为解决土压平衡盾构掘进过程中刀盘实时受力和温度分布缺乏精细化监测与分析的问题，探讨泡沫改良作用下盾构刀盘的热-力耦合机制及其演化规律。首先通过直剪试验与界面直剪试验，确定分散型泡沫剂改良前后土体的剪切强度参数及土体-刀盘界面摩擦因数； 在此基础上，基于三维有限元方法构建可反映土体-刀盘动态相互作用的热-力耦合数值模型，对刀盘掘进过程进行瞬态模拟分析，系统研究泡沫改良对刀盘应力场与温度场时空演化行为的影响，并揭示排渣效率、刀盘转速等关键施工参数对刀盘热-力学响应的影响机制。结果表明： 1）泡沫改良可显著降低土压平衡盾构刀盘等效切削应力峰值达22.3%，温度峰值降低19.8%，并通过提升排渣与换热效率有效抑制热应力和不均匀膨胀。2）在1.8 r/min高转速下，未改良地层中刀盘应力峰值达66.89 MPa，温度峰值高达133.3 ℃；泡沫改良可有效抑制高速掘进下刀盘的温度升高与应力集中，尤其在转速超过1.5 r/min时效果更为显著，1.8 r/min时刀盘应力降幅达11.12 MPa，温度降幅达16.9 ℃；建议在实际施工中将刀盘转速控制在1.5 r/min以内并结合渣土改良技术，以提升刀盘工作安全性及掘进效率。
To address the issue of insufficient real-time monitoring and refined analysis of the cutterhead′s mechanical loading and temperature distribution during earth pressure balance (EPB) shield tunneling, this study explores the thermo-mechanical coupling mechanism and its evolution in the cutterhead under the influence of foam conditioning. Firstly, direct shear tests and interface shear tests were conducted to determine the shear strength parameters of the soil and the soil-cutterhead interface friction coefficient, both before and after conditioning with dispersed foam. On this basis, a thermo-mechanical coupled numerical model capable of reflecting the dynamic soil-cutterhead interaction was established using three-dimensional finite element method, and transient simulations of the cutterhead excavation process were performed. Influence of foam conditioning on the spatiotemporal evolution of the stress and temperature fields on the cutterhead is systematically investigated, revealing the influence mechanisms of key construction parameters such as muck discharge efficiency and cutterhead rotation speed on the thermo-mechanical response of the cutterhead. The results indicate that: (1) Foam conditioning considerably reduces the peak equivalent cutting stress and peak temperature on the EPB shield cutterhead by 22.3% and 19.8%, respectively, and effectively suppresses thermal stress and uneven expansion by improving muck discharge and heat exchange efficiency. (2) At a high rotation speed of 1.8 r/min, the peak stress and temperature on the cutterhead in untreated ground reach 66.89 MPa and 133.3 ℃, respectively. Foam conditioning effectively mitigates temperature rise and stress concentration under high-speed excavation, with the effect being particularly significant when the rotation speed exceeds 1.5 r/min, the stress reduction can reach 11.12 MPa and the temperature reduction can reach 16.9 ℃ when the rotation speed reaches 1.8 r/min. It is recommended that the cutterhead rotation speed be controlled within 1.5 r/min in combination with soil conditioning technology during actual construction to enhance cutterhead operational safety and excavation efficiency.
