scholarly journals Research on the Prediction Model of Shield Advancement Rate in Sandy Cobble Ground of Beijing

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Qing He ◽  
Liying Xu ◽  
Zhiyong Yang ◽  
Weiqiang Qi ◽  
Zhigang Zhang ◽  
...  
Keyword(s):  
Prediction Model ◽  
Positive Impact ◽  
Earth Pressure ◽  
Screw Conveyor ◽  
Pressure Balance ◽  
Long Distance ◽  
Safety Control ◽  
Rate Prediction ◽  
Total Thrust ◽  
Cutter Head

The long distance and tight construction period of the earth pressure balance shield tunneling in Beijing sandy cobble ground have a very positive impact on grasping the construction progress and improving the organization efficiency. Based on the real-time monitoring data of on-site earth pressure, cutter head speed, total thrust, screw conveyor speed, and cutter head torque, this study investigated the correlation between the shield advancement rate and the above parameters based on multiple nonlinear regression analysis method, which lay down the foundation of shield advancement rate prediction. The prediction model achieved satisfactory results and was further applied to an airport project. The results show that it is of guiding significance to use multiple regression method to establish shield prediction model and put forward the best advancement parameters to ensure the construction progress. The order in which the four operational parameters affect the advancement rate is total thrust, cutter head torque, screw conveyor speed, and cutter head speed. When the advancement time is greater than 57 min, the average advancement rate and daily progress are highly positively correlated. The research provides a reliable basis for the advancement rate prediction, safety control, and parameter optimization of shield advancement in similar ground.

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.

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.

Shield’s EPB Simulation Device Based on Fluid Power Transmission Principle

2011 ◽  
Vol 480-481 ◽  
pp. 745-750
Author(s):  
Xiao Li ◽  
Xiao Jiang Su
Keyword(s):  
Power Transmission ◽  
Effective Means ◽  
Earth Pressure ◽  
Mathematic Model ◽  
Fluid Power ◽  
Screw Conveyor ◽  
Hydraulic Parameters ◽  
Pressure Balance ◽  
Scheme Design ◽  
Earth Pressure Balance

This article presents a shield’s earth-pressure-balance (EPB) simulation device based on fluid power transmission principle. The device was developed according to the mathematic model of shield’s EPB system. It is composed of load simulation subsystem and screw-conveyor speed control subsystem. With the regulations of the hydraulic parameters in the subsystems, the device is capable of simulating the situations of earth input and output in cutter chamber, as well as the changes of earth property and shield propulsive velocity. Experimental results proved that the working principle of the device is right, the regulation of hydraulic parameters is convenient, and the enhancement of experiment strength is feasible. Therefore, the experiment research expense on shield's EPB system is reduced and the experiment efficiency is increased. The developed device can provide an economical and effective means for the scheme design and characteristics analysis of shield's EPB system.

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.

Modeling of soil movement in the screw conveyor of the earth pressure balance machines (EPBM) using computational fluid dynamics

2015 ◽  
Vol 47 ◽  
pp. 136-142 ◽  
Author(s):  
Kaveh Talebi ◽  
Hossein Memarian ◽  
Jamal Rostami ◽  
Ehsan Alavi Gharahbagh
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Earth Pressure ◽  
Screw Conveyor ◽  
Pressure Balance ◽  
Soil Movement ◽  
The Earth ◽  
Earth Pressure Balance

scholarly journals A New Soil Conditioner for Highly Permeable Sandy Gravel Stratum in EPBs

2021 ◽  
Vol 11 (5) ◽  
pp. 2109
Author(s):  
Xin Lin ◽  
Xiong Zhou ◽  
Yuyou Yang
Keyword(s):  
Earth Pressure ◽  
Coarse Grained ◽  
Screw Conveyor ◽  
Plastic Behavior ◽  
Pressure Balance ◽  
Soil Conditioner ◽  
Sandy Gravel ◽  
Ground Collapse ◽  
Earth Pressure Balance ◽  
Full Face

Full-face water-rich gravel stratum is a large challenge during tunnel excavation with earth pressure balance shields (EPBs) because of accidents such as water spewing from the screw conveyor and ground collapse. Slurry and polymer have been used as conditioning agents to avoid such problems and thus ensure a successful tunneling. However, limited improvement of sandy gravel was achieved when traditional soil conditioner were applied. This study proposes a new conditioner (modified slurry) consisting of bentonite slurry, viscosity modifier, sodium silicate and polymer, which will enhance the properties of sand gravel stratum. Low reaction time, high apparent viscosity, good plastic behavior and low permeability were employed for investigating the optimum ratio of the ingredients. The proposed modified slurry has a good performance in conditioning sandy gravel soils and can be the reference for EPBs’ excavation in highly permeable, non-adhesive coarse-grained soil stratum.

scholarly journals Adaptability of the Cutter-Head of the Earth Pressure Balance (EPB) Shield Machine in Water-Rich Sandy and Cobble Strata: A Case Study

