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Construction ventilation runs through the entire construction process of large underground caverns and is the key to ensuring construction progress and project safety. For the specific underground cavern group of pumped-storage power plants, a three-dimensional model is constructed, and the CFD method based on fluid mechanics theory is used to simulate the ventilation flow field of the underground cavern group. Through the comparison of the airflow in the main caverns and the air velocity distribution law, Quantitative analysis of the influence of the diameter of the ventilation shaft and the inclination of the shaft on the ventilation flow field shows that when the diameter of the ventilation shaft is 8 m and the inclination of the shaft is 80°, the ventilation effect in the underground cavern group is the best. Applying this scheme to engineering practice and conducting on-site tests, the average relative error of the measuring points is 11.32% by comparing the measured data and the simulation results, which verifies the correctness of the CFD method used. It provides reference value for studying the construction ventilation of underground caverns.

TBM (tunnel boring machine) hob is the core component of the TBM for rock cutting, whose cutting performance can directly determine the overall tunneling efficiency of the TBM. The understanding of cutting rock caused by TBM hobs is still not enough due to the complex contact features between the TBM hob and rock. To study the dynamic cutting process of the TBM hobs deeply, the rock cutting numerical model of the TBM hob is built based on the SPG (smooth particle Galerkin) method, the influence of hob penetration and hob spacing on rock breaking dynamic process, rock cutting forces and specific energy consumption are investigated. The results indicate that the dynamic process of sequential cutting of TBM hobs can be simulated well, and the rock breaking patterns caused by TBM hobs can be reflected with the SPG method. It also shows that the cutting forces of the hob are positively correlated with the hob penetration and hob spacing. For a given hob penetration, there exists an optimum hob spacing to acquire the highest rock cutting efficiency. The hob penetrations of 5, 7, 9, and 11 mm correspond to the optimum hob spacing of 60, 80, 90, and 100 mm respectively. Finally, the simulated results based on the SPG method are verified by comparing the experimental results and the CSM model. This study can provide a new method for simulating the rock cutting dynamic process of the TBM hobs.

During tunnel boring machine (TBM) excavation, scrapers play the role in shoveling the broken rock fragments, directly contacting with them, which may result in seriously wear and failure, causing high economic loss. Therefore, it is an urgent problem to study the wear mechanism of scraper and how to reduce the blade wear. In this study, the wear prediction model of scraper was established based on working mechanism and wear mechanism analysis. The factors influence on wear characteristic were obtained. Then, the numerical model of TBM scraper shoveling the muck was established using discrete element method. The shovel capacity and wear characteristic of scraper were studied. The structural parameters of blade were optimal designed, comprehensively considering the shovel capacity and wear characteristics. The results indicate that abrasive wear is the main type of scraper wear. The main influencing factors of scraper wear are blade angles. When the front angle of the blade is 25° and the back angle is 8°, the wear performance of the scraper would be improved. The optimal results were successfully applied to a tunneling project and the actual data in the engineering construction of the scraper during the construction were analyzed to verify the structural design method of TBM scraper.

To investigate wear characteristics of tunnel boring machine (TBM) disc cutter rings interacting with types of rock, a range of wear tests were performed on a TBM cutter test rig, and laboratory-scale disc cutters were used in the experiments. The mass loss, vertical load, temperature field, wear mechanism and change rule of cutter tip for the disc cutter rings were obtained during the tests. The results indicate that the rock types and properties of rock exhibit great influences on the cutter wear. The variation of the weight loss testing with different types of rock is partially explained by the discrepancies of vertical load, cutting temperature, and the transition of wear mechanisms. In addition, the test results show that the wear characteristics of cutter rings are mainly affected by uniaxial compressive strength (UCS) rather than equivalent quartz content (EQC) for types of rock. This study will benefit the design of cutter rings with enhanced wear resistance.

