Experimental Investigation on the Law of Deformation and Fracture of Surrounding Rock of Soft and Gently Inclined Layered Tunnel

Aiming at the hot issue of the deformation and fracture law of the surrounding rock of soft and gently inclined layered tunnel, the deformation and fracture law of the surrounding rock of soft and gently inclined layered tunnel is experimentally studied using the physical simulation test system of small and medium-sized tunnel based on motor biaxial loading and the refinement digital photogrammetric measurement system named PhotoInfor. The results show that: The surrounding rock at the left spandrel of the soft and gently inclined layered tunnel forms a shear wedge and collapses first, and then fracture occurs in the surrounding rock at the left spandrel and continued to the deep part of the surrounding rock, forming a new shear wedge, which makes the deformation and fracture of the surrounding rock appear obvious left-right asymmetry; The thickness of the broken rock zone of the surrounding rock of this kind of soft and gently inclined layered tunnel is unevenly distributed from left to right, and the differential support suggestions are put forward, which can optimize and improve the stability of the surrounding rock of the tunnel and save the construction cost at the same time; Through the digital photogrammetric measurement technology, the change of surrounding rock displacement around the tunnel is obtained quantitatively in the whole process of the test. The displacement development condition is basically consistent with the macro failure process of surrounding rock.