The Application Of Ground Penetrating Radar To Shielded Tunnel Boring Machine's Frontal Detection Research

The logging quality of shielded tunnel boring machine's construction covers many aspects, especially involving the frontal geological condition of the shield machine. Because the shield machine works in one-way direction and the trend of current tunnel's depth is becoming more and more deeper, it is inevitable that the frontal geological condition of the shield machine has become more complex, such as special terrane, quick sand, sinked ship, air hole and peg etc. It is necessary to use ground-penetrating radar (GPR) to detect the frontal condition and to give an alarm when the machine encounters those special geologies so that the operator can deal with ahead of time and make the disaster evitable. Based on this sumption and the project of Shanghai Metro Shield Machine: "Assistant System Research of Intelligent Shield Machine", this thesis does a prophase systematic research about the application of GPR to shielded tunnel boring machine's frontal detection.First of all, the thesis gives some formulas about detection parameters of GPR, and makes a performance compare list of main GPRs that the writer had used by himself.Secondly, it analyses the diffuse characteristic of GPR's electromagnetic wave in electricity intermedia, and introduces the diffusion and reflection of electromagnetic wave at two intermedia's interface, and sums up the identify method of the target reflected electromagnetic wave.Thirdly, the thesis studies the mechanism of circular GPR, and makes a lot of numerical simulations about circular horizontal and vertical detection and has found some useful conclusions.Fourthly, the writer built an experimental platform of circular detection and uses many GPR's detecting pictures to verify the numerical simulation's validity, and makes some conclusions. Then the thesis puts forward some ideas about 3-D circular GPR image and mode verification of land layer.Fifthly, because of the single GPR's scanning cover, it exists blind area andcannot meet the big diameter of shielded machine. The thesis advances a creative method, which using GPR antenna array install on the shielded machine. It can resolve fake alarms and false detect. The writer provides two feasible plans to GPR array's layout.