To investigate the matching rules of cutters with different blade widths in hard rock and extremely hard rock environments, this study carries out a full-scale cutting test of 432-mm disc cutters with blade widths of 12 mm, 19 mm and 30 mm. A multifunctional cutter performance experimental system was used to test the cutting loads and rock-breaking quantity of rust stone granite (hereinafter referred to as hard rock) and granite (hereinafter referred to as extremely hard rock) as well as to analyse the specific energy consumption for rock breaking under different cutting parameters. The experimental results show that (1) the blade width has a greater influence on the normal force than on the rolling force. The rock-breaking resistance of the 12-mm-blade-width cutters under extremely hard rock conditions is 36.7% lower than that of conventional cutters. (2) Under the same conditions, the smaller the blade width is, the smaller the specific rock-breaking energy consumption is and the smaller the optimal cutter spacing is. Under extremely hard rock condition, the specific energy consumption of the 12-mm-blade-width cutters is 37.9% lower than that of conventional cutters. (3) With a certain gross thrust of a single cutter, the rock-breaking quantity of a single 12-mm-blade-width cutter is much larger than that of the 19-mm-blade-width cutter, regardless of the types of rock. Under extremely hard rock conditions, the S/P of the 12-mm-blade-width cutter with the highest rock-breaking efficiency is approximately 10–12.

The mud cake is easily formed during the tunnel boring machine (TBM) excavation in clay soils or rocks containing clay minerals. Mud cake will lead to soil disturbance of tunnel face, clogging cutterhead and even affect the construction efficiency and personnel safety. In this study, a discrimination method of mud cake formation based on cutterhead temperature was proposed. An online monitoring system was designed and installed on the slurry balance TBM. The results show that: (a) the cutterhead temperature data can be reliably detected and transmitted by the system; (b) in a tunneling cycle, the temperature at some positions of the cutterhead will increase first and then decrease; (c) during the field test, the temperature variation is around 2.5 °C under the normal condition, but the temperature variation will increase more than 50 °C due to the mud cake or geological change; (d) compared with the cooling rate, mud cake formation can be accurately discriminated.

As a key component of tunnel boring machines (TBMs), the disc cutter ring and its structural parameters are closely related to the TBM tunneling quality. Literature review shows that investigations on optimization design methods for cutter ring structure are seriously insufficient. Therefore, in this paper, a multiobjective optimization design model of structural parameters for disc cutter rings is developed based on the complex geological conditions and the corresponding cutter ring structure design requirements. The rock breaking capability, energy consumption, load-bearing capability, wear life, and wear uniformity of disc cutter are selected as the objectives, and the geometric structure of cutter rings, ultimate load-bearing capability, and cutterhead drive performance are determined as constraints. According to the characteristics of this model, a self-adaptive multipopulation genetic algorithm (SAMPGA) is utilized to solve the optimization problem, and the Fuzzy analytical hierarchy process (FAHP) is employed to calculate weight coefficients for multiple objectives. Finally, the applicability of the proposed method is demonstrated through a case study in a TBM project. The results indicated that the rock breaking performance and service life of the disc cutter are improved after optimization by using the proposed method. The utilization of SAMPGA effectively solves the premature local convergence problems during optimization. The geological adaptability should be considered in the cutter ring structure design, which can be realized by using the proposed method based on the suitable weight coefficients.

To study the wear characteristics of disc cutter rings, cutter-rock wear tests between cutter rings with six types of hardness and three typical types of rock are carried out based on the liner cutting machine (LCM). The wear mechanism and wear depth are also studied with a laser microscope. The research results show that the wear mechanism of cutter rings is micro cutting when the disc cutter rings wear against sandstone. The wear loss, wear depth and morphology of wear debris change insignificantly with the increase of the hardness. When the cutter rings wear against rust stone, the wear mechanism of cutter rings presents furrow deformation, followed by micro cutting with the increase of the hardness. When the hardness is increased to 57.5 HRC, the cutter wear mechanism begins to show brittle fractures. With the increase of the hardness, the wear loss and wear depth are decreased, but the decrease speed slows when the hardness is increased to 57.0 HRC. When disc cutter rings with different types of hardness wear against gneiss, the wear law is, on the whole, consistent with that in the case of rust stone. Finally, the rule for selecting the appropriate blade shape for cutter rings with different types of hardness when wearing against three typical rock formations is obtained based on the shape changes of the cutter blades.

