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 of Shield Tunnelling-Induced Ground Settlement Considering Soil-Water Coupled and around Soil Disturbance Damage

2010 ◽  
Vol 168-170 ◽  
pp. 357-364
Author(s):  
Ji Feng Liu ◽  
Bo Liu ◽  
Hui Zhi Zhang
Keyword(s):  
Numerical Simulation ◽  
Soil Water ◽  
Ground Surface ◽  
Soil Disturbance ◽  
Surface Settlement ◽  
Shield Tunnel ◽  
Tunnel Construction ◽  
Ground Settlement ◽  
Ground Surface Settlement ◽  
Shield Tunnelling

to evaluate the influence of soil-water coupled and shield tunnel construction induced around soil disturbance damage on ground surface settlement, the process of shield tunnel construction induced around soil disturbance is analyzed, the FLAC3D numerical simulation are carried out, and a newly-modified tunnelling-induced ground settlement calculation method based on disturbance degree of around soil and soil-water coupled is presented, and these methods are applied in case of Beijing Metro 10thLine. It is indicated that considering the influence of the shield tunnelling-induced around soil disturbance damage, and soil-water coupled induced soil properties weakening and the excess pore water pressure dissipating induced soil consolidation to the ground surface settlement are necessary, the calculating result of the newly-modified surface settlement prediction method, and the result FLAC3D numerical simulation all agree well with in-site observed data of Beijing Metro 10th Line.

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 Ground Surface Settlement Evaluation by Proportional Hazards Model in Tunneling Projects

2021 ◽  
Author(s):  
Ali Kazempour Osalou ◽  
sayfoddin moosazadeh ◽  
Ali Nouri Qarahasanlou
Keyword(s):  
Risk Factors ◽  
Ground Surface ◽  
Injection Pressure ◽  
Surface Settlement ◽  
Proportional Hazard ◽  
Ground Settlement ◽  
Cohesion Strength ◽  
Proportional Hazard Model ◽  
Ground Surface Settlement ◽  
Tunnel Depth

Abstract Nowadays, tunnel excavation plays a major role in development of countries. Due to the complex and challenging ground conditions, a comprehensive study and analysis must be done before, during and also after the excavation of tunnels. Hence, the importance of study and evaluation of ground settlement are dramatically increased, since many tunnel projects are performed in the urban areas where there are plenty of constructions, buildings and facilities. For this reason, the control and prediction of ground settlement is one of the complicated topic in the fields of risk engineering. Therefore, in this paper, proportional hazard model (PHM) is used to analyze and study the ground settlement induced by Tabriz Metro Line 2 (TML2) tunneling. The PHM method is a semi-parametric regression method that can enter environmental conditions or factors affecting settlement probability. These influential factors are used as risk factors in the analysis. After establishing a database for a case study and using proportional hazard model for surface settlement analysis, and then, by evaluating the effect of environmental conditions on the ground surface settlement, it has been found that the risk factors of grouting pressure behind the segment, the ratio of tunnel depth to groundwater level, and drained cohesion strength at a significant level of 5% have a direct effect on the probability of settlement. The results also showed that the effect of grout injection pressure on ground subsidence is more than other parameters, and with increasing injection pressure, the probability of exceeding safe subsidence values decreases. In addition, it has been found that increasing the risk factor for the ratio of tunnel depth to groundwater level reduces the probability of exceeding the safe ground settlement. Finally, increasing the number of risk factors for drained cohesion strength increases the probability of exceeding safe settlement.

