Junzhou Huo

Dynamic Characteristics Study with Multidegree-of-Freedom Coupling in TBM Cutterhead System Based on Complex Factors

A multidegree-of-freedom coupling dynamic model, which contains a joint cutterhead, an inner ring gear, a support shield body, and pinions, is established, considering the external stochastic excitations, time-varying meshing stiffness, transmission errors, clearance, and so forth. Based on the parameters of an actual project and the strong impact of external excitations, the modal properties and dynamic responses are analyzed, and the cutterhead joint surface loads are obtained and treated by rain flow count. Numerical results indicate that the low natural frequencies are 57u2009Hz and 61u2009Hz, and natural vibration modes are pinions-motors rotational mode and translational-overturning coupled mode of cutterhead with inner ring gear correspondingly. Besides, the axial and radial amplitude of dynamic responses are 0.55u2009mm and 0.25u2009mm, respectively. The frequencies of radial, torsional, and overturning vibrations are predominantly concentrated in 112u2009Hz and 120u2009Hz, which indicates that the vibration responses of cutterhead are mainly affected by the external excitations. Finally, as the rain-flow counting results have shown, the standard deviation of the cutterhead joint surface loads in each direction increases by 12–15 times, compared with that of the external excitations; therefore inertia effect should be considered in cutterhead design. The proposed research lays a foundation for dynamic performance optimization and fatigue crack growth life assessment of cutterhead structure.

Disc cutters plane layout design of the full-face rock tunnel boring machine (TBM) based on different layout patterns

The quality of plane layout design of the disc cutters for the full-face rock tunnel boring machine (TBM) directly affects the balance of force distribution on the cutter head during the excavating. Various layout patterns have been adopted in practice during the layout design of the disc cutters. Considering the engineering technical requirements and the corresponding structure design requirements of the cutter head, this study formulates a nonlinear multi-objective mathematical model with multiple constraints for the disc cutters plane layout design, and analyses the characteristics of a multi-spiral layout pattern, a dynamic star layout pattern and a stochastic layout pattern. And then a genetic algorithm is employed to solve a disc cutters multi-spiral layout problem, and a cooperative co-evolutionary genetic algorithm (CCGA) is utilized to solve a disc cutters star or stochastic layout problems. The emphasis was put on the study of superiority of three different layout patterns. Finally, an instance of the disc cutters plane layout design was solved by the proposed methods using three different kinds of layout patterns. Experimental results showed the effectiveness of the method of combining the mathematical model with the algorithms, and the pros and cons of the three layout patterns.

Study of TBM cutterhead fatigue crack propagation life based on multi-degree of freedom coupling system dynamics

Abstract Cutterhead is the core component of TBM tunneling equipment, which endures strong, multi-point distributed impact loads when the TBM tunnels, owing to the extreme surrounding rock environment of high hardness, high temperature and high quartz content. For this reason, the cutterhead works in an extremely severe vibration environment, which leads to engineering fault by a large area crack damage before the service life. Hence, the study on life prediction of TBM cutterhead under the impact loads is a core part of cutterhead design. This paper combines with the technology of system dynamics, linear elastic fracture mechanics and cumulative theory of fatigue damage, for the first time, proposes a method of fatigue crack propagation life prediction for the large and complex structures. In this paper, the TBM cutterhead of an actual project is taken as an example, to predict the fatigue crack propagation life of cutterhead piece and analyze the influences of plate thicknesses on fatigue life, then a new improved scheme of cutterhead structure is presented. The results show that the fatigue crack propagation life of actual cutterhead is 26.6xa0km, which is able to meet the requirement of 20xa0km service life. Moreover, the upper cover plate thickness has the greatest influence on cutterhead fatigue crack propagation life, with the thickness increasing 10%, the life increases nearly by 1.24 times. Then, the other influencing factors are as follows: thickness of the main support plate, thickness of the annular support plate and thickness of the support plate, whereas the influence of the lower cover plate thickness on fatigue life is minimal. Furthermore, the plate thickness limit sizes meeting the life requirement are obtained, and a new structure modified scheme of cutterhead is proposed. Compared with the original scheme, the new cutterhead scheme meets the requirements of structural strength and service life with 8.08% weight decrease, which achieves life determination design and lightweight design. The proposed method of fatigue crack propagation life prediction is feasible in the design and application stage of TBM cutterhead, besides, it is flexible enough and can also be applied in damage strength assessment, dynamic parameters optimization and establishment of nondestructive inspection cycle for the other large and complex structure, and takes on stronger project value and generality.

