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.

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.

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 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 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.

scholarly journals Analytical Method for Evaluating the Ground Surface Settlement Caused by Tail Void Grouting Pressure in Shield Tunnel Construction

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Changsheng Wu ◽  
Zhiduo Zhu
Keyword(s):  
Elastic Modulus ◽  
Ground Surface ◽  
Surface Settlement ◽  
Shield Tunnel ◽  
Tunnel Construction ◽  
Grouting Pressure ◽  
Ground Surface Settlement ◽  
Tunnel Depth ◽  
Surface Heave ◽  
Surrounding Soil

The tail void grouting is a key step in shield tunnel construction and has an important influence on the loading on the surrounding soil and on the resulting settlement. In order to estimate the ground surface settlement caused by tail void grouting pressure in tunnel construction, the loading on the surrounding soil is simplified as an expansion problem of the cylindrical cavity in semi-infinite elastic space. A simple analytical formula is deduced by using the virtual image technique and Fourier transform solutions. The effectiveness of the proposed method is verified by case studies. The effects of elastic modulus, tail void grouting pressure, tunnel radius, and tunnel depth on the ground surface heave are conducted. The results indicate that the computed results are in accordance with Ye’s solution and it is more rational to consider the ground surface heave induced by tail void grouting pressure in the prediction of ground settlement due to shield excavation. Moreover, the ground surface heave owing to tail void grouting pressure resembled a Gaussian distributed curve. Thus, no matter the ground surface subsidence or ground surface heave can be predicted by means of adding the presented empirical formula to the Peck formula which cannot predict the ground surface heave. The ground surface heave decreases with an increase in elastic modulus. On the contrary, as the tail void grouting pressure and tunnel radius increase, the ground surface heave increases, respectively. The ground surface heave first steadily increases and then declines gradually with the tunnel depth increase.

Effects of pile extraction and refilling with cement slurry on ground settlements

2013 ◽  
Vol 50 (3) ◽  
pp. 343-349 ◽  
Author(s):  
Y.D. Wu ◽  
J. Liu ◽  
Charles W.W. Ng
Keyword(s):  
Ground Surface ◽  
Surface Settlement ◽  
Beam Extraction ◽  
Ground Settlement ◽  
Cement Slurry ◽  
Ground Surface Settlement ◽  
Minimal Data ◽  
Maximum Surface Settlement ◽  
Surface Settlements ◽  
Ground Settlements

Secant pile walls reinforced with steel I-beams are widely used worldwide. Although ground surface settlement caused by the installation of secant pile walls has been investigated, there is minimal data available on ground surface settlement due to extraction of steel I-beams from secant pile walls. This note aims to investigate the effectiveness of cement slurry refilling on reducing ground settlements during extraction of steel I-beams. Measured ground surface settlements during the extraction of steel I-beams from secant pile walls with and without cement slurry refilling are reported, discussed, and explained. Two different influence zones due to steel I-beam extraction can be identified. Ground settlement due to steel I-beam extraction can be minimized with the refilling of cement slurry. By using such a refilling technique, measured maximum surface settlement was reduced by 70%. The average measured settlement rate was reduced by 61%.

Analysis of Surface Subsidence Rule of the Shallow Subway Tunnel Construction

2013 ◽  
Vol 671-674 ◽  
pp. 1081-1086 ◽  
Author(s):  
Fei Fei Wang ◽  
Hui Ren Bai ◽  
Jing Jing Li
Keyword(s):  
Ground Surface ◽  
Calculation Model ◽  
Surface Subsidence ◽  
Surface Settlement ◽  
Tunnel Construction ◽  
Maximum Point ◽  
Subway Tunnel ◽  
Monitoring Frequency ◽  
Ground Surface Settlement ◽  
Value Range

In order to study the Dalian Metro section 202(Cujin Road station-Chunguang Street station, which is shallowly buried and covered with plain fill)’s ground surface settlement, the monitoring measuring station was built during the construction. After 3 months’ measuring by precision level,the data shows that the maximum point is in the center line of the tunnel of the upper part. The settlement is about 25.66-31.82mm. This paper put forward the concept of the distance span ratio β, β effective value range was - 4 <β< 4,Surface subsidence is closely related with β, Severe surface subsidence stage is -2 <β< 2, Occupy whole deformation is 67.5-77.6%,settlement rate about 0.84-0.93mm/d, so should strengthen the monitoring frequency, Suggest increases site tour. Field test results and the ground surface settlement calculation model winkle are identical with each other; the monitoring results have important guiding significance and reference for Dalian subway and the similar shallow depth excavation tunnel construction.

scholarly journals Deformation Characteristics of Raising, Widening of Old Roadway on Soft Soil Foundation

Symmetry ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2117
Author(s):  
Keke Li ◽  
Wenyuan Xu ◽  
Liang Yang
Keyword(s):  
Lateral Displacement ◽  
Soft Soil ◽  
Ground Surface ◽  
Surface Settlement ◽  
Deformation Characteristics ◽  
Construction Methods ◽  
Ground Surface Settlement ◽  
Total Settlement ◽  
Soil Foundation ◽  
Soft Soil Foundation

The deformation characteristics of a raised and widened old Chinese roadway on a soft soil foundation are investigated in this study via finite element numerical simulation. The rules of ground surface settlement, slope foot lateral displacement, and ground surface settlement evolution of the roadbed under three modes (one-time construction of an eight-lane expressway, widened four-lane expressway, and raised/widened four-lane expressway) are compared. The ground surface settlement process of the eight-lane road foundation, which is formed by first widening and then raising the road, is highly complex. The ground surface settlement curve under the old road foundation increases and then decreases. The lateral displacement of the slope foot also interacts with the widening and raising of the eight-lane roadbed foundation. The range of lateral displacement is 70.05, 42.58, 124.81, 104.54 mm. Fifteen years after construction, the total settlement of the raised and widened roadbed is much larger than that of the one built directly. The total settlement values at the center of the two roadbeds are 297.05 and 234.85 mm, respectively. This manuscript provides data support for the reconstruction and expansion of roads on soft soil foundations, for choosing appropriate construction methods to build roads, and for avoiding major road damage, which is of great significance to the construction of road infrastructure in the future.

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.

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