of a cutterhead is essential to improving cutterhead structure design and predicting project cost. Through extensive research, this paper evaluates the performance of a tunnel boring machine(TBM) cutterhead for cutting ability and slagging ability. This paper propose cutting efficiency, stability, and continuity of slagging as the evaluation indexes of comprehensive cutterhead performance. On the basis of research of true TBM engineering applications, this paper proposes a calculation method for each index. A slagging efficiency index with a ratio of the maximum di erence between the slagging amount and average slagging is established. And a slagging stability index with a ratio of the maximum slagging fluctuation and average slagging is presented. Meanwhile, a cutting efficiency index by the weighed average value of multistage rock fragmentation of a cutter’s specific energy is established. The Robbins and China Railway Construction Corporation(CRCC) cutterheads are evaluated. The results show that under the same thrust and torque, the slagging stability of the CRCC scheme is worse, but the slagging continuity of the CRCC scheme is better. The cutting ability index shows that the CRCC cutterhead is more efficient.

Optimal design of structural parameters for shield cutterhead based on fuzzy mathematics and multi-objective genetic algorithm

In order to improve the strength and stiffness of shield cutterhead, the method of fuzzy mathematics theory in combination with the finite element analysis is adopted. An optimal design model of structural parameters for shield cutterhead is formulated,based on the complex engineering technical requirements. In the model, as the objective function of the model is a composite function of the strength and stiffness, the response surface method is applied to formulate the approximate function of objective function in order to reduce the solution scale of optimal problem. A multi-objective genetic algorithm is used to solve the cutterhead structure design problem and the change rule of the stress-strain with various structural parameters as well as their optimal values were researched under specific geological conditions. The results show that compared with original cutterhead structure scheme, the obtained optimal scheme of the cutterhead structure can greatly improve the strength and stiffness of the cutterhead, which can be seen from the reduction of its maximum equivalent stress by 21.2%, that of its maximum deformation by 0.75%, and that of its mass by 1.04%.

Real-time analysis and prediction of shield cutterhead torque using optimized gated recurrent unit neural network

An accurate prediction of earth pressure balance(EPB)shield moving performance is important to ensure the safety tunnel excavation.A hybrid model is developed based on the particle swarm optimization(PSO)and gated recurrent unit(GRU)neural network.PSO is utilized to assign the optimal hyperparameters of GRU neural network.There are mainly four steps:data collection and processing,hybrid model establishment,model performance evaluation and correlation analysis.The developed model provides an alternative to tackle with time-series data of tunnel project.Apart from that,a novel framework about model application is performed to provide guidelines in practice.A tunnel project is utilized to evaluate the performance of proposed hybrid model.Results indicate that geological and construction variables are significant to the model performance.Correlation analysis shows that construction variables(main thrust and foam liquid volume)display the highest correlation with the cutterhead torque(CHT).This work provides a feasible and applicable alternative way to estimate the performance of shield tunneling.

Evaluation of TBM Cutterhead’s Comprehensive Performance Under Complicated Conditions

A comprehensive performance evaluation method for the tunnel boring machine(TBM)cutterhead is proposed in this paper.The evaluation system is established on strength and vibration.Based on fracture mechanics theory,fatigue strength evaluation indices are determined under critical crack length.The concept of crack regions division is proposed to evaluate fatigue strength more accurately and specifically.In addition,the velocities in three directions of critical locations are obtained with dynamics equations.Then,the root-mean-square values of velocities are taken as the vibration severity indices.Taking the cutterhead of Jilin diversion engineering as an example,the evaluations of each index are completed;then,the vibration of the TBM cutterhead is measured and compared with the theoretical calculation results.There are similar change laws between the theoretical calculation results and the testing results of the cutterhead acceleration,which proves that the method of calculation of the vibration index is effective,the reliability of the cutter saddle welding should be paid attention to when the TBM is working,and the condition of vibration severity of the TBM cutterhead meets the requirements but needs to be improved.

