Application Of GPR In Debris Flow Disaster Investigation In Huairou Mountain Area,Beijing

Debris flow is one of the main geological disasters in China,which has the characteristics of sudden onset,large flow rate,fast coming and strong destructive power.When debris flow occurs,houses collapse,farmland is destroyed and roads are broken,and it causes a lot of property losses and even casualties.The research shows that the accumulation in the hillside or gully area is an important source of debris flow,and it is of great significance to find out the storage,thickness and looseness of debris flow.The traditional methods of breakage,geological sketch and remote sensing interpretation can be used to find out the thickness of the deposit,but that would cost lots of time and money,and even have some disadvantages like small investigation scope and low efficiency.Ground penetrating radar(GPR),as an increasingly mature nondestructive detection method,can use high frequency pulse electromagnetic wave to detect underground target body.It has the advantages of high efficiency,nondestructive,easy operation,low cost,high detection precision and low site condition.In this paper,the application of GPR to the investigation of debris flow deposit thickness and reserves is verified by theoretical knowledge study,forward simulation and field detection.The following paragrophy are main research contents and achievements :(1)By consulting the literature and learning the theoretical knowledge,the three main forming elements and main types of debris flow,the method principle and development trend of GPR are comprehensively expounded,which lays a theoretical foundation for the following forward simulation,data processing and image interpretation.(2)To study the reflection characteristics of electromagnetic waves and the finite difference method in time domain,and lay the foundation for forward simulation.Various forward models,such as different antenna frequencies,different formation media and different underground structure types,are established to perform forward simulation,and A corresponding scanning and B scanning radar images are obtained.By comparing and analyzing the imaging law,the feasibility of using GPR to detect debris flow is verified,and through the forward results,the suitable working parameters are set for field detection of GPR,which is beneficial to efficient field detection.(3)Field survey,in Beijing Huairou Liulimiao Town and other 48 gully and steep hillside layout 247 lines,collected 10083 data.Through indoor data processing and image interpretation,combined with some grooving data,the thickness and reserves of debris flow deposits in Huairou mountain area of Beijing are calculated,the risk of debris flow in Huairou mountain area is evaluated,and corresponding disaster prevention measures and suggestions are put forward.