Research Into The Impact Response Of Adjacent Blasting Vibration On Existing Tunnel

With the development of national economy, transportation industry faces hugechallenge and opportunities. Considering the requirement of exploitation ofunderground space and the restriction of geological conditions and road line, themultiline railway construction became imperative. In the process of tunnels construction,drilling and blasting method is widely applied because this method has high suitability,obvious characteristics of fast construction speed and the low cost. However, In general,as the distance between the new multiline tunnel and existing tunnel is very small,excavating blast in the new multiline tunnel will affect structure safety and the operationsafety of existing tunnel. Consequently, it will be of important social and economicbenefits to control the explosion vibration.Based on published results,3-D finite element model for Xiao-piaogou multilinetunnel is established by using of LS-DYNA dynamic software. Combined with the fieldmonitoring data, the characteristics of blast-induced vibration response of existingtunnel are numerically investigated for different excavation methods and differentcharge structures. Detailed achievements of this paper are summarized as follows:(1) A3-D finite element model is established to predict the blast-induced vibrationresponse for existing tunnels. The feasibility and rationality of this model is verified byusing of selected monitoring data of seven typical cases.(2) The effects of different charging structures on blast-induced vibration responseof existing tunnel are analyzed by using3-D finite element model, in which eight radialnon-coupling charging structures, seven axial non-coupling charging structures, and sixcompound non-coupling charging structures are considered in analysis. The range ofnon-coupling coefficients of charging structures is studied and optimized.(3) Considering the practical excavation method, numerical analysis is carried out to obtain the vibration responses of adjacent existed tunnels. The effects of free surfacesfor different excavation method and the distance between blasting center and tunnel onthe blast-induced vibration response of existing tunnel are investigated.(4) Vibration responses are obtained along the radial and axial of tunnel due to theblasting excavation. Vibration monitoring in the area of existing tunnel between10mahead and4m behind the explosive center should be given more attention.(5) The millisecond blasting which is effect to the blasting vibration intensity insmooth blasting is analysed. Peak velocity of existed tunnel occurs in the previous partof millisecond blasting, especially for the first part which is cut blasting. In order toreduce explosion vibration strength, we should focus on the control of cut blasting.