盾构穿越复杂水文地质地层时，常因刀盘刀具过量磨损而导致盾构被迫停机，这已成为困扰盾构施工的重要难题之一，进行刀具更换是目前解决这一难题，恢复盾构掘进的主要方法。然而，工程界尚未形成系统的盾构换刀技术体系。针对这一问题，在对已有技术研究理解和总结的基础上，阐述了盾构刀具更换技术的内涵和主要分类，并结合典型盾构工程换刀作业实例和笔者所在课题组的研究成果，对加固地层-常压换刀、基于常压可更换刀盘设计的换刀、带压换刀等3种主要换刀技术的原理、技术流程、关键技术、适用范围和优缺点等进行系统的分析和总结。最后介绍了日本最新的刀具更换技术，并对中国盾构隧道刀具更换技术进行了展望。结果表明：地层加固-常压换刀技术和带压换刀技术都是在常规刀盘设计条件下形成的，其关键都是保障开挖面地层的稳定性；差别在于，前者是使加固开挖面地层达到自稳后，在常压条件下实施的，而后者则是通过泥浆渗透成膜等辅助工艺提高开挖面地层的闭气性后，在气压支护条件下实施的；对于基于常压可更换刀盘设计的换刀技术来说，开挖面地层的稳定性不需要重点考虑，盾构机特殊的中空刀盘辐臂和常压可更换刀具设计才是该技术的关键。

Shield tunneling machines are often used in complex hydrogeological environments and have to be frequently shut down owing to excessive wear of the cutters. This has become one of the important problems affecting construction during tunneling operations. Cutter replacement is the primary method of solving this problem and restoring tunnel shields. However, a scientific system of cutter replacement has not yet been formulated for the engineering field. On the basis of understanding and summarizing existing research, a technique and classification of shield cutter replacement were expounded. Three main techniques of cutter replacement, namely exchanging cutters under normal pressure after formation reinforcement, exchanging cutters based on the design of permanent pressure replaceable cutter, and exchanging cutters under pressure, were utilized frequently in construction sites. The principles, processes, key technologies, applications, advantages, and disadvantages were analyzed and summarized based on typical cutter replacement operations and research results of the project. Moreover, the latest cutter replacement techniques used in Japan were introduced, and the cutting tool replacements for shield tunneling in China were evaluated. The results show that, the cutter replacement techniques under normal pressure after formation reinforcement and under pressure were formulated for conventional cutterhead design, and the key requirements were to ensure the stability of the excavation face. The differences between these were that, the former was performed under normal pressure after stabilizing the excavation face to achieve self-stability, whereas the latter was conducted under the condition of air pressure support using the auxiliary technology of slurry infiltration and filter cake formation to improve the air-tightness of the excavation face. The stability of the excavation face was not considered for the cutter replacement owing to the design of the permanent pressure replaceable cutterhead. The significance of this technique is the special design of the hollow cutter arm and the permanent pressure replaceable cutter for the shield machine.

中国土压平衡盾构采用不满舱施工非常普遍,因此施工过程中经常出现一些问题。通过对开挖面压力平衡状态的分析,结合工程实例对开挖面的整体稳定、渣土排出异常、开挖面部分坍塌、壁后注浆窜浆等现象进行讨论,解释其发生的主要原理。提出渣土泥浆化的概念、判断标准,明确其与喷涌的差异,并讨论不满舱施工时窜浆发生过程,给出判断窜浆发生的主要条件,明确发生局部渗透破坏的条件。研究结果表明:即使风化岩等高渗性地层开挖面整体稳定性计算满足不满舱施工的强度要求,也会出现局部渗透破坏甚至开挖面坍塌;不满舱施工开挖面局部渗透破坏等引起的超挖量大、窜浆引起盾尾充填效果差均导致地表沉降过大。基于上述问题产生的原理提出相应措施以维持土舱内压力与地层中土水压力的平衡,研究结果能够为土压平衡盾构施工提供一定技术支撑。

