Effect of Soil-Cutterhead Interface Temperature on the Consolidation and Hardening of Mud Cake Under Multi-factor Conditions

When shield structures pass through cohesive ground, the cutterhead is often blocked by muck, which reduces the tunnelling speed. In addition, due to the continuous thrust of the cutterhead on the soil, the temperature of the soil-cutterhead interface increases, which exacerbates the muck adhesion. This work investigated the effect of temperature on the consolidation and hardening of mud cake by means of a self-made shield tunnelling simulation equipment and proposed relevant indexes for reflecting the consolidation and hardening states of the mud cake. Depending on the heat transfer mechanism between cutterhead and soil, the effects of soil parameters (soil type, consistency index), excavation parameters (support pressure, cutterhead rotation speed) and foaming agent on the temperature development at the soil-cutterhead interface were analyzed experimentally. Results indicate that moisture content and fall cone penetration were closely related to temperature variation, and the increase of interface temperature intensified the consolidation and hardening of the mud cake. The interface temperature increased with the increase of the consistency index, support pressure and cutterhead rotation speed. Compared with pure clay, the tunnelling interface of sandy clay was rough, and the interface temperature increased significantly. The injection of foaming agent could effectively hinder the rise of interface temperature and reduce the adhesion area and degree of hardening of mud cake. This study has guiding significance for understanding the formation and development of mud cake on the shield in the process of shield construction.