Homogenization of Cemented Soil Stiffness and Application to the Study of Arching Effects between Jet-Grouted Columns

Abstract

This paper presents a study of the effect of jet-grouting on soil stiffness. Several homogenization techniques are tested at the scale of a Representative Elementary Volume to determine the stiffness of a mixture made of sand and grout. (1) The averaging method is employed to compute the mechanical stiffness of grouted soil under the assumption that internal stress is mostly supported by the soil skeleton. (2) A hollow sphere model is proposed to predict stiffness under the assumption that soil grains do not contribute to the mechanical resistance of cemented soil. (3) Eshleby’s homogenization scheme is used to model cemented soil stiffness for a dilute distribution of grains embedded in grout. The hollow sphere model gives more flexibility in the description of soil fabric, but does not account for soil grain mechanical properties. Eshelby’s technique is attractive, but more work is required to improve the representation of cemented soil fabric, especially the soil grain space distribution in the mixture of sand and grout. Settlements above a tunnel surrounded by two rows of jet-grouted columns are computed using the Finite Element Method. Numerical results for vertical displacements and stress are interpreted with Handy’s arching theory.