Fiber Reinforced Shotcrete (FRS) is an essential element of ground control in many types of underground structure. It has been found to be an important aid to the improvement of safety in underground spaces and is a highly effective method of ground control across a wide range of ground conditions. However, the design of FRS linings remains problematic and uncertainty exists regarding the true load capacity of linings, especially with regard to out‐of‐plane load resistance. Most existing methods utilize either an elastic method of analysis or Yield Line theory to estimate load resistance, but these methods fail to account for the beneficial effect that in‐plane restraint has on load resistance. To address this short‐coming, the present research describes an experimental programme to examine the effect of Compressive Membrane Action (CMA) on the out‐of‐plane load capacity of shotcrete panels. The results demonstrate that the in‐plane restraint against dilation around a localized failure in a wall could contribute to at least a doubling of out‐of‐plane load resistance compared to estimates based on standard unrestrained beam and panel tests. Results of the experimental study have been used to develop an approximate mathematical model that describes the observed behavior with regard to the flexural strength enhancement associated with membrane compression and the contribution to load resistance associated with the development of inclined membrane struts and arching action.

中文翻译：

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平面约束对纤维喷射混凝土点承载能力的影响

纤维增强喷浆混凝土（FRS）是许多类型地下结构中地面控制的重要组成部分。已经发现它是改善地下空间安全的重要帮助，并且是在广泛的地面条件下进行地面控制的高效方法。但是，FRS衬砌的设计仍然存在问题，并且衬砌的真实承载能力存在不确定性，尤其是在平面外负载阻力方面。现有的大多数方法都使用弹性分析法或屈服线理论来估计载荷阻力，但是这些方法未能说明平面约束对载荷阻力的有利影响。为了解决这个缺点，本研究描述了一个实验程序，以检查压缩膜作用（CMA）对喷射混凝土面板的平面外承载力的影响。结果表明，与基于标准无约束梁和面板测试的估计相比，针对壁局部破坏的平面约束能够至少使平面外载荷阻力增加一倍。实验研究的结果已用于开发一个近似的数学模型，该模型描述了观察到的与膜压缩相关的弯曲强度增强行为以及与倾斜的膜撑和拱起作用相关的对载荷阻力的贡献。结果表明，与基于标准无约束梁和面板测试的估计相比，针对壁局部破坏的平面约束能够至少使平面外载荷阻力增加一倍。实验研究的结果已用于开发一个近似的数学模型，该模型描述了观察到的与膜压缩相关的弯曲强度增强行为以及与倾斜的膜撑和拱起作用相关的对载荷阻力的贡献。结果表明，与基于标准无约束梁和面板测试的估计相比，针对壁局部破坏的平面约束能够至少使平面外载荷阻力增加一倍。实验研究的结果已用于开发一个近似的数学模型，该模型描述了观察到的与膜压缩相关的弯曲强度增强行为以及与倾斜的膜撑和拱起作用相关的对载荷阻力的贡献。