Optimal Disc Cutters Plane Layout Design of the Full-Face Rock Tunnel Boring Machine (TBM) Using an Ant Colony Optimization Algorithm

Cutter head is one of the most important components for the full-face rock tunnel boring machine (TBM), in which the layout design of the disc cutters is a key issue. Considering the complex engineering technical requirements, this paper studied an ant colony optimization (ACO) algorithm to solve the disc cutters plane layout problem. The searching space of the design variables (disc cutters position) were dispersed by setting several different search steps, then an ACO algorithm was adopted to search the best searching step of each design variable dynamically during the whole optimization process. Finally, the disc cutters layout design instance was solved by the ACO method to demonstrate its feasibility and effectiveness. The computational results showed that that ACO method can provide various disc cutters layout schemes for engineers choosing from.

Sensitivity Analysis of Major Equipment Based on Radial Basis Function Metamodel

A major equipment is generally an extraordinarily large and complex machine containing lots of parameters, understanding and assessment the performance of a major equipment is a great challenge as each of these parameters has uncertainty. In this work, a metamodel-based global sensitivity analysis MBGSA method is proposed for understanding the influence of the parameters on the different outputs. The MBGSA consists of global sensitivity analysis GSA method to identify the impact of each parameters on each of the outputs, moderate-fidelity computational models to mimic the physical model, and metamodeling technique that constructs the mapping between input and output with a limited sampling data. An example on applying the MBGSA in the dynamics analysis of a tunnel boring machines driving system is presented, where hierarchical dynamics model, radial basis function RBF metamodel and Sobols GSA are bonded together to achieve the aim. The results indicate that the proposed MBGSA is available and efficient for the analysis of TBM and thus can be of great help for other large and complex major equipments at the early stage of design.

Notice of Retraction Interval physical programming and its application to evaluation of soil state in shield tunneling

Considering the limitation that weights without physical meaning are required to be provided in traditional evaluation methods, physical programming is used in multiattribute evaluation. Considering the uncertainty of attribute value, the interval physical programming model (IPP) is developed. Decision-makers only need to set boundary values for each preference range, thereby the interval attribute values of selected projects are computed with IPP model. A satisfactory project can be selected by interval numbers ranking. To address the existing problems in comprehensive evaluation on plastic flow behavior of conditioned soil, an attribute set is established to describe soil characteristics. The interval number of each attribute is specified according to the transit time of conditioned soil in the working chamber. Engineering experience is used to determine the region limits of preference function, which can reflect the actual intention of decision-maker. The numerical example of modified soil demonstrates the effectiveness and practicality of the proposed method.

Cutters Layout Design of the Full-Face Rock Tunnel Boring Machine Based on Physical Programming

A cutters layout method of the full-face rock TBM is proposed in this paper, in which the technology requirements of the cutters layout are summarized, then the rock-broken volume estimation method for the non-equality cutters space is given and a nonlinear multi-objective cutters layout mathematical model with complex constraints is established, further, based on the coupling analysis of the multi-objectives and constraints of the mathematical model, a hierarchy solving strategy of polar radius and polar angle is given and physical programming is used to solve cutters layout design of the full-face rock TBM. Finally taking the some imported full-face rock TBM cutters layout design as an experimental example, compared with the computational results of the original layout design, the experimental results show that the proposed cutters layout mathematical model and corresponding solution strategy are feasible and effective.

Optimal Design on Cutterhead Supporting Structure of Tunnel Boring Machine Based on Continuum Topology Optimization Method

A continuum topology optimization method is introduced to the conceptual design of a cutterhead supporting structure of tunnel boring machine to avoid numerous empirical solutions. The conceptual design of the supporting structure is determined in the guidance of topology optimization combined with given working conditions. A finite element analysis indicates that the deformation and stress of the optimized cutterhead are reduced greatly as compared with those of the original design. Furthermore, the deformation distribution of the optimization is more homogeneous than that of the original one. The present work indicates that the continuum topology optimization plays an effective role in guiding the supporting structure design of cutterhead.