| The rapid development of capital construction in the fields of transportation,water conservancy and hydropower,and national defense often involves the construction of tunnels,which are susceptible to geological hazards.Therefore,effective tunnel advance geological forecasting is crucial to ensure the safety of tunnel construction.Ground-penetrating radar method is widely used in tunneling project advance geological forecasting because of its light,efficient and high-resolution features.In order to improve the detection capability and image interpretation accuracy of ground-penetrating radar,this paper conducts research and discussion on image noise reduction and three-dimensional imaging based on the numerical simulation of ground-penetrating radar,and investigates the main characteristics of electromagnetic waves embodied in tunnel overdetection with engineering examples,and the main research results are:(1)Using the gpr Max software,numerical simulations were conducted to systematically analyze the factors affecting Ground Penetrating Radar(GPR)detection capabilities.The simulations demonstrated the influence of various factors,such as target depth,size,shape,electrical properties,as well as the center frequency,transmitter-receiver spacing,and step size of the radar system,on GPR detection capabilities.The study summarized the characteristic features of target bodies suitable for GPR detection and provided a set of parameter ranges to enhance the effectiveness of GPR detection.(2)When determining the operating parameters,it is crucial to consider both the design resolution and detection depth,rather than relying solely on theoretical formulas.The selection of optimal parameter values should be based on the actual working conditions.(3)Based on the analysis of influencing factors,a rational two-dimensional numerical simulation was conducted to investigate geological hazards in tunnel engineering.A systematic numerical analysis was performed on features such as karst caves,faults,fractured zones,weak inclusions,and composite models encountered during tunnel excavation.Discriminant criteria for radar images related to these geological hazards were summarized.(4)The principle and method of Singular Value Decomposition(SVD)were investigated,and a preferable rule was proposed,which sets the first singular value to zero and utilizes the remaining singular values to reconstruct the GPR profile,aiming at selecting decomposition and eliminating interference waves.(5)Based on forward modeling data,three-dimensional cross-sectional images generated by processing the data using MATLAB software accurately depict the spatial morphology of target objects,thereby effectively enhancing the interpretation accuracy of radar images.(6)By comparing the waveform data obtained from field experiments with the two-dimensional numerical simulation results,a close agreement between the two was observed,thus confirming the accuracy of the proposed method.By carrying out ground-penetrating radar numerical simulation and imaging research,the method of improving ground-penetrating radar detection capability is summarized,and the way to improve the accuracy of radar image interpretation is further broadened from qualitative and quantitative perspectives,and the research results can provide guidance for tunnel geohazard ahead prediction. |
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