Abstract: During tunneling in high-viscosity strata, shield machines face various challenges, such as the accumulation of muck cake on the cutterhead and blockage. Traditional manual chamber entry with high-pressure water washing and single chemical conditioning presents high operational risks and poor adaptability to different strata. To address these challenges, an interfacial viscosity reduction technology that reduces clay-metal interfacial adhesion through the coupling of electric field driving and chemical regulation is proposed, and a series of interfacial viscosity reduction tests are conducted. Based on a metro project in Jinan, China, four soil samples with different clay contents, composed of sodium-based bentonite, kaolin, and standard quartz sand, are prepared to simulate field cohesive strata. Chemical conditioners, namely TecSoil-210NF foaming agent and TecSoil-260AC anti-sticking agent, are applied to conduct inclined plate interfacial viscosity reduction tests, rheological tests of conditioned soil, and electrochemical coupled permeation tests. Finally, the effects of voltage, conditioner concentration, and soil type on viscosity reduction performance are examined. The results show the following: (1) the viscosity reduction effect at the clay-metal interface is optimal, the clay detachment time is shortest, and the balance between energy consumption and viscosity reduction is best under a conditioner concentration of 3%, an anti-sticking agent/foaming agent ratio of 0.3, and a coupled voltage of 5 V; (2) the performance of the conditioner depends significantly on concentration and temperature, and the half-life is optimal at a concentration of 3% with an antisticking agent/foaming agent ratio of 0.3; higher temperature increases the foaming ratio but shortens the half-life; and (3) the viscosity reduction effect is significant when the conditioner concentration ranges from 3% to 6% and tends to saturate above 6%. This interfacial viscosity reduction technology greatly improves electro-osmosis efficiency compared with traditional single-component conditioning methods. It accelerates pore water migration to form a lubricating water film under the electric field and disrupts the clay flocculation structure through charge neutralization and steric hindrance of the conditioner, thereby achieving synergistically enhanced viscosity reduction and effectively reducing energy consumption.

Key words: cohesive strata, shield clogging, muck conditioning, electro-osmosis, interface viscosity reduction