【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。更多还原

【Abstract】 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.更多还原