In order to solve the problem of the influence on the existing tunnel and the safety evaluation under the construction of adjacent construction works, the destroying situation of a running tunnel occurred during the construction of the surrounding supporting foundation pit project is studied. The current safety of the running tunnel is evaluated and analyzed based on the status detecting results, deformation morphology analysis and safety margin calculation results of the tunnel. The results show that the tunnel deformation is basically stable, the force of the segment does not exceed the ultimate bending moment, and the tunnel structure is safe. The cracks and water leakage of the tunnel structure are controllable, and the durability meets the requirements of short-term use. The tunnel deformation does not exceed the construction clearance and meets the functional requirements. It is recommended to strengthen the monitoring of the tunnel deformation and repair the leakage, cracks, and other diseases in the tunnel for ensuring the construction safety of the adjacent foundation pit and the operation safety of the existing tunnel. The results can provide some references for the analysis and evaluation of the safe state of the tunnel under the close construction.