Foamed concrete as energy absorption material for high geo-stress soft rock tunnels has been proven to be feasible due to its high compressibility and lightweight. However, the lengthy curing and defoaming problems caused by the cast-in-place method of large-volume foamed concrete remain unsolved. In this study, we propose a novel energy absorber composed of foamed concrete-filled polyethylene (FC-PE) pipe and analyze its deformation and energy absorption capacity via quasi-static lateral compression experiments. Results show that FC-PE pipes exhibit typical three-stage deformation characteristics, comprising the elastic stage, the plastic plateau, and the densification stage. Furthermore, the plateau stress, energy absorption, and specific energy absorption of the specimens are 0.81–1.91 MPa, 164–533 J, and 1.4–3.6 J/g, respectively. As the density of the foamed concrete increases, the plateau stress and energy absorption increase significantly. Conversely, the length of the plastic plateau and energy absorption efficiency decrease. Moreover, based on the vertical slice method, progressive compression of core material, and the 6 plastic hinges deformation mechanism of the pipe wall, a theoretical calculation method for effective energy absorption is established and achieves good agreement with experimental results, which is beneficial to the optimization of the composite structure.

泡沫混凝土作为高地应力软岩隧道的吸能材料已被证明是可行的，因为它具有高压缩性和轻质等优点。然而，大体积泡沫混凝土现浇法造成的养护时间长和消泡问题仍未解决。在这项研究中，我们提出了一种由泡沫混凝土填充聚乙烯（FC-PE）管组成的新型吸能器，并通过准静态侧向压缩实验分析了其变形和吸能能力。结果表明，FC-PE管材表现出典型的三阶段变形特征，包括弹性阶段、塑性平台期和致密化阶段。此外，试样的平台应力、能量吸收和比能量吸收分别为 0.81-1.91 MPa、164-533 J 和 1.4-3.6 J/g。随着泡沫混凝土密度的增加，高原应力和能量吸收显着增加。相反，塑性平台的长度和能量吸收效率降低。此外，基于垂直切片法、芯材渐进压缩和管壁6塑性铰变形机制，建立了有效吸能的理论计算方法，与实验结果吻合良好，有利于复合结构的优化。