scholarly journals Effects of Different Construction Sequences on Ground Surface Settlement and Displacement of Single Long Pile due to Twin Paralleled Shield Tunneling

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Kan Huang ◽  
Yiwei Sun ◽  
Xianqiang Huang ◽  
Yujian Li ◽  
Meng Jiang ◽  
...  
Keyword(s):  
Urban Areas ◽  
Pile Foundation ◽  
Ground Surface ◽  
Horizontal Displacement ◽  
Element Model ◽  
Surface Settlement ◽  
Pile Foundations ◽  
Shield Tunneling ◽  
Construction Sequence ◽  
Ground Surface Settlement

Shield tunneling activities inevitably pass through pile foundations at close distance in densely urban areas. Various studies have investigated the interaction between newly constructed tunnels and existing pile foundations. However, the influence of different construction sequences of twin paralleled shield tunneling on single long pile is seldom considered. A case was found in the project of Changsha Metro Line 5, where the twin paralleled tunnels were constructed near the Wanjiali Viaduct piles. A three-dimensional finite element model was established to analyze the pier settlement, ground surface settlement trough, and the vertical and horizontal displacement of pile under different construction sequences in layered soil. The results show that the adjacent pile and surrounding environment are affected substantially with the change of construction sequence of twin paralleled tunnels. The construction sequence of condition (b), in which the tunnel closer to the pile foundation is first constructed and then the tunnel farther away from the pile foundation is second constructed, can reduce the settlement of pier by 13.1%, the maximum surface settlement by 7.0%, the maximum vertical displacement of pile foundation by 7.9%, and the maximum horizontal displacement by 6.9%. The present findings can provide reference for similar projects.

scholarly journals Slurry shield tunneling in soft ground. Comparison between field data and 3D numerical simulation

2019 ◽  
Vol 41 (3) ◽  
pp. 115-128
Author(s):  
Mohammed Beghoul ◽  
Rafik Demagh
Keyword(s):  
Urban Areas ◽  
Ground Surface ◽  
Injection Pressure ◽  
Tunnel Boring Machine ◽  
Surface Settlement ◽  
Ground Movement ◽  
Shield Tunnel ◽  
Shield Tunneling ◽  
Ground Movements ◽  
Ground Surface Settlement

Abstract In urban areas, the control of ground surface settlement is an important issue during shield tunnel-boring machine (TBM) tunneling. These ground movements are affected by many machine control parameters. In this article, a finite difference (FD) model is developed using Itasca FLAC-3D to numerically simulate the whole process of shield TBM tunneling. The model simulates important components of the mechanized excavation process including slurry pressure on the excavation face, shield conicity, installation of segmental lining, grout injection in the annular void, and grout consolidation. The analysis results from the proposed method are compared and discussed in terms of ground movements (both vertical and horizontal) with field measurements data. The results reveal that the proposed 3D simulation is sufficient and can reasonably reproduce all the operations achieved by the TBM. In fact, the results show that the TBM parameters can be controlled to have acceptable levels of surface settlement. In particular, it seems that moderate face pressure can reduce ground movement significantly and, most importantly, can prevent the occurrence of face-expected instability when the shield crosses very weak soil layers. The shield conicity has also an important effect on ground surface settlement, which can be partly compensated by the grout pressure during tail grouting. Finally, the injection pressure at the rear of the shield significantly reduces the vertical displacements at the crown of the tunnel and, therefore, reduces the settlement at the ground surface.

scholarly journals Analysis of the Additional Stress and Ground Settlement Induced by the Construction of Double-O-Tube Shield Tunnels in Sandy Soils

2019 ◽  
Vol 9 (7) ◽  
pp. 1399 ◽  
Author(s):  
Wen Zhao ◽  
Peng-jiao Jia ◽  
Lin Zhu ◽  
Cheng Cheng ◽  
Jianyong Han ◽  
...  
Keyword(s):  
Ground Surface ◽  
Field Measurements ◽  
Surface Settlement ◽  
Additional Stress ◽  
Underground Construction ◽  
Shield Tunneling ◽  
Engineering Project ◽  
Ground Surface Settlement ◽  
Potential Damage ◽  
Lateral Friction

Double-O-tube shield tunneling has attracted increasing attention because it offers cost-efficiency in underground construction. Prediction of ground surface settlement and the variety of additional stresses induced by shield construction is crucial to underground construction in metropolises since excessive settlement could trigger potential damage to the surrounding environment. The additional stresses induced by the propulsion of double-O-tube shields are calculated by means of the Mindlin’s equations of elasticity. The characteristics of additional stresses are analyzed with compound Gauss-Legendre integral arithmetic, and the frontal additional thrust, the lateral friction, and the ground loss are taken into account. Subsequently, based on field measurements, the maximum settlement coefficient and width of the settlement trough coefficient of the typical Peck formula are modified. The predictive curve of the Peck formula is closer to the engineering measured data than that of the typical formula. The cut-off functions of ground surface settlement caused by double-O-tube tunnel shield construction are proposed and can predict the shape of ground surface settlement, such as single peak or double peak. The correctness of the proposed functions is verified based on an engineering project.

scholarly journals Spatial Variability of Grouting Layer of Shield Tunnel and Its Effect on Ground Settlement

