As a new type of tunnel,a double-arch tunnel is connected by two arches without a middle wall.And too small a distance between them leads to a situation that the blasts in the subsequently excavated tunnel inevitably affect the support structure and surrounding rock of the antecedently excavated tunnel.So,it is necessary to monitor and control the blasting construction.Based on the Manla highway tunnel in Yunnan province,the blasting excavation of the subsequently excavated tunnel is studied by combining field test data with numerical simulation results.Blast vibrations of the antecedently excavated tunnel wall were first monitored during the blasting construction of the subsequently excavated tunnel to analyze the corresponding propagation and attenuation laws.Then,a numerical model was established to simulate the construction process of blasting excavation in the subsequently excavated tunnel,and the attenuation law of vibration propagation calculated by the model is compared with the field measured data to ensure the reliability and accuracy of the discrete element model.By analyzing the lining deformation and surrounding rock damage caused by blasting excavation in the model,the stability of lining supporting structure and surrounding rock is obtained.Based on the vibration propagation law and numerical simulation results,the maximum charge per delay for the tunnel is proposed on the premise of ensuring the safety of supporting structure and surrounding rock.Under the engineering conditions,it is suggested that the maximum charge per delay for the subsequently excavated tunnel should not exceed 15 kg.The maximum allowable vibration velocity is determined by combining the maximum charge per delay and vibration attenuation law,and the vibration velocity at the middle wall of the blasting side of the antecedently excavated tunnel on the same plane of the blasting working face is no more than 22 cm/s.The safety control method is reliable and effective in subsequent construction,which can provide reference for similar double-arch tunnel blasting excavation projects.