Preliminary Study On Geological Prediction Of Shield Tunneling Method

Tunnel engineering construction has its own particularity, whether it is blasting construction or tunneling boring machine excavation. Great risks will be faced when crossing complex strata. Thus, prediction and forecast of various kinds of bad geological hazards in the tunnel construction is an extremely important task.And shield construction is very sensitive to the geological conditions such as special soil, sand, boulders and so will seriously affect the normal shield machine tunneling work. Geological conditions in front of the excavation face are detected by the advanced geological prediction system, which is favorable for the early warning of these anomalies or special geological conditions and we can adjust or deal with it in time.Based on the study of a large number of domestic and foreign research data and the advanced geological prediction system of USEP21 of Beijing Key Laboratory of Underground Construction Forecasting and Warning of Beijing Municipal Engineering Research Institute, this paper researches on geological prediction method and system applied to the construction of shield machine.And the main results are as follows:(1) This paper summarizes the principle and characteristics of geological prediction methods commonly used in tunnel boring machine construction and the advantages and disadvantages of different methods according to the actual field forecast results. The validity of TSP is verified by simulating with Tesseral-2D software and the feasibility of advance geological prediction in the construction of shield tunneling is discussed by forward modeling.(2)Without affecting the construction of shield machine we used the mechanical vibration of the shield machine as source and the receivers arranged on the tunnel segments received the direct wave and the reflected wave. The geological conditions ahead of the excavation face is predicted through data processing and analyzing.(3)The field experimental data were processed by the methods of consistency analysis, repeated contrast, 3D joint imaging, and so on and geological conditions around the shield machine construction were speculated according to the results. Excavation of the site and the actual results were compared to verify the feasibility of the field test program preliminary geological conditions forecast.