新型盘式削片机刀盘结构设计及切削力研究

基于目前纤维板所需工艺木片的生产现状,为保证盘式削片机生产工艺木片的质量并解决盘式削片机飞刀快速更换的问题,设计一款采用差动螺旋结构实现飞刀伸出量微调,以及刀块整体更换的新型盘式削片机刀盘。对新型刀盘的削片工作原理以及切削力进行研究,对装刀块夹持力部分进行验证计算,通过Adams仿真软件对设计的新型刀盘进行了动力学分析,验证刀盘结构在额定转速下的稳定性。

Evaluation Method for Tunneling Stability of TBM Cutterhead

In the process of tunneling of tunnel boring machine (TBM), different geological conditions often correspond to different working conditions, and the randomness of geological conditions also causes the order of occurrence of each working condition to be different. Under the conversion of different working conditions, this makes the vibration of different types of cutterheads different. How to choose the appropriate type of cutterhead according to different geological conditions is very important for saving engineering cost and increasing cutterhead life. In view of the above situation, this paper proposes a stability evaluation method during the TBM tunneling process to select the appropriate cutterhead type. Firstly, the corresponding relationship between geology and working conditions is established according to different geological conditions, and the input loads corresponding to geological conditions are obtained. Then, it is substituted into the dynamic model of the cutterhead system, the vibration response boundaries of each degree of freedom are obtained by solving. And the average value of the maximum boundary amplitude of each degree of freedom is taken to represent the extreme vibration of the cutterhead under the corresponding working conditions. Finally, by comparing the fluctuation of the ultimate vibration amplitude of each type of cutterhead in the process of working condition conversion, the results are as follows: when the transition between homogeneous strata and composite strata is normal and there is no large turning and deviation correction, the vibration response of the two-part cutterhead is the smallest, and the two-part cutterhead is the best choice. Otherwise, the five-part cutterhead is the best choice, while the stability of the integrated cutterhead is the worst.

A Prediction Method for TBM Cutterhead Dynamic Tunneling Performance under Typical Composite Geological Conditions

The cutterhead system is a core component of TBM equipment,which works in the extremely severe environment,and the strong impact loads result in severe vibration,crack,damage failure and other engineering failures.Accordingly,the key for cutterhead system structure design and parameter matching is to evaluate and predict cutterhead tunneling per-formance reasonably.In this paper,a prediction method for TBM cutterhead dynamic tunneling performance is pro-posed under the typical composite geological conditions,based on the CSM model of multi-cutters and cutter loads field test data.Then an actual TBM cutterhead of a water conservancy project is taken as an example,a spatial three-dimensional separation zone model for cutterhead tunneling is established under the typical geological condition,and the parameters influence rules of cutterhead tunneling performance are analyzed.The results show that,the cutter-head loads and specific energy change rules with different parameters are basically similar.Moreover,under the condi-tion of penetration p=10mm,the cutterhead bending moment coefficient of variation magnitude exceeds 20%,which is the maximum,and the normal cutter spacing optimal value is 95mm.Also,when the normal cutter spacing is kept constant in 85mm,the penetration has a greater influence on the torque and specific energy coefficient of variations,which is increased from 2mm to 10mm,and the two indexes decrease by about 73%.It is indicated that proper increase of pene-tration is beneficial to reduce the vibration fluctuation degree of torque and specific energy.The proposed method of TBM cutterhead dynamic tunneling performance and the analysis results can provide theoretical basis and design refer-ence for TBM cutterhead layout and tunneling parameters matching.

