Artificial freezing method is the main means of shaft sinking in unsteady thick alluvium of underground mine, and drilling and blasting method for frozen rock and soil is the valid means to improve the sinking speed. In order to guarantee construction security and improve the sinking speed, blasting vibration test is necessary. Topbox vibration monitor is used and measure points were fixed on the location biggish deflective freezing pipes in the on-site test. Based on the test wave and data analysis using the analysis software, the relationship between radial vibration velocity, vertical vibration velocity and equivalent charge, equivalent horizontal distance, elevation discrepancy are established respectively. According to the test result, it can guide the blasting operation safety.
Until now, there are not relative criterions or standards, Which raise standardization to blasting vibration in the frozen region blasting engineering of the vertical shaft. In virtue of the restriction of the blasting engineering characteristic, it is very difficult to proce internal shaft blasting test, and often cause apparatus damage. Therefore, blasting vibration dynamic measurement analysis On vertical shaft is an important means to prosecute blasting test on shaft top.
Vibration measurement system principle showed as Figure 1. Topbox vibration monitor which was manufactured by Chengdu TOP electron Technique
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Company is adopted at on-site test. This apparatus is of small cubage, lightweight, high delicacy and high autoimmunization etc. This system avoided such work as lead layout, inspection and reclaiming, and eliminated the dependence of measure on alternating current, which made the test convenient, credibility, and data processing simple and exact.
Rational selection and correct layout of the sensor ensure the test succeed; so the following problems must be advertised when test.
Acceleration sensor, velocity sensor or displacement sensor may be selected in accordance with the objection of the investigation. Acceleration sensor and velocity sensor are used most frequently in engineering, and velocity sensor is often adopted in blasting vibration monitor of rock engineering and underground engineering. Based on the estimation of quake wave frequency that is produced by blasting, frequency range can be selected. Generally, the frequency range of the quake blasting is usually 30 ~ 300 Hz, and the range of velocity sensor which can be selected on market is usually I0 ~ 500 HZ, this sensor can satisfy the require approximately.
Sensor is susceptive apparatus and it is easily damaged when used in the bad environment, so it should
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be demarcated at least one time each year, and the biggish deflective linearity sensor must be prevented to be used.
Two aspects should be adverted, one is sensor fixing, the other is sensor direction. In order to reflect the magnitude of the vibration strength factually, sensor must be fixed firmly on the surface of the measure points to guarantee that it will not shift from the ground.