要提高在深埋、复杂条件下大直径隧道TBM（隧道掘进机）的应用效率，必须正确选择TBM的类型。为了给复杂条件下TBM的选型提供借鉴和指导，总结现有的各类型TBM的特点，分析其在混合地质条件下开挖大直径、长距离隧道的局限性，提出不同地质条件下大直径隧道TBM选型指南，介绍意大利SELI公司开发的3种新型TBM，即紧凑型双护盾通用TBM（DSU Compact TBM）、土压平衡双护盾通用TBM（DSU EPB TBM）和土压平衡单护盾通用TBM（SSU EPB TBM）及其运行特点和适用范围。得出结论：传统TBM没有专门针对复杂地质条件下的大直径隧道的研究与设计；为满足市场需求，必须开发新型TBM；意大利SELI公司开发的3种新型TBM，每种专门针对特定的地质条件，这些新型的TBM能够应对复杂的地质条件，并能克服在不同覆盖层下开挖长隧道时的最常见危险。

Right type of TBM should be chosen so as to improve the construction efficiency of TBM boring in large diameter tunnels under high cover and complex geologies. The characteristics of the existing TBM types and their limitations for large diameter and long tunnels under mix conditions are presented. A general guideline for the selection of the proper type of TBM under different conditions is made. The 3 pilot innovation projects developed by SELI are presented, including DSU Compact TBM, DSU EPB TBM and SSU EPB TBM. Conclusions drawn are as follows: Traditional types of TBM are not specifically studied/designed to bore large diameter tunnels in complex geologies; To satisfy the market demand, new types of TBMs should be developed; 3 new types of TMB developed by SELI are specifically suitable for a certain geological range, and these new types of TBM allow coping with complex geologies as well as overcoming the most common criticalities that might be encountered when boring a long tunnel under variable cover.