周俊,赵光明,孟祥瑞,等. 岩体模型双向加载巷道开挖卸荷效应[J]. 煤炭学报,2023,48(9):3384−3392. doi: 10.13225/j.cnki.jccs.2022.1406
引用本文: 周俊,赵光明,孟祥瑞,等. 岩体模型双向加载巷道开挖卸荷效应[J]. 煤炭学报,2023,48(9):3384−3392. doi: 10.13225/j.cnki.jccs.2022.1406
ZHOU Jun,ZHAO Guangming,MENG Xiangrui,et al. Unloading effect of roadway excavation based on simulation method in similar material[J]. Journal of China Coal Society,2023,48(9):3384−3392. doi: 10.13225/j.cnki.jccs.2022.1406
Citation: ZHOU Jun,ZHAO Guangming,MENG Xiangrui,et al. Unloading effect of roadway excavation based on simulation method in similar material[J]. Journal of China Coal Society,2023,48(9):3384−3392. doi: 10.13225/j.cnki.jccs.2022.1406

岩体模型双向加载巷道开挖卸荷效应

Unloading effect of roadway excavation based on simulation method in similar material

  • 摘要: 动态卸荷具有瞬时性,瞬态卸荷效应在深部岩体爆破开挖过程中产生影响。为了研究巷(隧)道围岩在动态开挖卸荷条件下的变形规律及破坏机制,实现围压加载条件下巷(隧)道开挖卸荷过程良好的模拟与再现,深入了解岩体开挖瞬态卸荷的动态特征及动力效应。采用自主研发的巷道围岩动力扰动相似模拟试验装置,进行巷道开挖瞬态卸载破坏的相似模拟试验,并使用应变仪、高速摄影仪及光纤解调仪对试验过程进行实时监测。获得了动态开挖卸荷全过程的应力−时间曲线,监测到裂纹产生与扩展及开挖后岩体测点的拉压状态。试验结果表明:在动态开挖过程中围岩应力经历了原岩应力阶段、动态加载阶段、动态卸载阶段、初始应力卸载阶段和蠕变阶段这5个阶段。巷(隧)道开挖后围岩布置的各监测点应变变化不一,有压变化也有拉变化,模型整体呈受压状态,开挖卸荷后岩体有蠕变现象。捕捉到卸荷效应过程中裂纹扩展,首先,动态冲击快速产生围岩径向裂纹,随开挖巷(隧)道形成,围岩储存能量快速朝临空面释放,在拉应力作用下产生环向裂纹。环向裂纹垂直径向裂纹产生并沿相邻径向裂纹扩展,产生的环向裂纹平行于临空面。巷道围岩动力扰动相似模拟试验系统监测到动态岩体模型开挖过程的瞬态卸荷效应,卸荷应变随距离产生变化,将开挖后的岩体模型分为卸荷近区、卸荷中区和卸荷远区。

     

    Abstract: Dynamic unloading is instantaneous, and the transient unloading effect has important influence on deep rock blasting excavation. In order to study the deformation law and failure mechanism of surrounding rock under dynamic excavation with unloading condition. And tunderstand further dynamic characteristics and the dynamic effects of transient unloading in rock mass excavation. There used a self-developed simulation test device for simulating the process of dynamic excavation in confining pressure loading. The experimental model was made similar material, and used the test device to impact it. It focus on monitoring the unloading effect in real time with the help of strain gauge, high-speed camera and fiber grating sensor. These devices that monitored effective strain-time curves, crack propagation image and the tensile state or compressive state of rock mass after excavation. The test results show that surrounding rock stress of model have experienced five stages that were called initial stress stage, dynamic loading stage, dynamic unloading stage, initial stress unloading stage and creep stage respectively. After model was impacted, each monitoring point occured different strain variation, and some occured compressive strrain, others occured tensile strain. The whole model in compressived state. The model showed creep phenonmen after excavation. Through observing crack propagation image, crack propagation process shown clearly. Firstly, radial cracks were rapidly generated during dynamic excavation. Then, with the free face increase constantly, the stored energy of surrounding rock of model was rapidly released toward the free face, resulting in annular crack occured. Annular crack belongs to tensile faiure, which was generated in vertical radial crack direction and propagated along the adjacent radial crack. Finally, annular crack was parallelled with the free face. The simulation test device system monitored the unloading effect of rock-like marterial well in whole time. Unloading strain value varied with distance, the rock mass model can be divided into near unloading area, middle unloading area and far unloading area after excavation.

     

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