Health evaluation method of highway tunnel structure based on bearing capacity

At present, the research on the deformation and damage evolution mechanism of tunnel structures under the action of loose load is relatively scarce, and the quantitative analysis of structural residual bearing capacity is lacking, which is not conducive to of structural health assessment and the determination of maintenance treatment program. For these problems, this paper studied the deformation regularity and damage characteristics of the structure under different surrounding rock conditions, summarized the key indexes of structural health assessment, established the standard of health classification based on bearing capacity through indoor model test and finite element analysis software. Through these researches, we can draw the following conclusions. (1) The failure process of the lining is divided into three stages, the arch cracking and the main crack opening as the dividing line. The inner side of the vault and the outside of the arch pull the steel bar apart, the structure turned into three-hinged arch at the same time. (2) Arch crown settlement is 3.3 cm with resistance coefficient 1.58 MPa/m and 0.23 cm with resistance coefficient 200 MPa/m under the same load of 100 kPa. Resistance coefficient increases from 1.58 MPa/m to 200 MPa/m, the ultimate bearing capacity increases from 196 kPa to 1 840 kPa. (3) Through taking lining cracking, crown sinking 3 cm, arch crown steel yield, arch haunch steel yield and arch crown steel breaking as key nodes, and taking crown settlement and side wall convergence as simple evaluation indexes, the 5 grade criterion of lining structure health degree is established. The control value of crown settlement for V-VI grade surrounding rock is suggested to take 5 cm. © 2018, Science Press. All right reserved.