基于RHT模型的层理分布与爆破损伤关联耦合性分析

Analysis of correlation coupling between bedding distribution and blasting damage based on RHT model

在层状围岩隧道钻爆施工中,层理往往会影响爆破效果,导致超欠挖、支护结构受力与设计不符、围岩稳定性不可控等不利后果,为此,基于某白云岩隧道掌子面特征及室内试验结果,通过数值模拟手段,利用RHT模型开展层理数量及分布对岩体爆破损伤关联耦合性影响分析。研究结果表明:用“接触”方式模拟层理能较好反映应力波在层理的反射、透射等力学行为特征,在特定条件下,应力波会在层理处形成应力波叠加,使得局部岩体的应力峰值变大,产生拉伸效应并激发裂纹;当冲击荷载超过层理强度阈值时,层理会被破坏而失去反射和透射作用;利用相邻层理间距的差值ΔH与损伤占比Dp作为拟合参数来揭示层理疏密程度与岩体爆破损伤的相关性,得到拟合公式Dp=6.54−0.12ΔH;当炮孔半径为R时,层理与炮孔距离小于18.3R时,层理对岩体爆破损伤演化的影响较小,大于18.3R时,层理对岩体爆破损伤演化的影响较大。

In the drilling and blasting construction of layered surrounding rock tunnels,bedding often affects the blasting effect,resulting in adverse consequences such as over-excavation,inconsistent support structure stress and design,and uncontrollable surrounding rock stability.Based on the characteristics of a dolomite tunnel face and the results of laboratory tests,the RHT model was used to analyze the correlation between the number and distribution of bedding and the blasting damage of rock mass using numerical simulation.The results show that the contact method can effectively simulate the mechanical behavior characteristics of stress wave superposition and reflection in bedding.Under certain conditions,the stress wave will form stress wave superposition at the bedding,so that the stress peak at some specific positions becomes larger,resulting in a tensile effect and cracks.When the impact load exceeds the bedding strength capacity,the bedding will be destroyed and lose the reflection and transmission effects.TheΔH(difference between adjacent bedding spacing)and L(damage value parameter)are used as fitting parameters to reveal the correlation between bedding density and blasting damage of rock mass,and the fitting formula Dp=6.54−0.12ΔH is obtained.When the blast hole radius is R,the bedding with the blast center distance of less than 18.3R has little effect on the rock damage during blasting,while it has great influence with a distance of more than 18.3R.