Controlling clay pore pressures for cut-and-cover tunnelling

Roberts, T. O. L.; Roscoe, H. K.; Powrie, W.; Butcher, D.

doi:10.1680/geng.2007.160.4.227

Cited by 5 publications

(3 citation statements)

References 11 publications

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“…Since Conwy, ejectors have been used widely throughout the UK and elsewhere, on projects including the Jubilee Line Extension, the Docklands Light Railway under the Thames to Lewisham, and the Channel Tunnel Rail Link (CTRL). Audaciously, the technique was used on CTRL Phase 1 to control pore pressures in the Weald Clay by acting through the fissures (Roberts et al, 2007); and in an application that Bill Ward would have appreciated, to preserve the integrity of the structure of the Bracklesham Beds by preventing delamination during basement excavation and construction of the raft foundation for the Skandia Life building in Southampton.…”

Section: Groundwater Control (Construction Dewatering)mentioning

confidence: 99%

Contributions to Géotechnique 1948–2008: Groundwater

Powrie¹

2008

Géotechnique

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This paper reviews work on the subject of groundwater published in Géotechnique over the past 60 years. Contributions relating to the effects of groundwater on geotechnical structures, measurement of pore water pressure using piezometers, analysis of groundwater flow, groundwater control or construction dewatering, estimating hydraulic conductivity, and passive vertical drains are summarised and discussed. Three major areas of significant impact are identified: (a) the realisation of the dominant role of pore water pressure equilibration in the delayed failure of cut slopes; (b) determination of the hydraulic conductivity of soils by means of rising-or falling-head tests in piezometers and boreholes; and (c) understanding the role of soil fabric in groundwater control, and using it to extend the operational range of pumped groundwater control techniques to soils of low permeability.

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Section: Groundwater Control (Construction Dewatering)mentioning

confidence: 99%

Contributions to Géotechnique 1948–2008: Groundwater

Powrie¹

2008

Géotechnique

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“…When the groundwater level is too high, water infiltrates the excavation through the seepage field, causing soil instability and failure. Conversely, when the groundwater level is too low, the soil inside the excavation consolidates and hardens, altering the stress field and resulting in settlement around the excavation [ 15 ]. Numerous scholars worldwide have conducted numerical simulation studies on excavation construction.…”

Section: Introductionmentioning

confidence: 99%

Research on the Deformation Law of Foundation Excavation and Support Based on Fluid–Solid Coupling Theory

Xia,

Zhao,

Wang

et al. 2024

Sensors

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To investigate the impact of underground water seepage and soil stress fields on the deformation of excavation and support structures, this study initially identified the key influencing factors on excavation deformation. Subsequently, through a finite element simulation analysis using Plaxis, this study explored the effects of critical factors, such as the excavation support form, groundwater lowering depth, permeability coefficient, excavation layer, and sequence on excavation deformation. Furthermore, a comprehensive consideration of various adverse factors was integrated to establish excavation support early warning thresholds, and optimal dewatering strategies. Finally, this study validated the simulation analysis through an on-site in situ testing with wireless sensors in the context of a physical construction site. The research results indicate that the internal support system within the excavation piles exhibited better stability compared to the external anchor support system, resulting in a 34.5% reduction in the overall deformation. Within the internal support system, the factors influencing the excavation deformation were ranked in the following order: water level (35.5%) > permeability coefficient (17.62%) > excavation layer (11.4%). High water levels, high permeability coefficients, and multi-layered soils were identified as the most unfavorable factors for excavation deformation. The maximum deformation under the coupled effect of these factors was established as the excavation support early warning threshold, and the optimal dewatering strategy involved lowering the water level at the excavation to 0.5 m below the excavation face. The on-site in situ monitoring data obtained through wireless sensors exhibited low discrepancies compared to the finite element simulation data, indicating the high precision of the finite element model for considering the fluid–structure interaction.

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“…Depending on the considerations of various factors such as geological conditions, environmental impacts, construction cost and period, and tunnel dimensions, a tunnel may be excavated using one of the commonly adopted methods including mainly the cut-and-cover method [7,8], drill-and-blast method [9,10], mechanized shield tunnelling method using a tunnel boring machine (TBM) [11,12], new Austrian tunnelling method [13,14], and jacked box tunnelling method [15,16]. Among these methods, the mechanized shield tunnelling method has been widely used for constructing metros in many urban areas in the world [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Ground Deformation Characteristics Induced by Mechanized Shield Twin Tunnelling along Curved Alignments

Guo

et al. 2021

Advances in Civil Engineering

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This paper investigates the ground deformation characteristics induced by mechanized shield twin tunnelling along curved alignments by adopting the nonlinear three-dimensional (3D) finite element method (FEM). The performance of the adopted FEM is demonstrated to be satisfactory by comparing the numerical analysis results with the field monitoring data in a typical case history and with the predicted results generated by a modified version of the Peck’s empirical Gaussian formula. It has been found that the tunnelling-induced transverse ground surface settlement troughs and the distributions of the subsurface horizontal and vertical ground displacements are mostly similar in both form and magnitude for the considered various radii of curvature of tunnel alignment including 50 m, 100 m, 150 m, 200 m, 250 m, 300 m, 400 m, and infinity (i.e., straight-line tunnel). Considering the variational characteristics of the ground deformations with the magnitude of the radius of curvature, the radius of curvature of 100 m can be regarded as a critical tunnel alignment radius of curvature controlling the transformation of the curved tunnelling-induced ground deformational behaviors. For the benefit of geotechnical engineers interested in curved tunnelling with a small radius of curvature, a discussion of the technologies for reducing the overexcavation and improving the accuracy of tunnel lining segment installation is also presented.

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Controlling clay pore pressures for cut-and-cover tunnelling

Cited by 5 publications

References 11 publications

Contributions to Géotechnique 1948–2008: Groundwater

Contributions to Géotechnique 1948–2008: Groundwater

Research on the Deformation Law of Foundation Excavation and Support Based on Fluid–Solid Coupling Theory

Ground Deformation Characteristics Induced by Mechanized Shield Twin Tunnelling along Curved Alignments

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