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针对目前参数设计不合理的卸压爆破常常导致巷道围岩损伤破坏,降低防冲效率的问题,采用PASAT-M型便携式微震探测系统,在煤矿井下现场原位开展煤层爆破振动试验,并结合预先加窗短时Fourier变换技术,定量研究卸压爆破下强冲击危险巷道围岩的振动规律。研究表明:(1)在距震源20 m范围内,爆破帮的振动主频随距震源距离的增大呈指数关系增大,顶板的振动主频随距震源距离的增大呈线性关系单调递增,而非爆破帮的振动主频随距震源距离的增大呈二次曲线关系先升高再降低;(2)爆破帮的振幅随距震源距离的增大呈指数关系衰减,超过20 m范围卸压爆破对围岩的损伤破坏效应变得十分微弱;(3)由于巷道各个方位的围岩受到面波和体波的影响程度各不相同,导致了不同方位围岩振动特征(类型、主频和振幅)的差异性;(4)卸压爆炸下巷道各方位围岩的振动类型、主频和幅值并不一致,由此爆破震动波下的损伤破坏效应也有较大区别。结合上述现场实测结果和现有理论,从控制卸压爆破振动的幅值、频率和持续时间3个指标以及增加巷道围岩抗震性能方面,提出优化爆破参数,防止卸压爆破对巷道围岩损伤的建议。
In view of the current unreasonable design of the pressure relief blasting often lead to roadway rock damage and reduce the impact of anti-efficiency problems, the use of PASAT-M portable microseismic detection system in the coal mine site in situ blasting vibration test carried out in combination with prior The windowed short-time Fourier transform technique is used to quantitatively study the vibration law of surrounding rock of roadway with strong impact and danger under pressure-relief blasting. The results show that: (1) In the range of 20 m from the source, the main frequency of the blasting vibration increases exponentially with the increase of the distance from the source, and the dominant frequency of the roof vibration increases monotonically with the increase of the distance from the source. (2) The amplitude of the blasting bombs exponentially decayed with the increase of the distance from the source, and the frequency of the blasting bosons exceeded the range of 20 m (3) As the influence of surface wave and body wave on surrounding rock in all azimuths of roadway is different, the vibration characteristics of the surrounding rocks in different azimuths (type, main Frequency and amplitude). (4) Vibration types, frequency and amplitudes of surrounding rock in various directions under the explosion of pressure relief are not consistent, so the damage and damage effects under blasting vibration wave are also greatly different. Combining with the above-mentioned field test results and existing theories, the authors put forward the optimized blasting parameters to prevent the surrounding rock of the roadway from being damaged by controlling the three indexes of amplitude, frequency and duration of relief blasting vibration and increasing the seismic performance of the surrounding rock of the roadway. Suggestions.