切槽对TBM刀具破岩机制的影响研究

高压水射流与机械滚刀相联合破岩技术的出现,改变了传统隧道掘进机（tunnel boring machine,简称TBM）的作业方式。以高压水射流在滚刀两侧岩体切槽的破岩模式为研究对象,开展常截面滚刀压头贯入不同预切槽深度白砂岩板状试样的试验和数值模拟计算分析,对破裂后图像进行DIC分析,研究发现：切槽的存在,阻断了刀具贯入裂纹的拓展,使能量能够更加集中于压头下方的局部岩石块体,有利于形成“八”字形贯通裂纹,促进岩石的破碎;随着槽深增加,压头下方岩石内部的应力状态和力学响应分区逐渐过渡改变。槽深较大时,压头下方的力学响应区域在原有裂纹扩展区、弹性区之间增加了破坏过渡区,该区域内微裂纹被压密,区域内岩石存在较大变形,但未出现明显破坏;切槽后,滚刀压头下方的岩体破坏机制由无切槽试样挤压剪切为主导的径向裂纹拓展,演变为由刀具和切槽共同控制作用—拉伸剪切为主导的主裂纹扩展。     

Rock burst and slabbing failure and its influence on TBM excavation at headrace tunnels in Jinping II hydropower station

Two headrace tunnels and the drainage tunnel were excavated by tunnel boring machines (TBMs) in Jinping II Hydropower Station. During TBM excavation, two types of slabbing failure were encountered in these deep buried marble tunnels. One is rock bursting and the other is non-violent slabbing. In order to study the rock burst and slabbing failure, a unique true triaxial rock burst test was carried out to simulate the rock burst process with different in situ stresses. Four rock samples in different marble layers were obtained in the site, and then four experiments are conducted under the same stressed conditions as the in situ field. The rock burst process and slabbing failure phenomena of the four experiments are in good accordance with the observations of corresponding excavation site. The failure modes of slabbing and rock burst in different rock groups can be predicted based on the experiments. The influence of the slabbing and rock burst failure on TBM excavation is analyzed in depth. Non-violent slabbing is beneficial to the rock breakage process. Rock burst with violent slabbing process greatly affects the tunnel support, cutter and cutterhead damage, gripper movement and force and so on.     

Some Attempts for Estimating Rock Strength and Rock Mass Classification from Cutting Force and Investigation of Optimum Operation of Tunnel Boring Machines

Summary. Tunnel face and wall collapse are common during excavations performed by tunnel boring machines (TBMs) due to the difficulty of correctly identifying the properties of the excavated rock. This identification, however, can be simplified by using the cutting force to estimate rock strength, a method that has already proved quite successful in Japanese tunnel excavations. This paper summarizes knowledge relating to the cutting force obtained through tunnel excavation experience, and the relationship between rock strength and TBM operation is discussed. Although TBM operators rely on intuition to set the cutter head speed appropriately, this decision process represents a logical method of operation that takes advantage of the variable speed capability of the cutter head. Selection of appropriate support methods for the excavated face is also a critical issue in tunnel excavation. This selection process is based on the condition of the rock, which is difficult to determine quickly and accurately during tunnel excavation. The present paper uses the excavation of two tunnels to demonstrate that it is possible to assign rock mass classifications accurately based on rock strength when boring a uniform rock type. It is also shown that the rock mass can be classified from the rock strength normalized by the uniaxial compressive strength when boring through mixed rock types.     

基于UDEC的隧道掘进机滚刀破岩数值模拟研究

现今全断面隧道掘进机（TBM）施工方法在长大深埋隧道工程中已被广泛采用,对滚刀破岩关键技术的进一步认识具有重要的工程价值。为了研究滚刀破岩机制,分析刀圈断面形态、岩石强度和节理角度对其的影响,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：滚刀破岩是滚刀下岩石拉破坏和剪破坏的综合反映,拉破坏是裂纹萌生与扩展的主要驱动机制;刃宽较大的平刀与刃角较大的楔刀破岩效果较好;平刀与楔刀在软岩中破岩效果相近,平刀在硬岩施工中比楔刀的破岩效果好;滚刀对节理角度为30°～60°的岩石破坏效果较好,由于楔刀的“劈裂”作用,楔刀比平刀更适合用于贯切含有节理的岩石。     

