基于低碳减排的隧道水封爆破优化效果研究

Optimization effect of tunnel water-decked blasting based on carbon emission reduction

为积极落实“碳达峰碳中和”战略,在隧道建设中,优化炮孔装药结构是钻爆法隧道实现绿色降碳的有效途径。通过现场试验和数值模拟对比研究水封爆破相对于常规爆破的降碳效果,并在工程实践中量化分析二者在碳排放评价上的优劣。首先,分析隧道爆破施工全过程的3个主要碳排放源,包括乳化炸药用量、风钻钻孔与炸药运输消耗的油品和通风降尘消耗的电力,并建立基于生产过程的隧道爆破碳排放计算模型。其次,通过有限元软件LS-DYNA分别建立空气、水与炸药轴向耦合爆破的数值分析模型,进一步探讨水封爆破破岩机理,由于水介质良好的低压缩性和更优的传能效率,水与炸药耦合装药结构加强了应力波正相作用时程和应力波峰值。因此,应力波叠加效应对岩体造成的损伤区域更大,岩体深部裂缝更加均匀。最后,依托贵州省董当特长隧道Ⅲ级围岩试验段,根据隧道爆破碳排放计算模型核算了水封爆破和常规爆破的碳排放量。研究结果表明,炮孔内水垫层雾化降低了烟尘浓度从而通风时间仅需15 min左右,施工通风消耗的电力能源是爆破开挖碳排放的主要贡献源,而水封爆破节省的炸药用量次之。本案例中,水封爆破每循环进尺减少碳排放量约63.065 kgCO_(2 eq)。本文研究成果可为相应隧道工程的绿色低碳减排优化提供参考。

A realistic technique to actively implement carbon neutrality and achieve green carbon reduction was to optimize the borehole structure when drilling and blasting tunnels.Field experiments and numerical simulations were used to compare the carbon reduction effect of water-decked blasting to traditional blasting.The pros and cons of each method in terms of evaluating carbon emission were quantified and compared in engineering practice.First,the three primary carbon emission sources of the tunnel blasting construction process were examined.The three main sources of carbon emissions were the usage of emulsified explosives in blasting,the utilization of oil to power drilling machinery and transport explosives,and the consumption of electricity to ventilate dust.Consequently,a carbon model was developed that considered three different types of carbon emissions produced over the entire tunnel construction process.Second,the numerical analysis was performed using the LS-DYNA program.Explosives coupled axially to the water(air)-deck were used in a single borehole blasting for the analysis.Further research was done on the mechanisms of rock breaking by water-decked blasting.The axial coupling charge structure of water and explosives enhances the stress wave positive phase and stress wave peak because water had a good low compressibility and greater energy transfer efficiency.As a result,the stress wave superposition created a bigger damage area to the rock and a more uniform fracture in the deep part of the rock.Finally,in order to evaluate the carbon emissions from two blasting techniques,the proposed carbon model was employed in the Dongdang Tunnel,a extra-long tunnel in Guizhou Province.The test segment was set up in the level Ⅲ surrounding rock area of the tunnel.The findings indicated that water decking atomization in the borehole reduced the concentration of soot,resulting in a ventilation time of only about 15 minutes.The electric energy consumed by construction ventilation is shown to be the main contributor to the carbon emission of blasting excavation,while the quantity of explosives saved by water-seal blasting was shown to be the second largest.In this case,every cycle of tunnel excavation reduces carbon emissions by about 63.065 kgCO_(2 eq) thanks to the water-decked blasting.As a result,the results can be used as the reference for lowering emissions in low-carbon,sustainable tunnel projects.