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Chaodong Wan ◽  
Zhiyi Jin
Keyword(s):  
Earth Pressure ◽  
Original Position ◽  
Pressure Balance ◽  
Central Opening ◽  
Earth Pressure Balance ◽  
Cutter Head ◽  
Shield Machine ◽  
Construction Efficiency ◽  
Epb Shield ◽  
Maximum Opening

Earth Pressure Balance (EPB) shield machines are considered to be the most efficient tunneling method for Metro tunnels due to their adaptability to a great variety of ground conditions, higher construction efficiency, and providing a safer working environment. There are many guidelines available for EPB shield machine selection. However, these guidelines are very general and cannot be used directly for an upcoming project. This paper takes Chengdu Metro Line 6 in China as the engineering background; the studied area is typical of a water-rich sandy and cobble stratum with high content of cobble. Three types of EPBs in the two continuous intervals exhibit significant differences in performance and encounter many difficulties such as wear of the cutter disc and tools, clogging, and severe surface settlement during the operation. These difficulties prevent the construction efficiency, increase the cost of the project, and cause delays in construction period. The causes of these difficulties are summarized by recording and comparing the operational parameters of the three types of EPBs. These parameters that are summarized include the advance rate, total thrust, torque, and the rate of rotation of the cutter-head. In addition, the surface settlements are also compared. The results indicate that the opening rate, maximum opening size, and the opening position of the cutter-head are key factors that affected the geological adaptability of the shield machine in water-rich sandy and cobble strata. Among the three factors, the maximum opening size and opening position are the most important factors influencing the strata adaptability of the cutter-head. To avoid frequent jams of the cutter-head, the maximum torque should be not less than 6,500 kNm. The maximum opening size should not be less than 420 mm × 420 mm. The effect of increasing the central opening of the cutter-head is that large cobbles and boulders can be discharged through the central opening when they cannot be discharged through the opening near the original position of the cobbles and boulders. This paper provides specific guidance on the selection of cutter-head for shield machines in water-rich sandy and cobble strata.

Study on Soil Improvement Technology of EPBS Tunnel

2011 ◽  
Vol 378-379 ◽  
pp. 484-488
Author(s):  
Gui He Wang ◽  
Yu You Yang
Keyword(s):  
Mechanical Load ◽  
Ground Improvement ◽  
Earth Pressure ◽  
Soil Improvement ◽  
Normal Operation ◽  
Screw Conveyor ◽  
Pressure Balance ◽  
Technical Problems ◽  
Earth Pressure Balance Shield ◽  
The Stability

The tunnel construction often encounters the problem of adaptability of sand-gravel formation and earth pressure balance shield (EPBS) construction, which has brought new technical problems and challenges to those who are participating in the construction project. In order to ensure the normal operation of shield construction, the soil must have ideal plasticity and liquidity, and low permeability to intercept groundwater. Therefore, we must adopt the soil improvement techniques ,namely, to inject the modified materials (mud, foam, polymer, etc.) into excavation face and earth pressure tank(if necessary, to the screw conveyor) to ensure the stability of excavation face, achieve EPBS driving, and help to reduce mechanical load, reduce land subsidence, and increase driving speed at the same time. The ground improvement technique is an important part of the EPBS method. The quality of the application of soil improvement technology is very important to maintain the stability of excavation face and the screw dump device’s dumping smoothly. It also has a significant impact on the shield machine’s functioning safely,economically and efficiently.

scholarly journals Study on the Mechanical Characteristics of the Screw Driving Torque during the Emptying of the Shield Soil Bin

2021 ◽  
Vol 2101 (1) ◽  
pp. 012004
Author(s):  
Xingchun Li ◽  
Yi Yang ◽  
Xinggao Li ◽  
Weilin Su ◽  
Zhi Liu ◽  
...  
Keyword(s):  
Earth Pressure ◽  
Screw Conveyor ◽  
Model Parameters ◽  
Pressure Balance ◽  
Negative Exponential Function ◽  
Earth Pressure Balance Shield ◽  
Earth Pressure Balance ◽  
Negative Exponential ◽  
Soil Bin ◽  
Driving Torque

Abstract This article studies the changing law of the driving torque of the screw conveyor during the emptying process of the earth pressure balance shield chamber. First, the discrete element method of discrete medium theory and 3D software SolidWorks were used to create the research object and the screw conveyor model, and then the model parameters were determined and calibrated through numerical calculations and indoor experiments. The final numerical calculation results show that: 1) the screw torque will drop in waves with the increase of the calculation time. When the screw conveyor rotates at 360 deg/s, the calculated screw torque fluctuation amplitude is small; 2) when the number of particles in the soil bin is reduced to a certain extent, the use of a higher screw speed to improve the “dumping soil effect” is of little significance; 3) the negative exponential function can be used to better fit the decrease of screw torque with time; 4) for the bulk medium, for a given particle size and screw structure, there is a suitable speed, so that the effect of “machine-soil collision” is small, and the torque change of the screw is relatively stable.

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