可变径全圆针梁台车在TBM施工隧洞衬砌中的应用

TBM开挖隧洞,由于刀盘及刀具的限制,目前开挖完的隧洞为同一直径,为了保证后期衬砌施工中结构的强度,需要对不同的围岩类别采取不同的衬砌厚度。研究表明,采取可变径全圆针梁台车进行这方面的衬砌,具有明显的优越性。本文基于吉林引松供水工程项目,论述了可变径全圆针梁台车在TBM施工隧洞衬砌中的应用。     

A Top Pilot Tunnel Preconditioning Method for the Prevention of Extremely Intense Rockbursts in Deep Tunnels Excavated by TBMs

The headrace tunnels at the Jinping II Hydropower Station cross the Jinping Mountain with a maximum overburden depth of 2,525 m, where 80% of the strata along the tunnels consist of marble. A number of extremely intense rockbursts occurred during the excavation of the auxiliary tunnels and the drainage tunnel. In particular, a tunnel boring machine (TBM) was destroyed by an extremely intense rockburst in a 7.2-m-diameter drainage tunnel. Two of the four subsequent 12.4-m-diameter headrace tunnels will be excavated with larger size TBMs, where a high risk of extremely intense rockbursts exists. Herein, a top pilot tunnel preconditioning method is proposed to minimize this risk, in which a drilling and blasting method is first recommended for the top pilot tunnel excavation and support, and then the TBM excavation of the main tunnel is conducted. In order to evaluate the mechanical effectiveness of this method, numerical simulation analyses using the failure approaching index, energy release rate, and excess shear stress indices are carried out. Its construction feasibility is discussed as well. Moreover, a microseismic monitoring technique is used in the experimental tunnel section for the real-time monitoring of the microseismic activities of the rock mass in TBM excavation and for assessing the effect of the top pilot tunnel excavation in reducing the risk of rockbursts. This method is applied to two tunnel sections prone to extremely intense rockbursts and leads to a reduction in the risk of rockbursts in TBM excavation.     

楔刀作用下岩石微观劣化的试验研究

通过改装RMT-150C系统,使用不同刃角的楔形刀具对花岗岩进行贯切试验,利用DISP声发射测试系统进行声发射的定位特征分析,研究岩石在楔形刀具作用下损伤劣化破坏的全过程。试验结果表明：声发射试验是一种研究TBM滚刀破岩微观机制的有效方法,脆性岩石材料的破坏过程是内部微裂纹的萌生和扩展过程的宏观反映;在楔刃刀具匀速贯入时,声发射信号随着荷载的变化呈一定对应趋势的变化,荷载-贯入度曲线能反映试件内的损伤历程;声发射2D定位结果显示,在岩石破碎区的密实核下方存在“损伤核”,它由微震裂源增生丛聚分布形成,核内劣化程度高,是孕育密实核的场所,为TBM滚刀作用下岩石的宏观破裂现象提供了解释和依据;楔刀跃进式的挤压贯切岩板试件,钝刃刀具产生“球状”损伤核,尖刃刀具产生“水滴状”损伤核,钝刃刀具贯切试件产生更深的贯入度和更宽的损伤核,致使试件中不仅破碎深度大,而且破损范围广,破岩效果优于尖刃刀具。     

激光辅助TBM盘形滚刀压头侵岩缩尺试验研究

为了验证高能激光技术能够辅助隧道掘进机(tunnel boring machine,简称TBM)盘形滚刀（以下简称滚刀）实现高效破岩,以滚刀破岩过程中基本的运动形式——侵岩为研究对象,参照17 inch（432 mm）工程用滚刀,按1:8的比例制备了缩尺比例滚刀压头（以下引述为滚刀压头）,开展了以孔孔距（2、3、4、5 mm）、刀孔距（3、4、5、6、7 mm）为变量的激光辅助滚刀压头侵岩L20(4×5)正交试验以及无激光作用的对照组试验。试验研究结果表明：随着刀孔距的增加,滚刀压头的破岩量与岩石破碎块度均增加,而垂直力和比能耗均降低,最优刀孔距为6 mm;随着孔孔距的增加,破岩量、垂直力和岩石侵入难度系数均降低,而岩石破碎块度和比能耗均增加,最优孔孔距为3 mm。与传统滚刀回转滚压破岩方式相比,在激光辅助作用下,可促进岩石张拉裂纹的产生,提高了滚刀侵岩效率。所提出的激光辅助滚刀耦合破岩模式在未来TBM极硬岩层隧道掘进中具有一定的应用前景。     

Full-scale linear cutting test in Chongqing Sandstone and the comparison with field TBM excavation performance

In this study, determination of some machine parameters and performance prediction for tunnel boring machine (TBM) are conducted based on laboratory rock cutting test. Firstly, laboratory full-scale linear cutting test is carried out using 432-mm CCS (constant cross section) disc cutter in Chongqing Sandstone. Then, the input parameters for TBM cutterhead design are extracted; some TBM specifications are determined and then compared to the manufactured values. Finally, laboratory full-scale linear cutting test results are compared with the field TBM excavation performance data collected in Chongqing Yangtze River Tunnel. Results show that laboratory full-scale linear cutting test results, combined with some engineering considerations, can be used for the preliminary and rough design of TBM machine capacity. Meanwhile, combined with some modification factors, it can also well predict the field TBM excavation performance.

