Key Technology of Improvement on Shield Muck in Water Rich Boulder Stratum

In order to reduce the adverse effects of shield construction in water rich boulder stratum and solve the problems such as large cutter head wear, sticking phenomenon and surface settlement during construction, the study of soil improvement technology during construction of the earth pressure balance (EPB) shield in the water rich boulder stratum with a particle size larger than 200mm is carried out, with Chengdu metro line 17 as the engineering background. The improvement characteristics of boulders are evaluated from three aspects including mobility, permeability and agitation resistance, and the idea of improvement on muck in water rich boulder stratum is developed, that is, the foam injection rate is about 45%, the water injection rate is about 5%, and the bentonite injection is about 2%. The results show that this technology can provide the best parameters for the EPB shield construction in water rich boulder stratum.