A major challenge that TBM performance is requested to deal with for a successful and effective progress is tunnelling through lithologically and geomechanically heterogeneous rock masses. Such heterogeneous environments are common and recent tunnel examples in the UK include the Hinckley Point C offshore cooling tunnels being driven through interbedded carbonaceous mudstone/shales and argillaceous limestone and the Anglo American’s Woodsmith Mine Mineral Transport System tunnel in Redcar Mudstone with beds of ironstone. This inherent geological heterogeneity leads to difficult tunnelling conditions that initially stem from predicting a sound and representative ground model that can be used to preliminary assess the TBM performance. In this work, an exhaustive review of existing TBM Penetration Rate (PR) methods identified that no models address the issue of parameter selection for heterogeneous rock masses comprising layers with different rock strengths. Consequently, new approaches are required for estimating rock mass behaviour and machine performance in such environments. In the presented work the Blue Lias Formation (BLI), which is characterised by its layered rock mass, comprising very strong limestone, interbedded with weak mudstone and shales, is investigated. BLI formation is considered herein being a representative example of lithological heterogeneity. Based on the fieldwork carried out in three localities in the Bristol Channel Basin (S. Wales and Somerset), geological models are produced based on which a geotechnical model is developed, and four ground types are determined. Implications of the current findings for TBM performance are assessed, including faulting, groundwater inflow and excavation stability with a particular focus on both PR and advance rate. A modified approach using the existing empirical models is proposed, developed and presented in this paper that can be used as a guide to determine TBM performance in heterogeneous rock masses reducing the risk of cost and time overruns.

TBM 性能需要应对的一个主要挑战是在岩性和地质力学非均质岩体中掘进。这种异质环境很常见，英国最近的隧道例子包括通过碳质泥岩/页岩和泥质石灰岩的互层驱动的欣克利角 C 海上冷却隧道，以及位于雷德卡泥岩的英美资源伍德史密斯矿矿物运输系统隧道，该隧道具有铁岩床。这种固有的地质异质性导致隧道掘进条件困难，最初源于预测可用于初步评估 TBM 性能的可靠且具有代表性的地面模型。在这项工作中，对现有 TBM 穿透率 (PR) 方法的详尽审查发现，没有模型解决包含具有不同岩石强度的层的非均质岩体的参数选择问题。因此，需要新的方法来估计这种环境中的岩体行为和机器性能。在所介绍的工作中，对 Blue Lias 地层 (BLI) 进行了调查，该地层的特点是其层状岩体，包括非常坚固的石灰岩，夹有弱泥岩和页岩。BLI 地层在本文中被认为是岩性非均质性的一个代表性例子。根据在布里斯托尔海峡盆地（南威尔士和萨默塞特）三个地方进行的实地工作，制作了地质模型，并在此基础上开发了岩土工程模型，并确定了四种地面类型。评估当前发现对 TBM 性能的影响，包括断层、地下水流入和开挖稳定性，特别关注 PR 和推进率。本文提出、开发和介绍了一种使用现有经验模型的改进方法，可用作确定非均质岩体中 TBM 性能的指南，从而降低成本和时间超限的风险。