To improve stemming effectiveness for tunnel excavation and blasting,a stemming device was designed utilizing the expansion characteristics of aluminum tubes under explosive action.The expansion-induced circumferential strain of the stemming device colliding with the steel tube was then measured using a dynamic strain gauge.The simulated explosive stemming devices were subjected to uniaxial compression deformation tests using a universal testing machine.The stemming effects were evaluated by recording the blasting process of cement pillars through high-speed photography.Results showed that the peak circumferential strain of the steel tube under the impact of the stemming device reached 0.02,indicating that the expansion impact force of the device on the blast hole wall was substantial which helped the device adhere to the wall.The compressive strength of the stemming device after adhesion to the blast hole wall was between 4.1 MPa and 5.5 MPa and its shear strength ranged from 0.49 MPa to 0.66 MPa,far greater than the conventional stemming material′s shear strength of 0.09 MPa.In practical use,the stemming device together with the stemming material could effectively prevent its movement.When the traditional stemming material was used for stemming cement pillars,punching phenomenon appeared while no damage was observed after blasting.However,when the stemming device was used instead,there was no punching,and the stemming device only shattered after creating cracks at the collar of the blast hole,resulting in the cement pillar being split into three parts.Therefore,the stemming device significantly improved the stemming effects,and helped increase rock-breaking efficacy of the explosive gas while also enhancing the throwing effect,which is of great significance in improving blasting effects for cut holes.