基于水-岩相互作用的富水断层破碎带隧道突涌灾害演化特征

Evolution Characteristics of Tunnel Inrush Disaster in Water-rich Fault Fracture Zone Based on Water-rock Interaction

为研究开挖卸荷和水力荷载耦合作用下富水断层破碎带隧道突涌灾害演化特征,以沈白高铁西谷隧道工程为依托,考虑不同富水破碎带构造形式及地下水赋存特征,开展隧道突涌灾害演化过程研究。基于水-岩相互作用原理,建立三维离散元粘合块体-裂隙流耦合模型,明确不同地质构造特征下的隧道突涌灾害模式,分析破碎岩体裂隙扩展和地下水渗流的时空演化规律。研究结果有:引入黏合块体模型和裂隙流组合模型,建立了富水断层破碎带水岩相互作用力学模型,再现了富水破碎带隧道突涌灾害演化过程。不同富水破碎带构造形式引起的突涌灾变模式差异显著,且具有不同的触发条件和表现形式。断层破碎带倾角为45°时,破碎岩体沿掌子面下部溜塌涌入隧道,倾角为90°时,围岩向掌子面挤出,倾角为-45°时,表现为拱顶围岩垮塌。富水破碎带突涌灾害程度随着水头增大而加剧,其中倾角为-45°时,突涌灾害程度受水头高度的影响最显著,倾角为90°时,水头高度影响相对较弱,但突涌灾害程度最严重。

To investigate the evolution characteristics of inrush disasters in water-rich fractured zones under coupled effects of excavation unloading and hydraulic loads,based on the Shenbai high-speed railway Xigu tunnel project,and considering different structural forms of water-rich fractured zones and the characteristics of groundwater occurrence,the evolution process of inrush disasters in tunnel was studied.A 3DEC discrete element numerical model,based on the principle of water-rock interaction in fractured rock masses,was established to explore the mode of tunnel inrush disaster under different geological structure characteristics and analyze the spatiotemporal evolution laws of fractured rock fissure propagation and groundwater seepage.The results show as follows.By introducing the bonded block modeling and fracture flow combination model,a mechanical model of water-rock interaction in water-rich fractured zones was established to reproduce the evolution process of inrush disasters in tunnels located in water-rich fractured zones.The disparities of inrush disaster modes caused by different structural forms of water-rich fracture zones are significant and the trigger conditions and manifestations of these inrush disasters are various.Under the 45°inclination angle,fragmented rock mass slides and surges into the tunnel along the footwall.While under the 90°dip,the surrounding rock extrudes to the palm face.When the dip is-45°,the surrounding rock of the vault collapses.The severity of inrush disaster in water-rich fractured zones increases with higher hydraulic heads.Under a-45°dip,the severity of water inrush disasters is most significantly affected by the hydraulic head.When the dip is-45°,the influence of hydraulic head is relatively weak,but the severity of inrush disasters is the most severe.