Aiming at the construction problems of a subway tunnel adjacent existing buildings in the section between Jialingjiang Road station and Xiangjiang Road station of Qingdao Metro Line 13,a new construction scheme of mechanical excavation combined with blasting is proposed.In the scheme,bench method is used with the upper bench in the weak stratum excavated by mechanical method,and the lower bench in the hard stratum excavated by blasting method.Furthermore,the vibration velocities of the adjacent buildings caused by the proposed scheme and the traditional full-section blasting scheme are analyzed and compared by using FLAC3D and blasting equivalent load method.The results show that,the peak vibration velocity of each monitoring point under the mechanical-blasting scheme decreases significantly compared with the full-section blasting with the maximum reduction rate of 61.1% which is within the allowable range and validates the new scheme.The construction parameters of the mechanical-blasting scheme are compared and selected based on the building settlement,plastic zone of surrounding rock mass,vibration velocity of the buildings,etc.Finally,the mechanical excavation advance of the upper bench is determined to as 0.5 m.Besides,the construction effect of the optimized parameters is monitored and evaluated.The mechanical-blasting construction scheme successfully solved the problems encountered in the project,and shortened the expected construction period by 3 months,which shows the rationality of the proposed construction scheme and parameters,as well as the validity of the calculation results.