A fuzzy logic model to predict specific energy requirement for TBM performance prediction

Prediction of tunnel boring machine performance is a critical key for successful tunnel excavations. Specific energy requirement of disc cutters, which is defined as the amount of energy required to excavate a unit volume of rock, is one of the important parameters used for performance prediction of these machines. Much research has been conducted to predict cutting parameters of disc cutters using analytical, empirical and numerical approaches. In recent years alternative methods, such as fuzzy logic, have been extensively used to deal with subjects having ambiguities and uncertainties. In this study, a model was established to predict specific energy requirement of constant cross-section disc cutters in the rock cutting process by using fuzzy logic method. This model is based on experience and the database which consists of linear cutting test results that were generated over for many years at the Earth Mechanics Institute of the Colorado School of Mines. The model predicts specific energy requirements of disc cutters using uniaxial compressive and tensile strength of rocks, disc diameter and tip width, penetration and spacing of cuts.     

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.     

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。     

Disc cutting tests in Colorado Red Granite: Implications for TBM performance prediction

A series of full-scale laboratory disc cutting tests was conducted with a single disc cutter (432 mm diameter and a constant cross-section profile) and a single rock type (a coarse-grained red granite). Normal, rolling, and side forces were measured for a series of spacings and penetrations, from which other cutting parameters also were calculated. Although the increases of normal and rolling forces with increased spacing and penetration are as expected, the results illuminate additional aspects of performance prediction. Specific energy (SE) considerations indicate that a spacing of 76 mm is close to optimum in this hard, brittle crystalline rock. At this spacing, penetration has very little effect on SE. These results show why spacings near 76 mm are commonly found on tunnel boring machines operating in hard rock. The relationship of rolling force to normal force was close and consistent: A nearly linear rise of the ratio of rolling force to normal force with increased penetration, and, conversely, a nearly unchanged ratio with increases in spacing. The results tend to validate performance prediction methodologies based on normal force-penetration models.     

The use of water jets to assist free-rolling cutters in the excavation of hard rock

Earlier work has shown that the use of water jets at moderate pressure enhances mechanical cutting in hard rock. To assess the potential of this technique for use in conjunction with free-rolling cutters, a series of laboratory tests was conducted with disc and button cutters to determine the effect of variations in the jet and cutting parameters on the cutter performance. In these tests, it was found that the use of water jets at pressure in the range of 5–40 MPa can reduce the forces on a free-rolling cutter by 40 per cent, which represents a significant improvement in cutting performance. The reduction in thrust force was found to be dependent on jet pressure: the greater the pressure, the greater the reduction. The reduction in rolling force was independent of jet pressure over the range investigated. The results indicate that no additional improvements in cutting performance of any significance are to be gained by an increase in jet pressure above 40 MPa. The most effective jet configuration for the reduction of cutter forces was found to be four coherent water jets, two laterally disposed on each side of the cutter and directed at the arc of contact between the cutting edge and the rock.     

Predicting performance of EPB TBMs by using a stochastic model implemented into a deterministic model

The current study is an attempt to address the stochastic nature of the rock excavation process by suggesting a stochastic performance prediction model implemented into a deterministic model developed for hard rock TBMs. Full-scale linear cutting experiments using constant cross-section and V-type of disc cutters are performed on two different limestone samples to provide the basic input required for the deterministic model used for estimation of instantaneous penetration rate, daily advance rate, thrust and torque requirements of TBMs. Stochastic estimation is performed by using a Monte Carlo simulation program by applying iterations to implement the probabilistic distribution of each model parameter and provide knowledge of a confidence level. Results of the suggested model are verified by measuring the field performance of two earth pressure balance (EPB) TBMs excavating competent rocks in semi-closed mode. The results indicate that the suggested model works well for prediction of instantaneous cutting/penetration rate for both TBMs and both types of disc cutters. However, an improvement on the model is required for estimation of cutterhead torque and thrust of EPB TBMs. The stochastic model implemented into the deterministic model results in almost similar predictions with the deterministic model in 50% (best guess) probability. However, the stochastic modeling provides a tool for exploring the full implications of linear cutting experiments and allows assessing the probability of occurrence and predicting variations of the TBM performance parameters, covering the uncertainties/risks.     

