Hydrogeological impact assessment by tunnelling at sites of high sensitivity

Pujades, Estanislao; Vàzquez-Suñé, Enric; Culí, Laura; Carrera, Jesús; Ledesma, Alberto; Jurado, Anna

doi:10.1016/j.enggeo.2015.05.018

Cited by 42 publications

(17 citation statements)

References 26 publications

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“…The importance of soil conditioning practice for EPB methods has conducted to high research efforts around the world [1]. Since the state of the art established by Milligan (2000) [2], many laboratory tests using newly developed devices [3], have brought insight into the working mechanisms of the different products and into the resulting soil behavior of different soils [4]. These advances have resulted in the analysis of working mechanisms and the development of new chemical compositionsof surfactant as product [2]).…”

Section:  Abstract: Chemical Foam Is Being Used More Frequently Withmentioning

confidence: 99%

Experimental and Modeling of Shear Mechanical Behavior of Soil Conditioned With Foaming Agent

Selmi

Kacem

Jamei

et al. 2019

IJITEE

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Chemical foam is being used more frequently with Earth Pressure Balance (EPB) shields to achieve underground works, which present a rising interest in the excavation technique. During tunneling with an Earth Pressure Balance shield in clayey soil, clogging of the clay occurs, leading to blocking the cutting head and clog then the shield chambers. Surfactants are commonly used as conditioning agents to reduce clay stickiness. This treatment leads to a change in the mechanical properties of conditioned soil. This paper aims tostudy the shear strength behavior of foam-conditioned soil basing on triaxial tests in the undrained consolidated conditions. Experimental results are modeled using the finite element code COMSOL Multiphysics with the aim of analyzing the effect of the percentage of foam on the shear strength behavior. The soil mixture made from 40% of kaolinite and 60% of sand was conditioned with a foaming agent based on anionic surfactant. Consolidated undrained triaxial tests have been performed in order to explain the effect of foam. Results show that foam reduces the shear stress thanks to their weak stiffness. Shear strength stress is affected by the percentage of the foam in the mixture before shearing by reduce the shear strength of the conditioned soil. Soil-foam mixture has been modeled as a medium containing spherical pore inclusions with a low stiffness compared to the stiffness of unconditioned soil. Stiffness of bubbles inclusions was identified using one of the known homogenization models for composite materials. Results show that the reduce shear stress strength is affected by the percentage of inclusions in the matrix. It confirms the friction angle of composite material decrease as function of the percentage of gas bubbles inclusion in the matrix.

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Section:  Abstract: Chemical Foam Is Being Used More Frequently Withmentioning

confidence: 99%

Experimental and Modeling of Shear Mechanical Behavior of Soil Conditioned With Foaming Agent

Selmi

Kacem

Jamei

et al. 2019

IJITEE

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“…Hydrogeologically, the Quaternary and pre-Quaternary materials can be regarded as a layered aquifer with high vertical heterogeneity, with an effective transmissivity of 100-200 m 2 /d. (Pujades et al, 2015). The hydraulic conductivity (K) of the Quaternary clay layers (low permeability layers) ranges from 0.001 to 0.01 m/d, and the K of the Quaternary sand and gravel layers (high permeability layers) ranges from 0.1 to 10 m/d.…”

Section: Geographical Geological and Hydrogeological Descriptionmentioning

confidence: 99%

Leveling vs. InSAR in urban underground construction monitoring: Pros and cons. Case of la sagrera railway station (Barcelona, Spain)

Serrano-Juan

Pujades

Vàzquez-Suñé

et al. 2017

Engineering Geology

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Monitoring is required when dewatering underground construction sites to anticipate unexpected events and preserve nearby existing structures and/or buildings. The most accurate and widespread monitoring method to measure displacements is leveling, a point-like surveying technique that typically allows for tens of discrete in situ sub-millimeter measures per squared kilometer. Another emerging technique for mapping soil deformation is the interferometric synthetic aperture radar (InSAR) method, which is based on SAR images acquired from orbiting satellites. This remote sensing technique can provide better spatial point density than leveling, more extensive spatial coverage and lower-cost acquisitions. This paper analyses, compares and discusses leveling and advanced multi-temporal InSAR measurements when they are used to measure the soil deformation induced by the dewatering associated with underground constructions in urban areas. This comparison, which has not been considered in previous works, is of paramount importance to ascertain the most suitable technique (or combination of techniques) in these contexts. To do so, an experiment was performed in the future railway station of La Sagrera, Barcelona (Spain), in which leveling and advanced multi-temporal InSAR were used to quantify ground deformation by dewatering. The results showed that soil displacements measured by leveling and InSAR were not always consistent. In the context of soil deformation measurements produced by dewatering in urban areas, InSAR measurements appear to be more accurate for investigating soil deformation, whereas leveling was more appropriate for quantifying the real impact on the nearby buildings.

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“…The protective wall was designed as a line of non-secant piles to allow for the passage of groundwater. Details of the groundwater analyses are described by Pujades et al (2014Pujades et al ( , 2015. Settlements induced by the tunnel excavation were a major concern.…”

Section: Tunnel and Soil Descriptionmentioning

confidence: 99%

Protecting sensitive constructions from tunnelling: the case of World Heritage buildings in Barcelona

Ledesma

Alonso

2017

Géotechnique

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Permission is granted by ICE Publishing to print one copy for personal use. Any other use of these PDF files is subject to reprint fees.Construction of the tunnel for the high-speed Madrid–Barcelona–France railway link across central Barcelona became a major technical and social challenge due to the impact of the tunnel on nearby historic buildings (two of them, the Sagrada Familia basilica and Casa Milà, being United Nations Educational, Scientific and Cultural Organization (Unesco) World Heritage structures). Protection of sensitive buildings from tunnelling-induced movements relied on the construction of a stiff pile wall, separating the tunnel from historic sites. This paper first presents a simplified procedure to analyse the wall–tunnel interaction in a straightforward manner. The main features of the tunnel, excavated by means of an earth pressure balance machine in tertiary clays and sands below the water table, are then described. Details of the design of the wall that was finally built are presented. Issues that were particularly important include the groundwater flow constraints and the use of small-strain soil stiffness properties to obtain realistic settlements. General criteria to design the protection wall are also presented. The good performance of the wall resulted in negligible tunnelling impact on the sensitive structures. The measured and predicted displacements are compared, suggesting that this type of solution is adequate to protect historic structures from tunnelling.Peer ReviewedPostprint (published version

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Hydrogeological impact assessment by tunnelling at sites of high sensitivity

Cited by 42 publications

References 26 publications

Experimental and Modeling of Shear Mechanical Behavior of Soil Conditioned With Foaming Agent

Experimental and Modeling of Shear Mechanical Behavior of Soil Conditioned With Foaming Agent

Leveling vs. InSAR in urban underground construction monitoring: Pros and cons. Case of la sagrera railway station (Barcelona, Spain)

Protecting sensitive constructions from tunnelling: the case of World Heritage buildings in Barcelona

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