不同开挖洞径深埋隧洞岩爆模型试验研究

Physical Model Experimental Investigation on Rockburst in Deep-buried Tunnels with Different Excavation Diameters

为研究开挖洞径对深埋隧洞围岩岩爆破坏的影响,开展3种不同洞径的类岩石材料大尺寸试件真三轴岩爆模型试验,利用智能摄像机和声发射监测系统对试件加载破坏进行全过程监测,对比分析不同洞径对试件岩爆的影响规律。结果表明:不同开挖洞径试件在加载过程中皆经历了初始损伤(Ⅰ)、损伤发展(Ⅱ)与损伤破坏(Ⅲ)3个阶段。洞径增大,试件隧洞破坏荷载减小,岩爆破坏范围与碎屑质量增大,大块碎屑质量占比增加。加载过程声发射事件能量最大值随洞径增大呈递减趋势,而累计能量呈递增趋势,反映小洞径试件破坏时能量释放更集中,破裂剧烈程度更高,洞径越大,试件内部产生裂纹的总体规模越大。加载过程声发射b值在进入损伤发展(Ⅱ)和损伤破坏(Ⅲ)阶段时皆有显著减小,反映在此阶段大裂纹事件的产生增多;声发射总体b值随着洞径的增大而减小,反映试件随洞径的增大,破碎程度降低及大尺度破裂增多。在损伤破坏(Ⅲ)阶段,低、中频高幅值声发射事件比例随着洞径的增大递增,反映试件随洞径增大在此阶段围岩大尺度破裂增多。声发射各阶段时频特征参数反映的试件各阶段的损伤破裂尺度与试件宏观破坏现象一致。

In order to study the influence of excavation diameter on the rockburst damage of deeply buried tunnels,three different hole diameters of large-size specimens of rock-like materials were tested in real triaxial rockburst model,and the whole process of loading damage was monitored by intelligent cameras and acoustic emission monitoring system,and the influence of different hole diameters on the rockburst of specimens was compared and analyzed.The results show that the specimens with different hole diameters experienced three stages of initial damage(I),damage development(II)and damage failure(II)during the loading process.As the hole diameter increases,the damage load of the specimen decreases,the damage range and debris mass of the rockburst increases,and the proportion of large debris mass increases.Loading process acoustic emission event energy maximum with increasing hole diameter is decreasing trend,while the cumulative energy is increasing trend,reflecting the smaller hole diameter specimen damage more concentrated energy release,the more intense rupture,the larger the hole diameter,the larger the overall scale of cracking within the specimen.The overall b-value of acoustic emission during loading decreases with the increase of hole diameter,reflecting the decrease of fragmentation and the increase of large scale rupture of specimens with the increase of hole diameter.In the damage failure(II)stage,the proportion of low and medium frequency high amplitude acoustic emission events increases with the increase of hole diameter,reflecting the lower degree of fragmentation of the surrounding rock damage and the increase of large scale rupture with the increase of hole diameter of the specimen.The damage rupture scale of the specimen at each stage reflected by the time-frequency characteristic parameters of acoustic emission is consistent with the macroscopic damage phenomenon of the specimen.