| Anchor bolt support,because of its "efficient,low-cost" features,has been widely used in mines,tunnels,bridges,excavation and other projects,and have achieved good economic and social benefits.However,in recent years,support failure have caused roof fall,slump and other accidents,bring unpredictable losses.Therefore,in the years of bolt support service,it is significant of timely and accurately monitoring the anchor bolt force to ensure the safety of people and property and economy.Stocktaking the research and development of bolt force monitoring at home and abroad,the existing anchor force monitoring device can be divided into two categories: one is ?power type?,that is,the need for power supply.For example: resistance strain gauge bolt tension monitoring system,converting the strain to anchor bolt force.Inadequacies of this type of monitoring device are that(1)increasing rock mass disturbance(2)causing great inconvenience to the under ground explosion-proof security and management.The other is "powerless type".For example,hydraulic bolt tension monitoring device,converting the anchor force into pressure gauge pointer changes.This kind of monitoring device has many defects,such as complex structure,large volume,and inconvenient installation and so on.This paper is based on summarizing the existing bolt force monitoring devices,for the deficiencies of existing monitoring device,utilizing the relationship between natural frequency and structure prestress,using the research methods of theoretical analysis and simulation combining,designs a new monitoring device that can judge the size of bolt axial force by listening different frequencies of sound.The main research contents and results are as follows:(1)Proposed monitoring device?s working principle and operating method have been introduced,it derives correlation formula by utilizing the related knowledge of mechanical vibration and verifies the theoretical feasibility of this monitoring device.(2)The design process of the monitoring device are introduced,utilizing the 3D modeling software Pro/E5.0 to build the mode,the strength and prestress mode of the monitoring device are explained by using finite element analysis software ANSYS14.5,and then the acoustic performance of the monitoring device is analyzed based on the LMS Virtual.lab Acoustic acoustic simulation platform.The analysis results show that the strength of the monitoring device meets the requirements,natural frequency and the stress are approximate linear relation,staff can achieve the ultimate goal of judging the size of bolt axial force by listening different sounds of frequencies.(3)Based on the introduction of the design process and the feasibility,changing the structural parameters of the monitoring device,and then discussing the influences of strength,sensitivity and auditory effect of the monitoring device by utilizing ANSYS14.5 and LMS Virtual.lab Acoustic12.0 combined simulation platform.The results show that the thickness of the vibrating plate,the thickness of the material,the thickness of the shell,the effective vibration height of the vibration plate and the diameter of the supporting-body have different effects on the performance of the monitoring device.(4)Utilizing the LMS Virtual.lab Acoustic12.0 simulation platform,the possible effect on the monitoring device that may caused by the size and location of excitation force,damping ratio,the angle and distance between monitoring personnel and monitoring device,is analyzed and discussed.The results show that the change of the excitation force size,position and damping ratio has no effect on the monitoring results,and there is no fixed position requirement between the monitoring personnel and the monitoring device.(5)Finally,the deviation of the final monitoring is analyzed for the "partial load" problem which may occur in the actual operation of the monitoring device.It is verified that the eccentric load must be avoided during the actual installation.This paper provides a simple and effective new idea for the work of anchor bolt axial force monitoring. |
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