Ground settlement during tunneling in groundwater drawdown environment – Influencing factors

Yoo, Chai H.

doi:10.1016/j.undsp.2016.07.002

Cited by 20 publications

(5 citation statements)

References 13 publications

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“…is may be due to the existence of low permeability silty clay and mucky silty clay in the affected area. In the soil layer with a low permeability coefficient, the groundwater seepage will cause the pore pressure redistribution of the surrounding saturated silty clay mixed gravel layer, causing further consolidation and settlement of the overburden layer of the tunnel [21,27,28]. Meanwhile, the permeability coefficient will gradually decrease with the consolidation stress in the soft soil layer, leading to a slower consolidation process and increasing consolidation time [37,38].…”

Section: Measurement Of Projectmentioning

confidence: 99%

“…Butscher et al [25,26] investigated the hydraulic effects of tunneling on groundwater flow and found that hydraulic conductivity and groundwater level of the aquifer were important indicators to estimate the swelling potential of clay sulfate rocks in tunneling. An artificial neural network analysis was then performed by Yoo [27] to qualitatively study the influence of soil stiffness within the groundwater seepage zone and the permeability coefficient of shotcrete lining on the tunnel surface settlement. Tang et al [28] presented a case history of Shenzhen Metro in which groundwater seepage was found to be the main cause of the rapid increase in surface settlement.…”

Section: Introductionmentioning

confidence: 99%

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Modification of Peck Formula to Predict Ground Surface Settlement of Twin Tunnels in Low Permeability Soil

Tang

Liang

Liu

et al. 2021

Advances in Civil Engineering

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Accurate prediction of surface settlement induced by tunnel excavation is significant for preventing damage to existing structures under complex geological conditions. The Peck formula is currently considered as an efficient solution for surface settlement prediction. This paper proposes a modified Peck formula considering geological conditions to improve the accuracy of surface settlement prediction of twin tunnels. The asynchronization of the sinking rate and stability of the vault settlement and surface settlement within the river-affected area may attribute to the groundwater drawdown caused by cofferdam construction on the river. A modified Peck formula is put forward with soil permeability and width-controlling parameters involved. There is a small settlement at the center of the twin tunnels, making the settlement trough upward buckling, which is like a “W” shape. This situation can be accurately predicted by the modified formula with a significantly increased adjusted R-square. The modified formula can accurately predict the surface settlement of tunnels excavated in low permeability soil layers with a permeability coefficient between 10−4 cm/s and 10−7 cm/s, especially in the groundwater drawdown environment. The reliability of the modified Peck formula is verified by other cases in Nanjing and Singapore.

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Section: Measurement Of Projectmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Modification of Peck Formula to Predict Ground Surface Settlement of Twin Tunnels in Low Permeability Soil

Tang

Liang

Liu

et al. 2021

Advances in Civil Engineering

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“…A land-use map was created based on a digital characteristics map provided by (National Geographic Information Institute) NGII; six land-use categories were analyzed in this study and the map is shown in Figure 3g. Underground water utilities are one of the most frequently cited factors impacting land subsidence [54,82].…”

Section: Factors Related To Land Subsidencementioning

confidence: 99%

Integration of InSAR Time-Series Data and GIS to Assess Land Subsidence along Subway Lines in the Seoul Metropolitan Area, South Korea

2020

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The aims of this research were to map and analyze the risk of land subsidence in the Seoul Metropolitan Area, South Korea using satellite interferometric synthetic aperture radar (InSAR) time-series data, and three ensemble machine-learning models, Bagging, LogitBoost, and Multiclass Classifier. Of the types of infrastructure present in the Seoul Metropolitan Area, subway lines may be vulnerable to land subsidence. In this study, we analyzed Persistent Scatterer InSAR time-series data using the Stanford Method for Persistent Scatterers (StaMPS) algorithm to generate a deformation time-series map. Subsidence occurred at four locations, with a deformation rate that ranged from 6–12 mm/year. Subsidence inventory maps were prepared using deformation time-series data from Sentinel-1. Additionally, 10 potential subsidence-related factors were selected and subjected to Geographic Information System analysis. The relationship between each factor and subsidence occurrence was analyzed by using the frequency ratio. Land subsidence susceptibility maps were generated using Bagging, Multiclass Classifier, and LogitBoost models, and map validation was carried out using the area under the curve (AUC) method. Of the three models, Bagging produced the largest AUC (0.883), with LogitBoost and Multiclass Classifier producing AUCs of 0.871 and 0.856, respectively.

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“…Researches regarding the effects of water drawdown on the stability of slopes and dams have been done by Viratjandr and Michalowski [4], Yan et al [5], Wang et al [6], Gao et al [7], Song et al [8] Brinkgreve et al [9] and Zieba et al [10]. The limited number of studies on this subject include Atkinson and Mair [11], Bowers et al [12], Addenbrooke [13], Shin et al [2], Anagnostou [14,1], Yoo et al [15], Moon and Fernandez [16], Wanga and Wang [17], Yoo et al [18], Shen et al [19] Xu et al [20], Alonso and Pinyol [21] and Yoo [3,22]. Yoo et al [18] reported an important case study about ground surface settlements during tunnelling.…”

Section: Figure 1 Ground Settlement Affected By Rapid Drawdown Durinmentioning

confidence: 99%

Study on the Rapid Drawdown and Its Effect on Portal Subsidence of Heybat Sultan Twin Tunnels in Kurdistan-Iraq

2017

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The excavation of tunnels below the water table causes variations in the hydraulic level, pore pressure and effective stresses. In this regard, rapid drawdown is considered as a destructive phenomenon as to the change in the flow regime which has mostly been studied for the reservoirs of embankment dams. The rapid drawdown occurred at the upstream shell of the dam gives rise to increase in the pore pressure at the upstream shell. This is as a result of the incompliance between the water loss inside the shell and the reservoir water level. Hence, it would be more likely to have instability and sliding at the upstream slope on account of decrease in the effective stress. Lack of sufficient studies performed on this matter in tunnelling projects on the one hand and the knowledge on the most important parameter for decreasing the destructive effects of this phenomenon on the other hand necessitates performing further studies on this matter. To this end, the reasons for the occurrence as well as the affecting parameters were studied by modelling the large subsidence of the inlet portal of Heybat Sultan twin tunnels located in Kurdistan-Iraq making use of the variations of the groundwater boundary conditions under Phase2 code. The modelling results depict the importance of the drawdown rate and the permeability coefficient of the surrounding rock mass. In the interim, the rapid loss in the hydraulic gradient caused by the drainage of a considerable volume of precipitations into the tunnels led to the rapid decrease in the pore pressure and increase in the effective stresses up to total stress. This has resulted in the consolidation settlement in the tunnel portal.

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Ground settlement during tunneling in groundwater drawdown environment – Influencing factors

Cited by 20 publications

References 13 publications

Modification of Peck Formula to Predict Ground Surface Settlement of Twin Tunnels in Low Permeability Soil

Modification of Peck Formula to Predict Ground Surface Settlement of Twin Tunnels in Low Permeability Soil

Integration of InSAR Time-Series Data and GIS to Assess Land Subsidence along Subway Lines in the Seoul Metropolitan Area, South Korea

Study on the Rapid Drawdown and Its Effect on Portal Subsidence of Heybat Sultan Twin Tunnels in Kurdistan-Iraq

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