This paper presents a study about the buckling behavior of thin stainless-steel lining (SSL) for trenchless repair of urban water supply networks under negative pressure. The critical buckling pressure and displacement (p–δ) curves, temperature changing curves, hoop and axial strain of the lining monitoring section and the strain changes with system pressure (p–ε) of the lining under the action of different diameters, different lining wall thickness and different ventilation modes were obtained through five groups of full-scale tests. The variation principles of the post-buckling pressure and the reduction regularity of the flowing section of the lining were further investigated. By comparing different pipeline buckling models and introducing thin-shell theory, the buckling model of liner supported by existing pipe was established. The comparison between the test results and thin-shell theory indicates that one of the significances of the enhancement coefficient k value is to change the constraint condition of the aspect ratio, l/R, thus increasing the critical buckling pressure of the lining. Finally, an improved lining buckling prediction model (enhancement model) is presented. A previous test is used as a case study with the results showing that the enhanced model is able to predict critical buckling pressure and lobe-starting amount of the liner, which can provide guidance for trenchless restoration of the liner with thin-walled stainless steel.

中文翻译：

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薄壁不锈钢内衬包覆给水管负压屈曲行为

本文介绍了在负压下非开挖修复城市供水管网的薄不锈钢衬里 (SSL) 屈曲行为的研究。衬砌监测段临界屈曲压力和位移（p-δ）曲线、温度变化曲线、环向和轴向应变以及应变随系统压力（p-ε ）变化)通过五组全尺寸试验得到不同管径、不同壁厚和不同通风方式作用下的衬砌。进一步研究了后屈曲压力的变化规律和衬砌流动断面的降低规律。通过比较不同管道屈曲模型，引入薄壳理论，建立了既有管道支撑的衬管屈曲模型。测试结果与薄壳理论的对比表明，增强系数k值的意义之一是改变纵横比的约束条件l/R，从而增加了衬砌的临界屈曲压力。最后，提出了一种改进的衬砌屈曲预测模型（增强模型）。之前的试验作为案例研究，结果表明增强模型能够预测衬管的临界屈曲压力和波瓣起始量，可为薄壁不锈钢衬管的非开挖修复提供指导。