Correlation of rock cutting tests with field performance of a TBM in a highly fractured rock formation: A case study in Kozyatagi-Kadikoy metro tunnel,Turkey

This paper presents and discusses detailed field and laboratory studies concerning boreability prediction of tunnel boring machines (TBMs) used in Kozyatagi-Kadikoy metro tunnels in Istanbul in a highly fractured rock formation. The determination of some design parameters and performance prediction of a tunnel boring machine (TBM) are carried out using full-scale rock cutting test. The intact rock samples having minimum sizes of 1.0 × 0.7 × 0.7 m are obtained from shale and limestone (Kartal Formation) along the tunnel line. The rock samples are subjected to full-scale laboratory rock cutting tests with different depth of cut and cutter spacing values using a constant cross section (CCS) disc cutter of 330 mm in diameter. Cutter forces, i.e., thrust force, rolling force and specific energy values are recorded for each cut. The results of the tests are first used to calculate TBM design and performance parameters such as torque and thrust requirements and cutting rates. In the second part of the research, the field performance of the TBM is recorded with the aid of data acquisition system installed within TBM and the predicted performance and design values obtained from full-scale rock cutting tests are compared with the field values. It is observed that fractured characteristics of the rock formation affect tremendously TBM performance and predicted values differ from the field data in some extend. It is believed that the results will serve as a guide for efficient selection and use of TBMs.     

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.     

岩石隧道掘进机的施工预测模型

分析了岩石隧道掘进机的破岩机理,介绍了自上世纪70年代以来发展的一系列施工预测模型,包括单因素预测模型、综合预测模型(CSM模型和NTNU模型)、岩体分类预测模型(QTBM模型)、概率模型、模糊神经网络模型。单因素预测模型中包括的主要岩石材料参数有岩石单轴抗压强度、抗拉强度及岩石的总硬度;CSM模型主要是基于线性切割试验机岩石试验数据,其初始预测模型中包括岩石单轴抗压强度及抗拉强度;NTNU模型是一套完整的预测模型,包括掘进速度、进度预测、刀具的磨损预测及经济分析,在它的施工进度预测模型中,考虑到了岩石的可钻性、孔隙度及岩体节理的密度及方向;QTBM模型源自于Q系统,加入了一些与隧道掘进机及与掘进速度相关的参数;概率模型是基于一个庞大数据库的类比模拟模型;模糊神经网络模型是一种黑箱模型,克服了输入与输出之间的不确定性关系。     

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.     

高地应力作用下大理岩岩体的TBM掘进试验研究

滚刀破岩效率的研究主要集中在室内线性试验机破岩试验和数值分析2个方面,在工地开展TBM掘进试验尚不普遍。锦屏二级水电站采用3台TBM开挖隧道群,3台TBM在不同洞深(不同地应力)条件对大理岩岩体进行TBM掘进试验、岩石渣片筛分试验及大渣片统计分析,研究岩体条件、TBM机器参数、TBM运行参数对TBM掘进速度的影响及高地应力作用下岩体可掘性指数的变化。研究结果表明:在高地应力条件下,尽管TBM掘进速度随推力增加而增大,但推力超过一定值后,TBM并不在优化状态下运行,TBM的运行需与岩体条件及地应力条件相匹配。     

基于协同破岩的TBM刀盘优化策略

岩石隧道掘进机工作时的刀具受力情况是影响刀盘破岩性能的关键。为了分析滚刀之间的协同破岩效应,提出3种基本的协同破岩模式,并将多把滚刀协同破岩过程等效为3种破岩模式的组合。不同破岩模式下,滚刀切割岩石的先后顺序不同,结合线性切割试验,证实了不同模式下3种滚刀力等级的大小关系。以引汉济渭岭北隧洞TBM工程为背景,研究得出名义磨损量与破岩模式的叠加效应具有较强的相关性,其中,由内而外模式占比与滚刀名义磨损量具有明显的正相关性,据此提出了考虑刀具磨损量的TBM刀盘刀具优化策略。     

基于耦合FDM-DEM方法的TBM滚刀最优化研究

为确定TBM盘型滚刀的最优布置,结合有限差分法(FDM)和离散元法(DEM)的优点,采用FDM-DEM耦合的数值模拟方法,对不同刀间距和贯入度条件下TBM双滚刀破岩过程进行三维动态仿真模拟,分析研究了不同滚刀配置对岩石破碎效果的影响。为了验证所提出方法的可行性和准确性,利用线性切割机(LCM)对科罗拉多红色花岗岩进行了切割试验,通过对比分析线性切割试验数据,验证了所提出方法的可行性。数值模拟结果表明：对于科罗拉多红色花岗,滚刀法向力和切向力会随着刀间距和贯入度比值的增加先减少后增大,当刀间距和贯入度的比值为20左右,滚刀法向力和切向力最小。线性切割试验和数值模拟结果均表明,当间距和贯入度的比值在17～20左右,岩石切割的比能量最低,此时TBM切割效率最高。文章提出方法的方法可以为TBM滚刀刀头配置提供重要依据。     

Developing a fuzzy model based on subtractive clustering for road header performance prediction

Road header performance prediction plays a significant role in the successful implementation of a tunneling project; so that, there is a need for accurate prediction of the advance rate of tunneling. However, there is relatively less study on predicting the performance of such machinery by using soft computing techniques although they have some advantages over the other methods. On the other hand, often models applied for road header performance prediction neglect interaction between machine and rock mass parameters. The Takagi–Sugeno (TS) fuzzy system model, one of the most popular fuzzy models, can be applied to solve complex problems by transferring a nonlinear system into a set of linear subsystems. However, in many situations, it is not convenient to identify all the rules; so, using the fuzzy clustering techniques in which the rules are resulted from measured data can be useful and valuable. In this paper, a new model based on the geological and geotechnical site conditions is developed to predict the road header performance. The model is developed using soft computing technique that applies the concept of fuzzy logic to take into account the uncertainty and complexity derived from the interaction between rock properties and road header parameters. The prediction capabilities offered by TS fuzzy model based on subtractive clustering method are demonstrated by using field data of obtained from Tabas coal mine in Iran.     