2020 ◽  
Vol 10 (14) ◽  
pp. 5002
Author(s):  
Zhongzheng Wang ◽  
Dalong Jin ◽  
Chenghua Shi
Keyword(s):  
Spatial Variability ◽  
Negative Impact ◽  
Ground Surface ◽  
Surface Settlement ◽  
Shield Tunnel ◽  
Ground Settlement ◽  
Shield Tunneling ◽  
Spatial Characteristics ◽  
Ground Surface Settlement ◽  
Prediction Approach

This study aims to investigate the effect of the spatial variability of grouting-layer thickness on ground-surface settlement caused by shield tunneling and to provide a rational prediction method. The spatial characteristics of grouting layers were obtained based on statistical analysis. The random finite element method was used to study the effect of spatial variability of different parameters on ground-surface settlement. Simulation results indicate that the spatial variability of the grouting layer has a negative impact on ground settlement. The surface settlement will be underestimated without considering the spatial characteristics of the grouting layer. Thus, a reliable prediction approach of the maximum ground settlement was proposed to control the construction quality.

Prediction on Ground Surface Settlement Caused by Subway Shield Construction in Xi'an

2013 ◽  
Vol 353-356 ◽  
pp. 1534-1538
Author(s):  
Rong Di Liu ◽  
Jian Guo Zheng ◽  
Kai Zhang ◽  
Zhi Yuan Li
Keyword(s):  
Ground Surface ◽  
Surface Settlement ◽  
Characteristic Parameters ◽  
Prediction Formula ◽  
Shield Tunneling ◽  
Ground Surface Settlement ◽  
Subway Construction ◽  
Actual Settlement ◽  
Relevant Calculation

In order to study the ground surface settlement induced by shield tunneling, on the background of Xi'an metro line 2, this paper made use of the measured ground surface settlement to conduct characteristic parameters fitting of the settlement trough by Peck formula and the modified stiffness approach, proposed the initial suggestive value of the relevant calculation parameters, predicted the ground surface settlement by the formula with the determined parameters and compared the settlement with the actual settlement observation. The results show that the determination of the parameters is basicly right, the revised formula can be used to forecast ground surface settlement of Xi'an subway construction and finally a modified prediction formula is given.

scholarly journals Sequential Measurement and Analysis of Large Underground Retaining Structures by Diaphragm Wall Anchor for the Spring Area

2019 ◽  
Vol 2019 ◽  
pp. 1-21
Author(s):  
Jicheng Shu ◽  
Jianping Sun ◽  
Dingwen Zhang ◽  
Huanwei Wei
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Ground Surface ◽  
Lateral Wall ◽  
Horizontal Displacement ◽  
Surface Settlement ◽  
Diaphragm Wall ◽  
Earth Pressures ◽  
Spring Area ◽  
Ground Surface Settlement

The performance of a diaphragm wall-anchor structure in spring area in Jinan city, China, is studied. Based on field measured data, lateral wall deflections, lateral soil movements, horizontal displacement of the capping beam, the maximum lateral wall deflection, ground surface settlement, lateral earth pressures on diaphragm wall, internal force of diaphragm wall, axial anchoring forces, settlements of adjacent building, and pore-water pressure are investigated. The results indicate that the maximum deflections of the lateral wall are 0.07%∼0.18% of the excavation depth (He). The ground surface settlement influence zone extends beyond 2.5He from the pit for this project. The δv,max ranges from 0.67 δh,max to 1.0 δh,max. The maximum lateral active earth pressures on diaphragm walls above the excavation bases range between 0.4He and 0.6He. The axial anchoring forces of the top three layers of anchors change significantly during the excavation while the axial anchoring force of the fourth layer of anchor is constant. The deformation of surrounding building has three stages, including a uniform subsidence stage, an accelerated subsidence stage, and a stable subsidence stage.

scholarly journals Prediction of ground surface settlement induced by twin shield tunnellings in urban conditions

2021 ◽  
Vol 62 (2) ◽  
pp. 47-56
Author(s):  
Thai Ngoc Do ◽  
Truong Duc Nguyen ◽  
Keyword(s):  
Urban Areas ◽  
Surface Deformation ◽  
Ground Surface ◽  
Ground Subsidence ◽  
Analysis Model ◽  
Shield Tunneling ◽  
Construction Technique ◽  
Ground Deformations ◽  
Ground Surface Settlement ◽  
Surface Settlements

Tunneling in urban areas is growing in response to the increased needs for efficient transportation. Many urban tunnels are constructed in soft ground at shallow depths. Metro tunnels are usually constructed as twin-parallel tunnels and their adjacent constructions may lead to surface deformation, affecting the surface environment and the safety of the tunnels. Shield tunnelling is a commonly used as construction technique because it is very effective in reducing ground deformations and thus damage to urban infrastructure. The paper presents a 3D simulation of shield tunneling machines via the finite element code Abaqus and analysis model of ground surface settlements induced by a construction of twin-parallel tunnels. The results show that ground surface settlements induced by a construction of the left tunnel causes surface settlements of about 22÷24 mm and after the construction of both tunnels, it will cause ground subsidence has the greatest value of 33÷35 mm.

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