     

基于新表面理论的TBM破岩效率评价指标

岩碴是岩-机作用的直接产物,也是评价隧道掘进机（TBM）破岩效率和优化TBM掘进参数的有效指标。依托兰州水源地建设工程和龙岩万安溪引水工程,开展不同岩性条件下TBM岩碴筛分试验,得到了岩碴粒径分布规律。基于新表面理论,从滚刀破岩能量转化角度出发,提出了一种新的TBM破岩效率评价指标。基于岩碴粒径分布规律和TBM掘进参数统计,探讨了新表面理论指标与比能、岩碴粗糙度指数之间的关系,指出了新表面理论指标在反映岩碴破碎程度和评价TBM破岩效率方面的优势。对新表面理论指标与TBM掘进推力以及刀间距s与贯入度p的比值进行回归分析,得到了硬岩（围岩等级为Ⅱ级）和软岩（围岩等级为III级）掘进条件下的TBM最优掘进推力和s/p取值区间。研究表明：（1）新表面理论指标符合岩石破碎学原理,可准确评价TBM破岩效率。岩碴越是破碎,新表面理论指标越大,掘进能耗越高,此时TBM破岩效率相对较低。（2）新表面理论指标与比能、岩碴粗糙度指数均具有良好的线性相关关系。岩碴越是破碎,破碎单位体积岩石的能量消耗越大,新表面理论指标越大,对应的粗糙度指数越小。软岩掘进条件下TBM掘进比能低于硬岩,而岩碴破碎程度高于硬岩。（...     

Influence of Rock Mass Parameters on the Performance of a TBM in a Gneissic Formation (Varzo Tunnel)

Summary The paper analyses the influence of rock mass quality on the performance of a double shield TBM in the excavation of a tunnel in a gneiss formation which is characterized by high strength and low fracture intensity.As full observation of the rock conditions was prevented by the use of segmental lining, a geomechanical survey of the face was performed during maintenance downtime and the observed conditions were correlated with the machine performance parameters for that same day. A statistical analysis of the data shows that penetration rate correlates well with a slightly modified RMR index (in which the influence of the water conditions and joint orientation were discounted), but the most important factor is by far the partial rating of the RMR classification related to joint spacing only. However in tunnels characterized by greater variability in rock strength and joint conditions, it could be worthwhile using the complete RMR index.Given the toughness of the rock, failure of the cutter bearings and supports were a frequent occurrence during excavation. Owing to this factor the influence of rock quality on the rate of advance was found to be weak and the correlation more scattered.The results obtained for the Varzo tunnel were compared with those relative to other tunnels in granitic rocks and found to be in good agreement. However the relationships obtained should be considered valid only for this type of rock; machine behaviour could be found to be markedly different in other rock types, even where rock material strength and joint frequency are the same.     

隧道掘进机施工条件下的隧洞围岩分类方法探讨

针对隧道掘进机(Tunnel Boring Machine--TBM)施工隧洞中的围岩分类问题,指出TBM施工条件下的隧洞围岩分类应针对围岩的可钻掘性,充分考虑影响TBM掘进效率的主要工程地质因素,提出了在《工程岩体分级标准》围岩稳定性基本分级的基础上,依据岩石的单轴抗压强度、岩石的耐磨性和岩体的完整性将TBM施工条件下的隧洞围岩分为A(好)、B(一般)、C(差)3个级别的围岩分类新方法。     

Mechanical response of surrounding rock of tunnels constructed with the TBM and drill-blasting method

