scholarly journals Displacement and Deformation of the First Tunnel Lining During the Second Tunnel Construction

2019 ◽  
Vol 5 (2) ◽  
pp. 332 ◽  
Author(s):  
Lin Wu ◽  
Xiedong Zhang ◽  
Zhihua Zhang ◽  
Luqing Luo ◽  
Weichen Sun
Keyword(s):  
Water Pressure ◽  
Three Dimensional ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
Tunnel Lining ◽  
Scale Model ◽  
Tunnel Construction ◽  
Soil Arching ◽  
Clear Distance ◽  
Twin Tunnels

A three-dimensional twin tunnels scale model was established utilizing the discrete element method (DEM) with PFC3D. This model aims to investigate the displacement (in horizontal and vertical directions) and deformation of the first tunnel lining in four different cases which the clear distance of twin tunnels are 5, 10, 15 and 20 m during the second tunnel construction process. The numerical results indicate that the clear distance between twin tunnels and the distance between the measurement points of the first tunnel and the excavation area of the second tunnel are two most critical factors that influence the displacement and deformation of the first tunnel lining. Meanwhile, the soil arching effect, gravity, water pressure and lateral pressure also have an impact on the behavior of the first tunnel. The maximum disturbance of horizontal and vertical displacements occurred in the time points of finishing of the second tunnel. However, the horizontal displacement of the first tunnel is much more sensitive to the vertical displacement. The first tunnel turns to the right and down in direction while having an anticlockwise rotation (φ) during the process of construction of the second tunnel. In addition, the displacement and deformation of the lining of the first tunnel are critical to monitor, and the necessary precautions should be taken to decrease the risk of craze. In conclusion, the influence of the second tunnel excavation on the first tunnel lining could be neglected when their distance is more than 15 m.

The Vertical and Horizontal Displacements of Cross-river Twin-tunnels Surroundings Induced by Tunneling

2018 ◽  
Author(s):  
Lin Wu ◽  
Zhihua Zhang ◽  
Xiedong Zhang ◽  
FaJin Lin
Keyword(s):  
Three Dimensional ◽  
Great Influence ◽  
Scale Model ◽  
Soil Arching ◽  
Tunnel Excavation ◽  
Large Cities ◽  
Vertical Displacements ◽  
The Difference ◽  
Twin Tunnels ◽  
Horizontal Displacements

<p>Twin-tunnels are widely constructed in large cities because of their many advantages. The first tunnel (named tunnel_1) constructed before a period time than the second tunnel (named tunnel_2) which is to reduce the disturbance between twin-tunnels. In this paper, a three-dimensional scale model of twin-tunnels is established utilizing the discrete element method (DEM) with PFC3D, this model aims to investigate the difference of the vertical displacements and the horizontal displacements of the surroundings in construction process. The numerical results indicate that the peak vertical and horizontal displacements of the surroundings around tunnel_2 are larger than those around tunnel_1. The vertical and horizontal displacements of particles decrease with the distance from the out edge of the twin-tunnels shield lining increases. The existence and evolution of soil arching during tunneling process exert great influence on the stress state and deformation of twin-tunnels surroundings. The peak horizontal displacements are larger in the lateral points of twin-tunnels, while the peak vertical displacements are larger in the vault and bottom points, the tunnel excavation leads the particles around the twin-tunnels move to new location to achieve new equilibrium state. The peak vertical and horizontal displacements occur in own tunnel excavation process, whereas the adjacent tunnel construction affects the displacements as well. The excavation and existence of tunnel_1 have magnified effect on the vertical and horizontal displacements of tunnel_2.</p>

scholarly journals 3D FEM Model on the Parameters’ Influence of EPB-TBM on Settlements of Single and Twin Metro Tunnels During Construction

2021 ◽  
Author(s):  
Masoud Forsat ◽  
Mohammad Taghipoor ◽  
Masoud Palassi
Keyword(s):  
Three Dimensional ◽  
Injection Pressure ◽  
Effective Parameters ◽  
Grout Injection ◽  
3D Fem ◽  
Supporting Pressure ◽  
Epb Tbm ◽  
The Face ◽  
Clear Distance ◽  
Twin Tunnels

