scholarly journals Influence of Water Inrush from Excavation Surface on the Stress and Deformation of Tunnel-Forming Structure at the Launching-Arrival Stage of Subway Shield

2019 ◽  
Vol 2019 ◽  
pp. 1-20
Author(s):  
Shusheng Lv ◽  
Wen Liu ◽  
Shihong Zhai ◽  
Peishuai Chen
Keyword(s):  
Simulation Analysis ◽  
Coupling Effect ◽  
Water Inrush ◽  
Ground Surface ◽  
Reinforced Soil ◽  
Soil Reinforcement ◽  
Shield Tunnel ◽  
Deformation Properties ◽  
Stress And Deformation ◽  
Shield Machine

The launching-arrival stage of the shield is the most dangerous construction stage in subway construction. During the conversion process of the soil and air medium in the shield machine, water inrush at the excavation surface often occurs because of the effect of groundwater. Previous research has focused on the overall stress and deformation of existing tunnels caused by water inrush from the excavation face of the shield machine excavation stage. However, the stress and deformation states of the segments and anchors at different assembly locations of the tunnel, as well as the interaction between the soil reinforcement region and the segments and anchors in the launching-arrival stage have not been considered in previous studies. In this study, the inrush model of the launching-arrival stage of the subway shield was established by utilizing the equivalent refinement modeling technology and ABAQUS simulation analysis with consideration of the fluid-solid coupling effect of water and soil to study the influences of different water head differences on the mechanical and deformation properties of segments and anchors in shield construction under the conditions of water inrush on the excavation surface. The results showed that the water inflow from the tunnel excavation surface caused significant surface subsidence at the tunnel portal, vertical convergence at the cross section of the shield tunnel, and significant increases in the axial and shear forces on the bolt. In addition, based on the existing subway regulation, combined with the simulation results of soil reinforcement measures at different depths, the emergency control criterion for controlling water inrush on the excavation surface was established by using the depth of soil reinforcement. The minimum depth of the reinforced soil from the ground surface at 15 m is recommended to ensure construction safety of the subway shield at the launching-arrival stage.

Numerical Simulation of Shield Tunnel Crossing Masonry Structure Building with Various Degrees

2011 ◽  
Vol 368-373 ◽  
pp. 889-893 ◽  
Author(s):  
Gang Wei
Keyword(s):  
Shear Strain ◽  
Shield Tunnel ◽  
Masonry Building ◽  
Strip Foundation ◽  
Maximum Shear Strain ◽  
Structure Building ◽  
Before And After ◽  
Stress And Deformation ◽  
Shield Machine ◽  
Central Base

Considering the interaction of building-soil-tunnel, the strip foundation masonry building vertical crossed by shield tunnel was simulated by 3D MIDAS/GTS software, and the stress and deformation of building before and after shield machine through the building were analyzed. The results showed that: the deformation and the force are different with different angles through the building; with the angle increases, the central base settlement slightly increased; the maximum overall differential settlement reached at 45 degrees; the maximum shear strain is reached when the machine is completely through the building; with the increase of crossed degree from 22.5 degrees, 45 degrees, 67.5 degrees to 90 degrees, the maximum shear strain of wall increases; the plastic zone of wall is mainly at the top cross position in the wall.

scholarly journals Numerical Analysis on Reinforcement Range of a Closed Steel Sleeve against Collapse

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Qing-Feng Yin
Keyword(s):  
Reinforced Soil ◽  
Soil Reinforcement ◽  
Longitudinal Reinforcement ◽  
Soil Pressure ◽  
Element Analysis ◽  
Jet Grouting ◽  
Soil Settlement ◽  
Steel Sleeve ◽  
Shield Machine ◽  
Closed Steel

Before the shield machine begins to excavate, the end of the station structure often requires extensive soil reinforcement to ensure construction safety. Closed steel sleeve can prevent water leakage, sand leakage, and cave door collapse by balancing the water and soil pressure on the tunnel surface, thereby reducing the reinforcement range. In this study, a launching project of a closed steel sleeve is investigated; the Madis GTS finite element analysis software is used to simulate the triple-tube high-pressure jet-grouting pile to reinforce the water-rich sand layer. Soil displacement and stress after opening of the tunnel door are studied in detail at different longitudinal reinforcement lengths and transverse reinforcement scopes. The results show that, as the longitudinal reinforcement length increases, the displacement of the soil shows a decreasing trend, and the greater the length of the reinforced soil, the smaller the reduction in displacement. Furthermore, with the decrease of the lateral reinforcement range, though the soil settlement area has increased, the displacement remains unchanged. However, changing the end reinforcement range has no effect on the soil stress. In general, based on the strength and stability of the soil after the gate is cut out, the reinforcement range of the closed steel sleeve can be appropriately reduced compared to traditional reinforcement methods.

