scholarly journals Experimental and Modeling of Shear Mechanical Behavior of Soil Conditioned With Foaming Agent

2019 ◽  
Vol 8 (11) ◽  
pp. 2616-2622
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Clayey Soil ◽  
Earth Pressure ◽  
Triaxial Tests ◽  
Pressure Balance ◽  
Foaming Agent ◽  
Strength Behavior ◽  
The Matrix ◽  
Earth Pressure Balance

Chemical foam is being used more frequently with Earth Pressure Balance (EPB) shields to achieve underground works, which present a rising interest in the excavation technique. During tunneling with an Earth Pressure Balance shield in clayey soil, clogging of the clay occurs, leading to blocking the cutting head and clog then the shield chambers. Surfactants are commonly used as conditioning agents to reduce clay stickiness. This treatment leads to a change in the mechanical properties of conditioned soil. This paper aims tostudy the shear strength behavior of foam-conditioned soil basing on triaxial tests in the undrained consolidated conditions. Experimental results are modeled using the finite element code COMSOL Multiphysics with the aim of analyzing the effect of the percentage of foam on the shear strength behavior. The soil mixture made from 40% of kaolinite and 60% of sand was conditioned with a foaming agent based on anionic surfactant. Consolidated undrained triaxial tests have been performed in order to explain the effect of foam. Results show that foam reduces the shear stress thanks to their weak stiffness. Shear strength stress is affected by the percentage of the foam in the mixture before shearing by reduce the shear strength of the conditioned soil. Soil-foam mixture has been modeled as a medium containing spherical pore inclusions with a low stiffness compared to the stiffness of unconditioned soil. Stiffness of bubbles inclusions was identified using one of the known homogenization models for composite materials. Results show that the reduce shear stress strength is affected by the percentage of inclusions in the matrix. It confirms the friction angle of composite material decrease as function of the percentage of gas bubbles inclusion in the matrix.

scholarly journals Shear Strength and Compression Coefficient for Conditioned Sand Subjected to Earth Chamber Stress Levels

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Yi Yang ◽  
Xinggao Li ◽  
Xingchun Li
Keyword(s):  
Shear Strength ◽  
Hydroxypropyl Methylcellulose ◽  
Earth Pressure ◽  
Compression Tests ◽  
Pressure Balance ◽  
Shield Tunneling ◽  
Initial Injection ◽  
Bentonite Slurry ◽  
Earth Pressure Balance Shield ◽  
Earth Pressure Balance

Ground conditioning agents are often needed when performing earth pressure balance shield tunneling in sand soils due to its high internal friction, low plastic ductility, and low compressibility. In this work, vane shear and compression tests for standard sand were performed using a homemade test device, and three types of conditioning agents composed of foam, bentonite slurry, and polymer were used in the tests. The effects of the agents on shear strength and compressibility of the conditioned soils were investigated under a typical earth chamber stress level as high as 2 bar. The measured results show that foam does better in reducing shear strength and improving the compressibility of the conditioned soils than bentonite slurry and polymer. Significant increases in the compressibility of foam-conditioned soils can be achieved using foam, and the shear strength of the conditioned sand can be decreased by more than 30% with an initial injection ratio of 40% foam. The bentonite- and polymer-conditioned sands have similar compressibility. The HPMC (hydroxypropyl methylcellulose) polymer does better in decreasing the shear strength of the conditioned soils than other liquid soil conditioners. The influences of the device shear rate on the shear strength of the conditioned soils are also presented.

Geological Adaptive Cutterhead Selection for EPB Shield Based on BP Neural Network

2014 ◽  
Vol 607 ◽  
pp. 118-123
Author(s):  
Lai Kuang Lin ◽  
Yi Min Xia ◽  
Fei He ◽  
Qing Song Mao ◽  
Kui Zhang
Keyword(s):  
Neural Network ◽  
Bp Neural Network ◽  
Earth Pressure ◽  
Training Model ◽  
Structure Design ◽  
Pressure Balance ◽  
Selection For ◽  
Earth Pressure Balance ◽  
Set Up ◽  
Epb Shield

In view of complex and fuzziness of geological adaptive cutterhead selection for earth pressure balance (EPB) shield, a cutterhead selection method based on BP neural network is put forward. Considering the structure characteristics of EPB shield cutterhead, typical cutterhead types are classified and summarized based on cutterhead topology structure and number of spokes. After analyzing the determinants of cutterhead selection, one-to-many mapping relation between cutterhead type and geological parameters is put forward, and then core geologic parameters related to cutterhead selection are concluded. The feasibility of using neural network method to choose the cutterhead type is analyzed, and a BP neural network training model for cutterhead selection is set up and tested in testing sample data. The result shows that the selected cutterhead and the construction cutterhead are basically consistent. The feasibility of this method is proved and it can be theoretical basis for the cutterhead structure design which will improve scientific of cutterhead selection.

scholarly journals Earth pressure balance control of shield tunneling machine based on nonlinear least squares support vector machine model predictive control

2018 ◽  
Vol 52 (1-2) ◽  
pp. 3-10 ◽  
Author(s):  
Xuanyu Liu ◽  
Kaiju Zhang
Keyword(s):  
Support Vector Machine ◽  
Least Squares ◽  
Balance Control ◽  
Earth Pressure ◽  
Screw Conveyor ◽  
Support Vector ◽  
Pressure Balance ◽  
Machine Model ◽  
The Earth ◽  
Earth Pressure Balance

