Abstract:  Shield launching is a key link in shield tunneling, and also a highrisk link. Based on the shield launching project of Shengjinta StationLiuyanjing Station of Nanchang Rail Transit Line 3,  a statistical analysis on the main tunneling parameters of the shield launching along a smallradius curve in the waterrich sandy stratum is conducted, and the advantage interval of related parameters are determined. Finally, based on the shield attitude control parameters and surface subsidence, the driving parameters control effect is evaluated. The results show the following. (1) In the horizontal direction, there is a significant difference between the two groups of cylinder thrust changes in the curved section and the straight section. The smaller the radius of the line horizontal curve, the greater the difference. The thrust differences of the two groups of cylinders in the horizontal direction of the left and right line in curved and straight section are 87.2% and 75.8% respectively. (2) The smaller the horizontal curve radius, the greater the total thrust and cutterhead torque, while the tunneling speed is slightly reduced. The average total thrusts of the left line and the right line are 1 397.6 t and 1 671.7 t, the average cutterhead torques are 3 101.1 kN·m and 3 723.9 kN·m, and the average tunneling speed is 38.8 mm/min and 35.1 mm/min, respectively. (3) As the stratum of the excavation section of the initial section is relatively uniform, the pressure of the soil chamber increases linearly with the buried depth of the tunnel, and due to the smaller radius of the curve on the right line, the dispersion degree of the soil chamber pressure is relatively high. (4) The grouting amounts of shield tail on the left and right lines vary little, and the dominant interval is 3~6 m3, with an average of about 4 m3. (5) The horizontal shield posture overrun rates of the initial section in the left and right line are only 2% and 4% respectively, and the maximum accumulated surface settlement is only 6.25 mm, which indicates that the control effect of driving parameters in the launching section in smallradius curve in this project is good, and the driving parameters have good adaptability to stratum conditions and line type.

Key words: earth pressure balance shield, waterrich sandy stratum, launching along a smallradius curve, tunneling parameters