Theoretical solution of multi-refrigerant heterogeneous frozen wall considering creep characteristics and shaft lining influence
摘要
To cope with the complex and changeable stratum environment, the low-temperature refrigerant in the artificial freezing method construction has gradually developed from a single type to the combined use of multiple refrigerants. The creep characteristics of frozen soil and the shaft lining construction process are important factors affecting the stability of this type of heterogeneous frozen wall. To explore the stress and deformation characteristics of multi-refrigerant heterogeneous frozen wall considering creep characteristics and the influence of shaft lining construction, the frozen wall formed by the combined freezing of brine and carbon dioxide was taken as the research object. The temperature characteristic cross-section at 1/4 of the pipe spacing away from the main surface of the frozen wall was selected to equivalatively replace the temperature distribution of the frozen wall, and a temperature field model of the frozen wall was constructed using a three-segment linear function curve. Based on viscoelastic theory and Newton Cotes numerical integration method, a mechanical calculation model for the interaction of heterogeneous frozen wall, shaft lining and peripheral soil with creep characteristics is established, and the analytical solutions of stress, strain and displacement of heterogeneous frozen wall with multiple refrigerants under different tunneling depths (Ⅰ, Ⅱ, Ⅲ) are derived. And the expressions of the external load and freezing pressure acting on the frozen wall and the outer shaft lining. The calculation results show that within 36 hours after the shaft lining pouring, the displacements and strains of both heterogeneous and homogeneous frozen walls show a nonlinear attenuation trend from the inside out. The displacements of the inner and outer edges of the frozen wall first increase and then decrease with the increase of creep time, while the external load of the frozen wall first decreases and then increases. The freezing pressure between the