Study On The Influence Of Subway Segments Structure Under Impact Vibration Induced By Collapse Of Buliding In Demolition Blasting

In recent years, more and more urban controlled blasting engineerings areconcentrated in downtown. A lot of buildings and underground pipelines are distributedaround the blasting areas. This phenomenon brings many challenges to the technologyof urban control blasting. So it is important to study the impact of subway structurecoused by impactvibration. We can guide the blasting opration and ensure the safety ofsubway structure by this significative research.Theoretical analysis, numerical simulation method and engineering practice arecombined to study the impact of subway strcture caused by impactvibration. Firstly,shock dynamic knowledge, stress wave theory and Hertz collision theory are adopted toget the distribution function and the characteristics of impact load on the rectangularplane and spherical surface. Secondly, making mechanics analysis and establishingmechanical model about the subway shield tunnel segment structure. Then numericalcalculation is took on the structure of subway shield tunnel segments with11membedded depth. The calculation results show that: the main deformation of subwayshield tunnel occurred on the roof and floor as well as the left and right side of thetunnel, the maximum of deformation is0.85mm. Thirdly, the modal analysis of thesubway shield tunnel segments show that: the first ten natural frequencies are between0.1~0.26Hz which belong to low frequency. So the structure of subway tunnel is moresensitive to the low frequency vibration, and the impactvibration with more lowfrequency can easier make damage to shield tunnel. Finally, using dynamic explicitfinite element software LS-DYNA to calculate the dynamic response of subway shieldtunnel. The quality, height of the center of gravity and horizontal distance makedifferent effect to shield tunnel structure. The calculation results show that: the peakvibration velocity and the maximum principal stress of the particle is proportional to thequality and height of the collapsing block. Furthermore, they develop a exponentialfunction with the horizontal distance.