Background: Earth pressure balance shield machines are widely used in underground engineering. To prevent ground deformation even disastrous accidents, the earth pressure in soil chamber must be kept balance to that on excavation face during shield tunneling. Therefore, in this paper an advanced control strategy that a least squares support vector machine model-based predictive control scheme for earth pressure balance is developed. Methods: A prediction model is established to predict the earth pressure in chamber during the tunneling process by means of least squares support vector machine technology. On this basis, an optimization function is given which aims at minimizing the difference between the predicted earth pressure and the desired one. To obtain the optimal control actions, an improved ant colony system algorithm is used as rolling optimization for earth pressure balance control in real time. Results: Based on the field data the simulation experiments are performed. The results demonstrate that the method proposed is very effective to control earth pressure balance, and it has good stability. Conclusion: The screw conveyor speed and advance speed are the major factors affecting the earth pressure in chamber. The excavation face could be controlled balance better by adjusting the screw conveyor speed and advance speed.

Gray Relational Analysis of Graded Gravel Base Asphalt Pavement Structure

2011 ◽  
Vol 255-260 ◽  
pp. 3282-3286
Author(s):  
Xiu Shan Wang ◽  
Li Wang ◽  
Xiao Jun Ding
Keyword(s):  
Earth Pressure ◽  
Planetary Gear ◽  
Gray Relational Analysis ◽  
Stress And Strain ◽  
Pressure Balance ◽  
Joint Point ◽  
Earth Pressure Balance Shield ◽  
Earth Pressure Balance ◽  
Shield Machine ◽  
Increasing Load

The method to analysis the strength of planetary trains’ carriers of EPB(earth pressure balance) shield machine is presented in this paper. The structure of the shield machine trains is analyzed and the 3-D solid model of the carrier is built with Pro/E. After the load on the carrier has been dealt with, the strength of carrier is calculated by means of finite element method. The results via ANSYS show that the max stress and strain on the carriers are increasing as the increasing load on it. The max stress is lying on the joint point of the carrier and planetary gear shaft because of the bending deformation of the shaft.

As-Encountered Prediction of Tunnel Boring Machine Performance Parameters using Recurrent Neural Networks

2020 ◽  
Vol 2674 (10) ◽  
pp. 241-249
Author(s):  
Kabir Nagrecha ◽  
Luis Fisher ◽  
Michael Mooney ◽  
Tonatiuh Rodriguez-Nikl ◽  
Mehran Mazari ◽  
...  
Keyword(s):  
Neural Networks ◽  
Recurrent Neural Networks ◽  
Precast Concrete ◽  
Earth Pressure ◽  
Tunnel Boring Machine ◽  
Operational Parameters ◽  
Pressure Balance ◽  
Tunnel Boring ◽  
Machine Performance ◽  
Earth Pressure Balance

The earth pressure balance tunnel boring machine (TBM) is advanced excavation machinery used to efficiently drill through subsurface ground layers while placing precast concrete tunnel segments. They have become prevalent in tunneling projects because of their adaptability, speed, and safety. Optimal usage of these machines requires information and data about the soil of the worksite that the TBM is drilling through. This paper proposes the utilization of artificial intelligence and machine learning, particularly recurrent neural networks, to predict the operational parameters of the TBM. The proposed model utilizes only performance data from excavation segments before the location of the machine as well as its current operating parameters to predict the as-encountered parameters. The proposed method is evaluated on a dataset collected during a tunneling project in North America. The results demonstrate that the model is effective in predicting operation parameters. To address the potential issue of gathering sufficient data to retrain the model, the possibility of transferring the trained model from one tunnel to another is tested. The results suggest that the model is capable of performing accurately with minimal or even no re-training.

Surface settlement during shield tunnelling at CH218 in Taipei

1998 ◽  
Vol 35 (1) ◽  
pp. 159-168 ◽  
Author(s):  
Chang-Yu Ou ◽  
Richard N Hwang ◽  
Wei-Jung Lai
Keyword(s):  
Ground Surface ◽  
Earth Pressure ◽  
Surface Settlement ◽  
Pressure Balance ◽  
Transit System ◽  
Ground Surface Settlement ◽  
Earth Pressure Balance Shield ◽  
Shield Tunnelling ◽  
Earth Pressure Balance ◽  
Twin Tunnels

This paper presents the surface settlement performance induced by the foamed type of earth pressure balance shield in contract CH218 of the Hsintien Line of the Taipei Rapid Transit System. The surface settlement characteristics caused by the single tunnel and by twin tunnels with reference to two sections spaced at 87 m are studied. Field observations indicate that the surface settlement trough due to the single tunnel can be represented by the normal distribution. The distance of the inflection point to the tunnel center and maximum surface settlement value are consistent with those found in the literature. The characteristics of the surface settlement trough are related to the type of the soil, particularly where the crown of the tunnel is located in a layered soil deposit. The ground surface settlement induced by twin tunnels was found to be larger than estimated using the principle of superposition.Key words: shield tunnelling, surface settlement, field observation.

Cutter-disc consumption during earth pressure balance tunnelling in mixed strata

2018 ◽  
Vol 171 (4) ◽  
pp. 363-376 ◽  
Author(s):  
Khalid Elbaz ◽  
Shui-Long Shen ◽  
Wen-Chieh Cheng ◽  
Arul Arulrajah
Keyword(s):  
Earth Pressure ◽  
Pressure Balance ◽  
Earth Pressure Balance
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