Study On The Method Of Measuring The Quality Of Water Tunnel Lining Based On Elastic Wave Method

Water diversion tunnel is an important part of China's tunnel engineering,which plays an important role in realizing the trans-basin water diversion to alleviate the shortage of water resources.In water tunnel,concrete lining is the key structure of waterproofing,and the internal defects and voidage in the back of concrete lining are the main causes of tunnel structure problems.On the basis of previous studies,this paper proposes a multi-method comprehensive interpretation technique based on elastic wave method,and designs a set of quality detection system for water tunnel based on elastic wave method,so as to realize rapid census and accurate interpretation,and accurately detect the quality problems in the lining construction process and the position of the empty area after lining.The system includes elastic wave data acquisition system and comprehensive interpretation software.The data processing method adopts the common offset time domain analysis method,frequency domain analysis method and two-dimensional Rayleigh wave method.In order to verify the accuracy of the method,the physical models of concrete lining with different structure types were tested,and the data analysis results were consistent with the predetermined abnormal positions of the physical models,which verified the reliability of the method and the stability of the system.At the same time,the system has been successfully applied to the detection of a section of water conveyance tunnel in central water supply Jilin province,and a good detection effect has been obtained.The main research contents of this paper are as follows:(1)Development of lining detection system based on elastic wave method.In order to achieve the purpose of convenient and fast data collection and high precision of data results,this paper designs an elastic wave signal receiving system,an automatic source excitation system and a data processing and interpretation system.In the aspect of receiving elastic wave signal,the receiving device of two sensors is designed,which can realize the setting of different channel spacing and the switching of sensors according to different concrete types,which has the characteristics of convenience and flexibility.The electromagnetic source device is used to ensure uniform and stable elastic waves.In addition,the mass of shock hammer can be changed to stimulate elastic waves of different frequencies.The time domain analysis,frequency domain analysis and Rayleigh wave velocity spectrum are used to process the detection data.(2)Physical model test of concrete lining based on elastic wave method lining test system.In this paper,the physical model of concrete lining structure designed and constructed by the scientific research institute of ZhongShui Northeast company is used as an experimental image.The model consists of four parts: plain concrete lining area,single layer reinforced concrete lining area,double layer reinforced concrete lining area and double layer reinforced concrete lining area with steel strand concrete lining area.In this paper,on the premise of analyzing and optimizing the factors that influence the detection results,the elastic wave method lining detection system designed by the optimization is used to carry out the detection experiment,and the actual defect status of the physical model is compared to analyze the detection accuracy of the system.(3)A case study of water tunnel lining detection.In this paper,a section of water supply project in central city of Jilin province is selected for the joint detection of radar method and elastic wave method.Firstly,the radar method is used for comprehensive detection,and then the elastic wave method is used to test the abnormal area.After the mutual verification of the two methods,the location of the defect is determined.In order to judge the grouting condition,a comparative analysis is made on the testing data of the lining of the unwatered and the already watered sections respectively.