Tunneling Machine Research Articles

Criteria for Cutting Head Clogging Occurrence during Slurry Shield Tunneling

Cutting head clogging is more frequently encountered as more tunnels are being excavated by slurry shield machines. So establishing criteria for cutting head clogging occurrence based on the machine driving parameters is of great engineering significance. Three construction cases of the Beijing south-to-north water diversion auxiliary project, the Jinan Huanghe River Crossing tunnel construction, and the Wuhan Metro Line 8 Yangtze River Crossing tunnel construction, are introduced. Development of the main driving parameters in the construction cases, including the total thrust, the cutting head torque, the advance rate, and the cutting head rotation speed of the tunneling machines before, during, and after the cutting head clogging, are presented and analyzed. The fact is that the total thrust and the cutting head torque of tunneling machines will increase, or will not, once the cutting head clogging occurs. It is recommended to take two combined parameters of total thrust/penetration depth and cutting head torque/penetration depth into account to judge whether the cutting head clogging will occur or not. The maximum increases of the composite parameters by 2–6 times are found in the construction cases. But for the minimum increase, a 30–50% increase of the composite parameter should be noted. The findings can be of great help for similar projects.

Comparative study of dust pollution and air quality of tunnelling anchor integrated machine working face with different ventilation

To study the influence of the air volume of the dust removal fan on dust diffusion during the excavation process, in this study we selected a fully mechanized excavation face with an anchor-integrated tunneling machine for simulation research. We sought to determine the optimal dust removal air volume. ANSYS FLUENT software was used to simulate the working environment of the dust removal fan under different air volumes. Through analysis of the dust movement law of air flow, the dust accumulation position and state are observed. As the exhaust air volume continues to increasing, the same trend is seen with the increase in the wind speed in the tunnel, and dust accumulation and diffusion are effectively controlled. An analysis of temporal and spatial evolution of dust migration showed, that when the exhaust volume Qs reaches more than 300 m3/min, the dust accelerates to the rear of the roadway, and the change in dust distribution is no longer obvious. Considering the situation in the field, it was shown that the optimal exhaust volume was Qs = 300 m3/min. We also found that with increasing air extraction volume, the air-flow speed in the roadway accelerated, which strengthened the pollutant discharge capacity of the far-pressing-near-absorption (FPNA) ventilation system. Finally, field tests were performed to analyze and compare the simulated data with actual data. The deviation rate was < 15%, thus the reliability of the numerical simulation was verified. The research methods and conclusions of this study provide an important reference for the effective control of construction tunnel dust and cleaner production, the protection of tunnel workers’ health, and the optimization of tunnel ventilation systems.

Моделирование взаимосвязей между условиями труда и состоянием здоровья персонала нефтешахт с использованием нечеткой логики

Currently, occupational risk assessment at the workplace is a mandatory procedure. However, for qualitative and quantitative risk assessment, there is often not enough statistical data on negative health consequences. The issue of accounting the contribution of heterogeneous factors of the working conditions is also insufficiently studied. The article considers the workplace of a tunnelling machine operator for mining of high-viscosity oil, where the working conditions are rated class 3.2 (harmful of the second degree). The main contribution to the formation of harmful working conditions is made by the vibroacoustic factors, which is a consequence of the technological process in the oil sheds and maintenance of mining machines. Construction of a fuzzy model with two input vibroacoustic parameters (noise and general vibration), and an output parameter (sensorineural hearing loss as an occupational disease) is described. Modeling includes 4 stages: fuzzification; construction of the database of rules for fuzzy productions; composition using aggregation methods; defuzzification. Variant of fuzzification; of three selected parameters for assessing the risk to the personnel health is proposed: low, medium, high. In the interactive mode, the development and visualization of the fuzzy output system of the problem being solved using the graphical tools of the Fuzzy Logic Toolbox extension package of the MATLAB computer mathematics program was performed. As a result, the visual dependences of the output parameter on vibroacoustic factors are obtained: fuzzy output table, 3D-surface of the fuzzy output, functions of the dependence of the occurrence of sensorineural hearing loss from noise and general vibration. The proposed model can be supplemented with other input parameters that characterize the working conditions, thereby becoming more complicated at the fuzzification stage, refined at the stage of writing fuzzy production rules.

