Study On Blasting Vibration Control Of Long-span Tunnel Passing Through Existing High-speed Railway Tunnel

Based on the Weizailing tunnel project of Wangpeng Avenue in Shenzhen Shantou Special Cooperation Zone,aiming at the problem that the blasting vibration speed of long-span tunnel passing through the existing high-speed railway tunnel in close distance is seriously out of limit,this paper studies the dynamic response characteristics of the existing tunnel high-speed railway tunnel structure by means of dynamic finite element simulation combined with theoretical derivation and calculation verification,and divides the construction interval of strong and weak blasting vibration according to the law of blasting vibration response,Put forward feasible vibration reduction optimization measures,carry out sensitivity analysis of blasting parameters,and give a recommended drilling and blasting construction scheme integrating various factors.The main research results are as follows:(1)By means of dynamic finite element simulation,the distribution laws of velocity field and stress field of existing tunnel in different spatial positions and different construction stages of tunnel drilling and blasting penetration construction are studied and analyzed,the safety of existing tunnel structure is evaluated,and the construction areas with slight disturbance,medium disturbance and serious disturbance are given.Based on the results of cylindrical charge waveform function,the accuracy of LS DYNA numerical simulation is verified;A modified Sadovsky formula suitable for specific working conditions is proposed,and its applicability is verified by various calculation methods.(2)Based on the existing research,the advantages are retained to overcome the defects,and vibration reduction measures such as deep hole bottom charging mixed cutting and upper step right pilot tunnel method with good vibration control effect are put forward;The sensitivity of blasting parameters is studied through numerical simulation and theoretical calculation.Based on the influence law of various parameters on blasting vibration and combined with engineering characteristics,the feasibility of each blasting parameter in vibration reduction optimization is obtained.Taking the vibration reduction effect as the index,the optimal initiation delay and footage ratio of the front and rear sections of the mixed cutting with charge at the bottom of the deep hole are determined;Through the RHT constitutive model,the damage forms of surrounding rock under different cutting modes are compared and quantitatively analyzed to verify the cutting effect of deep hole bottom charge mixed cutting.(3)The blasting vibration velocity of the existing tunnel under the combination of blasting parameters such as different excavation methods,cutting methods,excavation area and single footage is calculated,and the evolution law of blasting vibration velocity under the comprehensive influence of various factors is analyzed;The applicability of different excavation methods and cutting methods in each construction section is discussed from the perspectives of blasting vibration speed,deformation of surrounding rock support structure,construction difficulty and progress;Taking the blasting vibration speed as the main evaluation index,combined with the advantages and disadvantages of surrounding rock support structure deformation,construction difficulty,progress and cost,the proposed drilling and blasting excavation scheme of Weizailing tunnel crossing the existing Guangzhou Shantou high-speed railway tunnel under different engineering conditions is given respectively.Figures 55,Tables 45,References 82...