深埋隧洞钻爆开挖瞬态卸荷诱发围岩振动特性研究
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摘要
爆破开挖面上地应力瞬态卸荷产生的围岩振动是深埋洞室爆破开挖动力扰动主要因素之一。针对静水地应力场条件下深埋圆形隧洞浅孔爆破开挖,采用LS-DYNA动力有限元数值模拟方法研究了地应力瞬态卸荷诱发围岩振动的幅值和频率特性及其影响因素。结果表明:在地应力水平一定的情况下,炮孔孔深是影响地应力瞬态卸荷诱发围岩振动的主要因素;随着炮孔孔深的增加,地应力卸荷速率降低,诱发围岩振动的幅值减小、频率降低、质点峰值振动速度随距离衰减变慢。因此可从优化炮孔孔深的角度控制爆破开挖面上地应力瞬态卸荷诱发的围岩振动。
During blasting excavation of deep tunnels,the rock vibration caused by transient unloading of in-situ stress on blast-created excavation boundaries is one of the major dynamic disturbances.For a deep circular tunnel excavation with short-hole blasting method in a hydrostatic in-situ stress field,the transient unloading inducing vibration including peak particle velocity(PPV) and frequency content was investigated by using LS-DYNA dynamic finite element method.Results show that blasthole depth is the main factor affecting the transient unloading inducing vibration at the same stress levels.With the blasthole depth increase,the PPV and the frequency get decreased due to the reduced unloading rate.The lower vibration frequency at longer blasthole depth leads to slower PPV attenuation as the distance increases.Therefore,the rock vibration caused by transient unloading can be controlled by properly blasthole depth design.
During blasting excavation of deep tunnels,the rock vibration caused by transient unloading of in-situ stress on blast-created excavation boundaries is one of the major dynamic disturbances.For a deep circular tunnel excavation with short-hole blasting method in a hydrostatic in-situ stress field,the transient unloading inducing vibration including peak particle velocity(PPV) and frequency content was investigated by using LS-DYNA dynamic finite element method.Results show that blasthole depth is the main factor affecting the transient unloading inducing vibration at the same stress levels.With the blasthole depth increase,the PPV and the frequency get decreased due to the reduced unloading rate.The lower vibration frequency at longer blasthole depth leads to slower PPV attenuation as the distance increases.Therefore,the rock vibration caused by transient unloading can be controlled by properly blasthole depth design.
引文
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[15] 周俊汝,卢文波,张乐,等.爆破地震波传播过程的振动频率衰减规律研究[J].岩石力学与工程学报,2014,33(11):2171-2178.[15] ZHOU Jun-ru,LU Wen-bo,ZHANG Le,et al.Attenuation of vibration frequency during propagation of blasting seismic wave[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(11):2171-2178.(in Chinese)
[2] 周小平,毕靖,钱七虎.动态开挖卸荷条件下深埋圆形洞室各向同性围岩的分区破裂化机理[J].固体力学学报,2013,34(4):352-360.[2] ZHOU Xiao-ping,BI Jing,QIAN Qi-hu.The zonal disintegration mechanism of isotropic rock masses around a deep circular tunnel subjected to dynamic unloading[J].Chinese Journal of Solid Mechanics,2013,34(4):352-360.(in Chinese)
[3] ZHU W C,WEI J,ZHAO J,et al.2D numerical simulation on excavation damaged zone induced by dynamic stress redistribution[J].Tunnelling and Underground Space Technology,2014,43(7):315-326.
[4] 董春亮,赵光明,李英明,等.深部圆形巷道开挖卸荷的围岩力学特征及破坏机理[J].采矿与安全工程学报,2017,34(3):511-518.[4] DONG Chun-liang,ZHAO Guang-ming,LI Ying-ming,et al.Mechanical properties and failure mechanism of surrounding rocks in deep circular tunnel under excavation unloading[J].Journal of Mining and Safety Engineering,2017,34(3):511-518.(in Chinese)
[5] 姚强,杨兴国,李洪涛.爆破振动舒适性评价方法研究现状及展望[J].振动与冲击,2016,35(22):152-160.[5] YAO Qiang,YANG Xing-guo,LI Hong-tao.Review on status quo and prospect of assessment methods for comfort under blasting vibration[J].Journal of Vibration and Shock,2016,35(22):152-160.(in Chinese)
[6] TOKS Z M N,KEHRER H H.Tectonic strain release by underground nuclear explosions and its effect on seismic discrimination[J].Geophysical Journal International,1972,31(1-3):141-161.
[7] CAO W Z,LI X B,TAO M,et al.Vibrations induced by high initial stress release during underground excavations[J].Tunnelling and Underground Space Technology,2016,53:78-95.
[8] YANG J H,LU W B,JIANG Q H,et al.A study on the vibration frequency of blasting excavation in highly stressed rock masses[J].Rock Mechanics and Rock Engineering,2016,49:2825-2843.
[9] HUSTRULID W A.Blasting principles for open pit mining[M].Rotterdam,A A Balkema Publishers,1999:303-305.
[10] 卢文波,周创兵,陈明,等.开挖卸荷的瞬态特性研究[J].岩石力学与工程学报,2008,27(11):2184-2192.[10] LU Wen-bo,ZHOU Chuang-bing,CHEN Ming,et al.Research on transient characteristics of excavation unloading[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(11):2184-2192.(in Chinese)
[11] LI X B,CAO W Z,ZHOU Z L,et al.Influence of stress path on excavation unloading response[J].Tunnelling and Underground Space Technology,2014,42(4):237-246.
[12] D P Blair.The free surface influence on blast vibration[J].International Journal of Rock Mechanics and Mining Sciences,2015,77:182-191.
[13] 范勇,卢文波,杨建华,等.深埋洞室开挖瞬态卸荷诱发振动的衰减规律[J].岩土力学,2015,36(2):541-549.[13] FAN Yong,LU Wen-bo,YANG Jian-hua,et al.Attenuation law of vibration induced by transient unloading during excavation of deep caverns[J].Rock and Soil Mechanics,2015,36(2):541-549.(in Chinese)
[14] TRIVI?O L F,MOHANTY B,MILKEREIT B.Seismic waveforms from explosive sources located in boreholes and initiated in different directions[J].Journal of Applied Geophysics,2012,87(1):81-93.
[15] 周俊汝,卢文波,张乐,等.爆破地震波传播过程的振动频率衰减规律研究[J].岩石力学与工程学报,2014,33(11):2171-2178.[15] ZHOU Jun-ru,LU Wen-bo,ZHANG Le,et al.Attenuation of vibration frequency during propagation of blasting seismic wave[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(11):2171-2178.(in Chinese)