A Novel Hybrid Deep Neural Network Prediction Model for Shield Tunneling Machine Thrust

Shield thrust is a critical operational parameter during shield driving, which is of vital significance for adjusting operational parameters and ensuring efficient and safe propulsion of shield tunneling machine. In this paper, a novel hybrid prediction model (CLM) combining attention mechanism, convolutional neural networks (CNN) and Bi-directional long short-term memory (BiLSTM) network is proposed for shield thrust prediction. Correlation analysis based on Maximal Information Coefficient (MIC) between the thrust and other parameters is first conducted to select optimal parameters and reduce input dimension. An attention mechanism is introduced into CNN to distinguish the importance of different features, with the convolution layer and pooling layer further extracting dimension features of the data. Then, a BiLSTM neural network integrating first attention layer is employed to extract time-varying characteristics of the data, with a second attention layer added to capture important time information. Field data during shield cutting bridge piles are investigated to support and validate the effectiveness and superiority of the proposed method. Results show that the proposed CLM model are general enough to avoid overfitting problems and have good performance at prediction. The predicted value match reasonably well the monitoring data, with coefficient of determination (R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) equaling to 0.85, root mean square error (RMSE) equaling to 0.05, mean absolute error (MAE) equaling to 0.02. The CLM model in this paper can accurately predict the thrust even under complicated construction conditions, which provides reference for similar industrial application.

RELIABILITY ANALYSIS OF FULL-FACE TUNNEL BORING MACHINES WITH THE MONTE CARLO SIMULATION TECHNIQUE

The high boring capability of full-face tunnel boring machines, especially in urban tunnels, has led to their increased use in tunnel excavation in various and unfavourable geological conditions. Therefore, many efforts have been made to predict and improve the performance of these machines. In this regard, most of the previous studies have focused on the effect of geological and mechanical properties of rock or soil. However, delays due to the maintenance and repair of these machines, which contribute to a major share of unwanted and unpredicted stops at work, have not been considered. Reliability analysis is a practical method based on studying the behaviour of breakdowns and maintenance of machines and systems. This approach can be suggested as part of the appropriate planning for machine maintenance and consequently reducing downtime and costs. In this way, it is possible to identify weaknesses and critical points of a machine or system of the boring process. In the present study, the reliability of the full-face tunnelling machine was analysed with the Monte Carlo simulation method. The studied machine is divided into 5 subsystems including mechanical, electrical, hydraulic, water and compressed air subsystems. Using breakdown data of about 24 months of boring operation, the reliability of each subsystem was simulated and evaluated. Eventually, the reliability of the boring machine was simulated using the Kamat-Riley (K-R) method. The results showed that if no maintenance operation is performed on the subsystems, the overall reliability of the boring machine will decline to zero after about 38 hours of continuous boring operation. Finally, to improve the overall reliability of the boring machine, based on accomplished reliability analysis, we suggest an effective preventive maintenance and repair system for keeping the machine in optimal operating conditions for a longer period.

Study on Rock Cutting Mechanism and Efficient Shield Tunneling Control in Mixed-Ground with Different Strengths

Mixed ground condition exerts very significant influences on the rock fragmentation mechanism, rock cutting efficiency, and operational parameters selection of the shield boring machine. In order to reveal the rock cutting mechanism when the shield tunnel boring machine advances through the mixed grounds in Line 13 of the Shenzhen Metro Tunnels, according to several linear cutting tests were conducted using a constant cross-section disc-cutter and five rock types with different strengths. The change of disc-cutter cutting force and rock boreability index were analyzed, and some suggestions were proposed to fulfill the safe and efficient tunneling of the shield machine in mixed ground conditions. The results of this study can offer useful suggestions for the operation parameter selection of the shield tunnel boring machine tunneling through the mixed ground in the Shenzhen Metro Line 13 and similar projects.

