Dewatering of a deep excavation undertaken in a layered soil

Pujades, Estanislao; Vàzquez-Suñé, Enric; Carrera, Jesús; Jurado, Anna

doi:10.1016/j.enggeo.2014.06.007

Cited by 110 publications

(53 citation statements)

References 26 publications

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“…If the tunnel is fully or partly under the groundwater level, dewatering is often carried out during construction. Although the benefit of dewatering is well known in tunnelling practice (Pujades et al, 2014), a consistent model to quantitatively assess its effect is not available. The present authors have presented a numerical model based on the finite-element method with an advanced constitutive model.…”

Section: Discussionmentioning

confidence: 99%

Face stability of shallow tunnels in partially saturated soil: centrifuge testing and numerical analysis

Soranzo

Tamagnini

2015

Géotechnique

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In this paper the face stability of shallow tunnels in partially saturated soil is investigated by means of centrifuge testing and numerical analysis. A loess soil is chosen for this study and its properties are characterised by laboratory testing. Centrifuge model tests are carried out at different soil densities and with different depths of water table. The numerical analyses are performed with an advanced constitutive model for partially saturated soil. The constitutive model is implemented in a finite-element code using the Bishop's effective stress. The model parameters are calibrated based on drained triaxial compression tests on partially saturated soil. The wetting collapse of the tunnel face is simulated by imposing a zero pore pressure condition at the ground surface. The numerical results are compared with the centrifuge tests.

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Section: Discussionmentioning

confidence: 99%

Face stability of shallow tunnels in partially saturated soil: centrifuge testing and numerical analysis

Soranzo

Tamagnini

2015

Géotechnique

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“…But the net effect was a significant increase in the OCR in all the 10 sediments. As a result, pumping settlements should be small and the soil should behave 11 elastically in response to groundwater oscillations when these are smaller than the maximum 12 drawdown caused in the past (Pujades, et al, 2014a(Pujades, et al, , 2014b. Groundwater fluctuations larger 13 than the maximum historical drawdown would cause unrecoverable movements.…”

Section: Soil Overconsolidation 5mentioning

confidence: 99%

“…Fine materials are related to transgression 12 events and coarse sediments to regression events. The Pliocene is affected by faults, one of 13 which is located in the Cartagena street (Figure 3 tunnel project and other projects developed in Barcelona (Pujades et al, 2014a(Pujades et al, , 2014b. 3 4 2.3.2.…”

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confidence: 99%

Hydrogeological impact assessment by tunnelling at sites of high sensitivity

Pujades

Vàzquez-Suñé

Culí

et al. 2015

Engineering Geology

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hydrogeological impacts of the construction were raised. These concerns were addressed 8 during the design stage to forestall any unexpected events. The methodology consisted of 1) 9 characterising the geology in detail, 2) predicting the impacts caused in the aquifer, 3) 10 predicting the soil displacements due to water table oscillations produced by the construction, 11 and 4) monitoring the evolution of groundwater and soil settlements. The main estimated 12 impact on groundwater was a moderate barrier effect. The barrier effect, the magnitude of 13 which matched the predictions, was detected during construction. The monitoring of soil 14 settlements revealed short and long term movements. The latter movements matched the 15 analytical predictions of soil displacements caused by the groundwater oscillations. 16 This paper proposes a realistic procedure to estimate impacts on groundwater during tunnel 17 construction with an EPB. Our methodology will considerably improve the construction of 18 tunnels in urban areas. 19

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“…However, increases in groundwater head in shallow aquifers impacts the safety of the underground space structures. When underground structures are constructed, the rise in water head increases the water pressure on the excavation bottom and pipes [10][11][12][13][14]. On the other hand, when the underground structures are in use, the buoyancy force increases with the rise in water head, and the stability of the structures will be affected.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Groundwater Withdrawal and Recharge Affecting Underground Structures in the Shanghai Urban Area

Yang

et al. 2019

Sustainability

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In this paper, the hydrogeological features of Quaternary deposits in Shanghai as well as the characteristics of groundwater withdrawal and recharge in urban areas are investigated. One phreatic aquifer and five confined aquifers (AqI to AqV) are present in Shanghai, and these aquifers are separated by five aquitards. Groundwater withdrawal from confined aquifers has resulted in land subsidence in Shanghai. To control land subsidence, the groundwater withdrawal volume has been decreased, and the groundwater recharge volume has been increased since 1965. Correspondingly, the pressure head in confined aquifers has risen. The groundwater head increases in shallow aquifers may impact underground structures and lead to the following issues: i) an increased risk of water in-rushing hazards caused by confined water pressure during structural excavations and ii) an increased instability risk caused by groundwater buoyancy. Both excavation anti-uprush and underground structure anti-floating are discussed in this paper. Based on the risk possibilities, the anti-uprush of the excavation is divided into six regions, and the structural anti-floating is divided into five regions in urban areas. To avoid geohazards caused by the rise in groundwater head, real-time monitoring of the pressure head in AqII is recommended.

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Dewatering of a deep excavation undertaken in a layered soil

Cited by 110 publications

References 26 publications

Face stability of shallow tunnels in partially saturated soil: centrifuge testing and numerical analysis

Face stability of shallow tunnels in partially saturated soil: centrifuge testing and numerical analysis

Hydrogeological impact assessment by tunnelling at sites of high sensitivity

Investigation of Groundwater Withdrawal and Recharge Affecting Underground Structures in the Shanghai Urban Area

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