<p>Soil conditioning is one of the essential methods to ensure the stability of the tunneling face and excavation efficiency in the EPB construction. Exiting soil conditioners, include foam, bentonite slurry, polymers, and other materials, have been successfully applied in shield construction. However, there is still a lack of technology on how to quickly and accurately evaluate the properties of conditioned soil. In this paper, an indoor experimental apparatus for measuring the rheological and compressive properties is proposed, which enables rapid and accurate determination of conditioned soil. The foam agent and bentonite slurry were applied to the soil conditioning of gravel stratum soil respectively, and the proposed apparatus was applied to determine the rheological curves with different conditioning proportions. Design-expert analysis software was applied to regression analysis of consistency coefficient, yield strength, and slump. And the functional relationship between the conditioner parameters and the property parameters was obtained. The optimal soil conditioning proportion obtained in this paper will provide construction guidance and theoretical support for the construction of the EPB construction in the gravel stratum.</p>