基于电测法构建出一套测试系统对孔壁压力进行直接测量,以获得现场岩石炮孔中的孔壁压力实测数据,根据灵敏度、抗冲击和抗干扰能力等参数,选择PVDF压电传感器作为压力测试系统的敏感元件;根据爆炸荷载的加载特性,选择并联25 Ω碳膜电阻的电流模式作为系统的测试电路;最后根据带宽、采样率等参数选择示波器进行数据采集.将测试系统应用于高速公路边坡爆破开挖中,试验得到炮孔壁轴向距炸药0、0.1、0.2、0.3 m 4个位置的压力时程曲线,结果表明:在90/32的装药条件下,轴向距炸药0～0.3 m范围内,孔壁峰值压力范围为1 446～156 MPa;各测点的压力上升时间为6.1～1.5μs,距离炸药越近、压力上升时间越长;对试验值进行拟合,发现在轴向距炸药0～0.3 m范围内孔壁压力峰值呈幂函数递减.试验验证了孔壁压力直接测试系统的可靠性.
Experimental study on direct measurement of initial shock pressure on the hole wall
Based on the electrical measurement method,A test system is constructed to directly measure the hole wall pressure,so as to obtain the measured data of the hole wall pressure in the rock borehole in the field.According to the parameters of sensitivity,impact resistance and anti-interference ability,PVDF piezoelectric sensor is selected as the sensitive element of the pressure test system.According to the loading characteristics of explosion load,the parallel current mode of 25 Ω carbon film resistor is selected as the test circuit of the system.Finally,according to bandwidth,sampling rate and other parameters,Oscilloscope is selected for data acquisition.The test system was applied to the blasting excavation of highway slope,and the pressure time history curves of the four positions of 0 m,0.1 m,0.2 m and 0.3 m from the blasting explosive were obtained.The results show that under the condition of 90/32 charging,the peak pressure range of the blasting explosive is 1 446～156 MPa in the range of 0～0.3 m from the axial distance.The pressure rise time of each measuring point is 6.1～1.5 μs,and the closer to the explosive,the longer the pressure rise time.By fitting the test values,it is found that the peak value of hole wall pressure decreases as a power function in the range of 0～0.3 m from the explosive.The reliability of the direct measurement system for hole wall pressure is verified by experiments.
contour blastinghole wall pressuretest systemPVDF piezoelectric film sensorfield test
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