| 摘要 |
A method for controlling parametric variations in processes where one variable is subject to an exponential change with time. One application is particularly advantageous in underground mine roof bolting using mechanical anchors where a device utilizing the method can be employed to install mine roof bolts at varying initial tensions in such a manner that the bolt tensions found among a population of roof bolts converge to one tension value within one or two hours after installation due to individual differences in tension decay rate. Since roof bolt tension decay bears an exponential relationship to time, variability in bolt tension which develops after mentioned convergence has taken place is small for a long period of time, in marked contrast to a conventional installation which is characterized by bolt tension variability which grows rapidly into a far wider range immediately after installation. An extension of said mine roof bolting application further allows an exact assessment of mine roof movements using the roof bolts themselves. A device embodying the invention in mine roof bolting as described, senses the roof bolt tension decay rate during the installation process and automatically tensions the roof bolt to a value appropriate to achieve tension convergence as described. |
