Experimental Study on Mix Proportion of Fluid Solidified Soil of Shield Muck Foundation

Abstract

In order to solve the problem of resource utilization of shield muck produced by underground engineering construction in Qingdao area, taking the shield muck of a project in Qingdao as the research object, using cement and lime as curing agents, a three-factor and four-level orthogonal test was designed to optimize the mix ratio of fluid solidified soil. The influence of cement content, lime content and water content on the unconfined compressive strength of 7 d and 28 d of fluid solidified soil was investigated by range analysis and variance analysis, and a multiple linear regression model of compressive strength and various influencing factors was established. The results show that the cement content is a very significant factor affecting the compressive strength of the solidified soil, the water content is a significant factor, and the lime content is an insignificant factor. The order of influence of each factor is cement content > water content > lime content. The optimal mix ratio of fluid solidified soil is 12% cement content, 4% lime content and 30% water content. Under this ratio, the unconfined compressive strength of 7d and 28d reaches 1.86 MPa and 3.22 MPa respectively, which meets the technical requirements of engineering backfilling in Qingdao area. The established multiple linear regression model has good fitting degree and high prediction accuracy. The relative error between the predicted value of 7d and 28d compressive strength and the actual test value is less than 5%, which can effectively predict the compressive strength of the shield muck solidified soil. The research results provide experimental basis and theoretical support for the engineering application of shield muck solidified soil in Qingdao area.