基于非连续介质力学的多刀盘矩形顶管掘进性能分析

为探明多刀盘矩形顶管的掘进性能,基于非连续介质力学,运用离散元数值建模的手段,建立全尺寸的多刀盘矩形顶管掘进三维离散元模型。模型中考虑刀盘群切削、螺旋输送机排土等多种动态过程,分析刀盘组转动速度对顶管机掘进性能的影响。通过对比分析现场实测与数值计算的刀盘扭矩值,验证了数值模型的有效性与可靠性。研究结果表明,在刀盘群的旋转切削作用下,刀盘附近渣土颗粒的流动性优于土仓内渣土颗粒的流动性,除了靠近刀盘中心区域的渣土颗粒外,其他位置渣土颗粒流动性较好。后置刀盘组的切削作用有利于渣土从土仓向螺旋输送机流动,因此后置刀盘应尽可能靠近螺旋机入口位置布置。刀盘组中两侧刀盘承受的土压力略高于中心的刀盘,且作用在中心鱼尾刀具和辐条周围区域上的压力相对较高。在砂质粉土地层中,考虑到经济与环保效益,刀盘组转速建议控制在2 rpm左右。研究成果可为类似矩形顶管掘进工程的刀盘布置与掘进参数设置提供合理的参考与借鉴。

考虑刀盘推力的泥水盾构隧道开挖面平衡机理研究及应用

现有泥水盾构隧道开挖面平衡机理中,开挖面的支护多认为全部由泥浆压力提供,刀盘推力在支护中的作用少有提及。针对穿沁泥水盾构隧洞工程存在的开挖面支护具体问题,结合开挖面支护主控参数分析,揭示了考虑刀盘推力的泥水盾构隧道开挖面平衡机理,给出了刀盘推力具体表达式。运用所揭示的平衡机理,结合提出的一种盾壳外侧摩阻力估计方法,对该工程的3个重点穿越段进行了开挖面支护力计算和稳定分析。研究表明:3个重点穿越段的掘进中,刀盘推力分别占开挖面支护力的21%,24%,11%;同时考虑泥浆压力和刀盘推力的开挖面支护力,与仅考虑泥浆压力相比,在开挖面前方的轴向水土合力存在区间内占比分别由0,0和78%分别提高至78%,32%和88%,表明刀盘推力在开挖面支护中发挥了重要作用。

基于WaveNet网络的盾构刀盘扭矩超前预测方法

[目的]刀盘扭矩是表征盾构掘进安全和设备运行状态的关键参数,为了解决刀盘扭矩预测难、掘进参数难以及时修正的问题,提出一种基于WaveNet网络的盾构刀盘扭矩超前预测方法。[方法]介绍了工况数据的预处理方法,并提出基于WaveNet网络的初始静态模型基本架构和构建方式;提取初始50 m掘进距离内的盾构施工监控历史数据,并构建训练集;基于当前状态前20个施工步的盾构监控数据,超前预测5个施工步后的刀盘扭矩;随着盾构掘进距离的增加,每隔5个施工步就利用新产生的数据集重新训练和更新模型,提出刀盘扭矩超前预测的长期动态模型;以济南轨道交通1号线玉符河站—王府庄站区间盾构隧道左线数据为例,对刀盘扭矩预测效果进行分析及验证。[结果及结论]前50 m掘进距离超前预测的刀盘扭矩值与实际值变化趋势基本一致,且其平均相对误差为10.07%,初始静态模型具有较高的预测精度。随着掘进距离的增加,初始静态模型相对误差从10%上升至30%左右,而连续更新的长期动态模型相对误差始终稳定在10%左右。长期动态模型每次的更新时间基本分布在1~6 s,平均耗时为3.92 s,可满足模型高效动态更新的需求。