There are two kinds of excavation methods in underground engineering: the tunnel boring machine (TBM) and the drill-blasting method. A large number of studies have shown that the deformation and failure, the degree of disturbance, the stability and the reinforcement measures of surrounding rock using the TBM and drill-blasting method vary from each other. To accurately master these macroscopic damages, it is necessary to focus on the investigation of the micro-mechanical responses of the surrounding rock. Scanning electron microscopy tests, acoustic emission tests and tunnel acoustic detection tests were carried out to analyze the mechanical response of surrounding rock of tunnels, which were excavated in marble by, respectively, the TBM and the drill-blasting method. The tests results showed that most of the rock fractures cut by TBM is wipe along the crystal, and the failure mechanism is mainly cutting, while most of the rock fractures induced by the TBM coincide with crystal planes, its mechanism is mainly tensile. The stress–strain curves of rocks cut by the TBM method are rather flat around the peak strength, which means a strong resistance to deformation around the peak load. The response of AE for the rock cut by the TBM method appears after larger strains than the response of the rock constructed by the drill-blasting method. This suggests that the resistance to damage is higher under TBM excavation conditions. The relaxation depths of the tunnel excavated by the drill-blasting method are larger than the tunnel excavated by the TBM method. The research can provide more insight into tunnel failure mechanisms and provide a framework for reinforcement measures.     

Experimental and analytical studies of the parameters influencing the action of TBM disc tools in tunnelling

The use of tunnel boring machines (TBMs) is increasingly popular in tunnelling. One of the most important aspects in the use of these machines is to assess with certain accuracy the effectiveness of the action of the discs on the cutter-head in the different rock types to be excavated. A specific machine, called an intermediate linear cutting machine (ILCM), has been developed at the Politecnico di Torino in order to study, on a reduced scale in detail in the laboratory, the interaction between the discs of the TBM and the rock: this machine allows a series of grooves to be cut on a rock sample of 0.5 × 0.3 × 0.2 m, through the rolling of a 6.5-in. disc, and evaluation, during testing, of the parameters associated with the action of the cutting tool. The parameters measured during the tests were compared with the results obtained employing two analytical methods widely used for predicting the performance of TBMs: the Colorado School of Mines (CSM) model and the Norwegian University of Science and Technology (NTNU) model. The latter showed a greater ability to reproduce tests conducted using the ILCM. However, as with the CSM model, it does not allow the optimal excavation condition (the ratio, which minimizes the specific energy of excavation, between the groove spacing and the penetration of the disc), necessary for the correct design of the TBM cutter-head, to be identified. An example, based on a real case of a tunnel in Northern Italy, allowed a demonstration of how the NTNU model provides results in line with the measurements taken during the excavation and represents, therefore, a model that is able to reliably simulate both laboratory tests and the action of a TBM on site. The NTNU model, together with the results of the tests with ILCM targeted on the identification of the optimal conditions of excavation, may allow the correct dimensioning of the TBM cutter-head to be attained in order to effectively implement the excavation.     

TBM岩体可掘性预测及其分级研究

全断面硬岩隧道掘进机（tunnel boring machine, TBM）对岩体条件极其敏感,且其前期投入较大,准确地评估岩体可掘性、预测TBM掘进性能对TBM隧道施工至关重要。基于来自中国、伊朗两国涵盖3种不同岩性的5条TBM施工引水隧洞约300组现场数据,以现场贯入度指数FPI为岩体可掘性评价指标,分析了岩石单轴抗压强度UCS、岩体完整性指数 、岩体主要结构面与洞轴线的夹角?、隧洞直径D等与岩体可掘性之间的关系;探讨了适用于岩体可掘性研究的岩体参数统一方法,进一步建立了精度较高的（相关系数为0.768）岩体可掘性经验预测方法。基于该预测方法,运用K中心聚类分析方法,将岩体可掘性分为6类,探讨了不同岩体可掘性条件下TBM平均单刀推力、刀盘转速分布规律,相应成果可为实际工程中TBM施工隧洞岩体可掘性评估、掘进参数的选择、施工进度的安排提供一定的指导。     

A Completely 3D Model for the Simulation of Mechanized Tunnel Excavation

For long deep tunnels as currently under construction through the Alps, mechanized excavation using tunnel boring machines (TBMs) contributes significantly to savings in construction time and costs. Questions are, however, posed due to the severe ground conditions which are in cases anticipated or encountered along the main tunnel alignment. A major geological hazard is the squeezing of weak rocks, but also brittle failure can represent a significant problem. For the design of mechanized tunnelling in such conditions, the complex interaction between the rock mass, the tunnel machine, its system components, and the tunnel support need to be analysed in detail and this can be carried out by three-dimensional (3D) models including all these components. However, the state-of-the-art shows that very few fully 3D models for mechanical deep tunnel excavation in rock have been developed so far. A completely three-dimensional simulator of mechanised tunnel excavation is presented in this paper. The TBM of reference is a technologically advanced double shield TBM designed to cope with both conditions. Design analyses with reference to spalling hazard along the Brenner and squeezing along the Lyon–Turin Base Tunnel are discussed.     

