| The paper aims to researching device of monitoring axial force ofmine-used rock bolt with low cost, high reliability，easy observation, powerlessand suitable for large-scale installation. Because rock bolt cancoupling,combination and strengthening the rock, so it can improve strengthand self-stability of rock which greatly reduce the structural weight, saveconstruction materials, ensure the construction security and engineering stabilityand have significant economic and social benefits. Therefore, countries in theworld rapidly develop geotechnical engineering rock bolt anchoring technology.However, with passing of the time, the stability of rock is weaken by thedecrease of the rock strength and increase of rock stress, which cause that rockbolt axial force is increased by the rock. If the force exceed the ultimate strengthof the rock bolt, the rock bolt will be failure, which will cause the tunnellandslide. In order to avoid the accident, the safety of rock bolt must beimproved. Therefore, the study of the rock bolt axial force monitoring hasbecome an essential and urgent task.However, the traditional monitoring device still have many defect, such asnot only need power, water-proof, explosion-proof, low reliability, hard observation, security management complexity, high cost of manufacturing andso on, but also some devices requiring specialized personnel and monitoringonly a small area and not suitable for large-scale installation. Thus, a device ofmonitoring axial force of rock bolt with low-cost, high reliability, easyobservation, powerless and suitable for large-scale installation is indispensable.According to the shortcoming of current monitoring device, this paperpropose a new monitoring device. First of all, determine the monitoring program:the monitoring device is composed of elastic structure and display device.Millimeter-level deformation of compressed elastic structure is converted intodifferent figure by display device, by observing those figures, we can judgerock bolt axial force. And then，determine display device. Taking into accountthe special conditions of the dark tunnel, when headlight illuminated withreflective stripe the figure is particularly striking. Therefore, this article decideto use reflecting stripe as figure of display device.And then, according to rockbolt axial force load which need to be monitored, elaborating the workingprinciple of the device display. Secondly,determine elastic structure, to meet therequirements of the monitoring device, a elastic structure with manufacture andmaintenance low cost, suitable for large-scale installation, withstanding12~18tload, small volume of space occupied and not occurring plastic deformation isindispensable. Through analysis, the elastic structure include disc spring andannular spring. this paper regard disc spring and annular spring as referenceelastic structure and use Ansys Workbench to analysis, design and optimize forthem which make them volume of space more reasonable, lower maximumstress, greater amount of axial deformation to meet the monitoring devicedemand. Finally the elastic structure with diameter under100mm, height under80mm, maximum deformation less than3.4mm and the parameter of displaydevice are accomplished. And then,assembling the elastic structure and thedisplay device. Test results showed the powerless device of monitoring the axialforce of the rock bolt meet the observation demands. |
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