近区锚喷结构的爆破振动特性研究
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摘要
选用水泥砂浆和玻璃钢分别模拟岩石和锚杆,浇筑2.5 m×1.8 m×2.1 m尺寸的岩体模型,通过模型试验研究近区锚喷结构在掏槽爆破作用下的振动特性。利用测试锚杆测得不同设置情况锚杆上的应变波。试验结果表明,端锚锚杆中部锚固段与锚杆尾部自由段测得的振动波形和变形形式完全不同,中部锚固段振动幅值稍大;在不设置喷层和预应力时,尾部自由段的应变波规律性更强,且持续时间长;随着离爆源距离的增加,锚杆的振动频率和幅值衰减明显,但振动持续时间则稍有增长;通过小波变化的时频方法分析应变波的能量,临近工作面锚杆的振动能量大,但能量分布分散,振动时间有限,稍远的锚杆虽振动能量小,但能量集中,持续时间长;两种不同能量对锚喷结构产生不同的损坏模式。试验和实践发现,爆破容易造成附近喷层的损坏和锚杆的失效,钢纤维混凝土可增加喷层的抗动载性能,调整支护工艺也是减小爆破影响的有效方法。
In order to explore influence of engineering blasting on rockbolt and shotcrete,cement mortar and glass fiber reinforced plastics are used to simulate the rock and rockbolt respectively;and some 2.5 m×1.8 m×2.1 m rockmass models are built.By model test,construction process is simulated according to similarity.Vibration characteristics of rockbolt and shotcrete structures near the explosion source are studied under cut blasting load.Strain waves were obtained from the measured rockbolts at different setting condition.Test results show that:(1) For end-anchored rockbolts,vibration waveforms and deformation pattern are different between the anchoring segment of rockbolts’ middle and the free segment of its tail.And vibration amplitude of anchoring segment is relatively larger than free segment.(2) Without shotcrete and prestress,strain wave on free segment of bolt tail shows better law and lasts longer.(3) Vibration frequency and amplitude of rockbolt decay distinctly with the distance from the working face;but duration of rockbolt slightly increases with the distance.By time-frequency analysis of stains waves basing on wavelet transform,it is found that:(1) For vibration energy of rockbolts close to working face is large;but vibration energy distributes widely and duration is limited.(2) For the more distance rockbolts,although vibration energy is less,vibration energy is more concentrated and vibration lasts more time.The two different vibration energies cause different damage patterns for the rockbolt and shotcrete structure.Tests and practices show that blasting vibration can easily cause damage in shotcrete and failure to rockbolts near the explosion source.Steel fiber concrete has a better anti-dynamic performance and is helpful to shotcrete near explosion source when subjected to blasting.Adjusting the support process is an effective method to decrease blasting effect.
In order to explore influence of engineering blasting on rockbolt and shotcrete,cement mortar and glass fiber reinforced plastics are used to simulate the rock and rockbolt respectively;and some 2.5 m×1.8 m×2.1 m rockmass models are built.By model test,construction process is simulated according to similarity.Vibration characteristics of rockbolt and shotcrete structures near the explosion source are studied under cut blasting load.Strain waves were obtained from the measured rockbolts at different setting condition.Test results show that:(1) For end-anchored rockbolts,vibration waveforms and deformation pattern are different between the anchoring segment of rockbolts’ middle and the free segment of its tail.And vibration amplitude of anchoring segment is relatively larger than free segment.(2) Without shotcrete and prestress,strain wave on free segment of bolt tail shows better law and lasts longer.(3) Vibration frequency and amplitude of rockbolt decay distinctly with the distance from the working face;but duration of rockbolt slightly increases with the distance.By time-frequency analysis of stains waves basing on wavelet transform,it is found that:(1) For vibration energy of rockbolts close to working face is large;but vibration energy distributes widely and duration is limited.(2) For the more distance rockbolts,although vibration energy is less,vibration energy is more concentrated and vibration lasts more time.The two different vibration energies cause different damage patterns for the rockbolt and shotcrete structure.Tests and practices show that blasting vibration can easily cause damage in shotcrete and failure to rockbolts near the explosion source.Steel fiber concrete has a better anti-dynamic performance and is helpful to shotcrete near explosion source when subjected to blasting.Adjusting the support process is an effective method to decrease blasting effect.
引文
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[11]单仁亮,周纪军,夏宇,等.粘结式锚杆在爆炸动载下轴向应力分布研究[J].岩土力学,2011,32(10):2965-2971.SHAN Ren-liang,ZHOU Ji-jun,XIA Yu,et al.Axialstress distribution of grouted rockbolts subjected to blastloading[J].Rock and Soil Mechanics,2011,32(10):2965-2971.
