Study on the Effect of Combined Application of Foam and Bentonite Slurry on Conditioned Soil Properties in Sandy Soil Strata

Soil conditioning is one of the essential methods to ensure the stability of the tunneling face and excavation efficiency in EPB construction. Existing commonly used soil conditioners include foam, bentonite slurry, polymers, and other materials. Existing research has conducted experimental studies on foam-conditioned soil and bentonite slurry-conditioned soil respectively, and there is a lack of research on the effect of the combination of foam and bentonite slurry on the properties of conditioned soil. In this paper, an indoor self-developed test apparatus was employed to carry out experimental research on the rheology and compressibility of conditioned soil in sandy soil strata, which is conditioned by a combination of foam and bentonite, the rheological mechanical equations and the variation rules of the compression characteristic parameters were obtained. Based on the indoor experiment results, the optimal conditioning proportions of gravel, gravelly sand, and medium-coarse sand were obtained, and the judgment criteria for sandy soil conditioning were proposed. The research results of this paper will provide technical support and theoretical guidance for soil conditioning technology in sandy soil stratum, and provide judgment criteria for EPB shield construction.