Study On Vibration Frequency Characteristics And Parameters Optimization Of Near Region Induced By Blasting Excavation

The economical and efficient blasting excavation method is innovated continuously and widely used in all kinds of important infrastructure construction.The impact load and vibration caused by the explosion will cause the surrounding rock to break and damage when the rock is excavated.Due to the complexity of rock mass vibration response,the vibration velocity,frequency and energy should be considered to check and control the blasting damage of surrounding rock.It is necessary to study the attenuation law of blasting vibration frequency and energy of rock mass.In this paper,theoretical analysis,field measurement and numerical calculation methods are used.The distribution of vibration frequency,amplitude and vibration energy of rock mass in the concentrated area of single section blasting is systematically studied.The following results are obtained:(1)The rock breaking mechanism,vibration frequency and vibration energy propagation and attenuation law of rock mass are expounded by summarizing the vibration response law of rock mass blasting near region.The distribution of vibration frequency,amplitude and vibration energy of rock mass near the central region induced by different single-stage bore hole arrangement is analyzed(2)Combined with the measured data of blasting excavation of tianchi pumped storage power station.The variation of PPV and attenuation of main frequency of blasting vibration is analyzed.The vibration response and spectrum characteristics of the surrounding rock within a distance of 10 m from the blasting center of the singlehole blasting model are analyzed by using dynamic finite element software.(3)The actual project is simplified into four basic models: single hole,double hole,three hole and four hole.Based on dynamic finite element fluid-solid coupling algorithm.Numerical simulation of vibration response of rock near the bore hole is carried out.The superposition effect of the stress wave in the near central region excited by different hole arrangement and azimuth bore blasting is studied.The attenuation law of vibration velocity,frequency and energy in the near region of blasting is obtained.(4)The blasting vibration response of the lower rock mass caused by the change of the uncoupling coefficient in the charging structure is studied.And considering the vibration velocity,frequency and energy,the relationship between the optimal hole spacing layout parameters and the influence is obtained.The optimal charge uncoupling coefficient is obtained also.Monitoring and controlling rock mass vibration response only by PPV or only combined with vibration dominant frequency cannot fully reflect the impact of blasting vibration frequency and energy on rock mass.The vibration response of surrounding rock should be evaluated by considering the vibration velocity,frequency and energy,so as to control the rock blasting and ensure the stability of surrounding rock.The results provide a theoretical basis for the arrangement of bore hole and the design of hole network parameters,which is expected to improve the efficiency and safety of blasting construction.