Abstract:  To investigate the control effect of negative Poisson′s ratio(NPR) anchor cable on large deformation of Dongmachang tunnel in soft rock across faults, static tensile experiments are conducted on the NPR anchor cable to validate their constant resistance to large deformations and their effectiveness in resisting external forces. Subsequent experiments on three-dimensional physical modeling of NPR anchor cable for deformation control of the surrounding rock in the Dongmachang tunnel. The experimental phenomena and results show the following: (1) In the excavation process, the tunnel surrounding rocks exhibit no large collapse, indicating that the NPR anchor cable has a better support effect on the soft rock tunnel surrounding rocks. (2) After loading, the maximum displacement of the surrounding rock at nonfaulted section after using NPR anchor cable is approximately 14 mm, and that at faulted section is approximately 21 mm. The irregularity of the stress distribution applied to the tunnel area leads to extrusion and deformation of the tunnel surrounding rock with an oscillating displacement curve. (3) Under the support of NPR anchor cable, the maximum surrounding rock stress occurs at the left arch shoulder, and the maximum shear stress occurs at 3 cm on free face (reaching 0.3 MPa). Large-scale asymmetric damage does not appear in the tunnel, and the general deformation can be controlled.

Key words: tunnel crossing fault, soft rock large deformation, negative Poisson′s ratio anchor cable, physical model test