The Study Of Signal Acquisition And Imaging Method On Tunnel Geological Prediction

Recent years, Along with the highway, high-speed railway, large water conservancy and other various infrastructure construction of rapid development. the demand of convenient transportation in west province is also increasing, in this condition, the engineering in the southwest may face more severe challenge.Usually, the southwest geological condition is complicated, especially in yunnan, where have many mountainous regions and the orogenic belt, fault zone development, groundwater is rich, so the corresponding condition of engineering geology and hydrogeology conditions are very complicated. In such a complicated hydrogeological conditions, the construction of all kinds of tunnel engineering may meet fault, karst cave, underground river, crushing zone, high geostress area and all kinds of bad geological body, If you can’t keep abreast of the geological conditions ahead, you may probably induced landslides, water burst, rock burst puking even engineering accident such as debris flow. And these incidents, will not only influence the construction progress, and even bring severe geological disasters, cause serious casualties and economic loss. In order to ensure construction safety, it needs faster development of tunnel prediction technology, to adapt to a higher application requirements. To the complicated geological conditions of the tunnel, we should process geological forecast before and in the construction, to find out the geological diseases may met in tunnel excavation process, Forecast possible accident and danger, in order to take timely measures to nip in the bud to ensure construction safety; At the same time, also provide basis to the tunnel construction method and the changes of timbering, reduce the blindness of tunnel construction, saving investment. So in the tunnel construction the advance of geological forecast is great significance.However, due to the complicated environment of the tunnel with all the space of, we usually consider problem in half space, thus determines the complexity of seismic waves, as well as the actual advance geological forecast. so if you want to have a accurate forecast, design a reasonable and effective observation system is the basis and premise for advanced prediction, at the same time, data processing method and technology is also very important, which is the premise and guarantee for advanced prediction. In addition to the conventional data processing step outside, extract the effective reflection wave and migration imaging technology is also very important, which influence the accuracy of the advanced prediction.This paper reviews the various geophysical methods of the application in the geological advanced prediction, introduces the seismic reflection wave method to the principle of advanced prediction. According to theory basis of the advanced prediction in seismic reflection method and the algorithm principle of the dynamic finite element method, to establish the layered system, in able to check the possible of the dynamic finite element method being used to simulate the seismic wave. To use computer numerical simulation technology, to discuss the influence of the different observation methods applied to results, and consider using different number of receiver and different arrangement, to analyse the reflected signal characteristics, identification method, aquifer, broken belt and different type, location and range of bad geological body in different geological conditions. According to the results of numerical simulation, access to all kinds of observation method, the applied conditions and the best observation system, in order to meet the urgent needs of advanced prediction work, to improve the accuracy of tunnel advanced prediction. By using2-d f-k filtering method, can effectively extract the reflected wave in front of the working face, and verified through the theoretical model and actual model. Based on the principle of stack seismic wave with common reflection surface and migration imaging, use the theoretical model data and the measured data of tunnel into3d imaging, to achieve a certain effect.However, in the actual advanced prediction method of tunnel geological, there is no one kind of method is universal, each detection method has the ability to solve the special geological problems, but also has certain limitations. For the very complex geological condition on the detection problem, if you want to just rely on a certain technical to find out all the geological conditions, it must has certain blindness. After a lot of practice and theoretical research, I think in forecast works, only combining engineering geophysical with geological analysis and integrated elastic wave method with electromagnetic method can greatly improve the accuracy of the advanced prediction and obtain the optimal forecast results.