Characterizing the influence of stress on foam conditioned sand for EPB tunneling

Mori, Lisa; Mooney, Mike; Cha, Min-Seok

doi:10.1016/j.tust.2017.09.018

Cited by 70 publications

(20 citation statements)

References 7 publications

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“…In these conditions, the mix changes its behaviour because the bubbles reduce their size and, consequently, their effectiveness in reduc ing the shear strength. Zumsteg et al [29], Psomas [30], Mooney et al [3], Mori et al [36], Meng et al [31] and Yi et al [33] evaluated the shear strength, the compressibility of the soil and the void index in pressurized chambers. Largescale pressure tests were proposed by Thewes and Steeb [37] and Martinelli [38].…”

Section: Pressurized Testsmentioning

confidence: 99%

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Soil conditioning in EPB shield tunnelling – An overview of laboratory tests

Peila

Martinelli

Todaro

et al. 2019

Geomechanics and Tunnelling

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The application of full‐face mechanized tunnelling, mainly with EPB shielded machines, has widely increased in the last years and today it can be considered the key technology when tunnelling in soils above and below the water table. The applicability range of EPB machines has widened thanks on one side to the technological and mechanical progresses and on the other side to the quality and effectiveness of the conditioning products. No recognized standards are available for laboratory testing of conditioned soil and each research centre has developed its own procedures and methods. In this paper, an overview of the most frequently used procedures is presented and discussed briefly.

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Section: Pressurized Testsmentioning

confidence: 99%

“…The Hobart mixer has been used by [40], [49] and [50]. For powdered clay tests it is also often used the mini flow test while some researchers combine small slump test and the flow table measuring the height and diameter vari ation of the cone after a certain number strokes [36].…”

Section: Adhesion Tests On Powdered Claymentioning

confidence: 99%

Soil conditioning in EPB shield tunnelling – An overview of laboratory tests

Peila

Martinelli

Todaro

et al. 2019

Geomechanics and Tunnelling

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“…Injected in the clay soil, foam's gas bubbles are dispersed in the clay matrix of the soil like spherical inclusions surrounded by clay particles [13]. However, in the case of purely sandy soil, Mori et al (2018) suggested that the foam can be considered as fluid mixed with water. The mixing fluid occupies the porous volume and it was usually studied as compressible fluid.…”

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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“…By contrast, interfacial active materials, eg, foam, can be used in variety of strata, eg, waterless sand‐pebble stratum, argillaceous siltstone with high content of clay minerals, cobble strata, sandy, and gravel strata mylonite fault zone . The soil (or rock) conditioned by foam features high elasticity, low permeability, high compressibility, low shear strength, and high flowability . Therefore, foam conditioning can be employed to deal with many problems during tunnel excavation, such as soil clogging, screw conveyor spewing, serious wear of cutterhead, and groundwater inflow .…”

Section: Introductionmentioning

confidence: 99%

“…[28][29][30][31] The soil (or rock) conditioned by foam features high elasticity, low permeability, high compressibility, low shear strength, and high flowability. [32][33][34][35][36] Therefore, foam conditioning can be employed to deal with many problems during tunnel excavation, such as soil clogging, screw conveyor spewing, serious wear of cutterhead, and groundwater inflow. [37][38][39][40][41][42][43][44][45][46] Moreover, foam conditioning agent is lower cost and more environmentally friendly than the above three conditioning agents.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of foam conditioning effect on groundwater inflow at tunnel cutting face

Liu

Shen

Zhou

et al. 2018

Num Anal Meth Geomechanics

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Summary This paper presents an analytical evaluation on the influence of foam conditioning on groundwater inflow at shield tunnel cutting face by the force‐equilibrium principle. Three key variables are highlighted, namely, the maximum foam infiltration distance, the critical infiltration distance, and the hydraulic conductivity of foam‐conditioned soil or rock fissure. To capture the variation of water level induced by foam injection, a dynamic water‐level equation is considered in the force‐equilibrium principle. The proposed analytical equations are employed to analyze a water inflow case during shield tunneling in a weathered mylonite fault. The results indicate that the hydraulic conductivity of foam‐conditioned mylonite and the infiltration distance decrease with an increase of shear stress of foam fluid. A three‐dimensional finite element model is employed to validate the analytical solutions. The comparison between the observed and calculated results confirms that the proposed method can predict groundwater inflow in foam‐conditioned soils.

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Characterizing the influence of stress on foam conditioned sand for EPB tunneling

Cited by 70 publications

References 7 publications

Soil conditioning in EPB shield tunnelling – An overview of laboratory tests

Soil conditioning in EPB shield tunnelling – An overview of laboratory tests

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

Evaluation of foam conditioning effect on groundwater inflow at tunnel cutting face

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