Model Test on the Synchronous Technology Combining with Shield Tunneling and Segment Assembling Based on the Linear Distribution Principle of the Thrust Force

Hydraulic thrust system is a critical part of shield tunneling machine. The precise control of the thrust force is a significant task of thrust system during tunneling excavation. In this paper, an operation principle of the hydraulic thrust system test rig is illustrated. Taking into account the variable deadband nonlinear characteristics of proportional relief valve which is used for regulating the thrust pressure, several compensation control strategies are adopted to achieve the precise control of thrust force. Analysis and comparison which bases on simulation and experiment is done at last. The result shows that Fuzzy control can both eliminate the error and reduce the adjustment time which can basically meet the requirement of practical tunnel excavation.

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Three-Dimensional Discrete Element Analysis on Tunnel Face Instability in Cobbles Using Ellipsoidal Particles

Materials ◽

10.3390/ma12203347 ◽

2019 ◽

Vol 12 (20) ◽

pp. 3347

Author(s):

Chao Liu ◽

Liufeng Pan ◽

Fei Wang ◽

Zixin Zhang ◽

Jie Cui ◽

...

Keyword(s):

Model Test ◽

Discrete Element ◽

Soil Disturbance ◽

Triaxial Tests ◽

Shield Tunnel ◽

Shield Tunneling ◽

Tunnel Face ◽

Element Analysis ◽

Micro Scale ◽

Dem Simulations

Soil disturbance has always been the major concern in shield tunneling activity. This paper presents the investigation on the micro-scale responses of the soils during shield tunnel excavation in sandy-cobble stratum. The code paraEllip3d is employed in discrete element method (DEM) analysis in which the soils are mimicked as an assembly of ellipsoids. Triaxial tests on the micro-scale responses of cobbles are carried out using the materials sampled from the tunnel face during construction period, and corresponding DEM simulations are performed to calibrate the micro parameters for the ellipsoids. On this basis, the face instability process during the shield tunneling in cobbles is studied using 1 g model test as well as corresponding DEM simulation. The micro-scale responses of cobbles are investigated by triaxial test as well as corresponding DEM simulations. Multiple material responses are discussed in the DEM simulations, including the stress–strain relationship, the contact distribution, and the force chain evolution in the elementary and model test. Finally, the mechanism of tunnel face instability in cobbles are discussed on the basis of aforementioned investigations.

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Model Test and Simulation Comparison for an Inclined-Leg TLP Dedicated to Floating Wind

Volume 10: Ocean Renewable Energy ◽

10.1115/omae2017-61652 ◽

2017 ◽

Author(s):

François Caillé ◽

Pauline Bozonnet ◽

Timothée Perdrizet ◽

Yann Poirette ◽

Cécile Melis

Keyword(s):

Wind Turbine ◽

Model Test ◽

Thrust Force ◽

Rotation Speed ◽

Numerical Models ◽

Natural Period ◽

Simulation Tools ◽

Simulation Strategy ◽

And Behavior ◽

Fully Coupled

A new floating foundation for multi-MW wind turbine is being developed within a collaboration between SBM Offshore and IFP Energies nouvelles. This inclined leg TLP, is made up of four immersed buoys and a bracing structure, making the floater transparent to wave excitation. The particular mooring arrangement gives the floater interesting motion properties since it creates a fixed point close to the nacelle, strongly reducing the motion at this elevation. In order to validate the concept and the simulation strategy, a model test campaign has been carried out during three weeks in 2015 at MARIN’s offshore basin. The downscaling is performed according to the Froude law of similitude to maintain the hydrodynamic loadings and behavior. The tower bending natural period, the mooring stiffness, and the turbine rotation speed are also maintained in order to reproduce the relevant structural modes and check that no unexpected phenomena occur in the system during production or parked conditions. The scale 1/50 was initially selected so that the MARIN Stock Wind Turbine (MSWT) can be used. This model wind turbine was designed by MARIN with low Reynolds blade airfoils to mimic the NREL 5 MW wind turbine, especially the thrust force. However because of mass distribution issues, the scale has to be changed from 1/50 to 1/40, at this scale only the thrust force and the rotation speed can be replicated. First, a set of calibration tests are performed in the basin and simulated with Orcaflex™ and DeepLinesWind™ for a better understanding of the system and to validate independently the various components of the numerical models. Secondly, design parked and operational cases are conducted with wind, wave and current loadings for two floater orientations and two water depths. The objective of this campaign is to validate the concept behavior as well as the simulation tools and methodologies. Hydrodynamic and structural models are very similar in both software and are checked with the calibration tests from the basin, whereas two strategies are implemented to model the aerodynamic contribution. The Simplified Coupled Simulations (SCS), performed with Orcaflex, use the aerodynamic forces recorded during the model tests to be imposed at tower top; the Fully Coupled Simulations (FCS), run with DeepLinesWind, use the aerodynamic loading computed with the BEM theory from the measured wind.