Three Dimensional Numerical Analysis of Ground Settlement Induced by Shield Tunneling

2012 ◽  
Vol 182-183 ◽  
pp. 937-940
Author(s):  
Zhong Chang Wang
Keyword(s):  
Soil Layer ◽  
Three Dimensional ◽  
Ground Surface ◽  
Vertical Displacement ◽  
Ground Subsidence ◽  
Shield Tunnel ◽  
Ground Settlement ◽  
Shield Tunneling ◽  
Tunnel Face ◽  
Maximum Settlement

The fine numerical simulation is used to study the ground settlement of complex stratum owing to shield construction by ANSYS program. It is shown that the closer the distance between soil layer and the axis of tunnel is, the smaller the disturbance of construction is, the obvious the ground surface settlement is. The value of the maximum settlement at the center of the surface is 7.4mm. The maximum settlement of vault is 14mm. The ground subsidence in cross section distribution is shaped of normal distribution. The closer the distance between soil layer and ground surface is, the smaller the vertical displacement is, the bigger the width of settlement trough of soil layers is. The width of settlement trough is 25m. The volume loss rate of shield tunnel is about 0.32%. The width coefficient of ground settlement trough is 0.56. The tendency of ground settlement decrease to become gentle with the advance of shield construction. The ground settlement keeps constant after tunnel face advancing to 30m.

Control Standard of Ground Surface Settlement Induced by Running Tunnel Construction in Beijing Subway

2011 ◽  
Vol 117-119 ◽  
pp. 721-725 ◽  
Author(s):  
Cheng Ping Zhang ◽  
Li Min Li ◽  
He Li ◽  
Jian Chen Wang
Keyword(s):  
Numerical Simulation ◽  
Ground Surface ◽  
Control Valve ◽  
Surface Settlement ◽  
Tunnel Construction ◽  
Ground Settlement ◽  
Simulation Based ◽  
Ground Surface Settlement ◽  
Subway Construction ◽  
Beijing Subway

Ground settlement, especially the ground surface settlement induced by subway tunneling is an important issue. However, there is no an agreed standard for controlling ground surface settlement during the subway construction at present. The control standard of ground surface settlement was studied using the methods of statistical analysis and numerical simulation based on the running tunnel in Beijing subway. According to the research results, a conclusion could be obtained that the ground surface settlement can be controlled within 40 mm using the general construction measures in Beijing subway running tunnel construction, and furthermore, the settlement of 40mm will not damage the existing nearby structures and utilities including neighboring buildings, bridges and pipelines, etc. So the control valve of 40 mm is rational, which can be adopted as the control standard of ground surface settlement induced by running tunnel construction in Beijing subway.

scholarly journals Three-Dimensional Ground Settlement Induced by Metro Tunnel Excavation Considering the Influence of Group Piles

2016 ◽  
Vol 2016 ◽  
pp. 1-13
Author(s):  
Zou Jin-feng ◽  
Zhang Yan-jun ◽  
Dan Han-cheng
Keyword(s):  
Three Dimensional ◽  
Ground Surface ◽  
Soil Mass ◽  
Surface Settlement ◽  
Stochastic Medium ◽  
Ground Surface Settlement ◽  
Shear Displacement Method ◽  
Metro Tunnel ◽  
Group Piles ◽  
Prediction Approach

Considering the influence of group piles, a prediction model for three-dimensional ground surface settlement induced by circular metro tunnels excavation in incompressible rock masses is proposed based on the stochastic medium theory and the shear displacement method. The surface settlement caused by the metro tunnel opening is divided into two parts. One part is soil mass settlement caused by the metro tunnel opening and calculated by the stochastic medium theory. The other part is the settlement induced by the friction force between the group piles and the soil mass around the metro tunnel cross section and calculated by the shear displacement method. The three-dimensional prediction of the ground surface settlement is obtained by the linear superposition of the two parts. The validation of the proposed prediction approach is proved by comparing with the measured data and the numerical model of the double tunnels under thePuyuanoverpass where metro tunnels undercrossed group piles. The effects of buried depth, radial convergences, center distance of double tunnels, position and size of piles, and group piles are analyzed and discussed. The improved prediction approach can be applied to calculate the three-dimensional ground settlement, especially for the metro tunnels crossing through group piles.

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