基于克里金插值法的常压刀盘刀梁区域泥饼发育程度算法及应用研究

为解决刀盘结泥饼影响盾构施工进度的问题,以某泥水盾构刀盘为研究对象,展开对刀盘刀梁部位泥饼发育程度的研究,提出一种基于克里金插值法的常压刀盘刀梁区域泥饼发育程度算法,并进行应用案例研究。利用全刀盘布置温度传感器获取刀盘温度数据,选取线性插值扩展刀梁区域温度数据,运用克里金插值法进行全刀盘区域的温度仿真计算,结合空间和时间2个维度分析刀盘在正常掘进、外侧结泥饼及内侧结泥饼3种工况下的判断条件,提出分离相邻测温点正/负差值,以刀盘整体正/负差值之和呈现同方向变化作为泥饼发育初始环评判指标;结合所建温度场,引入从泥饼发育初始环到当前环的温度变化率总和作为泥饼发育程度评判指标。针对某大直径常压刀盘泥水盾构案例进行分析判定,对比采用反距离权重插值法、克里金插值法和扩展样本克里金插值法构建的3种温度场用于泥饼发育程度计算,结果表明扩展样本后的克里金插值法的适用性最强,并与工程实际情况进行对比,准确率达70.87%。

一种高效的刀盘掘进过程数值模拟算法

从岩土单元网格划分和接触对搜索过程两方面入手,提出一种高效的盾构刀盘掘进过程数值模拟算法。引入六结点三棱柱单元,该单元边长比接近于1,且每一个面上的内角近似相等,相比于传统六面体单元,计算效率更高,据此建立一种高效的岩土有限元模型,并通过圆柱体单轴压缩数值模拟实验验证了模型的可靠性和高效性。根据盾构刀盘的掘进行为特点,直接得到可能发生接触的岩土网格结点,相比于传统的全局搜索,更加省时,优化了接触对搜索过程,从而提出了一种新颖高效的搜索算法,并通过自编软件开展单刀破岩过程数值模拟,验证了搜索算法的可靠性和高效性。基于自编软件和上述两种策略,使用单核CPU实现了实际工程中使用的复合盾构刀盘掘进全过程的直接数值模拟,得到了掘进后的岩土掌子面形貌和刀盘刀具的法向力载荷时程曲线及分布规律,并通过与商业软件仿真结果和文献得到的刀盘刀具法向力均值对比验证了自编软件的可靠性。

砂卵石地层大直径盾构施工的关键技术

[目的]总结分析砂卵石地层大直径盾构施工中盾构机选型、盾构始发与接收、盾构掘进姿态控制等施工关键技术,并提出具体的施工控制参数与施工控制措施,以减轻刀盘刀具磨损、降低地层损失、减小地层沉降变形。[方法]针对砂卵石地层结构松散、颗粒无胶结或弱胶结、颗粒粒径大、透水性强的工程结构特性,采用理论分析、现场监测等方法,从盾构机选型、盾构始发接收、盾构掘进姿态控制、盾构刀盘刀具的检测维修等方面深入分析砂卵石地层大直径盾构施工关键技术。[结果及结论]大直径盾构的刀盘开口率、刀盘刀具类型、渣土改良方案等应根据地层结构特性进行特殊设计,且有利于盾构排渣和超前切割;盾构井端头宜采取地层注浆加固、大管棚支护、施工降水等综合加固措施以保证大盾构始发或接收时地层的稳定;大直径盾构的掘进施工应重点控制刀盘转速、出渣量、出渣温度等参数,并应适当增大注浆量,提高渣土改良效果,避免过大超挖,保证地层损失处于合理范围内。采用上述施工参数与施工措施后,盾构掘进风险可控,施工质量与施工效率明显提升,同时大大降低了施工成本。

北山1号TBM刀盘破岩振动影响参数分析

隧道掘进机在掘进过程中,刀盘破碎岩石会产生振动,刀盘振动对TBM机械与施工会造成负面影响。依托甘肃北山地下实验室斜坡道工程TBM施工段,在北山1号TBM上搭载振动监测系统,通过跟踪现场施工和开展掘进试验,收集研究区段的隧道设计工况信息、围岩信息、掘进参数与刀盘振动信息。开展不同隧道设计工况、围岩类别、掘进参数对刀盘破岩振动的影响分析。研究结果表明:1)隧道转弯段与直线段的TBM刀盘振动强度、主振频率具有一定差异,转弯段TBM刀盘振动强度更大、主要频率更高;2)不同围岩类别下,转弯段刀盘振动主振频率差异较大,而直线段差异较小;3)随着推力、转速的提高,刀盘的振动强度增大,但刀盘三轴振动主振频率不发生改变。

