Control Parameters of EPB Shield Tunneling in Weathered Granite Ground and Below Existing Tunnels

2011 ◽  
Vol 243-249 ◽  
pp. 3572-3581
Author(s):  
Xing Gao Li ◽  
Da Jun Yuan ◽  
Hao Hu
Keyword(s):  
Collaborative Work ◽  
Earth Pressure ◽  
Measured Data ◽  
Second Phase ◽  
Control Parameters ◽  
Shield Tunneling ◽  
Weathered Granite ◽  
The Earth ◽  
Epb Shield ◽  
Advance Speed

The choice of reasonable parameters of EPB shield tunneling in weathered granite ground is of great importance to reduce tunneling-induced effects on existing tunnels. Combined with the practice of the EPB shield tunneling below existing interval tunnels from Kexueguan station to Dajuyuan station of Shenzhen metro line No.1, the method of design and regulation of main parameters including the earth pressure in excavation chamber, the ground conditioning, the volume of the discharged soil, the grouting control and the advance speed, of the EPB shield tunneling are studied. The practice of the below-crossing shows in the weathered granite ground, it is reasonable that the earth pressure in excavation chamber is taken as 0.15-0.2 mpa, and that FER, FIR and CF of foam are taken as 8-15, 30-50% and 3-5% respectively, and that the amount of synchronization grouting is 8-10 m3 per ring along with the injecting pressure of 0.3-0.4 mpa, and that the second phase injection is employed to control the further settlement of existing tunnels when necessary, and that the advance speed is taken as 8-10 mm/min, and as steady as possible. Meanwhile, adjustments according measured data must be performed when necessary. Moreover, the real-time monitoring and a collaborative-work environment among the Parties involved in project are also very crucial to facilitate the risk management of the below-crossing.

Research on Chamber Earth Pressure of EPB Shield Considering Soil Arching Effect

2014 ◽  
Vol 1065-1069 ◽  
pp. 373-377
Author(s):  
Jing Cao ◽  
Hai Xing Yang ◽  
Bo Liang ◽  
Hai Ming Liu
Keyword(s):  
Earth Pressure ◽  
Shield Tunnel ◽  
Pressure Balance ◽  
Soil Arching ◽  
Shield Tunneling ◽  
Arching Effect ◽  
Soil Arching Effect ◽  
Earth Pressure Balance ◽  
Tunnel Depth ◽  
Epb Shield

Chamber earth pressure is one of the significant parameters during the Earth Pressure Balance (EPB) shield construction processing. The soil arching effect is existence when the tunnel depth is enough. It is significant to consider the influence of arching effect to analyze the pressure in soil chamber in shield tunneling. In this paper, the influence of arching effect is considered to calculate the chamber earth pressure. Firstly, the soil is supposed as loose media, and the necessary buried depth of producing arching affects is deduced according to the loose media theory. Then, based on the characteristic of proper arching axis, the equation and the height of proper arch are obtained. At last, the calculation formula of minimum chamber earth pressure of EPB shield tunnel is deduced which can consider the effect of arching effect.

Performance Simulation Analysis and Design of the Scale Model for the Earth Pressure Balance Shield

2011 ◽  
Vol 346 ◽  
pp. 364-371 ◽  
Author(s):  
Xu Chen ◽  
Zhu Feng Shao ◽  
Xiao Qiang Tang ◽  
Ping Fa Feng
Keyword(s):  
Optimization Design ◽  
Driving Forces ◽  
Simulation Analysis ◽  
Earth Pressure ◽  
Scale Model ◽  
Pressure Balance ◽  
Analysis And Design ◽  
The Earth ◽  
Earth Pressure Balance ◽  
Epb Shield

Referring to the Earth Pressure Balance (EPB) shield with the diameter of 6.25m, a new experiment station of EPB shield is proposed, which is loaded with mechanical structure instead of traditional soil box. The structure of the experiment model is designed for the performance analysis of the EPB shield. The mechanical loading device, which is called the soil simulator, can simulate different geological environments. The soil simulator is capable of realizing three work states, such as earth balance pressure, earth under pressure, and earth over pressure. By adopting virtual prototype technology, parametric model of the shield station is established and the co-simulation scheme is determined. Besides, the kinematic analysis as well as variation principles between the displacement and driving forces of the propulsion system are obtained, which build the foundation for optimization design and control of the shield prototype.

scholarly journals Disturbance Process of Sandy Gravel Stratum Caused by Shield Tunneling and Ground Settlement Analysis

2021 ◽  
Vol 9 ◽  
Author(s):  
Nie Qingke ◽  
Sun Guang ◽  
Gao Siyuan ◽  
Liu Hongtao ◽  
Zhou Lichao ◽  
...  
Keyword(s):  
Pore Pressure ◽  
Soil Layer ◽  
Earth Pressure ◽  
Surface Settlement ◽  
Urban Rail Transit ◽  
Shield Tunneling ◽  
Tunnel Excavation ◽  
Sandy Gravel ◽  
Working Surface ◽  
The Earth