AbstractThe present research exposes the investigation on three-dimensional modeling of the single and twin metro tunnels for the case of the Tehran metro line. At first, simulation implemented on the comparison of the ground movements in the single and twin tunnels. Then the simulation has been performed on the influence of effective parameters of EPB-TBM on the surface settlements throughout excavation. The overcutting, shield conicity, grouting, and the final lining system modeled and the influence of face supporting pressure, grout injection pressure, as well as the clear distance of the tunnels, has been analyzed. The initial results showed a valid ground settlement behavior. The maximum settlements occurred at the end of the shield tail and it was higher in the single tunnel. The face supporting pressure had more effect on the surface settlement in comparison to the grout injection pressure. By increasing the face pressure in the single tunnel, the place of maximum settlement moved back while the grout pressure is insignificant for decreasing the settlements. Furthermore, the influence of the clear distance in the twin tunnels led to zero after the length of 30 m. Accordingly, for more distances, the tunnels must be examined independently and as two different single tunnels.

scholarly journals Comparison of Dynamic Characteristics between Small and Super-Large Diameter Cross-River Twin Tunnels under Train Vibration

2021 ◽  
Vol 11 (16) ◽  
pp. 7577
Author(s):  
Lin Wu ◽  
Xiedong Zhang ◽  
Wei Wang ◽  
Xiancong Meng ◽  
Hong Guo
Keyword(s):  
Dynamic Characteristics ◽  
Large Diameter ◽  
Horizontal Displacement ◽  
Element Model ◽  
Vertical Displacement ◽  
Decisive Factor ◽  
Cross River ◽  
Static Responses ◽  
Train Vibration ◽  
Twin Tunnels

Train vibration from closely aligned adjacent tunnels could cause safety concerns, especially given the soaring size of the tunnel diameter. This paper established a two-dimensional discrete element model (DEM) of small (d = 6.2 m) and super-large (D = 15.2 m) diameter cross-river twin tunnels and discussed the dynamic characteristics of adjacent tunnels during the vibration of a train that runs through the tunnel at a speed of 120 km/h. Results in the D tunnel showed that the horizontal walls have the same horizontal displacement (DH) and the vertical walls have the same vertical displacement (DV). The stress state of the surroundings of the D tunnel is the decisive factor for DH, and the distance from the vibration point to the measurement point is the decisive factor for DV. Results in the comparison of the d and D tunnels showed that the D tunnel is more stable than the d tunnel with respect to two aspects: the time the tunnel reaches the equilibrium state and the vibration amplitude of the structure’s dynamic and static responses. The dynamic characteristic of the d and D tunnel is significantly different. This research is expected to guide the design and construction of large diameter twin tunnels.

scholarly journals Stability Improvement Method for Embankment Dam with Respect to Conduit Cracks

2022 ◽  
Vol 12 (2) ◽  
pp. 567
Author(s):  
Young-Hak Lee ◽  
Jung-Hyun Ryu ◽  
Joon Heo ◽  
Jae-Woong Shim ◽  
Dal-Won Lee
Keyword(s):  
Large Scale ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Three Dimensional ◽  
Internal Erosion ◽  
Scale Model ◽  
Seepage Analysis ◽  
Large Scale Model ◽  
Proposed Model ◽  
Improvement Method

In recent years, as the number of reservoir embankments constructed has increased, embankment failures due to cracks in aging conduits have also increased. In this study, a crack in a conduit was modeled based on the current conduit design model, and the risk of internal erosion was analyzed using a large-scale model test and three-dimensional deformation–seepage analysis. The results show that when cracks existed in the conduit, soil erosion and cavitation occurred near the crack area, which made the conduit extremely vulnerable to internal erosion. Herein, a model is proposed that can reduce internal erosion by applying a layer of sand and geotextiles on the upper part of the conduit located close to the downstream slope. In the proposed model, only partial erosion occurred inside the conduit, and no cavitation appeared near the crack in the conduit. The results suggest that internal erosion can be suppressed when the water pressure acting intensively on the crack in the conduit is dispersed by the drainage layer. To validate these results, the pore water pressure, seepage line, and hydraulic gradient were investigated to confirm the erosion phenomenon and reinforcement effect.

