scholarly journals Clogging Potential of Earth-Pressure Balance Shield Driven Tunnels

2020 ◽  
Vol 14 (1) ◽  
pp. 185-195 ◽  
Author(s):  
Alireza Rashiddel ◽  
Fatemeh Amiri Ramsheh ◽  
Asma Ramesh ◽  
Daniel Dias ◽  
Mohsen Hajihassani
Keyword(s):  
Water Content ◽  
Free Water ◽  
Earth Pressure ◽  
Underground Water ◽  
Atterberg Limits ◽  
Pressure Balance ◽  
Earth Pressure Balance Shield ◽  
Boring Machines ◽  
Cutter Head ◽  
Water Amount

Background: Nowadays, the construction of urban tunnels for rapid transportation in metropolises is necessary. Since these tunnels are excavated at low depths, they are often associated with different problems and hazards. Some of them can reduce the efficiency of the tunnel boring machines and sometimes will stop the project. Among these problems the clogging can cause problems at the cutter head, in the chamber, and in other sections where the material transference occurs. Objective: The main purpose of this paper is to evaluate and determine the risk of clogging in the tunneling boring machine in Line 6 of the Tehran Metro. It includes stations: Amirkabir, Shohada Square, Emam Hossein Square and Sayyadeh Shirazi. This phenomenon induces an adhesion of the shield with the soil, increasing the necessary shear forces and it can eventually leads to the project interruption. Methods: Due to the fact that the criterion for the behavior of fine soils against moisture is Atterberg Limits, therefore, Atterberg Limits and the water content were utilized. For this purpose, the new method proposed by Hollman and Thewes (2013) was used. In this study, in addition to the Atterberg limits, the amount of free water resulting from the machine and from the underground water inflow was included in the calculations. Results: It was found that the water content should be increased carefully as the soil is very sensitive to this parameter. An increase of 15% of the water content permits to reduce the risk of clogging. If the added free water amount 15%, the probability of clogging becomes high. Whereas, in case where the added free water amount reaches 20%, the risk of clogging decreases significantly. Conclusion: According to the performed assessments, it was found that critical areas for the clogging aspect are both the cutter head and the chamber. The sensitivity of the soil is very important to the free water amount. Therefore, due to the behavior of sticky and plastic of clay soils against increasing water, it is necessary to determine the percentage of allowable water used in mechanized excavation projects.

Comparison of predicted and actual states in tunnels: lessons to be learned from the Gerede Water Transmission Tunnel, Turkey

2020 ◽  
pp. qjegh2020-060
Author(s):  
Ahmet Apaydin
Keyword(s):  
Water Pressure ◽  
Earth Pressure ◽  
High Water ◽  
Pressure Balance ◽  
Earth Pressure Balance Shield ◽  
Completion Date ◽  
Earth Pressure Balance ◽  
Boring Machines ◽  
Water Transmission ◽  
Route Cost

The Gerede Tunnel is a large inter-basin project in Turkey. As with many long tunnels, some of the predictions in the project report and the tender contract have not been realized. Completion of the tunnel has been delayed for more than twice the time given in the tender contract. Unexpectedly complex geological–tectonic–hydrogeological conditions and the selection of tunnel-boring machines (TBMs) are the main reasons for this long delay. There were some discrepancies between the predicted and actual geology. The groundwater pressure encountered was much higher than expected. Plastic clays in the limestone and breccia and loose agglomerates with a high water pressure in the faults decreased the advance rate and led to several long stoppages. One of the three double-shield TBMs became stuck in the tunnel and could not be recovered. The last quarter of the tunnel was excavated more slowly, but without severe problems, by a modified earth pressure balance shield TBM. As a result, the TBM type, drive direction, length, route, cost and completion date of the Gerede Tunnel have all changed.

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.

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.

Three-Dimensional Face Stability Analysis of EPBS Tunnels

2011 ◽  
Vol 378-379 ◽  
pp. 449-452
Author(s):  
Xue Gang Huang ◽  
Yu You Yang ◽  
Gui He Wang
Keyword(s):  
Three Dimensional ◽  
Earth Pressure ◽  
Pressure Balance ◽  
Circular Tunnel ◽  
Face Stability ◽  
Analysis Theory ◽  
The Face ◽  
Earth Pressure Balance Shield ◽  
Earth Pressure Balance ◽  
Kinematical Approach

A three-dimensional (3D) failure mechanism, based on the framework of the kinematical approach of limit analysis theory, is applied to calculate the face supporting pressure of a circular tunnel driven by the Earth Pressure Balance Shield (EPBS). The geometry of the mechanisms considered is composed of a sequence of truncated rigid cones. The numerical results obtained are presented.

Earth pressure balance control for shield tunneling machine based on adaptive dynamic programming

2020 ◽  
Vol 42 (13) ◽  
pp. 2440-2449
Author(s):  
Xuanyu Liu ◽  
Sheng Xu ◽  
Kaiju Zhang
Keyword(s):  
Cost Function ◽  
Balance Control ◽  
Earth Pressure ◽  
Screw Conveyor ◽  
Pressure Balance ◽  
The Earth ◽  
Gradient Descent Algorithm ◽  
Action Network ◽  
Earth Pressure Balance ◽  
Cutter Head

In order to avoid the safety accidents caused by earth pressure imbalance during shield machine tunneling process, the earth pressure between excavation face and that in chamber must be maintained balance, but it is difficult for practical engineering. Therefore, a data-driven multi-variable optimization method based on dual heuristic programming (DHP) is proposed. First, a cost function with respect to the chamber’s earth pressure is given in light of Bellman’s principle. Then, based on back propagation neural networks (BPNN), the action network, model network and critic network are established that compose the DHP controller. The networks’ weights are updated through the gradient descent algorithm. By minimizing the cost function, the action network utilizes the critic network’s error to optimize the control variables, so that the optimal advance speed, cutter head torque, cutter head speed, total thrust and screw conveyor speed are obtained. Finally, the simulation experiments are carried out, and the results indicate that the method can effectively control the earth pressure balance in chamber and has strong anti-interference ability.

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