Assessment of rate of penetration of a tunnel boring machine in the longest railway tunnel of Turkey

One of the most important issues in tunnels to be constructed with tunnel boring machines (TBMs) is to predict the excavation time. Excavation time directly affects tunnel costs and feasibility. For this reason, studies on the prediction of TBM performance have always been interesting for tunnel engineers. Therefore, the purpose of the study is to develop models to predict the rate of penetration (ROP) of TBMs. In accordance with the purpose of the study, a new database including 5334 cases is obtained from the longest railway tunnel of Turkey. Each case includes uniaxial compressive strength, Cerchar Abrasivity Index, α angle, weathering degree and water conditions as input or independent variables. Two multiple regression models and two ANN models are developed in the study. The performances of the ANN models are considerably better than those of the multiple regression equations. Before deep tunnel construction in a metamorphic rock medium, the ANN models developed in the study are reliable and can be used. In contrast, the performances of the multiple regression equations are promising, but they predict lower ROP values than the measured ROP values. Consequently, the prediction models for ROP are open to development depending on the new data and new prediction algorithms.

A Finite Element Analysis of the Effects of Graphene and Carbon Nanotubes on Thermal Conductivity of Co Phase in WC-Co Carbide.

In engineering practice, the service life of cemented carbide shield tunneling machines in uneven soft and hard strata will be seriously reduced due to thermal stress. When carbon nanotubes (CNTs) and graphene nano-platelets (GNPs) are added to WC–Co carbide as enhanced phases, the thermal conductivity of carbide is significantly improved. Research should be performed to further understand the mechanism of enhancement in composites and to find ways to assist the design and optimization of the structure. In this paper, a series of finite element models were established using scripts to find the factors that affect the thermal conduction, including positions, orientations, interface thermal conductivity, shapes, sizes, and so on. WC–Co carbide with CNTs (0.06%, 0.12%, and 0.18% vol.), GNPs (0.06%, 0.12%, and 0.18% vol.) and hybrid CNTs–GNPs (1:1) were prepared to verify the reliability of finite element simulation results. The results show that the larger the interface thermal conductivity, the higher the composite phase thermal conductivity. Each 1%vol of CNTs increased the thermal conductivity of the composite phase by 7.2%, and each 1% vol. of GNPs increased the thermal conductivity of the composite phase by 5.2%. The proper curvature (around 140°) of CNTs and GNPs with a proper diameter to thickness ratio is suggested to lead to better thermal conductivity.

Analysis of Asymmetrical Deformation of Surface and Oblique Pipeline Caused by Shield Tunneling along Curved Section

The deformation of existing pipelines caused by the tunneling of a shield machine along curved sections has not been sufficiently researched, and a corresponding theoretical prediction formula is lacking. This paper derives a prediction formula for the deformation of an existing pipeline caused by shield machine tunneling along a curved section. Further, a finite difference model (FDM) corresponding to an actual project is built. Finally, the deformation of the surface and existing pipelines caused by shield machine tunneling along the curved section is analyzed. The research results show that the results of theoretical prediction, FDM calculation, and field monitoring data are consistent. In addition, the deformation of the surface and the existing pipeline are asymmetrically distributed when the shield machine tunnels along the curve section instead of symmetrically distributed (for straight line segment). When the pipeline is perpendicular to the tunnel axis, the maximum deformation position of the existing pipeline deviates from the tunnel axis by about 0.5 times the tunnel radius. In addition, as the angle β between the pipeline axis and the tunnel axis increases, the maximum deformation position of the pipeline gradually approaches the tunnel axis.

Improving the properties of remanufactured wear parts of shield tunneling machines by novel Fe-based composite coatings

With the aim of remanufacturing high-value wear parts of shield tunneling machines, novel Fe-based composite coatings were prepared by collaborative modification with nano-TiC and nano-CeO2 particles. This work aims to improve the wear properties of Fe-based alloy coatings by regulating the morphology and dispersion of TiC through the addition of different contents of nano-TiC and nano-CeO2. First, the coatings with different contents of nano-TiC (from 5 wt% to 15 wt%) and nano-CeO2 (from 1 wt% to 2 wt%) were prepared by laser cladding. Subsequently, the microstructure, phase composition, microhardness, and wear properties of the coatings were examined. Furthermore, the wear morphology and the influence mechanism of nano-particles on the wear resistance of the coatings were investigated. It was found that the addition of nano-TiC eliminates the macro-defects of Fe55 alloy coating. Meanwhile, the morphology and dispersion of TiC particles in coatings were affected by the content of nano-TiC and nano-CeO2. Specifically, the addition of 1 wt% nano-CeO2 facilitates to the formation of near-spherical tiny TiC particles with low agglomeration in the coating. Therefore, the Fe55 + 10 wt% nano-TiC+1 wt% nano-CeO2 coating exhibits the best wear property among all the prepared Fe-based coatings. This paper provides theoretical guidance for the preparation of the modified Fe-based coating with excellent wear resistance.

