The mechanical behavior of interfaces is a hot research topic in the field of geotechnical engineering. The soil-rock contact surface

as a widely existing interface in various geological bodies

its mechanical behavior is closely related to engineering stability and geological hazard development. Geometric shape is an important factor affecting the mechanical behavior of soil-rock interfaces. Different shapes of soil-rock interfaces were regarded as objects

and the natural contact surface morphology was restored through 3D printing technology. Bedrock models containing rectangular

serrated

and arc-shaped contact surfaces were printed

and soil-rock samples with different interface shapes were prepared. On this basis

indoor shear tests were conducted to investigate the influence of regular interface morphology on the shear behavior of specimens under different asperity widths. The results indicate that: (1) For the same material

natural interfaces have obvious shear peaks

while regular interfaces have no significant peaks. When the proportion of asperity width is less than 35%

the curved interface exhibits the highest shear strength

followed by the serrated interface and then the rectangular interface. When the proportion of asperity width exceeds 35%

the serrated interface shows the highest shear strength

followed by the curved interfaces and then the rectangular interface. Additionally

as the asperity width increases

the shear strength gradually increases. (2) Interface cohesion decreases in the order: serrated>arc-shaped>rectangular

whereas the internal friction angle decreases in the order: rectangular>serrated>arc-shaped. (3) During shear process

two shear planes form at the interface of a protruding body: a primary shear plane at the soil-rock interface and a secondary shear plane within the protrusion. The secondary shear plane primarily accounts for the differences in shear behavior of interfaces with different shapes.