Research On The Relation Of Tension State Of Anchorage Cable And Nonlinear Vibration Characteristics

As the main supporting means in large anchorage engineering,the anchorage cable can be embedded in the stable rock mass,connecting the unstable rock mass with the stable rock mass,so that the bearing capacity of the anchorage structure is greatly improved,and the anchor cable has the advantages of simple structure,strong engineering adaptability and low cost.So it has been widely used in the fields of mine,hydropower,transportation and architecture.The tension state of the anchor cable is related to the safety and stability of the whole anchorage project.However,in the actual anchorage engineering,the tension state of the anchor will inevitably be influenced by various factors,so the inspection of the tension state of the anchor cable has always been an important topic of concern in the engineering field.But,there are many defects and deficiencies in the detection methods of anchor cable tension at present.Further research on relevant theories and testing methods is urgently needed.In this paper,the method of using nonlinear vibration characteristics to detect the tension state of the anchorage cable is proposed.The analytical mode decomposition and Hilbert transform of the free vibration acceleration signal under the loading state of the test component are processed,and the index of the frequency variation,which reflects the nonlinear vibration degree of the component interface state,is obtained.The relationship between the tension state of the anchorage cable and the nonlinear characteristics of the component is established by analyzing the variation of the interface state of the anchorage cable system with different tension states.The results show that it is feasible to identify the tension state of the anchor cable by using the nonlinear vibration characteristics.The main contents and conclusions of this paper include:(1)The structure and difference between the prestressed anchorage cable with the free segment and the full length bonding anchor cable are introduced.The transmission mechanism and failure mode of anchor cable system are expounded and the contact interface model of the anchorage plate concrete are deeply analyzed.(2)The basic characteristics of elastic stress wave under excitation are described briefly.The vibration model of the anchor cushion plate and the cable body are analyzed in detail,the causes and changes of the nonlinear vibration model are analyzed in detail according to the tension action of axial anchor cable.(3)The classification of vibration and vibration signals is introduced,and the processing methods of several non-stationary vibration signals are compared.In view of the nonlinear vibration characteristics of the test signal,the applicability of the analytical mode decomposition and Hilbert method used in this paper is analyzed in detail,and the simulation example is carried out to verify the results.(4)3 anchorage cable members were designed and manufactured,experiments on nonlinear vibration characteristics of cable tension state are carried out.The frequency amplitude curve of component loading at all levels and the indexes reflecting the degree of nonlinear vibration are obtained by processing and analyzing the free vibration acceleration signal of each component loading at different levels.(5)The frequency amplitude curve and the frequency variation are analyzed,and the following conclusions are obtained: the frequency amplitude curve at the anchor pad and the middle of the anchor cable shows a obvious nonlinear characteristic,that is,the frequency decreases with the increase of amplitude,and the nonlinear characteristics in the middle of the anchor cable are influenced by the superposition of the grouting segment interface and the interface effect of the anchor pad.The nonlinear characteristics of the anchor pad are mainly from the interface effect between the anchor plate and the concrete.The greater the tension force of the anchor cable is,the greater the nonlinear degree is.Based on the previous research,the relationship between the change of cable tension and the variation of nonlinear vibration characteristics is studied by using the nonlinear vibration theory.The main innovation points include: deep analysis of the debonding development of the grouting interface in the anchorage section and the vibration model of the cable structure under the lateral excitation,and the experimental results verify the interface.The debonding development and the vibration model are reasonable.The study of the nonlinear vibration characteristics of the tension state of the anchor cable is designed and carried out.The signal detection process will not cause damage to the anchorage structure.The test instrument is easy to install,and the test operation is easy to be widely used.The analytic mode decomposition and Hilbert transform analysis of the free vibration signal under loading state are carried out,and a nonlinear vibration characteristic index,frequency variation is introduced effectively,and the feasibility of determining the tension state of the anchor cable by the nonlinear characteristics caused by the interface effect is verified.