Numerical Simulation of New Support Structure for High In-situ Stress Tunnel of Sichuan–Tibet Railway

Existing support technology can easily cause the shield machine to jam. A novel ductile support structure is proposed for large deformation tunnels in soft rock along the whole Sichuan–Tibet railway on the basis of the concept of consuming energy of ductile multilevel yielding support. The design of the support structure is to ensure the safety of the shield machine through the large deformation section of soft rock as quickly as possible. In-situ stress data obtained by hydraulic fracturing measurement method were used as boundary conditions of models. The support structure deformation of front shield tunnelling machine and long-term deformation of corrugated steel primary support, steel waist beam and reinforced concrete secondary lining support system were simulated and analysed on FLAC3D software. The variation of the new support structure under the large deformation of soft rock was predicted. Results show that the force path of ductile multilevel yielding support structure is clear. After the excavation of the tunnel and before the application of the concrete lining support, displacement increment of the primary support structure is large. The latter gradually slows down with time, but it still shows an increasing trend. In terms of total displacement distribution, the displacement in the Z direction is obviously larger than that in the X direction, which is consistent with the actual tunnel deformation characteristics. When the tunnel is in operation for 2, 10, 50 and 100 years, stress concentration is found in the arch foot of the assembled supporting system. This condition is mainly manifested as compressive stress after 10 years and tensile stress between 10 and 100 years.

From rock‐boring organisms to tunnel boring machines: A new rock breaking technology by bioinspiration

The purpose of this study is to achieve better understanding of associated mechanisms and to recommend and identify new strategies to develop new rock breaking technology for Tunnel Boring Machines (TBMs). Tunnel Boring Machine tunnelling mainly depends upon the rock breakage caused by cutters moving on a rock surface in a rolling and sliding motion while under the action of thrust force. The rock breaking behaviour is controlled by the mechanical interaction between the cutters and the rock. Due to the high hardness and high abrasiveness of rock, the cutters have to work under very high thrust force and suffer heavy-load-impact and abrasive wear, causing serious wear and low rock breaking efficiency. Rock-boring organisms exist in nature, which achieve drilling and/or tunnelling in rocks through a tribochemical interaction. This phenomenon is called bioerosion and the organisms are natural ‘TBMs’ to some degree. In this study, the interaction between TBM cutters and rock is presented, and current measures to improve cutter wear and rock breaking efficiency and their limitations are reported. Then, the connotation, mechanism and typical cases of bioerosion are presented. Finally, inspired by bioerosion, a new chemically assisted rock breaking technology is proposed for TBMs.

Periodic tunnelling reloaders improvement

The investigated object - periodic action tunnelling bunker-loaders. It is proposed to increase the mining operations efficiency by introducing an intermediate loading and transport element in a periodic action bunker-reloader form into the tunnelling machine - main transport technological chain, which ensures mining machine continuous operation while implementing the minimum time for loading a vehicle. It has been established that there is an experience in the bunker designs - loaders use with a traction-transporting body reciprocating movement: the transporting elements wedge-shaped or with variable geometry. To eliminate the identified shortcomings, fundamentally new technical solutions are proposed, based on a forward-acting hydraulic drive and transported elements use that provide material single movement in large volumes, at their movement low speeds. A proposed design detailed description protected by RF patents is given. The methodology general provisions for conducting experimental studies on a model setup are considered.

Combine technology in construction of transport tunnels

Article reviews the questions of using the combine technology in construction of transport tunnels with mechanized mining, taking into account the standard being developed, which establishes characteristic features and procedures of classifying the tunnels in public roads. Restrictions in connection to environmental safety of transport activities are specified. It was suggested, along with tunnelling machines of selective effect, to use reloaders with reciprocated motion of traction transporting units and with variable geometry of transporting elements.

