工作面坑透场强传播规律及有效透视宽度研究

为求取工作面有效透视宽度,推导了适合坑透仪器实测场强值的工作面坑透实测场强值计算公式,其场强H变化取决于初始场强值H_0、收发距r和吸收系数β。对于相同初始发射场强值的坑透探测,场强传播距离的制约因素为吸收系数值β,β值越小,场强传播距离越大,越适合于坑透探测。提出了利用发射巷近场源区场强数据计算初始场强值,再利用该初始场强值和接收巷透视场强数据计算吸收系数的方法,计算结果比单独的透视场强数据或发射巷场强数据计算更加可靠。提出了煤层工作面坑透有效透视宽度计算公式,由工作面初始场强值、吸收系数值和背景场强值可以计算出坑透探测仪器在某个工作频率探测下的工作面有效透视宽度。淮南矿业集团谢桥矿工作面实际坑透探测资料表明,利用双巷实测的场强数据所计算的初始场强、吸收系数是客观的,由初始场强值、吸收系数值和背景场强值所确定的工作面有效透视宽度值是可靠的,可以合理地指导工作面坑透设计与施工。

Field strength propagation law of radio wave penetration and effective perspective width for coal face

In order to get an effective perspective width for a coal face,a field strength formula of radio wave penetration for coal face is derived,which is suitable for measuring field strength values observed from receivers.The field strength H is determined by initial field strength H0,transmit-receive distance r and absorption coefficient β.To the same H0,r is controlled by β,the smaller β can get a farther distance and be more suitable for detection.A new method to calculate H0 and β values is put forward,the H0 values can be derived from the H data near the transmitter in the transmitting gateway,while β values can be derived from the H0 values and H data observed in the receiving gateway.The calculated H0 and β values are more reliable than those derived from single gateway,transmitting or receiving gateway.It is also put forward that the effective perspective width value for coal face can be calculated by the H0,β and background field strength HB with a special instrument and operating frequency.The tests in the coal faces of Xieqiao Mine,Huainan Coal Mining Group Corporation,demonstrate that the calculated initial field strength values and absorption coefficient values are more objective,and the effective perspective width values determined by H0,β and HB are more reliable,which can be used to guide the design and detection of radio wave penetration for coal faces.