| With the rapid development of national infrastructure,especially transportation infrastructure,tens of thousands of miles of traffic tunneling projects,especially karst tunneling projects,are or will be built in geological environments with extremely complex geological conditions,which are difficult to find out before tunnel construction.The unfavorable geological conditions along the line,combined with the concealment,suddenness and complexity of the tunnel rich water area,cause the tunnel to face a major risk of inrush water during construction,which seriously threatens the construction safety of the tunnel construction.The root cause of the unpredictable water-rich area of the tunnel is the complexity of the characteristics of the water-rich disaster source,the limitations of the long-distance forecasting system itself and the multi-solution of the short-distance forecasting results.In recent years,the newly introduced tunnel three-dimensional geological prediction system TGS360 Pro has significant features such as long forecast distance,small construction disturbance and extremely rich forecasting results,especially the stress gradient change and percentage of water content in surrounding rock.The radar system GPR has obvious advantages such as high efficiency and convenience,intuitive image and small construction interference,especially sensitive to aqueous media.Therefore,a clear understanding of the two forecasting systems,the prediction method of the water-rich region of the tunnel,a method for identifying the water-rich section of the karst tunnel,and the establishment of its corresponding identification mark can scientifically and effectively predict the tunnel.Rich water area.In this paper,based on the water-rich problem of surrounding rock during the construction of karst tunnel,relying on the comprehensive analysis method such as theoretical analysis method,geological analysis method,numerical analysis method and parameter analysis method,relying on the comprehensive analysis method such as theoretical analysis method,geological analysis method,numerical analysis method and parameter analysis method,Disaster-causing characteristics and identification methods of flood-rich sources.By revealing the disaster characteristics of different types of water-rich disaster sources,the data processing of TGS360 Pro and GPR systems is analyzed by theoretical methods.The gushing method is used to analyze the causes of water inrush in tunnels,and the variation characteristics of seismic waves in tunnel water-rich areas are analyzed by parameter method.The numerical characteristics and parameter methods are used to analyze the variation characteristics of electromagnetic waves in the tunnel water-rich section,and the method of identifying the water-rich region of the tunnel is studied.Based on the comprehensive forecasting principle established in China,a method for identifying the water-rich section of karst tunnel is proposed,which is the karst tunnel water-rich identification method,and its corresponding identification mark is established,and the water richness of Guizhou Ping tunnel is successfully predicted.region.Specifically include:(1)The paper systematically analyzes the cases of major inrush water in tunnels in recent years.Based on the karst development conditions,the types of water-rich sources of karst tunnels are proposed,and the disaster-causing characteristics of the disaster sources are analyzed.(2)Explain in detail the system composition,method principle and physical parameters involved in the data interpretation process of the TGS360 Pro and GPR systems of the forecasting system,analyze the acquisition process and processing process of these two systems,and propose a complete set of TGS360 Pro system.The forecasting process,and designed the detector layout type and compiled the data acquisition field record table of the system;optimized the layout of the GPR system antenna based on the change of the two parameters of water content and surrounding rock grade;according to the data processing results,analysis and study of various parameters.(3)Based on the comprehensive forecasting principle established in China,a comprehensive method for identifying the water-rich areas of karst tunnels is proposed.Based on the geological survey method,the GGS and GPR analysis methods are defined as comprehensive methods.The karst tunnel is rich in water identification and has established corresponding identification marks.That is,when the seismic wave propagates in the water-rich region,a particularly obvious reflection region of the seismic wave signal is formed.The worst value of the stress gradient changes is about 5.0,and the degree of stress attenuation is large;the percentage of water content is not less than 15%;the longitudinal wave velocity is 2000~ Between 3200 m / s;the shear wave velocity does not change basically;the wave speed ratio is between 1.8 and 2.4;the Poisson’s ratio is between 0.35 and 0.5;the Young’s modulus is between 3.0 and 5.0 GPa;the hazard level is 2 to 5.When the radar wave propagates in the water-rich region,the morphological feature of “white-grey-white” will be formed in the grayscale image.The continuity of this feature change is good and irregular.The waveform diagram shows radar wave reflection.The response is relatively strong,the waveform is relatively uniform,the wavelength is long,the frequency is low,the amplitude is high,the width and the distribution are not uniform,the continuity of the same phase axis is better and the waveform coherence is more uniform;the energy map shows the radar wave reflection energy is large,energy The attenuation is extremely fast,the loss is large,and the energy cluster distribution is extremely uneven.In the spectrogram,the main frequency value of the radar wave signal is about 50 MHz,and the high frequency basically disappears,mostly single peak.(4)Applying the proposed identification method to the actual project of Guizhou Ping Tunnel and successfully predicting the water-rich area of Guizhou Ping Tunnel,the feasibility and reliability of the method are proved. |
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