Physical Simulation Experiment of Granite Rockburst in a Deep-Buried Tunnel in Kangding County, Sichuan Province, China
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摘要: 四川康定折多山某隧道因其埋深大、构造应力高度集中,在修建过程中极易产生岩爆.为探索折多山某隧道花岗岩段不同深度条件下岩爆机制,利用真三轴岩爆实验系统,开展了不同深度下的花岗岩岩爆物理模拟实验.借助应力监测、高速摄像和声发射等系统,从声、光、力等多角度研究了折多山某隧道花岗岩岩爆的阶段特征、时间特征、主要破坏方式、裂纹演化等规律.结果表明:折多山花岗岩岩爆具有时滞性特征(time delaying rockburst,TDR),在500~1 100 m不同埋深条件下,约770 m为折多山花岗岩单面临空真三轴强度的临界深度;不同深度下的岩爆有明显阶段特征,可分为平静期、劈裂成板、板折剥落、整体弹射4个阶段;声发射特征揭示折多山花岗岩岩爆主要为张拉破坏,随深度增加,张拉裂纹逐渐增加,剪切裂纹逐渐减少;根据岩爆时应力差与单轴抗压强度比值将折多山花岗岩岩爆分为3种破坏模式:小颗粒弹射破坏、岩板劈裂破坏、岩屑混合弹射破坏;且应力比值$ \left({\sigma }_{v}-{\sigma }_{h1}\right)/{\sigma }_{c} $越大,岩爆烈度越大.Abstract: The deep-buried tunnel planned in Zheduo Mountain, Kangding County, Sichuan Province, is likely to rockburst due to its large buried depth and concentrated tectonic stress. In order to figure out the rockburst failure mechanism under different depths, in this study, the triaxial rockburst physical experiments of the granite in the Zheduo Mountain tunnel at different depths were carried out employing the stress monitoring system, high-speed camera system, and acoustic emission monitoring system. The phase characteristics, time characteristics, failure modes, and crack evolution of the granite in the Zheduo Mountain tunnel at different depths were studied with regard to the sound, light, and force and the experimental results show that the rockburst of Zheduo Mountain granite has obvious characteristics of time delaying rockburst (TDR). 770 m is the critical depth of the granite triaxial strength with one free face, and the lag characteristics of the excavation rockburst around this depth is obviously weakened. Rockburst at different depths can be divided into different stages: quiet period, splitting into plate stage, plate folding and spalling stage, and overall ejection stage. Rockburst acoustic emission characteristics reveal that the rockburst of Zheduo Mountain granite is mainly tensile failure, and with the increase of the depth, the number of tension cracks gradually increases and the number of shear cracks gradually decreases. According to the ratio of the stress difference and the uniaxial compressive strength at the time of the rockburst, the rockburst of Zheduo Mountain granite is divided into three failure modes: small particle ejection failure, rock slab splitting failure and mixed ejection failure, and the greater the stress ratio (σv-σh1)/σc is, the greater the rockburst intensity is.
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Key words:
- deep-buried tunnel /
- high geostress /
- rockburst /
- triaxial experiment /
- acoustic emission /
- geotechnical engineering
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图 7 ZYB-1实验过程典型高速照片
a. $ {\sigma }_{v} $=22.81 MPa,$ {\sigma }_{h1} $=30 MPa,$ {\sigma }_{h2} $=0 MPa;b.$ {\sigma }_{v} $=132.69 MPa,$ {\sigma }_{h1} $=30 MPa,$ {\sigma }_{h2} $=0 MPa;c.$ {\sigma }_{v} $=132.71 MPa,$ {\sigma }_{h1} $=30 MPa,$ {\sigma }_{h2} $=0 MPa;d.$ {\sigma }_{v} $=132.92 MPa,$ {\sigma }_{h1} $=30 MPa,$ {\sigma }_{h2} $=0 MPa;e.$ {\sigma }_{v} $=139.97 MPa,$ {\sigma }_{h1} $=30 MPa,$ {\sigma }_{h2} $=0 MPa;f.$ {\sigma }_{v} $=140.11 MPa,$ {\sigma }_{h1} $=30 MPa,$ {\sigma }_{h2} $=0 MPa;g.$ {\sigma }_{v} $=140.05 MPa,$ {\sigma }_{h1} $=30 MPa,$ {\sigma }_{h2} $=0 MPa;h.$ {\sigma }_{v} $=104.60 MPa,$ {\sigma }_{h1} $=30 MPa,$ {\sigma }_{h2} $=0 MPa
