The Study Of Advanced Detecting Methods On Tunnel Geological Hazards

Tunnel belongs to the underground construction engineering, during the construction, we often meet multifarious geological hazard, such as dashing out the mud, water, gas and the rock outbursts. With the increasing of tunnel engineering in our country, they become into deeper, bigger, longer, the engineering geological and hydrological geology problem being more complex, the theory study and practice on the ahead detecting and predicting are becoming more significant.Ahead detecting is basic on the difference of the medium's geophysical property. Its is the application of the geophysical exploring methods in the tunnel, underground well, stope. Through the observing distributions and the mutative rules of underground physical field, we can find the geological abnormality and make certain their scale and state.Base on principal and prediction law of TSP(Tunnel Seismic Predication) and GPR (Ground Penetrating Radar), combining their application in the ahead prediction,the author develops research. The paper have elucidate the main types, reasons, geological features and the physical mechanical properties of the tunnel geological hazard.Base on samdwich model and the principal of seismic reflection method, author deduces the equation of the time-distance curve,discusses features. The composed record of multilayer modles are simulated using Ricker subsidiary wave and minimal phase subsidiary wave.The resolaving power of seismic wave on folium was discussed from tune thickness.The relation was take apated between the reflectance and an incidence angle and stratum "space angle".The author also presents the characteristics, data processing procedures of TSP203 system, and discusses the main influencing factors .The author has design an "equator combined demodulation observation system".An accurate first velocity has been afford for after reveision.On the ather hand, basic on the principal of the GPR, the author simulates some models of dual layers horizontal medium and combined cylinder using Finite-Difference Time-Domain Method and exceed absorb bound condition.The rationality and validity of this kind of simulation are proved by Qian-Gui railroad' radar detacting. The general principal of radar images of different rock strata and karst are summarized.The main influencing fators and key technology of GPR were discussed in this paper.Theory and pratice have make know,tthat TSP method mainly reflects the rock's mechanical property so belongs to the long distance geological forecast, and its detecting effects is better to the layered media, but detacting effect is unperfect on minitype karst,its interpret to the long distance is not enough accurate. GPR mostly reflects the electric property and dielectric properties of the media, its resolving power is upper.It has a higher resolution so the capacity of discernment of the karst, interlining, fault zone is rather high.But its detating distance is not enough long.TSP shoud be adopt on long distance ahead forecast. GPR shoud be adopt on witch there is dubitable by TSP or there is a karst. Combined with the geology structural properties, we have to comprehensively analyze and explain the observating data to test, verify, supplement each other, to advance the reliability of the ahead forecast.