The fronts of tunnels excavated under particularly difficult ground conditions by employing conventional tunnelling methods are commonly supported: the stabilization is usually achieved either by improving the mechanical properties of the soil (injections, jet grouting, soil freezing, etc.) or by introducing linear inclusions. This last technique, consisting in the introduction of pipes (usually made of fibreglass reinforced polymers) in the front, is particularly popular since it is very simple to adapt the reinforcement geometry, length and number to the different conditions encountered during the excavation. The design of this reinforcement technique is nowadays based on very simplified approaches: on either empirical formula or the limit equilibrium method. In a previous paper, the authors numerically studied the mechanical response of unreinforced fronts in cohesive soils and defined a non-dimensional front characteristic curve. In this paper, the authors intend to take into consideration the role of reinforcements by following the same approach. A procedure allowing the definition of the reinforced non-dimensional front characteristic curve, once the reinforcement pattern is assigned, is introduced. The practical use of this curve is described.

中文翻译：

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不排水条件下粘性土壤中的深隧道前沿：基于位移的玻璃纤维增​​强材料设计方法

通常支持通过使用传统的隧道方法在特别困难的地面条件下开挖的隧道前端：通常通过改善土壤的机械性能（注入，喷射灌浆，土壤冻结等）或通过引入线性夹杂物来实现稳定。 。最后一种技术是在前部引入管道（通常由玻璃纤维增​​强的聚合物制成），这种技术非常受欢迎，因为将钢筋的几何形状，长度和数量适应于开挖过程中遇到的不同条件非常简单。如今，这种加固技术的设计基于非常简单的方法：基于经验公式或极限平衡法。在上一篇论文中，作者对粘性土中未加筋的前沿的力学响应进行了数值研究，并定义了无量纲的前沿特征曲线。在本文中，作者打算通过遵循相同的方法来考虑增强的作用。一旦指定了加固图案，就会引入允许定义加固的无量纲前特性曲线的过程。描述了该曲线的实际使用。