scholarly journals Study of the Construction Sequence of Overlapping Tunnels by the Shield Tunneling Method: A Case Study of the Longest Overlapping Tunnel in China

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Zhiyong Yang ◽  
Yaowen Ding ◽  
Yusheng Jiang ◽  
Kuanda Fang ◽  
Linwei Dong ◽  
...  
Keyword(s):  
Working Conditions ◽  
Radial Stress ◽  
Three Dimensional ◽  
Vertical Displacement ◽  
Tunnel Lining ◽  
Shield Tunneling ◽  
Construction Sequence ◽  
Tunneling Method ◽  
The Difference ◽  
Small Change

In this study, the reasonable construction sequence of an overlapping tunnel shield is investigated. Taking the overlapping tunnel of Tianjin Metro Line 5 as the background, a three-dimensional numerical model was established using Flac3D software to study the influence of the “first up and then down” and “first down and then up” construction sequences of the overlapping tunnel on the surface settlement, stratum displacement, lining radial stress, and displacement. The research results show that the shape and width of the final settlement tank on the ground under the two conditions are basically the same, and the difference between the maximum cumulative settlements is small. The accumulated ground settlement caused by the first up and then down construction sequence is 1.8 mm larger than that caused by the first down and then up sequence. The difference between the two working conditions on the vertical displacement of the stratum mainly occurs in the middle stratum of the upper and lower tunnels, and the proportion of the strata in the uplifted state and subsidence state is different. The construction sequence has little effect on the radial stress on the lining of the upper and lower tunnels. Under these two conditions, the excavation of the second tunnel causes a small change in the radial stress of the preceding tunnel lining, both within 4.2%. Under the working condition of first down and then up, the construction of the second tunnel causes the lining of the preceding tunnel to rise by 7.2∼9.2 mm. Under the condition of first up and then down, the construction of the second tunnel causes the lining of the preceding tunnel to sink again by 9.1∼10.4 mm. By comparing the effects of the two working conditions on the stratum and the tunnel lining, it is recommended that the construction be carried out in the order of first down and then up.

Numerical Simulation on Effect of Shield Tunnel Construction on Pipelines with 45* Skew Angle and Tunnel

2014 ◽  
Vol 889-890 ◽  
pp. 1414-1416
Author(s):  
Dong Liang Guo ◽  
De Shen Zhao
Keyword(s):  
Horizontal Displacement ◽  
Vertical Displacement ◽  
Shield Tunnel ◽  
Tunnel Construction ◽  
Analysis Model ◽  
Skew Angle ◽  
Element Analysis ◽  
Tunnel Excavation ◽  
Soil Movement ◽  
The Right

Shield tunnel construction cause soil movement to harm the adjacent underground pipelines. This paper, taking Dalian Spring Street subway station as the background, uses the finite difference software to establish 3-D finite element analysis model to simulate the deformation of pipeline with 45* skew angle in the tunnel construction work. The results show: when the left tunnel push towards pipelines, due to the skew of the pipeline and tunnel, vertical displacement of pipelines is a certain shift to the left. When the right tunnel excavation is complete, the pipeline maximum settlement has a return to the center of the two tunnels. The settlement of pipeline is much bigger than horizontal displacement.

scholarly journals Research and Analysis on the Influence of Small Clear Distance Drilling and Blasting Method on the Existing Tunnel Structure

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Haibin Huang ◽  
Peng Li ◽  
Chuang Wang ◽  
Bingxiang Yuan ◽  
Minjie Chen ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Simulation Analysis ◽  
Peak Load ◽  
Vertical Displacement ◽  
Tunnel Construction ◽  
Finite Element Software ◽  
Resultant Velocity ◽  
Clear Distance ◽  
Under Construction ◽  
Blasting Method

