Evaluation Method of Loose Characteristics of EPB Shield Slag Considering the Formation Heterogeneity and Plastic Fluidization Process

Accurate assessment of the EPB shield slag is conducive to the determination of the slag treatment process, treatment capacity, and treatment cost. Based on the three-phase composition theory of soil in soil mechanics, it analyzes the calculation principle of the loose characteristics of slag soil and deduces the evaluation formula, and forms the evaluation method of the loose characteristics of the slag soil of EPB shield. Based on the geotechnical test (density and water content test), the coefficient of looseness was determined by this evaluation method and compared with the engineering measurement results. The results show that the loose coefficient of the slag soil without considering the formation unevenness and plastic fluidization is 1.50, the loose coefficient only considering the formation unevenness is 1.52, the loose coefficient only considering the formation plastic fluidization is 1.53, the loose coefficient considering the formation unevenness and plastic fluidization is 1.54, and the loose coefficient obtained by the actual measurement of the project is 1.64. It can be seen that the plastic fluidization process is the main factor and the formation unevenness is the secondary factor. The results are in good agreement with the actual measurement results. This method provides a basic data acquisition method for the accurate prediction of the amount of residual soil.