Study on Application Effect of Energy-Accumulating Hydraulic Blasting in Fractured Rock Mass of Long Tunnel with Thick Overburden
To solve blasting effect of a long tunnel with thick overburden in the fractured rock mass,the Bashkorgan No.2 tun-nel of Xinjiang Urumqi-Yuli Highway PPP Project is presented as the research object.The energy-accumulating hydraulic blas-ting method which is based on the principles of the cumulative effect were used to overcome difficulties and challenges during the fractured rock mass tunneling.The blasting parameters and the production process of the energy-accumulating tube were determined.The effects of the dust reduction,the transverse section shaping,the surrounding rock disturbance,the cost re-duction and benefit enhancement are studied by using the method of the field measurement.The results show that,compared with the smooth blasting method,the peak value of the dust concentration produced by the energy-accumulating hydraulic blas-ting method is about 11.23mg/m3,and the time of ventilation and dust removal is saved by 50％.As far as the Class Ⅲ sur-rounding rock is concerned,both blasting methods are applicable.The advantages of the energy-accumulating hydraulic blasting method smooth effect are not obvious;For the Class Ⅳ surrounding rock(abundant joint fissure)and the Class Ⅳ surrounding rock(f80 fault),the maximum overbreak value of the energy-accumulating hydraulic blasting method is controlled at 7cm and 9cm,respectively.The overbreak and underbreak values are significantly improved.The use of the energy-accumulating hy-draulic blasting method can effectively reduce the blasting vibration and the disturbance of surrounding rock.The maximum vi-bration speed is 0.78cm/s.The cost saving of the single tunnel can be 9.1216 million yuan.
Energy-Accumulating Hydraulic Blasting MethodDeeply Buried TunnelFractured Rock MassOverbreak and UnderbreakEconomic PerformanceBashkorgan No.2 Tunnel
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