High ground stress-chemical erosion coupling effect on carbonaceous shale creep experiment and nonlinear creep damage model

In order to overcome the elevation obstacles and reduce the construction risks, long tunnels can be used to cross the lofty mountains, but these tunnels are often in deep-buried high-geostress environments and affected by chemical erosion. In order to solve these problems, a large deformation tunnel in charcoal slate of the Lijiang—Shangri-La was taken as the research object, and the deformation characteristics of the surrounding rock in deeply buried charcoal slate tunnels subjected to chemical erosion were investigated by using indoor experiments and theoretical derivation. On the basis of the Poyting-Thomson body creep body, according to the mechanical properties of the model elements, damage elements, chemical damage elements, and nonlinear elements were superimposed, and the proposal of the high geostatic stress-chemical erosion coupling effect was made. The results show that: 1) The carbonaceous slate specimen is significantly affected by chemical erosion, and the axial creep strain produced by the specimen with 90 d of erosion is 2.02 times that of the specimen with 0 d of erosion, and the radial creep strain produced by the specimen with 60 d of erosion is 1.85 times that of the specimen with 0 d of erosion; 2) Eroded carbonaceous slate specimens ruptured in triaxial compression are dominated by diagonal through fissures with some slip misalignment fissures, the tensile splitting damage along the axes is suppressed significantly by peripheral compression, and no vertical through fissures are produced. © 2024 Central South University of Technology. All rights reserved.