This paper analyzed the earth pressure, pore pressure, and surface settlement of the Luoyang urban rail transit tunnel in a sandy gravel stratum (Henan Province, China) under different burial depths by using field measurement methods. The results showed that the earth pressure as well as pore pressure of the soil layer above the working surface increased sharply and reached their maximum values when the cutter head of the shield gradually crossed the working surface. During the completion of synchronous grouting, the earth pressure and pore pressure increased slightly; when shield tunneling passed through the working surface, the earth pressure is smaller than the original earth pressure due to the unloading effect. The surface settlement curve above the tunnel took on a “V” shape after the completion of the left-side tunnel excavation, conforming to the normal distribution pattern. The surface settlement curve above the two tunnels took on a “W” shape after the completion of the right-side tunnel excavation, which is in good agreement with the proposed theoretical calculations. The findings of this study can help for better understanding the control of safety risk during shield construction.

scholarly journals Experimental Study on the Soil Conditioning Materials for EPB Shield Tunneling in Silty Sand

2020 ◽  
Vol 2020 ◽  
pp. 1-21
Author(s):  
Chi-Hao Cheng ◽  
Shao-Ming Liao ◽  
Xiao-Bo Huo ◽  
Li-Sheng Chen
Keyword(s):  
Earth Pressure ◽  
Test System ◽  
Cutting Performance ◽  
Silty Sand ◽  
Test Results ◽  
Pressure Balance ◽  
Shield Tunneling ◽  
Soil Conditioning ◽  
Sand Stratum ◽  
Epb Shield

Earth pressure balance (EPB) shield tunneling in a silty sand stratum is frequently faced with the wear of rotary cutter disc, clogging, or even collapse of workface due to its noncohesive and discrete properties of silty sand material. Soil conditioning is an effective way to reduce the discrete and friction properties of silty sand and to increase its rheology and fluidity, thus improving the cutting performance of EPB machines. However, soil conditioning materials were generally prepared and injected based on past limited field experiences or lab tests which were far from reality. In this article, a ground suitability test system for simulating shield tunneling in a conditioned ground was specially developed and used in a series of tests to investigate the influences of key factors of soil conditioning on the shield cutting performance. In addition, a field experiment of shield tunneling in silty sand of Wuhan Metro was conducted for verification. The major findings were obtained as follows. (1) The proposed test system performed well in simulating and assessing the cutting performance of EPB shield in conditioned soils, and the test results agreed well with the field test. (2) The soil conditioning materials can significantly reduce the cutting torque of shield tunneling in silty sand by up to 60%–70%. (3) The optimal foam and slurry parameters are suggested in the paper for shield tunneling in silty sand, respectively. (4) The test results reveal that the slurry conditioning is better than the foam in decreasing the cutter torque in silty sand. To achieve the same effect of soil conditioning, the injection ratios of foam and slurry should be 45% and 10%, respectively, to achieve the torque reduction ratio of 60%. These findings can provide a practical reference for engineers to determine the best-fit conditioning materials and construction parameters in the silty sand stratum.

Online Fault Prediction for EPB Shield Tunneling Based on Neural Network

2012 ◽  
Vol 457-458 ◽  
pp. 1287-1293 ◽  
Author(s):  
Bu Hai Shi ◽  
Wei Qing Li
Keyword(s):  
Neural Network ◽  
Earth Pressure ◽  
Risk Process ◽  
Fault Prediction ◽  
Pressure Balance ◽  
Shield Tunneling ◽  
The Neural Network ◽  
Earth Pressure Balance ◽  
Artificial Neural Network Ann ◽  
Epb Shield

For the complex earth conditions and uncertain factors, the earth pressure balance (EPB) shield tunneling is a complicated and high-risk process. There would cause some faults, such as earth caking, soil occluding in the capsule, water spewing, surface settlement. To avoid them, this paper applies artificial neural network (ANN) to predict the common shielding faults. The neural network is trained by several samples about the tunnel boring machine’s (TBM) parameters, and then it will have self-learning to identify the fault. With the parallel computing ability, the network could detect and predict abnormal behaviors online. This paper includes three parts, firstly, the introduction of EPB, and four usual blockings; and then the principle of BP neural network is present, for the defect of BP algorithm, two kinds of improved BP algorithms are applied in the network; finally, an simulation is given to illustrate the prediction.

scholarly journals Earth Pressure of Three-Dimensional Stress States under Different Strength Criteria and Its Application

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Yu Zhang ◽  
Jin Liu ◽  
Te-Jia Fan ◽  
Chen-Yang Xu ◽  
Tian-Yi Meng ◽  
...  
Keyword(s):  
Stress State ◽  
Principal Stress ◽  
Three Dimensional ◽  
Earth Pressure ◽  
Measured Data ◽  
Intermediate Principal Stress ◽  
Stress Effect ◽  
Passive Earth Pressure ◽  
The Earth ◽  
Stress States

