合理的支护力是维持盾构隧道开挖面稳定的重要保障，然而现有针对矩形盾构隧道开挖面支护力的研究较少。为有效解决矩形盾构隧道开挖面破坏形式不明确以及极限支护力设计方法不精确等问题，基于摩尔-库仑屈服准则，通过优化传统三维楔形体模型，将矩形盾构隧道开挖面土体破坏形式进行修正，建立适用于矩形盾构隧道的主动和被动土体破坏计算模型，并推导提出极限支护力计算公式。采用有限元分析软件Plaxis3D对盾构隧道开挖面的主动和被动极限破坏状态进行模拟，并对提出的土体破坏模式、主动和被动极限支护力的变化规律进行验证分析。研究表明，提出的土体破坏计算模型与数值模拟结果具有较高的吻合性，研究结果较好地揭示了土体黏聚力、内摩擦角、埋深比和地下水水位高度对极限支护力的影响，其中被动极限支护力与以上参数呈现正相关关系，而主动极限支护力随着黏聚力和内摩擦角的增加而减小。
A rational support force is
a crucial factor ensuring the stability of the shield tunnel excavation face.
However, limited research has been conducted on the support force concerning
the rectangular shield tunnel excavation face. To clarify the failure forms of
tunnel excavation face of rectangular shield tunnels and determined an accurate
design method for limit support forces, the soil failure forms on the tunnel
face of rectangular shield tunnels is modified based on the Mohr-Coulomb yield criterion by optimizing the traditional three-dimensional wedge model. An active and passive soil failure
calculation model tailored for rectangular shield tunnels is established and
corresponding formulas for calculating the limit support force are derived.
Additionally, finite element analysis software Plaxis3D is employed to simulate
the active and passive limit failure states of shield tunnel excavation face,
thus to validate the proposed soil failure mode and the variation law of active
and passive limit support forces. The results demonstrate a strong agreement
between the proposed soil failure mode and the numerical simulation results.
The findings reveal the influence of soil cohesion, internal friction angle,
burial depth ratio, and groundwater level height on the limit support force.
The passive limit support force is positively correlated with the above-mentioned parameters, while the active limit support force decreases
with increasing cohesion and internal friction angle.