A novel constrained dense convolutional autoencoder and DNN-based semi-supervised method for shield machine tunnel geological formation recognition

Accurately acquiring the geological information of the tunnel face will help to set the optimal operational parameters, so that the shield machine can achieve better tunneling performance. The design of the shield machine prevents the operator from observing the surrounding environment directly, and the soft methods which can utilize machine parameters to recognize geological conditions indirectly are becoming a research hotspot. However, current soft methods are all supervised methods which can only use the few machine data with geological type labels, and the unlabeled machine data that is much more than the labeled machine data is wasted. To make the most of all the collected in-situ data to boost the performance of the geological formation recognition model, a novel constrained dense convolutional autoencoder and DNN-based semi-supervised method is proposed. To begin with, 177 machine parameters related to geological conditions are selected and preprocessed. Then, a novel geological feature extractor is obtained via the proposed constrained dense convolutional autoencoder and the unlabeled data. Eventually, a DNN-based geological feature classifier is trained on the basis of the established feature extractor and the labeled machine data, which is capable of recognizing geological formation of the tunnel face. In-situ data collected from a Singapore project (stacked twin bored tunnels) was used to prove the superiority of the proposed method. The results show the constrained dense convolutional autoencoder can extract geological-related features accurately, and the proposed method outperforms other supervised soft methods. Its classification performance in one tunnel is 23.98%, 17.47%, 1.93%, and 18.52% higher than the random forest-based, decision tree-based, KNN-based, and SVM-based methods, respectively. Its classification performance in another tunnel is 33.54%, 33.75%, 42.87%, 43.58%, 33.75%, 49.91%, 37.77%, and 27.04% higher than the random forest-based, SVM-based, decision tree-based, DNN-based, KNN-based, CNN-based, ResNet-based, and DenseNet-based methods, respectively. Thus, the novel semi-supervised method has significantly better generalizability than the currently adopted supervised soft methods.

An accurate and adaptative cutterhead torque prediction method for shield tunneling machines via adaptative residual long-short term memory network

During the tunnel excavation, accurate cutterhead torque prediction is helpful to adjust shield machine operation parameters for avoiding cutterhead jamming, which greatly improves the safety and efficiency and reduces the cost. However, due to complex and changeable geological environments, it is improper to directly apply the trained model into other domains under changeable geological conditions. To solve the cross-domains issues, this paper presents a novel Adaptive Residual Long Short-Term Memory Network (ARLSTM) to predict cutterhead torque across domains. To begin with, residual blocks are applied into extracting beneficial features from the tunneling parameters automatically. And then, these extracted features are fed into feature regression predictor for obtaining final prediction results. Furthermore, the introduction of domain classifier is used for reducing probability distribution discrepancy from different domains via adversarial procedure. Finally, we used the actual dataset collected from Singapore Metro T225 project for evaluating ARLSTM. The experimental results present that ARLSTM improves the prediction performance by reducing 0.0571 MSE on average, 0.0695 MAE on average and 5.20% MAPE on average using the knowledge of source domain dataset. Meanwhile, compared with other data-driven methods, the comparison results present that the proposed network structure achieved better prediction performance. Consequently, ARLSTM has potential as a promising precise tool for cutterhead torque prediction used in the tunneling process.

Synchronization Control of a Dual-Cylinder Lifting Gantry of Segment Erector in Shield Tunneling Machine under Unbalance Loads