To solve the Earth pressure problems in practical engineering, such as retaining walls and foundation pits, we derive active and passive Earth pressure formulas in accordance with the relationship between intermediate principal stress and excavation under three-dimensional stress states. The formulas are derived on the basis of the Mohr–Coulomb, spatially mobilized plane (SMP), σ 3 SMP, Lade–Duncan, axisymmetric compression- (AC-) SMP strength, and generalized Mises (Gen-Mises) criteria and then extended to clay. We also compare the calculated Earth pressure with the measured data. Results indicate that the Earth pressure considering medium principal stress contribution under a three-dimensional stress state is consistent with the actual engineering. The calculated active Earth pressure in the Mohr–Coulomb strength criterion is larger, and the passive Earth pressure is smaller than the practical one because the intermediate principal stress effect is not considered. The calculated results of the SMP, σ 3 SMP, Lade–Duncan, AC-SMP strength, and Gen-Mises criteria are close to the measured data, among which the result of the Gen-Mises criterion is closer. The Earth pressure calculated using the Lade–Duncan criterion is no longer appropriate to describe the Earth pressure under medium principal stress condition in this study. The results of this study have theoretical significance for retaining structure design under a three-dimensional stress state.

scholarly journals Experimental Study of the Influence of Excavation Surface Stability and Sand Flowability Caused by Dense Slurry–Earth Pressure Balance Shield Tunneling in Silty Sand Stratum

2020 ◽  
Vol 2020 ◽  
pp. 1-14 ◽  
Author(s):  
Yongjin Qian ◽  
Fanlu Min ◽  
Zhenze Mo ◽  
Xihui Fan
Keyword(s):  
Pore Pressure ◽  
Filter Cake ◽  
Earth Pressure ◽  
Rate Of Change ◽  
Silty Sand ◽  
Pressure Balance ◽  
Shield Tunneling ◽  
Earth Pressure Balance ◽  
Sand Stratum ◽  
Epb Shield

Silty sand is highly permeable and has a large internal friction angle. To ensure the stable and efficient construction of the Earth pressure balance (EPB) shield in silt stratum, it is necessary to reduce the disturbance to the stratum during tunneling and reduce the risk of spewing and blocking during soil discharge. Thus, a new type of dense slurry-EPB shield construction technology is proposed. Using a custom-made test device, the consolidation tests were conducted on sand after mixing it with different amounts of slurry to study the change in the pore pressure in the mixed soil and sand stratum and analyze the stress transmission rule. In addition, slump tests were conducted on the mixed soil to study the change in the fluidity. Based on the laboratory test results, a field investigation was carried out to study the effects of the amount of slurry addition on the pore pressure in the stratum, the driving parameters, and the sand’s flowability during shield tunneling. The results show that when the amount of slurry reaches a certain value, the filter cake effect occurs. The greater the amount of slurry added during the shield tunneling, the smaller the rate of change of the pore pressure in the stratum. When the amount of BC2 slurry added reached 8 m3 per ring, the rate of change was reduced by 57%, and the slump value improved by 93%. The type of filter cake of the DS-EPB shield was only internal filter cake during tunneling, which reduced the disturbance of the excavation face and improved the flowability of the sand. These results are of great significance to the application and promotion of DS-EPB shields in sandy cobble strata.

scholarly journals Muck Problems in Subway Shield Tunneling in Sandy Cobble Stratum

2016 ◽  
Vol 23 (s1) ◽  
pp. 175-179 ◽  
Author(s):  
Kai Cui ◽  
Weikang Lin
Keyword(s):  
Control Method ◽  
Low Cost ◽  
Earth Pressure ◽  
Reference Value ◽  
Field Application ◽  
Geological Condition ◽  
Construction Technology ◽  
Shield Tunneling ◽  
Shield Machine ◽  
Epb Shield

Abstract Experiments aiming at the muck improvement for Chengdu’s subway shield tunneling in water-rich sandy cobble ground initially finds out the kinds and ratio of muck improver suitable for the this strata, and through the field application determines the reasonable ratio of muck improver for shield tunneling in sandy cobble ground, providing a reference to other muck improvement for shied tunneling in similar ground. And the earth pressure balanced shield is widely used in tunnel engineering, with its characteristics as wide adaptability, safe operation, fast driving speed, low environmental noise and low cost. Taking Chengdu Metro Line as the background, aiming at the difficulty faced by EPB shield tunneling in water-rich sandy cobble ground, and based on the explorations and researches of the predecessors and scholars, engineering and technical personnel, the present paper combines with engineering examples to make a systematic summary and research on key construction technology of EPB shield tunneling through sandy cobble ground from the aspects of EPB shield adaptability, , structure and transformation of cutter and helical unearthed wares, settlement control method, and muck improvement measures. It has certain reference value and guiding significance to the selection of shield machine and the reconstruction of shield machine in complex geological condition.

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