A supporting-thrusting system is the main load-bearing component of a tunnel boring machine (TBM) and the centralization of vibration response under TBM working. This study combines the structure and working principle of the supporting-thrusting system. Based on the vibration theory and test results at a construction site, the main influence factors of the vibration response of the supporting-thrusting system are the main beam structure, the characteristic parameters of advance cylinder, and the support pressure to surrounding rock. Under the different influence factors, the vibration response of the supporting-thrusting system is calculated and analyzed via computer simulation. The results indicate that, under the equivalent input-load on the TBM and increase in the length of the front main beam, the vibration acceleration at the front area of the TBM increases. The change rate of vertical vibration will be maximum, while the vibration acceleration at the rear area of TBM decreases. When the structure size of the thrusting cylinder increases, the vibration acceleration on the main beam decreases and those of the gripper shoe and saddle frame increase. However, the response to the axis vibration is the most sensitive. As the horizontal support pressure to the surrounding rock increases, the vibration acceleration on supporting-thrusting system decreases. When the level of support pressure exceeds 1.6e4 kN, the vibration acceleration changes gradually. These results provide a reference for designing and operating TBM parameters.

The cutterhead of a full-face rock tunnel boring machine (TBM) is constantly subjected to varying impact and dynamic loads during tunneling processes, resulting in relatively large vibrations that could easily lead to fatigue cracking of the entire machine and affect the tunneling performance and efficiency. To explore the dynamic characteristics of the TBM mainframe, a TBM from a water-diversion project is investigated in this research. According to the TBM vibration transmission route, an equivalent dynamic model of the TBM mainframe is established using the lumped-mass method in which the relevant dynamic parameters are solved. Additionally, the dynamic response characteristics of the TBM mainframe are analyzed. The results indicate that the vibration levels in three directions are approximately the same, the multi-directional vibration of the cutterhead is more intense than that of other components, and the vibration and external excitation exhibit identical change trends. A set of vibration field tests is performed to analyze the in situ dynamic responses of the mainframe and verify the correctness of the dynamic model. The theoretical and measured acceleration values of the TBM mainframe have the same magnitude, which proves the validity of the dynamic model and its solution. The aforementioned results provide an important theoretical value and practical significance for the design and assessment of the TBM mainframe.

To improve the wear resistance of disc cutters for tunnel boring machines (TBMs), this study is devoted to investigating the effects of rocks and cutter ring properties on the wear behaviors of dis...

Geological adaptability matching design of a disc cutter is the prerequisite of cutter head design for tunnel boring machines (TBMs) and plays an important role in improving the tunneling efficiency of TBMs. The main purpose of the cutter matching design is to evaluate the cutter performance and select the appropriate cutter size. In this paper, a novel evaluation method based on multicriteria decision making (MCDM) techniques was developed to help TBM designers in the process of determining the cutter size. The analytic hierarchy process (AHP) and matter element analysis were applied to obtaining the weights of the cutter evaluation criteria, and the fuzzy comprehensive evaluation and technique for order performance by similarity to ideal solution (TOPSIS) approaches were employed to determine the ranking of the cutters. A case application was offered to illustrate and validate the proposed method. The results of the project case demonstrate that this method is reasonable and feasible for disc cutter size selection in cutter head design.

To study the wear behaviors of the tunnel boring machine (TBM) disc cutter ring under drying, water and seawater conditions, a series of cutter-rock wear tests were conducted based on the self-designed TBM cutter performance test bench. The results indicate that the wear behaviors of the cutter ring are affected significantly by wear conditions. The largest mass loss of the cutter ring is under the drying condition, followed by the seawater condition, and the smallest is under the water condition. The differences in mass loss were explained by the cutter force, wear mechanism, and wear debris etc of the cutter ring. These results can provide some references for the wear resistance design and service life prediction of the TBM cutter ring.