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[13]李利平,李术才,张庆松.浅埋大跨隧道施工爆破监测与减震技术[J].岩土力学,2008,29(8):2292-2296.LI Li-ping,LI Shu-cai,ZHANG Qing-song.Monitoringblasting excavation of shallow-buried large-span tunneland vibration reduction technology[J].Rock and SoilMechanics,2008,29(8):2292-2296.
[14]饶增.隧道钻爆施工对初期支护的影响及控制标准的研究[硕士论文D].北京:北京交通大学,2010.
[15]吴华军,王圣武.望峰岗矿-817m北翼轨道石门新型支护试验研究[J].煤炭技术,2006,25(11):53-54.WU Hua-jun,WANG Sheng-wu.Experimental study onnew type support at north railway crosscut of-817 m ofWangfenggang coal mine[J].Coal Technology,2006,25(11):53-54.
[2]蔚振廷,张小康.改进锚喷工艺提高掘进速度[J].山西焦煤科技,2008,(增刊1):34-37.WEI Zhen-ting,ZHANG Xiao-kang.Improve bolt-shotcreting process raise tunneling speed[J].ShanxiCoking Coal Science&Technology,2008,(Supp.1):34-37.
[3]黄东.高地应力与爆破动载作用下喷锚支护结构响应特性数值模拟研究[硕士论文D].长沙:中南大学,2011.
[4]李宁,张西前,于冲.爆破应力波对边坡预应力里锚索的动力影响[J].岩石力学与工程学报,2007,26(增刊1):2593-2600.LI Ning,ZHANG Xi-qian,YU Chong.Research ondynamic response of prestressed anchor cables subjectedto blasting load on slope[J].Chinese Journal of RockMechanics and Engineering,2007,26(Supp.1):2593-2600.
[5]张云,刘开运.近区爆破对锚固设施的影响研究[J].水利发电,1996,(8):23-26.ZHANG Yun,LIU Kai-yun.Research on influence ofclose-proximity blasting on anchored installations[J].Water Power,1996,(8):23-26.
[6]薛亚东,张世平,康天合.回采巷道锚杆动载响应的数值分析[J].岩石力学与工程学报,2003,22(11):1903-1906.XUE Ya-dong,ZHANG Shi-ping,KANG Tian-he.Numerical analysis of dynamic response of rock bolts inmining roadways[J].Chinese Journal of RockMechanics and Engineering,2003,22(11):1903-1906.
[7]张亮亮,夏元友,顾金才.爆炸波作用下预应力锚索受力特征研究[J].岩土工程学报,2009,31(7):1099-1104.ZHANG Liang-liang,XIA Yuan-you,GU Jin-cai.Stresscharacteristics of prestressed anchor cables underexolosive waves[J].Chinese Journal of GeotechnicalEngineering,2009,31(7):1099-1104.
[8]ZHOU Y.X,JENSSEN A.Internal separation distancesfor underground explosives storage in hard rock[J].Tunnelling and Underground Space Technology,2009,24:119-125.
[9]TANNANT D D,BRUMMER R K,YI X.Rockbehaviour under dynamic loading:field tests andmodelling[J].Int.J.Rock Mech.Min.Sci.&Geomech.Abstr,1995,32(6):537-550.
[10]候忠杰.爆破对树脂锚杆载荷的影响[J].矿山压力与顶板管理,1997,36(1):36-39.HOU Zhong-jie.Influence of blasting on resin rockboltloading[J].Ground Pressure and Strata Control,1997,36(1):36-39.
[11]单仁亮,周纪军,夏宇,等.粘结式锚杆在爆炸动载下轴向应力分布研究[J].岩土力学,2011,32(10):2965-2971.SHAN Ren-liang,ZHOU Ji-jun,XIA Yu,et al.Axialstress distribution of grouted rockbolts subjected to blastloading[J].Rock and Soil Mechanics,2011,32(10):2965-2971.
[12]林大超,白春华.爆炸地震效应[M].北京:地质出版社,2007:63-67.
[13]李利平,李术才,张庆松.浅埋大跨隧道施工爆破监测与减震技术[J].岩土力学,2008,29(8):2292-2296.LI Li-ping,LI Shu-cai,ZHANG Qing-song.Monitoringblasting excavation of shallow-buried large-span tunneland vibration reduction technology[J].Rock and SoilMechanics,2008,29(8):2292-2296.
[14]饶增.隧道钻爆施工对初期支护的影响及控制标准的研究[硕士论文D].北京:北京交通大学,2010.
[15]吴华军,王圣武.望峰岗矿-817m北翼轨道石门新型支护试验研究[J].煤炭技术,2006,25(11):53-54.WU Hua-jun,WANG Sheng-wu.Experimental study onnew type support at north railway crosscut of-817 m ofWangfenggang coal mine[J].Coal Technology,2006,25(11):53-54.
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