The Technology Of Tunnel Seismic Geological Prediction

Nowadays, Tunnel Geological Engineering work has entered a new stage which marked by tunnel geological prediction and preventing geological disasters in fornt of tunnel face. Design of the tunnel project is basically based on geological survey data, the tunnel construction is mainly based on design documents. Lots of tunnel construction practices show that because the limitation of geological survey's accuracy and project funds and many other conditions, design always not in agreement with actual situation, so that accidents and fatalities which in the tunnel Cave occur repeatedly, that is immensely harmful for tunnel construction. During the tunnel constrution, people always apply various kinds of techniques and methods so that can predict the geological condition which in front of tunnel face timely and precisely, it is also the key of taking preventive measures in advance, preventing geological disasters, reducing losses and guaranteeing the tunnel Construction's safty.Tunnel geological prediction is an important guarantee for construction of tunnel safety.Now Taking a tunnel geological prediction methods include: geological methods (including surveys prediction, fault parameter method etc.), advanced pilot tunnel (Parallel pit or tunnel advance) method, advanced horizontal drilling methods, advanced drilling acoustic logging method, cross-hole sonic perspective, wave reflection method (including the HSP method, TSP method, ground penetrating radar, seismic method), tomographic imaging (CT acoustic tomography method, TRT reflection seismic tomography) and so on. In these methods reflection of seismic waves with its high precision, advanced detection technology Detection distance, preferred very much by the engineering sector.In the procedure of collecting data for tunnel geological prediction using reflecting sesic method, obtaining high SNR data is the most important thing. Effective extraction and reflected wave reflector depth migration are two key technologys. They influence the reliability and accuracy of tunnel geological prediction. By mastering the feature of reflect wave which generating from different interfaces, we can locate the observation system available, obtain high SNR data of V H dates. These are theoretical direction of data processing and geological interpretation.In this paper ,we make numerical simulation for tunnel elastic wave field ,which is based on rock (body) physical properties and elastic wave theory,with and without abnormal body using staggered grid finite difference techniques, respectively. And then we analyze the feature of reflect waves which produced by the different propagation characteristics of layers.During interpreting the snapshot of numerical simulations of tunnel waves ,we provides a theoretical basis for ultimate realization of prediction of the geological anomalies.It must be emphasized that to grasp the geological conditions in which detection of The Tunnel complex geological conditions,is the key to success.in geophysical methods in tunnel geological prediction.