Double lining with outer segmental lining and inner reinforced concrete lining is extensively used for water conveyance tunnel with internal water pressure. In order to improve the performance of the double lining, the steel rebar and fibre reinforced concrete (R/FRC) is designed for inner lining to enhance the tensile strength of reinforced concrete (RC). Full-scale tests were conducted to compare the mechanical behaviour of double lining with inner RC and R/FRC linings. The test results showed that both types of lining failed in four stages: elastic stage, inner lining cracking stage, crack stabilization and segmental joint damage stage, and failure stage. The cracks firstly occurred in the inner lining near the segmental joints and then propagated to the whole inner lining ring. Finally, the crack width and segmental joint opening successively exceeded the thresholds, and the double lining failed until the breaking of segmental joints. Compared with inner RC lining, R/FRC lining had better performance in terms of the initial cracking load, cracking-control ability, post-cracking stiffness, service limit capacity of inner lining and waterproof capacity of segmental lining. The improvement ratios were 36.3%, 50.3%, 46.3%, 37.2% and 31.1%, respectively. The influences of fibre volume fraction, fibre aspect ratio, and reinforcement ratio of steel rebar on the mechanical performance of R/FRC lining were also investigated based on a previously proposed analytical model. The parametric analysis demonstrated that higher fibre volume fraction and fibre aspect ratio can result in more significant increase of mechanical performance of R/FRC lining. The steel fibres were found to have more significant effects on the post-cracking behaviour of the lining than same amounts of reinforcing bars. Finally, an optimized function was proposed to fulfil a balance of lining performance and economy. The experimental and analytical results indicated that R/FRC lining can substitute RC lining and perform higher mechanical performance in water conveyance tunnels.

中文翻译：

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内水压力下外节段衬砌和内纤维增强混凝土衬砌的双衬砌的力学性能


外管片衬砌和内钢筋混凝土衬砌的双衬板广泛用于具有内部水压的输水隧道。为了提高双层衬里的性能，内衬设计了钢筋和纤维增强混凝土 （R/FRC），以提高增强混凝土 （RC） 的抗拉强度。进行了全尺寸测试，以比较双衬里与内 RC 和 R/FRC 衬里的机械性能。试验结果表明，两种类型的衬砌破坏分为弹性阶段、内衬开裂阶段、裂缝稳定和节段节理损伤阶段和破坏阶段4个阶段。裂纹首先出现在节段节理附近的内衬中，然后蔓延到整个内衬环。最后，裂缝宽度和节段节理张开度依次超过阈值，双衬失效，直到节段节理断裂。与RC内衬相比，R/FRC内衬在初始开裂载荷、开裂控制能力、开裂后刚度、内衬使用极限能力和节段衬防水能力等方面具有更好的性能。改善率分别为 36.3% 、 50.3% 、 46.3% 、 37.2% 和 31.1%。还基于先前提出的分析模型研究了纤维体积分数、纤维纵横比和钢筋加固率对 R/FRC 衬里力学性能的影响。参数分析表明，较高的纤维体积分数和纤维纵横比可以导致 R/FRC 衬里的机械性能得到更显着的提高。 研究发现，与相同数量的钢筋相比，钢纤维对衬里的开裂后行为的影响更显着。最后，提出了一种优化功能，以实现衬里性能和经济性的平衡。实验和分析结果表明，R/FRC 衬砌可以替代 RC 衬砌，在输水隧道中具有更高的力学性能。