Experimental and Modeling of Shear Mechanical Behavior of Soil Conditioned With Foaming Agent
Moez SELMI1, Mariem KACEM2, MehrezJAMEI3, Philippe DUBUJET4
1Moez SELMI, 1Tunis El Manar University, National Engineering School of Tunis, Civil engineering Laboratory,Tunis, Tunisia. 2Université de Lyon, Ecole Nationale d’Ingénieurs de Saint-Etienne, Laboratoire de Tribologie et Dynamique des Systèmes, Saint Etienne, France
2Mariem KACEM, Université de Lyon, Ecole Nationale d’Ingénieurs de Saint-Etienne, Laboratoire de Tribologie et Dynamique des Systèmes, Saint Etienne, France
3MehrezJamei, Tunis El Manar University, National Engineering School of Tunis, Civil EngineeringLaboratory,Tunis, Tunisia.
4Philippe DUBUJET, Université de Lyon, Ecole Nationale d’Ingénieurs de Saint-Etienne, Laboratoire de Tribologie et Dynamique des Systèmes, Saint Etienne, France.
Manuscript received on 23 August 2019. | Revised Manuscript received on 09 September 2019. | Manuscript published on 30 September 2019. | PP: 2616-2622 | Volume-8 Issue-11, September 2019. | Retrieval Number: K19120981119/2019©BEIESP | DOI: 10.35940/ijitee.K1912.0981119
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© The Authors. Blue Eyes Intelligence Engineering and Sciences Publication (BEIESP). This is an open access article under the CC-BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Abstract: 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.
Keywords: Tunneling, conditioned soil, foaming agent, shear strength, experience, triaxial tests, modeling.
Scope of the Article: Soil-Structure Interaction