关于TBM施工隧洞围岩分类方法的研究

本文针对TBM施工隧洞中的围岩分类问题，通过分析研究国内外大量TBM施工实例和一些现场及室内岩石力学试验结果，指出TBM施工条件下的隧洞围岩分类应针对围岩的可钻掘性，充分考虑影响TBM掘进效率的主要工程地质因素，提出了在《工程岩体分级标准》围岩稳定性基本分级的基础上，依据岩石的单轴抗压强度、岩石的耐磨性和岩体的完整性将TBM施工条件下的隧洞围岩分为A（好）、B（一般）、C（差）3个级别的围岩分类新方法，并将该方法应用于掌鸠河引水供水工程TBM施工段工程实践，取得了良好的效果。     

水力切缝上方TBM滚刀贯入破坏机制模拟研究

为了提高坚硬岩层隧道掘进机（tunnel boring machine, TBM）贯入度和降低滚刀受力,高压水射流辅助TBM滚刀破岩已在工业界初步应用。为了揭示水力切缝滚刀破岩机制,基于水力切缝岩石滚刀贯入试验进行了三维颗粒流模拟,研究了滚刀贯入力和贯入刚度随切缝深度的变化规律,揭示了不同切缝深度滚刀纵横剖面内的裂纹扩展和力链演化过程,分析了拉裂纹和剪裂纹随切缝深度的变化规律,明确了不同切缝岩石滚刀贯入的破坏模式和破坏机制。结果表明,第1次贯入的贯入刚度和贯入力随切缝深度的增加大致呈线性降低,第2次贯入的峰值力和贯入刚度小于第1次。而且,50～80 mm刀间距的变化对峰值贯入力的影响并不显著。随着切缝深度的增加,滚刀下方力链集中区边缘的倾角变大。由此导致破坏倾向于倾斜向下发展,当刀间距增加时,破坏由切缝一侧倾斜破坏向两切缝中间岩脊倾斜破坏转变,研究结果可为TBM滚刀与水射流布置和切缝深度的选取提供一定参考。     

灰岩隧道掘进机隧道点荷载试验评价岩石强度方法的研究与探讨

使用隧道掘进机（TBM）开挖隧道时刀盘和盾体阻碍了对岩石状态的观察,这时可使用岩渣对岩石条件进行预测和评价。从滚刀破碎掌子面产生的岩渣中选取块状岩石进行点荷载试验可以获得岩石强度,但是受过滚刀损伤作用的岩石强度值与未受损伤的岩石强度值之间的关系尚不明确。从吉林引松供水工程TBM破岩产生的岩渣中挑选块状试样进行点荷载试验,同时在产生岩渣的相应位置钻取岩芯获取点荷载强度,与单轴抗压强度进行了对比,记录了取样地点地质状态、试样的尺寸、破碎状态以及等效断裂面积。结果表明：岩渣中的岩块受到滚刀作用产生的损伤强度值有所下降,为完整取芯试样的63.25%,原岩越完整受损程度越大;灰岩点荷载强度换算岩石单轴抗压强度系数约为25.3,直接使用岩渣时建议系数约为42.1;峰值荷载与等效断裂面积成正比;尺寸过大的试块往往与岩体原有裂隙有关,强度极低,不适宜用作点荷载试验。研究结果为TBM隧道现场快速获取岩石强度参数提供了方法和依据。     

深埋隧洞不同开挖方式下即时型岩爆微震信息特征及能量分形研究

基于锦屏二级水电站深埋隧洞钻爆法及隧道掘进机（TBM）开挖过程中大量微震监测数据及不同等级的岩爆案例,对不同开挖方式下即时型岩爆的孕育及发生过程的能量释放展开研究,并运用分形几何原理研究微震能量分布的变化规律,得到以下结论：（1）即时型岩爆的孕育及发生过程中,岩爆区围岩岩体处于破坏加速集聚并不断扩展的过程;（2）钻爆法开挖过程中储存在岩体内的弹性应变能消耗于岩体破裂过程大于TBM开挖,而转化为岩体动能小于TBM开挖;（3）钻爆法开挖微震能量分形维度在即时型岩爆的孕育过程不断增加,岩爆临近前会增加到某个临界值以上;（4）TBM开挖即时型高等级岩爆能量分形维度值大于钻爆法开挖,并且其分形维度值可以反映低等级岩爆伴随发生的特征。