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Model test and discrete element method simulation of shield tunneling face stability in transparent clay

Frontiers of Structural and Civil Engineering ◽

10.1007/s11709-020-0704-6 ◽

2021 ◽

Author(s):

Huayang Lei ◽

Yajie Zhang ◽

Yao Hu ◽

Yingnan Liu

Keyword(s):

Discrete Element Method ◽

Model Test ◽

Discrete Element ◽

Shield Tunneling ◽

Face Stability ◽

Discrete Element Method Simulation ◽

Element Method

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Model Test and Back Analysis of Shield Tunnel Load Distribution in Soft Clay

Advances in Materials Science and Engineering ◽

10.1155/2021/9992348 ◽

2021 ◽

Vol 2021 ◽

pp. 1-15

Author(s):

Haoshuang Niu ◽

Xiaolin Weng ◽

Chao Tian ◽

Deng Wang

Keyword(s):

Model Test ◽

Load Distribution ◽

Soft Clay ◽

Back Analysis ◽

Horizontal Load ◽

Vertical Load ◽

Linear Distribution ◽

Parabolic Distribution ◽

Mode 2 ◽

Distribution Mode

Combined with the soft clay layer of Foshan metro, a back-analysis method combining model test and numerical simulation is developed. First, the similitude criterion for the model used in this study was derived from similarity theory and elasticity mechanics equations. Artificial clay is prepared by mixing kaolin, bentonite, loess, and river sand in proportions of 4 : 2: 3 : 1. Gypsum, water, and borax are mixed in proportions of 1 : 0.7 : 0.015 to simulate the tunnel lining. The model tests were carried out based on four load modes: the combination of mode 1, vertical load distribution and horizontal load linear distribution, mode 2, vertical load distribution and horizontal load parabolic distribution, mode 3, vertical load parabolic distribution and horizontal load linear distribution, and mode 4, vertical and horizontal load parabolic distribution. Then, the calculation model corresponding to the four load modes is established using ABAQUS, and the measured data is back-analyzed as the known quantity. The specific load values obtained were 359 kPa, 380 kPa, 361 kPa, and 368 kPa by the load-internal force curve. The bending moment and axial force are calculated by substituting the back-analysis load values back into the model and comparing the results with the measured values; it was found that the internal forces under the back-calculation load still deviated by varying degrees. By using the comprehensive error function E to evaluate the advantages and disadvantages of the four distribution modes, the comprehensive errors are 4.3%, 1.7%, 6.5%, and 5.9%, respectively. That is, the error of load distribution of mode 2 (the combination of vertical load distribution and horizontal load parabolic distribution) is the lowest and is highly consistent with the measured value, which is the closest to the characteristics of the load pattern of the stratum.

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A Data-Driven Method for Predicting the Cutterhead Torque of EPB Shield Machine

Discrete Dynamics in Nature and Society ◽

10.1155/2021/5980081 ◽

2021 ◽

Vol 2021 ◽

pp. 1-11

Author(s):

Kairong Hong ◽

Fengyuan Li ◽

Zhenjian Zhou ◽

Feng Li ◽

Xunlin Zhu

Keyword(s):

Linear Regression ◽

Short Term Memory ◽

Thrust Force ◽

Change Point Detection ◽

Linear Regression Method ◽

Pressure Balance ◽

Shield Tunneling ◽

Start Up ◽

Shield Machine ◽

Epb Shield

The prediction of cutterhead torque of earth pressure balance (EPB) shield machine is mainly studied. First, the idea of shield tunneling stage division is proposed. The process of shield tunneling from start to stop (or pause) is divided into start-up and stationary driving stages. Using the change point detection method based on linear regression, the separation points between start-up stage and stationary driving stage are identified from the original construction data, and the datasets of the two stages are extracted, respectively. Then, for the start-up stage, the linear regression method is suggested for the cutterhead torque prediction, since there is a strong linear correlation between the key parameters such as the cutterhead torque and the thrust force. Meanwhile, for the stationary driving stage, considering the fact that the key parameters vary smoothly and show obvious inertia, the long short-term memory (LSTM) network method can be used to establish the relationship model between cutterhead torque and other key parameters, such as the thrust force. Through the test experiments of construction data in Zhengzhou, Luoyang, and Dalian shield projects, the results show that the proposed segmented modeling method possesses good adaptability and the cutterhead torque prediction model has high prediction accuracy.

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