全断面竖井掘进机锥形刀盘破岩机理研究

刀盘刀具系统作为全断面竖井掘进机的关键组成部分,不同刀盘锥度及刀间距对滚刀破岩起决定性的作用。运用ABAQUS软件建立滚刀动态破岩模型,分析不同刀盘锥度和不同刀间距对滚刀破岩的影响,并获取了滚刀在破岩过程中的受力情况及破岩效率。结果表明:滚刀破岩效率随着刀盘锥度的增大而减小,滚刀破岩效率随着滚刀安装半径的增大而减小,综合滚刀受力、破岩效率和实际工况,得到刀盘锥度为120°、滚刀刀间距为40 mm时,滚刀破岩效率最高。为竖井掘进机锥形刀盘设计提供了理论依据,有效提高了竖井掘进机破岩效率和整机研制水平。

机械法联络通道管片切削下主隧道力学行为研究

为了解机械法联络通道破洞过程中主隧道管片结构响应变化,依托宁波市轨道交通5号线海晏北路站—民安东路站区间工程,采用动力显式有限元法,建立全刀盘三维精细化模型并引入材料累进破坏失效准则,对不同施工阶段下主隧道管片力学行为进行研究,得到了施工初始阶段、预撑阶段及刀盘切削阶段下全切削环和半切削环管片衬砌变形图、弯矩图和轴力图,绘制了主隧道管片在3种切削阶段下应力云图,并与原型管片加载试验结果对比验证了模拟结果的准确性。主要研究结论如下:内支撑体系可为主隧道分担水土压力,有效减小管片整体内力与竖向变形;联络通道破洞后,切削区管片洞口表现出悬臂效应,最大位移位于全切削环洞口下侧,在破洞后应尽快施作强支护加固,限制管片开口处变形进一步发展;刀盘磨削管片过程中,半切削环弯矩变化相对于全切削环具有滞后性,两者均在靠背侧拱腰部位产生弯矩最大值,轴力总体上则从拱腰至拱顶底较为平滑地减小;在切削阶段,管片洞口外壁与靠背侧中部存在应力集中,半切削环与标准环的交界处发生了应力突变,应适当加大钢隔舱管片与普通混凝土管片之间的连接螺栓强度,避免螺栓破坏引起主隧道管片错台。

基于参数化建模方法的复合式盾构机刀盘力学性能分析与结构优化

刀盘是盾构机的核心部件之一,合理的刀盘结构设计是安全高效掘进的基础。为了快速高效建立刀盘有限元模型并分析其力学性能,采用基于APDL(ANSYS parametric design language)命令流开发的参数化建模方法,建立某型号复合式盾构机刀盘的数字模型。对刀盘施加极限工况下的推力和扭矩,通过静力学分析得到刀盘的应力分布和变形分布,确定最大应力和最大变形位置,校核刀盘的静强度和静刚度。进一步以刀盘总质量为优化目标,以刀盘强度和刚度为约束条件建立基于参数化建模的刀盘结构优化方法,提出刀盘结构优化流程。通过参数敏感性分析确定刀盘优化参数,探究相关参数对刀盘强度和刚度的影响。对复合式盾构机刀盘的关键参数进行优化。结果表明:优化后刀盘的最大应力降低了12%,最大变形降低了20%,质量减轻了119 kg。因此,基于参数化建模的优化方法可以提供刀盘的强度与刚度,并同时降低刀盘质量。研究成果可为后续多目标刀盘结构优化提供参考。