STUDY ON MECHANICAL CHARACTERISTICS OF GYPSUM ROCK TUNNEL LINING STRUCTURE UNDER DRY WET CIRCULATION
Based on the indoor triaxial compression test,the failure characteristics and mechanical properties evolution law of gypsum rock after dry-wet cycle are obtained.Combined with numerical simulation,the mechanical influence law of gypsum surrounding rock on the initial support structure of tunnel after dry-wet cycle is studied.The results show that with the increase of the number of dry-wet cycles,the shear surface decreases when the gypsum rock is destroyed,and a large area of rock spalling occurs on the surface of the rock sample;at the same time,with the increase of Poisson's ratio,the elastic modulus and peak deviatoric stress decrease,and the deterioration of elastic modulus is the most serious,which is about 49%lower than that of the same period.After 11 dry-wet cycles,the horizontal displacement of the side wall is the largest,about 1.5 times higher than that of the year-on-year,and the vertical displacement peak appears in the vault,which is 1.2 times higher than that of the year-on-year.The safety factor of each position of the initial support is reduced,and the vault,wall foot and side wall are greatly reduced,which are reduced by about 63%,36%and 53%respectively.The vault,wall foot and side wall of the primary support structure are weak points,which need to be strengthened and reinforced to ensure the safe operation of the tunnel.
万方数据
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