关键词: 隧道工程;衬砌结构;喷射混凝土;弯曲荷载;快速碳化

Abstract: In order to investigate carbonation durability of tunnel lining shotcrete, using spring-four points bending loading method, considering the influence of forming mode and steel fiber mixing, carbonation durability of shotcrete under bending loading ratio of 0.25, 0.50 and 0.75 was carried out.Meantime, compressive, splitting tensile and flexural strengths of carbonation concrete specimens were measured. Based on Zhang's carbonization model, instructing the effective coefficient of bending loading, steel fiber and forming mode, the carbonation depth predictive model of bending loading shotcrete was established. The result shows that carbonation depth of concrete with bending stress obeys Fick's first law. Carbonation coefficient has relationship with force mode, bending ratio, steel fiber mixing and forming mode.Shotcrete has better carbonation durability than ordinary concrete.Furthermore, steel fiber mixing can improve shotcrete carbonation resistance.With carbonation depth increasing, compressive and splitting tensile strengths of carbonation concrete increase.However, flexural strength of those is first decreased quickly and then stable.Comparison with predictive values and experiment data, the mean deviation is less than 10% and the standard deviation is 0.07.It has good applicability for predicting carbonation depth of bending loading shotcrete.

Key words: tunneling engineering;lining structure;shotcrete;bend loading;accelerated carbonation