In order to study the vibration influence of tunnel drilling and blasting method on the built tunnel with small clear distance, taking the intersection of Zhuhai Dahengqinshan No. 1 tunnel and Zhuji urban rail tunnel as the engineering background, we used ABAQUS finite element software to conduct numerical simulation analysis on the influence of different blasting loads on existing tunnels with small clear distance in Zhuji tunnel construction. The following conclusions were drawn: the blasting construction of the tunnel under construction had the greatest impact on the vault of the existing tunnel; when the peak load was reduced by half, the stress value, vertical displacement, and resultant velocity of Mises were also reduced by half, which indicates that reducing the peak value of blasting load appropriately can ensure the safety of tunnel construction. When the peak load is 2.7 MPa, the measured and simulated values were less than the resultant velocity limit required by the specification. In addition, the relative error between the measured value and the simulated value was less than 5%, indicating the accuracy of the numerical simulation.

scholarly journals An underground three-dimensional displacement measurement system

2018 ◽  
Vol 232 ◽  
pp. 02053
Author(s):  
Yifeng Cheng ◽  
Qing Li ◽  
Nanying Shentu ◽  
Chao Zhang
Keyword(s):  
Measurement System ◽  
Tilt Angle ◽  
Group Structure ◽  
Three Dimensional ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
Displacement Sensor ◽  
Monitoring Methods ◽  
Geological Disaster ◽  
On Line

With the development of society, the damage of geological disaster to people's life and property is more serious, so the improvement of monitoring means of geological disaster is particularly urgent, there are some shortcomings in traditional monitoring methods, and it is impossible to measure the three-dimensional displacement of underground. The authors have designed an integrated three-dimensional displacement sensor to measure underground horizontal displacement and vertical displacement and tilt angle, and realize the real-time on-line monitoring of underground three-dimensional displacement visually through multi-group structure co-measurement.

scholarly journals Evaluation of a Tunnel Underpass Building Scheme in Yunnan Province

2019 ◽  
Vol 136 ◽  
pp. 04019
Author(s):  
Xiwen Yang ◽  
Tiefeng Zhou ◽  
Xiangyang Cui ◽  
Hongyan Guo ◽  
Ke Li
Keyword(s):  
Structural Damage ◽  
Yunnan Province ◽  
Residential Buildings ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
Surrounding Rock ◽  
Tunnel Construction ◽  
The Impact

Side-crossing residential buildings in tunnel construction may lead to building subsidence, structural damage by tension and affect the use of buildings. Aiming at the structural damage caused by the side-crossing structure of Re Shuitang Tunnel NO.1, by simulating the influence of tunnel construction on the building, it is concluded that the surrounding rock above the tunnel will be deformed when the tunnel crosses the building. The maximum horizontal displacement is 0.64 mm and the maximum vertical displacement is 4.43 mm. According to the analysis results, the surrounding rock above the tunnel should be strengthened in time, and attention should be paid to the impact of blasting on residential buildings, so as to ensure the safety of buildings and provide reference for future construction.

Analysis of Seismic Experiment of Hexagonal Multi Bundle Model Using Core Assembly Mock-Up

2020 ◽  
Author(s):  
Akihisa Iwasaki ◽  
Shinichiro Matsubara ◽  
Hidenori Harada ◽  
Tomohiko Yamamoto
Keyword(s):  
Fast Reactor ◽  
Three Dimensional ◽  
Reactor Core ◽  
Vertical Direction ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
The Core ◽  
Vibration Behavior ◽  
Seismic Experiment ◽  
Core Elements

Abstract The fast reactor core is composed of hundreds of core elements that stand independently on the core support plate, but does not have support to constrain vertical displacement in order to avoid effects such as thermal elongation. When the earthquake occurs, the group vibration behavior is shown, including the rising of core elements in vertical direction, the collision with adjacent core elements in horizontal direction, and the fluid structure interaction. The three dimensional core group vibration analysis code (REVIAN-3D) was constructed to evaluate them. In the case of fast reactor cores in Japan, the horizontal displacement of core elements at the outermost periphery is restricted by the core former (core barrel). However, since there is no core former in fast reactors other than Japan and the boundary conditions are different from those in Japan, the vibration behavior also differs. In this study, to grasp and estimate the group vibration behavior with and without a core former under the earthquake motion, seismic experiment of hexagonal multi bundle model using core assembly mock-up was conducted [1]. These test results show that the horizontal displacements are larger and impact force between pads of core assembly mock-up is smaller without the core former. In this paper, the analysis was verified by group vibration tests with and without a core former.

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