scholarly journals Effects of Water Inrush from Tunnel Excavation Face on the Deformation and Mechanical Performance of Shield Tunnel Segment Joints

2017 ◽  
Vol 2017 ◽  
pp. 1-18 ◽  
Author(s):  
Tingsheng Zhao ◽  
Wen Liu ◽  
Zhi Ye
Keyword(s):  
Mechanical Performance ◽  
Coupling Effect ◽  
Water Inrush ◽  
Bending Moment ◽  
Sharp Decrease ◽  
Shield Tunnel ◽  
Cross Sectional ◽  
Tunnel Excavation ◽  
Water Head ◽  
Control Criterion

Water inrush from the excavation face often occurs in the current shield construction of metro tunnels. In this study, the discontinuity of shield tunnel lining and the interaction between the tunnel segments, the grouting layer, and the surrounding rock are considered. Based on the 3D nonlinear contact theory, a hybrid model of the shield tunnel is constructed. Considering the fluid-solid coupling effect of water and soil, the influences of different water head differences on the mechanical performance and deformation of segments and joints in the shield tunnel are studied. The water gushing from the excavation face leads to vertical convergence of the cross-sectional area of the shield tunnel, and joint opening and dislocation result in sharp decrease of the waterproof capacity of joints. Meanwhile, the stress in the vicinity of segment joints increases sharply, and local cracks occur in the segment lining. The axial force, shear force, and bending moment in the joint bolt are also significantly increased. Based on the current metro standard and the computational results in this study, an emergency control criterion is put forward by means of controlling the discharge of water: the water head difference over the excavation face is required less than 4.6 M.

scholarly journals Multi-Step Combined Control Technology for Karst and Fissure Water Inrush Disaster During Shield Tunneling in Spring Areas

2021 ◽  
Vol 9 ◽  
Author(s):  
Xing Huang ◽  
Linfeng Li ◽  
Chaofan Zhang ◽  
Bin Liu ◽  
Kejin Li ◽  
...  
Keyword(s):  
Water Inrush ◽  
Ground Surface ◽  
Surrounding Rock ◽  
Control Technology ◽  
Shield Tunneling ◽  
Tunnel Face ◽  
Karst Caves ◽  
Combined Control ◽  
Fissure Water ◽  
Shield Machine

Shield tunneling in highly fractured karst water-rich conditions easily results in water inrush disaster or even causes the roof of the karst caves to collapse. Severe water inrush disasters have occurred during the EPB (earth pressure balance) shield machine of the Jinan Metro Line R1 advanced through a karst and fissure groundwater-rich limestone ground in the spring area. To cope with the extreme water inrush risk, a multi-step combined control technology was put forward. First, a detailed geological exploration was carried out by ahead geophysical prospecting using high-density resistivity method, geological radar, etc., and geological borehole drilling was conducted from the ground surface before excavation. As a result, the distribution orientation, size, fissure development degree, and water inflow channel within the surrounding rock of the karst caves were detected. Second, multi-step grouting was performed to reinforce the surrounding rock, including pre-grouting treatment and filling rock blocks to the big karst caves from the ground surface, multiple grouting with a small amount of inert slurry each time inside the tunnel, and secondary circumferential hoop grouting at the shield tail. Third, the tunneling process was optimized, including optimizing the tunneling parameters, making full use of the air-pressurized tunneling technology of the EPB to press bentonite into the fractures around the excavation cabin to seal the fissure water, and using the drainage system of EPB and muck improvement technology to reduce the water inrush disaster. Meanwhile, shield protection slurry technology is applied to cutter inspection and replacement in the pressurized chamber under dynamic water flow environment of the spring terrain. The practice shows that the water inrush on the tunnel face is obviously alleviated after the shield machine advanced into the grouting area. According to statistics, the water inflow on the tunnel face decreases from about 4 m3/h before treatment to less than 0.3 m3/h after the abovementioned control, and the water seepage between the segmental linings reduces to almost zero. The average advance rate increased from 3 m/day without stopping or even zero when the shield machine needs to shut down 2–3 days for drainage to about 6 m/day. In addition, the treatments prevented the shield machine from jamming and the head descending disaster. This study provided a reliable control method for shield tunneling through the karst and fissure water-rich area and played an essential role in protecting the spring water.