Segment assembling is one of the principle processes during tunnel construction using shield tunneling machines. The segment erector is a robotic manipulator powered by a hydraulic system to assemble prefabricated concrete segments onto the excavated tunnel surface. Nowadays, automation of the segment erector has become one of the definite developing trends to further improve the efficiency and safety during construction; thus, closed-loop motion control is an essential technology. Within the segment erector, the lifting gantry is driven by dual cylinders to lift heavy segments in the radial direction. Different from the dual-cylinder mechanism used in other machines such as forklifts, the lifting gantry usually works at an inclined angle, leading to unbalanced loads on the two sides. Although strong guide rails are applied to ensure synchronization, the gantry still occasionally suffers from chattering, “pull-and-drag”, or even being stuck in practice. Therefore, precise motion tracking control as well as high-level synchronization of the dual cylinders have become essential for the lifting gantry. In this study, a complete dynamics model of the dual-cylinder lifting gantry is constructed, considering the linear motion as well as the additional rotational motion of the crossbeam, which reveals the essence of poor synchronization. Then, a two-level synchronization control scheme is synthesized. The thrust allocation is designed to coordinate the dual cylinders and keep the rotational angle of the crossbeam within a small range. The motion tracking controller is designed based on the adaptive robust control theory to guarantee the linear motion tracking precision. The theoretical performance is analyzed with corresponding proof. Finally, comparative simulations are conducted and the results show that the proposed scheme achieves high-precision motion tracking performance and simultaneous high-level synchronization of dual cylinders under unbalanced loads.

The control effect of 3D spiral wind-curtain generator on respirable dust pollution during tunnelling process.

The respirable dust pollution produced in the cutting process of tunnelling machine during tunnelling process is a serious threat to the health of workers. The key to solve this problem is to build an effective ventilation system in the tunnel. In this paper, experiments were designed and implemented to obtain the temporal-spatial evolution of respirable dust pollution before and after the 3D spiral wind-curtain generator was used for tunnel auxiliary ventilation, and the CFD method was used to supplement and visualize the experimental results. Before the 3D spiral wind-curtain generator was used, the respirable dust gradually diffused from the cutting face to other spaces of the tunnel, and finally presented a stable state with time. After using the 3D spiral wind-curtain generator for auxiliary ventilation, the dust diffusion speed in the tunnel was slower than before, and the dust concentration was lower than before. When adjusting the position of the generator and installing it 20m away from the cutting face, an effective dust control wind-curtain formed within the range of 3.5 ~ 6.5m away from the cutting face. With the increase of time, the dust is stably controlled within the space of 4.5m away from the cutting face, and then pumped away by the exhaust fan, so as to purify the tunnel environment and ensure the tunnel's cleanliness and safety and efficient excavation.

Effective method for adjusting the uplifting of shield machine tunneling in upper-soft lower-hard strata

The control and treatment of excessive uplifting of a shield machine during tunneling in the upper-soft lower-hard strata is challenging. This is because buoyancy of the shield machine is induced by the gap between the shield machine and the ground, and the upper ground has less resistance than the lower ground in the upper-soft lower-hard composite strata. In this paper, a new method for adjusting the excessive uplifting of a shield tunnel machine is proposed. This method utilizes a special drill beneath the shield machine’s cutter head that operates on the middle shield machine position and can result in subsidence of the ground under the heavy weight of the shield machine. Based on this new technique, a case study of the excessive uplifting of a shield tunnel machine in the line No. 3 of China’s Nanning Metro is presented. The shield tunnel machine’s maximum uplifting amount of 118 mm was successfully corrected, and the treatment processes had no influence on the surrounding environment. The correction method for the excessive uplifting of shield machines proposed in this study can provide a reference for future projects with similar conditions.

A modular design method based on TRIZ and AD and its application to cutter changing robot

Modular design, Axiomatic design (AD) and Theory of inventive problem solving (TRIZ) have been increasingly popularized in concept design of modern mechanical product. Each method has their own advantages and drawbacks. The benefit of modular design is reducing the product design period, and AD has the capability of problem analysis, while TRIZ’s expertise is innovative idea generation. According to the complementarity of these three approaches, an innovative and systematic methodology is proposed to design big complex mechanical system. Firstly, the module partition is executed based on scenario decomposition. Then, the behavior attributes of modules are listed to find the design contradiction, including motion form, spatial constraints, and performance requirements. TRIZ tools are employed to deal with the contradictions between behavior attributes. The decomposition and mapping of functional requirements and design parameters are carried out to construct the structural hierarchy of each module. Then, modules are integrated considering the connections between each other. Finally, the operation steps in application scenario are designed in temporal and spatial dimensions. Design of cutter changing robot for shield tunneling machine is taken as an example to validate the feasibility and effectiveness of the proposed method.