ELASTOPLASTIC ANALYSIS OF MULTI-REFRIGERANT HETEROGENEOUS FROZEN WALL CONSIDERING FROST HEAVE CHARACTERISTICS

In order to reasonably analyze the mechanical properties of the multi-refrigerant heterogeneous artificial frozen wall, the frozen wall is regarded as functionally graded material whose elastic modulus and cohesion change linearly with the radius, and the frost heave coefficient n is introduced to reflect the frost heave characteristics of the frozen wall. Based on different yield criteria, the implicit equations of stress, displacement and relative radius of plastic zone of multi-refrigerant heterogeneous artificial frozen wall in elastoplastic state are derived respectively. The calculation results show that after considering the heterogeneity characteristics, the elastic ultimate bearing capacity of frozen wall calculated based on M-C, D-P, generalized Tresca and twin shear unified strength criterion is reduced by 4.01%, 4.02%, 3.19% and 2.57%, respectively, while the plastic ultimate bearing capacity is increased by 8.13%, 8.13%, 8.04% and 7.95%, respectively. After further considering the frost heave characteristics, the elastic ultimate bearing capacity of the heterogeneous frozen wall is calculated based on the four yield criteria, which is increased by 6.91%, 6.92%, 5.93% and 5.19%, respectively. Taking the M-C criterion as an example, considering the frost heave characteristics, when the frozen wall is in the elastic limit state (r_c = 1), the displacement of the inner and outer edges of the heterogeneous frozen wall increases by 3.850 cm and 17.159 cm, respectively. When the frozen wall is in the elastoplastic state (r_c = 1.2), the displacement of the inner and outer edges of the heterogeneous frozen wall increases by 5.544 cm and 16.024 cm, respectively. When the relative radius of the plastic zone is 1 ≤ r_c ≤ 1.2, the displacement of the inner edge increases with the increase of the plastic zone, and the displacement of the outer edge decreases first and then increases. Compared with homogeneous frozen wall, the heterogeneous frozen wall exhibits higher bearing capacity at the same plastic zone expansion radius, and this difference becomes more prominent with the increase of plastic zone radius and the influence of frost heave characteristics. This study has important reference significance for the design of multi-refrigerant frozen wall in water-rich strata.