Engineering Application Of TRT7000 Tunnel Advanced Geological Prediction System And Research On Its Improvement Method

With the continuous development of national infrastructure construction,a large number of tunnel projects will be constructed in the fields of water conservancy,transportation,mining and so on,and the engineering-related geological conditions are more complicated.Some bad geological bodies will be inevitably encountered that can pose a great threat to the security of tunnel construction.In order to guarantee the steady and efficacious construction of the tunnel and to protect the construction personnel and mechanical equipment,it is necessary to carry out the three-dimensional geological structure analysis of the geological conditions in front of the palm face during the course of tunnel construction,and to approach the timely and precise geological prediction results.Consequently,the bad geological body in front of the palm face can be supported in advance,which is an important foundation to realize the information-based and intelligent tunneling in the tunnel construction process.True Reflection Tomography(TRT)is a combination of traditional seismic wave geophysical exploration methods and emerging 3D rock image technology.It has been widely used as a bad geological prediction tool in various types of tunnels.The hardware and software of TRT7000 tunnel advanced geological forecast system have been optimized and upgraded on the basis of TRT6000,but in the process of practical application,there still remain some problems such as the lack of standard arrangement for sources and receivers,the low efficiency of sensor installation,the unstablity of seismic source energy,complicated software operation,subjectivity of background wave velocity determination,and limitations of elastic wave method itself,which need to be improved through further research.This paper,relying on a TBM water conveyance tunnel project in Sinkiang,focuses on the following practical problems,regarding the engineering application of TRT7000 tunnel advanced geological prediction system:(1)Starting from the basic principle of TRT technology,the elastic theory related to seismic wave exploration,the types of triggered seismic waves,and the basic rules of seismic wave propagation are systematically summarized.The basic principle,hardware configuration requirements,field exploration methods,data processing and image analysis methods of TRT7000 are comprehensively described.(2)Based on the test results of TRT7000 field exploration,the typical characteristics of bad geological bodies,including fault and fault fracture zone,joint fracture zone,water-rich body and weak stratum,and their influencing factors of survey accuracy are studied by using the methods of geological data comparison,rock mass exposure comparison and statistics of prediction accuracy.The forecast results in TBM water conveyance tunnel project are analyzed,and the assets of TRT system in practical application are discussed.(3)According to the supplementary field exploration test,the specifications for the arrangement of the source points and sensor points under TBM working conditions is formulated and compared with the conventional arrangement method;the installation method of the sensors under special working conditions is improved with reference to practical engineering experience;the selection criteria of sources and the application prospect of the magnetostrictive acoustic transducer are briefly discussed.(4)In view of the problems existing in data processing,this paper discusses how to simplify the operation by using tree catalog,pre-processing program,and relative coordinate system;analyzes the main factors affecting the recognition and judgement of TRT images and their potential solutions;studies the optimization method of direct wave velocity calculation and background wave velocity selection.The practical effects of some optimization methods are also verified and analyzed in this paper.By optimizing and improving the field exploration tests and the data processing methods,the efficiency and accuracy of TRT technology in advanced geological prediction are improved,which lays a solid foundation for the efficacious and secure construction of tunnel engineering.