Soil-water inrush induced shield tunnel lining damage and its stabilization: A case study

2020 ◽  
Vol 97 ◽  
pp. 103290 ◽  
Author(s):  
Linchong Huang ◽  
Jianjun Ma ◽  
Mingfeng Lei ◽  
Linghui Liu ◽  
Yuexiang Lin ◽  
...  
Keyword(s):  
Soil Water ◽  
Water Inrush ◽  
Tunnel Lining ◽  
Shield Tunnel

Impact of Double-O-Tube Shield Tunnel Construction on Grillage Beams Foundation Frame Building

2011 ◽  
Vol 71-78 ◽  
pp. 32-36 ◽  
Author(s):  
Xin Jiang Wei ◽  
Jie Hong ◽  
Gang Wei
Keyword(s):  
Principal Stress ◽  
Differential Settlement ◽  
Shield Tunnel ◽  
Tunnel Construction ◽  
Foundation Settlement ◽  
Ground Settlement ◽  
Shield Tunneling ◽  
Frame Building ◽  
Shield Machine ◽  
The Impact

Considering the interaction of building-soil-tunnel, the grillage beams foundation frame building vertical crossed by Double-O-Tube (DOT) shield tunnel was simulated by 3D MIDAS/ GTS software, and the impact of construction on the building was analyzed. The results show that: the ground settlement trough caused by DOT shield tunnel can be fitted by peck formula; during the passage of the shield tunneling through the building, the settlement of the building increased and settlement trough was wilder; the settlement was stable and had a little rebound when shield machine already passed the building; with the increase of driving distance, the first principal stress P1 increased and then was stable; with the increase of L, the shape of foundation settlement curve changed, and the maximum differential settlement between columns increased but was small.

Numerical Simulation Analysis for Scroll of Scroll Compressor Based on ABAQUS

2014 ◽  
Vol 488-489 ◽  
pp. 1047-1051
Author(s):  
Qing Qian Zheng ◽  
Bin Yang ◽  
Ning Chen ◽  
Hui Min Yang ◽  
Min Hu
Keyword(s):  
Numerical Simulation ◽  
Stress Distribution ◽  
Thermal Deformation ◽  
Vortex Flow ◽  
Simulation Analysis ◽  
Temperature Load ◽  
Stress And Deformation ◽  
Finite Method ◽  
Abaqus Software ◽  
Main Factor

In this paper, the finite method is applied and ABAQUS software is used, the vortex flow field is loaded as boundary condition of wraps. The stress and deformation in scroll under the action of gas pressure, temperature load and both of them is analyzed, the stress distribution and deformation of wraps in different shaft rotation angles is discussed, the stress distribution and deformation discipline of wraps are also respectively obtained. The results show that the overall stress and deformation in scroll are the largest when compression chamber is moving near the vent position and the thermal deformation is the main factor of affecting the overall deformation of scroll.

Construction Monitoring on Steel Truss Bridge’s Maintenance and Reinforcement

2018 ◽  
Vol 878 ◽  
pp. 89-94 ◽  
Author(s):  
Er Lei Wang
Keyword(s):  
Simulation Analysis ◽  
Analysis Model ◽  
Element Analysis ◽  
Construction Monitoring ◽  
Finite Element Analysis Model ◽  
Bridge Steel ◽  
Steel Truss ◽  
Stress And Deformation ◽  
Site Test

Implementing monitoring over construction process of old bridge’s reinforcement serves as an important measure to ensure construction quality and safety and realize the goal of reinforcement. This paper, with a case study of the maintenance and reinforcement project of Zhicheng Yangtze River Bridge (steel truss highway-railway combined bridge), adopted MIDAS to establish finite element analysis model, and with stress and deformation as monitoring parameters, completed the construction monitoring work, numerical simulation analysis and site test for the reinforcement project.

Simulation Analysis of Clamping Force in Welding Process of Aluminum Alloy Flankwall of Urban Rail Vehicle

2018 ◽  
Vol 773 ◽  
pp. 214-219
Author(s):  
Ying Shi Sun ◽  
Duo Sun
Keyword(s):  
Aluminum Alloy ◽  
Simulation Analysis ◽  
Local Heating ◽  
Welding Process ◽  
Source Model ◽  
Clamping Force ◽  
Welding Stress ◽  
Ansys Analysis ◽  
Urban Rail ◽  
Stress And Deformation

In the welding process, the welding strain and deformation of the city rail aluminum alloy flankwall are inevitable as a result of local heating, and carrying capacity of the structure will be affected by the welding stress and deformation. In the mean time, it puts forward some requirements for the clamp process, the clamping force can reduce the deformation of the workpiece. But a great change of force will produce in the clamp position during the process of welding, this force changes are easy to cause brittle fracture and fatigue damage of the clamp. In this paper, it gives simulation analysis to workpiece by using ANSYS analysis software and Gauss heat source model. Finally, the conclusion is sum up compared with the actual data.

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