To improve the automated management level on construction sites, real-time monitoring of excavators' working stage for production efficiency and economic consumption analysis has been implemented in many projects, revealing great advantages. However, existing vision-based and non-vision-based working stage identification methods ignore the influence of response delay of hydraulic system on the recognition results. To overcome this problem, three machine learning algorithms, which select the control signals of operating handles that can reflect the actuator real-time operating status as segmentation marks, are used to establish the excavator working stage identification model in this study. The results show that the Long Short-Term Memory (LSTM) classifier has an accuracy of 93.21% and effectively reduces the lagging misidentification to 4.68%. This study contributes to automatic measurement of the excavator operational efficiency. For future work, the approach is combined with the adjustment strategy of engine working point to realize the staged energy-saving control of excavators.

To investigate the specific matching characteristics of Tunnel Boring Machine (TBM) cutter ring properties and rock, matching friction tests for six kinds of TBM cutter ring specimens with different properties and two kinds of typical TBM rock samples were performed on a bespoke TBM cutter performance test bench. The results indicate that the matching characteristics of the TBM cutter ring properties and rock type have significant effects on the wear of a TBM cutter ring and that the specific properties of the cutter rings that demonstrate the best matching characteristics with the two types of rock are different. For the cutter ring that exhibits the best matching behaviours with China granite, the hardness is 58.0 HRC, and the toughness is 3.1 J/cm 2 , while the hardness and toughness for the cutter ring that exhibits the best matching characteristics with Bianco Argento granite are 57.0 HRC and 3.7 J/cm 2 , respectively. These results provide basic experimental data for the geological matching design of TBM cutter ring properties.

Disc cutter performance evaluation and selection is one of the typical and challenging kinds of Multiple criteria decision-making (MCDM) problems. To improve the construction efficiency as well as decrease cost of tunnel boring machine (TBM) project, it is essential to evaluate the cutter performance according to the geology and construction demand. This paper develops a novel hybrid fuzzy MCDM approach to address this kind of MCDM problems in the fuzzy environment. To determine more justified weights for criteria with consideration of subjective and objective weights, a hybrid weight-determining method that integrates fuzzy AHP, entropy weight (EW), and game theory (GT) is presented. The fuzzy comprehensive evaluation and fuzzy TOPSIS are combined to obtain the evaluation results with consideration of both quantitative and qualitative criteria. The proposed approach is applied to a case study of disc cutter performance evaluation, and the final rankings of alternatives with the weights of the criteria are discussed. To verify the evaluated results, a comparative study is carried out with engineering practical data, the proposed approach, and some classical MCDM methods. Additionally, a sensitivity analysis is performed based on varying the criteria weights. The investigations show the proposed approach is reasonable, robust, and effective, which can be a precise decision-making aid to deal with many practical MCDM problems in a variety of engineering areas.

The Tunnel Boring Machine (TBM) tunneling process always contains a certain degree of vibrations due to the step broken phenomenon of the cutting tools. Undoubtedly, there is a quite difference in the fragment characteristics which are related to the construction efficiency of TBM under the static load and the combination of static and impact load. In this study, a series of rock breaking tests with a 216 mm diameter disc cutter and marble samples were conducted under different load cases. Based on the Rosin–Rammler distribution curve, the fragments from the cutting tests were also sieved to calculate the absolute size constant (x’) and coarseness index (CI). The relationship between coarseness index, absolute size parameter and the cutting parameters, specific energy, production rate was evaluated. The results show that there is an increasing trend of x’ and CI with the increase of cut spacing and penetration as well as adding impact load component. An overall downtrend in specific energy and upward trend in production rate which are associated with the high efficiency can be observed with the increasing CI and x’. It is believed that the conclusions are of great significance for improving TBM construction efficiency and cutterhead design.