Stress Characteristics and Pressure Relief Effect Analysis of EPP Concrete in Soft Rock Tunnel
JILI Ciqie1, LU Junfu1, WANG Mingsheng2, LIU Feng1
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1. State Key Laboratory of Geohazard Prevention and Geoenironment Protection, Chengdu University of Technology, Chengdu, Sichuan 610059, China; 2. China Railway City Development Investment Group Co. Ltd, Chengdu, Sichuan 610000, China
Research purposes: During the operation of soft rock tunnel, the creep of surrounding rock leads to large deformation and cracking of tunnel lining, which seriously affects the operation safety. Based on the mechanical parameters of EPP (polypropylene) foam concrete obtained in the previous test, the stress characteristics and pressure relief effect of EPP foam concrete buffer layer in soft rock tunnel are analyzed, and a method to resist the creep of tunnel surrounding rock and reduce the deformation of lining is proposed, which provides a reference for similar tunnel engineering design. Research conclusions:(1) EPP foam concrete, as a buffer layer of soft rock tunnel, has a good effect on improving the pressure of lining. (2) When the concrete with 64% EPP foam particles is used as the buffer layer and the thickness is 0.8 m, the compressive stress of the lining is the smallest, the lining is in the full section compression state, and the ultimate bearing capacity is the highest. (3) The yielding deformation of the buffer layer is the direct reason that determines its pressure relief effect. The higher the content and thickness of EPP foam in the buffer layer, the greater the yielding deformation, and the best pressure relief effect. (4) EPP foam concrete is applied to the buffer layer structure between the initial support and the secondary lining of soft rock tunnel in the direction of railway and highway engineering in the field of civil engineering. Its application prospect is broad. In order to further improve the pressure relief performance of EPP foam concrete and enhance the engineering practicability, it is necessary to carry out optimization research on the material mix ratio and compression characteristics.
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Stress Characteristics and Pressure Relief Effect Analysis of EPP Concrete in Soft Rock Tunnel[J]. Journal of Railway Engineering Society, 2023, 40(1): 97-102
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