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.

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.

scholarly journals A Displacement-Based Theory for Predicting the Support Force on the Shield Tunneling Surface in Sandy Soil Layers

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Guang Sun ◽  
Han Liu ◽  
Zhiyuan Guo ◽  
Ranjie Li ◽  
Tao Li
Keyword(s):  
Numerical Simulation ◽  
Sandy Soil ◽  
Soil Layer ◽  
Three Dimensional ◽  
Earth Pressure ◽  
Shield Tunnel ◽  
Soil Pressure ◽  
Pressure Balance ◽  
Shield Tunneling ◽  
Support Force

Due to the poor stability of the loose sandy soil layer, if the support force is not properly controlled during the construction process of the shield tunnel using the earth pressure balance method, it is easy to cause the ground to collapse or uplift. Therefore, understanding the support force of the excavation surface of shield tunneling in sandy soil layer is very vital to ensure the stability of the excavation surface. Firstly, it is assumed that the damaged soil is a three-dimensional wedge and a modified three-dimensional wedge in the active and passive failure modes, respectively. The shallow soil pressure theory and the soil plastic limit equilibrium theory are derived by analyzing the stress distribution on the damaged soil. The equation for revealing the inner essence between the support force of the shield excavation surface and excavation surface displacement under the condition of sand-covered soil is used. Secondly, the numerical simulation method analyzes the displacement of the excavation surface when the support force changes under different working conditions, and the relationship curve between the excavation surface support force and the shield tunneling displacement is obtained. The comparison and analysis between the numerical simulation calculation and the theoretical analysis indicate that the deduced calculation equation for the excavation surface support force based on the displacement earth pressure is reasonable.

New Method for Measurement of Lateral Earth Pressure in Cohesive Soils

1975 ◽  
Vol 12 (1) ◽  
pp. 142-146 ◽  
Author(s):  
K. Rainer Massarsch
Keyword(s):  
Pore Pressure ◽  
Effective Stress ◽  
Basic Concept ◽  
Earth Pressure ◽  
New Method ◽  
Cohesive Soils ◽  
Pressure Measurements ◽  
Lateral Stress ◽  
Lateral Earth Pressure ◽  
The Earth

A new method is described by which the total lateral stress in cohesive soils can be measured. When used in combination with pore pressure measurements, the lateral effective stress, the stress change, and the coefficient of lateral earth pressure at rest, K0, can be calculated. The basic concept of the earth pressure cell and its installation, as described in this report, are simple.

Ground Movements in Shield Tunneling and Impacts on Railway Culvert

2014 ◽  
Vol 680 ◽  
pp. 190-193
Author(s):  
Yu Zhuo Jia ◽  
Rui Li
Keyword(s):  
High Speed ◽  
Soil Layer ◽  
Element Model ◽  
Soil Mass ◽  
Shield Tunnel ◽  
Shield Tunneling ◽  
Tunnel Excavation ◽  
High Speed Railway ◽  
Railway Operation ◽  
Box Culvert

The excavation of the tunnel will inevitably cause the displacement of soil layer, and then further threatens the safety of high-speed railway operation. Under the engineering background of high-speed rail’s box culvert, using the technique of MIDAS/GTS, the establishment is based on 3 d finite element model of tunnel, soil mass and box culvert, to analyze the effects of box culvert settlement that led by shield tunnel excavation. The research indicates that tunnel excavation causes settlement of box culvert to some large extents, the soil mass should be reinforced to ensure the safety of the high-speed railway operations during the shield construction.

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