Experimental Study on Critical Safe Thickness of Existing Rock Wall Adjacent to Railway Line under Blasting Demolition
Research purposes:The safety of rock blasting for cutting expansion has always been a major concern in the second railway line construction.In the process of cutting expansion,the reserved rock wall is widely set when carrying out rock blasting,which results in difficulties in blasting demolition of the reserved rock wall.In order to ensure the safety of blasting demolition of the reserved rock wall,theoretical analysis about the critical safe thickness of rock wall under blasting demolition was conducted,and row-by-row blasting experiments for validating the theory were carried out during blasting demolition of the reserved rock wall in Chongqing-Huaihua railway.Research conclusions:(1)The critical safe thickness of rock wall under blasting demolition was proposed,and the corresponding calculation approach of the critical safe thickness was developed based on the theory of rock blasting with multiple free surfaces.(2)The critical safe thickness of the reserved rock wall should be twice the minimum burden,which was acquired by analyzing the variation of the surface feature,the acoustic velocity,and the vibration velocity during blasting demolition of the reserved rock wall.(3)The critical safe thickness is a key factor ensuring the safety of blasting demolition of the reserved rock wall,whose determination can provide technical support for rock blasting in cutting expansion of double track railway.
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