岩石掘进机盘形滚刀的安装及侧滑量的计算

本文探讨了盘形滚刀的安装方式，给出了各安装方式情况下盘形滚刀破岩工作时侧滑量的计算方法和计算公式，可为盘形滚刀的安装设计提供理论参考。     

基于等摩擦耗能的滚刀多目标优化布局

基于接触力学理论建立了滚刀摩擦耗能数学模型,对影响摩擦耗能的主要参数进行了显著性分析。以滚刀摩擦耗能差异最小为原则,通过遗传算法对原刀盘极径、极角以及滚刀半径选型建立优化模型。以TB880E刀盘为实例,研究表明:优化边缘滚刀刀间倾角后,摩擦耗能标准差降低88.78%;优化中心滚刀刀间距后,摩擦耗能标准差降低4.15%;重选边缘滚刀半径后摩擦耗能标准差降低16.4%;极角优化后径向不平衡力降低28.22%;倾覆力矩降为10.33 N·m。该研究可用于刀盘的布置设计及滚刀半径选型,对减少滚刀磨损量差异和提高掘进效率具有重大意义。     

Influence of rock mass fracturing on the net penetration rates of hard rock TBMs

Penetration rates during excavation using hard rock tunnel boring machines (TBMs) are significantly influenced by the degree of fracturing of the rock mass. In the NTNU prediction model for hard rock TBM performance and costs, the rock mass fracturing factor (k_s) is used to include the influence of rock mass fractures. The rock mass fracturing factor depends on the degree of fracturing, fracture type, fracture spacing, and the angle between fracture systems and the tunnel axis. In order to validate the relationship between the degree of fracturing and the net penetration rate of hard rock TBMs, field work has been carried out, consisting of geological back-mapping and analysis of performance data from a TBM tunnel. The rock mass influence on hard rock TBM performance prediction is taken into account in the NTNU model. Different correlations between net penetration rate and the fracturing factor (k_s) have been identified for a variety of k_s values.     

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。     

基于随机森林的复合地层盾构#br# 切口泥水压力预测与分析

盾构切口泥水压力是维持开挖面稳定最重要的因素。针对目前切口泥水压力与盾构掘进参数之间关系不明确的问题,基于Python提出了一种随机森林预测模型。以京张高铁清华园隧道工程为依托,考虑盾构几何参数、施工掘进参数以及泥水参数等因素的影响,通过网格搜索方法以及5折交叉验证法进行模型超参数调整,建立了盾构切口泥水压力的随机森林预测模型。研究结果显示随机森林模型对于复合地层盾构切口泥水压力预测具有较高的准确性与泛化性,在训练集与测试集的表现得分分别为0.963与0.946,结合RMSE和R2等各项数据的评估再次验证了该模型的预测能力。最后通过重要度分析得到对模型预测影响较大的参数分别为泥舱压力、埋深比、推力和扭矩。该研究可为同类条件下盾构开挖面切口泥水压力的预测提供一种有效的方法,对于泥水盾构开挖面的预测控制具有重要的现实意义。     

Clearance angle and evolution of depth of cut in actuated disc cutting

This paper investigates the effect of cutter clearance angle on variation of depth of cut and cutting process with an actuated disc cutting(ADC). ADC is a cyclic cutting method with two main characteristics:(i) a disk-shape cutter is used to attack the rock in an undercutting mechanism; and(ii) the cutter is dynamically actuated as it is moved across the rock. Hence, the cutting process of such system is periodic, each recurrence known as actuation cycle. The first ADC model, developed in 2016, represented an idealization of the technology with a flat disc cutter, where no clearance angle was considered. The evolution of the contact between the disc and the rock was, therefore, computed only on horizontal x-y plane, ignoring the effect of normal component of the force acting on cartridge. This article reports on a study that incorporates the cutter inclination angle in derivation of cutter/rock interface laws. It extends the proposed kinematic and geometry based model to take into account the variable depth of cut in estimating the forces associated with cutting in one actuation cycle. Experiments were conducted using Wobble to test the predictions of the improved model at various operating conditions. The model predictions are matched with the experimental results and effects of various factors are analysed.