冻结立井爆破冻结壁成形控制与井壁减振研究

Research on the shaping control of frozen wall and blasting vibration mitigation of shaft wall effect in mine vertical shaft

控制爆破动载荷对冻结管、冻结壁及井壁的扰动和破坏是冻结井筒施工的重要环节。以万福矿井筒掘进工程为依托,采用周边眼普通光面爆破、半圈切缝药包和整圈切缝药包3种形式,运用多重分形理论,提取了3种条件下冻结壁成形图像多重分形谱特征参数;利用频率切片小波实现了3方案下不同频带信号重构;通过小波包算法对井壁爆破振动进行了监测分析,获取了相应信号频带能量分布。结果表明：多重分形谱可用来客观评价切缝药包对冻结壁的护壁作用;井壁振动信号主频较地面爆破振动高,通常在150 Hz左右;随着频率的升高,井壁振动信号振幅和能量都不断降低;在低频段（0-250 Hz）,相对于周边眼普通光面爆破,半圈切缝药包能量降低了41.54%,整圈切缝药包能量降低了52.42%,切缝药包在低频段具有显著的＂吸能＂作用;在中频段（300-500 Hz）,由于半圈切缝药包装药能量释放不均衡及井筒结构体非严格对称导致频带能量出现了＂选择放大＂效应;在高频段（700-900 Hz）,能量沿高程＂区域集中＂现象说明切缝药包的减振效果更多地体现在爆破近区。验证了切缝药包的减振和对冻结壁的护壁作用。

The disturbance and destruction of frozen pipe, frozen wall and shaft wall by blasting is an important control point in the construction of mine shaft. In Wan-fu Mine shaft project,a smoothing and slotted cartridge blasting in peripheral holes was conducted. Through multi-fractal theory, the muhi-fractal spectrum parameters of frozen wall three dimensional image were extracted under three conditions. Using frequency slicing wavelet, different frequency band sig- nal reconstruction was achieved under three schemes. Through the wavelet packet algorithm, the vibration of the shaft wall was monitored, and the energy distribution of the corresponding signal band was obtained. The results show that the muhi-fractal spectrum can be used to evaluate the protective effect of the slotted cartridge on the frozen wall. The blasting vibration frequency of shaft wall is higher than ground one, usually about 150 Hz. With the increase of fre- quency,the amplitude and energy of vibration signal decrease. In the low frequency range （0 -250 Hz） , compared with the smoothing blasting of the peripheral holes, the energy of the half-circle slotted cartridge was reduced by 41.54% and in the whole circle it was reduced by 52.42%. In the low frequency band, slotted cartridge has a significant ＂energy absorption＂ effect. In the middle frequency band （300 -500 Hz） , due to half-circle slotted cartridge en- ergy release is not balanced and shaft wall structure is non-strict symmetry, the characteristic frequency band has an energy ＂selective amplification＂ effect. In the high frequency range （700 -900 Hz） , the ＂regional concentration＂ phenomenon of energy reflects that the mitigation of vibration is more close to the blasting area. The frozen wall protection and shaft wall vibration mitigation of slotted cartridge is verified.