During low-pressure construction in the earth pressure balance (EPB) shield in China, problems often occur in the construction process due to the unfilled chamber. Based on an analysis of the pressure balance state of the excavation face, combined with engineering examples, problems, such as the abnormal discharge of soil in the high-permeability stratum, unstable failure of the excavation face, grout leakage, and excessive surface settlement, were studied to clarify the main principles of their occurrence. The concept of the judgment standard of chamber soil sliming was proposed, and the difference between sliming and spewing was clarified. Even if the stability calculation of the excavation surface of the high-permeability strata, such as weathered rock, met the strength requirements of the overall stability of the surface, partial seepage failure was considered to occur and gradually develop into the collapse of the excavation face. In addition, the conditions for partial seepage failure were examined. Furthermore, the process of backfill grouting leakage during construction with a unfilled chamber was investigated, and the main conditions for determining the occurrence of grout leakage were determined. The significant over-excavation of the stratum due to seepage failure and the poor grouting effect due to grout leakage are expected to lead to excessive surface settlement. Based on the principles of the above-mentioned problems, corresponding measures were proposed to maintain the balance between the chamber pressure and the earth and water pressures in the stratum. The findings of this study may provide technical support for EPB shield construction in China.

当盾构近距离穿越邻近隧道时，由于存在既有隧道的刚度约束，隧道周围土体的破坏模式会受到既有隧道影响。考虑盾构近距离穿越紧邻已有隧道的特殊施工形式，构建三维弹塑性有限元计算模型，分析盾构处于不同位置时其开挖面失稳破坏形态、开挖面支护压力与盾构掘进位移之间的关系以及隧道上方地表沉降规律；基于极限平衡法，推导盾构近距离穿越紧邻隧道时开挖面极限支护压力变化模式，并对相关参数的敏感性进行验证讨论。研究结果表明：既有隧道的存在使得破坏区域受到抑制，沿开挖方向两滑动面不对称，靠近既有隧道的滑动面张开角比另一滑动面张开角小；随着楔形体倾斜角增大，相同内摩擦角条件下的开挖面支护压力不断增大，同时由于盾构掘进产生的土拱效应和盾构开挖面上方既有隧道的刚度约束，随着内摩擦角的不断增大，开挖面支护压力呈先增大后逐渐减小的抛物线形变化；相同参数条件下，盾构在黏性土层中掘进时，由于黏性土层中产生的土拱效应较弱，所需提供开挖面稳定的支护压力略大，开挖面支护压力较盾构在砂性土层中掘进时略大，随着埋深比的增加，维持盾构开挖面稳定的极限支护压力逐渐增大，且随着内摩擦角的增大，开挖面极限支护压力相应增大。研究成果可为类似盾构隧道工程建设提供一定的理论参考。

When shield tunnels pass through adjacent tunnels at close distance, the failure modes of soil around tunnels are affected by the rigidity constraints of existing tunnels. A three-dimensional elastic-plastic finite element model was used to analyze the failure modes of the shield excavation surface. The relationship supports that the pressure of the excavation surface and the displacement of shield excavation, ground settlement, and law are higher than those of the tunnels. On the basis of the balance method, the variation model of the ultimate abutment pressure of the shield tunneling face was deduced when shield tunneling approached the tunnel, and the sensitivity of relevant parameters was verified and discussed. The results show that the existing tunnel restrains the damage area, the asymmetrical sliding surfaces along the excavation direction, and the opening angle of the sliding surface near the existing tunnel is smaller than that of the other sliding surface. With the increase of the inclination angle of the wedge, the supporting pressure of the excavation face increases continuously at the same internal friction angle. At the same time, owing to the soil arch effect caused by shield tunneling and the rigidity constraint of the existing tunnel above the shield excavation face, with the increase of the internal friction angle, the supporting pressure of the excavation face first increased and then decreased gradually. Under the same parameters, when the weak soil arch affects shield tunneling in the clay layer, the support pressure needed to provide stable excavation face is slightly larger, and the support pressure of the excavation face is slightly larger than that of shield tunneling in sandy soil layer. With the increase of burial depth ratio, the role of maintaining the stability of the shield excavation face is maintained. The limit support pressure gradually increased, and with the increase of the internal friction angle, the limit support pressure of the excavation face increased correspondingly. The research results provide a theoretical reference for similar shield tunnel construction.