Application Of Comprehensive Advance Geological Prediction In Menghua Railway Tunnel

With the increasing in the amount of tunnel construction,the construction process encountered complex geological conditions,and even the possibility of more and more dangerous geological conditions,tunnel construction safety has been tested.As an important part of tunnel construction,the role of advanced geological prediction of tunnels becomes more and more important as an integral part of tunnel engineering.Based on the Xiaonanyuan tunnel and the gentleman tunnel of Menghua Railway,this paper systematically introduces TGP technology,geological radar technology and infrared water exploration technology.At the same time,it also discusses the principle and application technology of advanced geological prediction.In the small southern subway tunnel and the gentleman tunnel different geological section,take the corresponding advance geological prediction.The main contents of this paper are:(1)Introduce the basic principles and technical parameters of infrared exploration technology,geological radar technology and TGP technology respectively.The applicability and forecasting characteristics of these methods are discussed,and the waveform of geological radar is analyzed from the principle of electromagnetic wave Feature,from the principle of elastic wave analysis of the technical characteristics of TGP.(2)In view of the complexity of TGP technology operation,this paper introduces the working points of TGP instrument installation and data acquisition,and provides the description and standard for proper use of TGP.And to provide a theoretical basis for TGP site layout,so that the future TGP site layout adjustments and program modifications well documented.(3)In the field geological prediction of the small Southland tunnel and the gentleman tunnel,the multi-method comprehensive utilization,the corresponding plan of different geology,the comparative analysis of the forecasting results of the adjacent mileage,the preliminary interpretation of the theoretical results,the timely verification of the site,etc.Means,summed up a lot of lessons learned for the past scientific research to provide material.(4)obtained the different structures in the geological radar reflected wave amplitude intensity of the law:Earth-rock junction(dry)<sandstone in the fragment or empty(no water)<sandstone fissure or rock boundary(water)This rule,for us to use geological radar predicting abnormal structure has an important role.(5)The longitudinal wave velocity of TGP is proportional to the square root of Young’s modulus E,which is inversely proportional to the square root of density ρ.In general,the change of ρ is small,so Vp is mainly determined by E.Therefore,the P-wave velocity Vp can be used to evaluate the elastic strength of the rock mass,and the increase of the P-wave velocity indicates that the strength of the rock mass becomes stronger;the decrease of the P-wave velocity indicates that the rock mass is weakened.(6)The TGP technique,the shear wave propagates only in the solid,and when the water structure and the void or the fracture band appear,the reflection coefficient is zero,and no reflection is generated thereafter.At this interface,the amplitude of the transverse reflection is obviously enhanced.TGP this feature,can be used as a water structure and void or fragmentation and other qualitative judgments.