| At present,there area large number of power tunnels in some large and medium-sized cities in China,which play an important role in ensuring the urban power supply and helping the urban development.In Beijing,for example,there are 718 kilometers of power tunnels in service.Because the tunnel has been buried underground,with the growth of service life,the change of the properties of underground soil body and the development of city construction projects,the power tunnel faces many aspects.At present,there is no effective means to monitor the deformation of the tunnel structure during the service period.The monitoring equipment used in the tunnel construction is not entirely applicable to the power tunnels during the service period.In addition,due to the narrow internal space of the power tunnel,the requirement for space is very high.In the face of complex underground environment and external force changes,it is necessary to establish an effective tunnel structure monitoring system for long-term monitoring,especially for structural deformation monitoring,in order to detect and predict the danger in time and ensure the safety of tunnel operation.In view of the above situation,this paper presents a method for monitoring the deformation of power tunnels during service.The main contents are asfollows:(1)This paper analyzes the common hidden dangers in the use of cable tunnels,as well as some deformation and damage caused by external or self structural problems.Combined with some detection methods and equipment commonly used in the detection of cable tunnel,taking into account the detection results and actual situation of the project site,according to the damage degree of the tunnel,the stability of the soil and the deformation of the tunnel structure,this paper provides a reference for the safety evaluation of the cable tunnel structure;(2)Combined with the main deformation and failure forms of cable tunnel structure,and through data analysis,the conversion calculation between the change of component surface angle α and the maximum deformation of component m is studied.The change of cable tunnel structure angle is successfully converted into settlement,inclination and section convergence deformation,and the practical monitoring method of cable tunnel structure deformation is realized;(3)A distributed deformation monitoring system including data acquisition,transmission,processing and early warning is established.Taking "caihuyingqiao South cable tunnel in Beijing" as a monitoring example,the relevant parameters of tunnel structure and surrounding soil layer are understood after detection,the finite difference numerical analysis model is established by using FLAC3 D,the key points of deformation monitoring are determined according to the numerical analysis results,sensors are set up and monitoring system is established to effectively monitor the cable tunnel;(4)The establishment of cable tunnel deformation monitoring system realizes the function of cable tunnel structure deformation early warning,provides a guarantee for the safety of cable tunnel structure,and provides an effective solution of remote real-time deformation monitoring for the old cable tunnel structure.At the same time,the first-hand data obtained in real-time monitoring can provide basic data for the future cable tunnel structure stress,deformation,detection,monitoring,simulation analysis,etc. |
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