Fig. 7. Typical high-speed photos of ZYB-1 experimental process
图 8 ZYB-2实验过程典型高速照片
a.$ {\sigma }_{v} $=29.86 MPa,$ {\sigma }_{h1} $=40 MPa,$ {\sigma }_{h2} $=0 MPa;b.$ {\sigma }_{v} $=110.98 MPa,$ {\sigma }_{h1} $=40 MPa,$ {\sigma }_{h2} $=0 MPa;c.σv=111.01 MPa,$ {\sigma }_{h1} $=40 MPa,$ {\sigma }_{h2} $=0 MPa;d.$ {\sigma }_{v} $=119.05 MPa,$ {\sigma }_{h1} $=40 MPa,$ {\sigma }_{h2} $=0 MPa;e.$ {\sigma }_{v} $=120.1 MPa,$ {\sigma }_{h1} $=40 MPa,$ {\sigma }_{h2} $=0 MPa;f.$ {\sigma }_{v} $=100.93 MPa,$ {\sigma }_{h1} $=40 MPa,$ {\sigma }_{h2} $=0 MPa
Fig. 8. Typical high-speed photos of ZYB-2 experimental process
图 9 ZYB-3实验过程典型高速照片
a.$ {\sigma }_{v} $=37.91 MPa,$ {\sigma }_{h1} $=50 MPa,$ {\sigma }_{h2} $=0 MPa;b.$ {\sigma }_{v} $=118.61 MPa,$ {\sigma }_{h1} $=50 MPa,$ {\sigma }_{h2} $=0 MPa;c.$ {\sigma }_{v} $=118.62 MPa,$ {\sigma }_{h1} $=50 MPa,$ {\sigma }_{h2} $=0 MPa;d.$ {\sigma }_{v} $=118.58 MPa,$ {\sigma }_{h1} $=50 MPa,$ {\sigma }_{h2} $=0 MPa;e.$ {\sigma }_{v} $=71.79 MPa,$ {\sigma }_{h1} $=50 MPa,$ {\sigma }_{h2} $=0 MPa
Fig. 9. Typical high-speed photos of ZYB-3 experimental process
图 10 ZYB-4实验过程典型高速照片
a.$ {\sigma }_{v} $=36.50 MPa,$ {\sigma }_{h1} $=60 MPa,$ {\sigma }_{h2} $=0 MPa;b.$ {\sigma }_{v} $=146.10 MPa,$ {\sigma }_{h1} $=60 MPa,$ {\sigma }_{h2} $=0 MPa;c.$ {\sigma }_{v} $=148.01 MPa,$ {\sigma }_{h1} $=60 MPa,$ {\sigma }_{h2} $=0 MPa;d.$ {\sigma }_{v} $=158.25 MPa,$ {\sigma }_{h1} $=60 MPa,$ {\sigma }_{h2} $=0 MPa;e.$ {\sigma }_{v} $=158.4 MPa,$ {\sigma }_{h1} $=60 MPa,$ {\sigma }_{h2} $=0 MPa;f.$ {\sigma }_{v} $=150.04 MPa,$ {\sigma }_{h1} $=60 MPa,$ {\sigma }_{h2} $=0 MPa
Fig. 10. Typical photos of ZYB-4 experimental process
表 1 试样矿物成分相对含量
Table 1. Relative content of mineral components
矿物 石英 钠长石 斜长石 绿泥石 伊利石 含量 38.04% 21.29% 30.54% 4.96% 5.17% 表 2 岩爆烈度判别指标
Table 2. Evaluation index of rockburst tendency
B < 10 10≤B < 18 B≥18 无岩爆 中等程度岩爆 强烈岩爆 注:据李庶林等(2001). 表 3 实验工况一览
Table 3. List of experimental conditions
试样编号 深度(m) 初始应力值 σv(MPa) σh1(MPa) σh2(MPa) ZYB-1 500 25 30 20 ZYB-2 700 30 40 22 ZYB-3 900 35 50 26 ZYB-4 1 100 40 60 30 注:σv:垂直主应力:σh1:最大水平主应力;σh2:最小水平主应力. 表 4 实验结果
Table 4. Experimental results
试样编号 各阶段垂直向应力值(MPa) 发生最终岩爆破坏现象描述 破坏
区域岩板劈裂 板折剥落 整体弹射 ZYB-1 132.69 132.92 140.1 实验过程中首先出现小颗粒弹射并伴随岩板劈裂的现象,随即劈裂的岩板发生弯曲并以一定的速度脱离母岩,从开始出现劈裂到岩板脱离试样整个过程约持续0.16 s,最后试样发生颗粒、碎屑、粉尘等整体弹射. E、F、G、H ZYB-2 110.98 119.05 120.1 首先在G、H区出现裂纹,岩板外鼓,随后I、J区岩板发生弯曲开裂并脱离试样,持续时间0.24 s.之后在G、I两区域发生碎屑整体弹射现象,弹射过程持续约5 s. G、I ZYB-3 118.61 - 118.6 试件顶部首先出现颗粒弹射喷出现象,紧接着B区右上角初现了拉裂纹并发生了二次弹射,最终在B区大块碎屑被弹出,整体弹射阶段大约8 s. B ZYB-4 146.10 148.01 158.4 首先在A、B两区之间形成了一条张拉裂缝,A区岩板发生板折弯曲并脱离试样,整个过程持续约5 s.约1 s后,A、B两区岩体发生整体破坏. A、B 表 5 应力比值与主要破坏形式
Table 5. Stress ratios and main failure modes
试样
编号峰值应力(MPa) 应力比值 主要破坏
形式应变能 σv σh1 $ \left({\sigma }_{v}-{\sigma }_{h1}\right) $/σc ZYB-1 140.06 30 0.87 岩屑混合弹射破坏 0.34 MJ/m3 ZYB-2 120.16 40 0.63 岩板劈裂
破坏0.24 MJ/m3 ZYB-3 118.64 50 0.55 小颗粒弹射破坏 0.23 MJ/m3 ZYB-4 158.4 60 0.76 岩屑混合弹射破坏 0.48 MJ/m3 -
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