Abstract
It is important to guarantee the safety of adjacent underground structures during the foundation pit blasting excavation of modern city construction. The blasting excavation construction of a large, deep foundation pit near an existing metro station of Guangzhou Metro Line 3 is used as the example in this study. Based on blasting vibration field test results, the influence of blasting dynamic load on the lining of an adjacent metro tunnel is numerically analyzed in simulation using Fast Lagrangian Analysis of Continua 3D (FLAC3D), and the relationships between the blasting vibration velocity and stress and the displacement of the metro tunnel lining are obtained. The results show that the stress of lining structure is within the allowable range under the experimental blasting conditions, the lining displacement increases linearly with the applied dynamic vibration velocity, and the vertical displacement of the lining is more obviously affected than the horizontal displacement by the dynamic load. This study can be used as a basis for the control of blasting vibration in a complex urban environment. Its practical application shows that the proposed blasting plan and parameters are reasonable and effective.
Highlights
Blasting is an efficient and fast excavation method for hard rock mass, and it has been widely used in the excavation of urban building foundation pits
Xia et al researched the impact of the cavity effect on tunnel excavation blasting vibration by a series of blast tests. e results suggested that the cavity effect on the ground only worked within a limited scope in shallow tunnel excavations, and an empirical equation was proposed to calculate the amplifying coefficient [6]
To analyze the relationship between the applied blasting dynamic load and the maximum displacement, we summarize the stress of the tunnel lining, the maximum displacement, and the stress of the lining under static conditions and a dynamic load in Table 4, from which we can see the following: (1) e stress and displacement of the metro tunnel lining increase as long as the blasting dynamic load strength improves
Summary
Blasting is an efficient and fast excavation method for hard rock mass, and it has been widely used in the excavation of urban building foundation pits. Research on the response characteristics of foundation pit on a metro tunnel has been widely considered by scholars [1,2,3,4,5]. Shock and Vibration the field-testing results of ground vibration induced by blasting during the construction of the Istanbul KadikoyKartal metro tunnel. Park and Jeon proposed an air-deck method to reduce blast-induced vibration in the direction of tunneling, and its effect was investigated through numerical and experimental studies [13]. Jiang et al focused on safety of buried pressurized gas pipelines subject to blasting vibrations induced by metro foundation pit excavation [18, 19]. The dynamic response characteristics of metro lining and rock mass under different load conditions are calculated and analyzed. The dynamic response characteristics of metro lining and rock mass under different load conditions are calculated and analyzed. e relationships between maximum displacement and vibration velocity of lining under different dynamic load conditions are calculated and analyzed. e prediction formula of metro lining PPV is established, which can guide the parameters’ design of foundation pit blasting
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