关键词: 土压平衡盾构, 富水砂层, 曲线始发, 掘进参数 , 统计分析

Abstract: Shield starting is a key link in shield construction, and also a high-risk link in shield construction. In order to provide tunneling parameters setting samples for shield starting construction along a curved alignment under the condition of water-enrich sand stratum in Nanchang. Based on the shield originating project of Shengjinta Station ~ Liuyanjing Station of Nanchang Rail Transit Line 3, this paper conducts a statistical analysis on the main tunnelling parameters of the shield originating along a small radius curve alignment in the water-enrich sandy stratum and determines the advantage interval of related parameters. Finally, based on the shield attitude control parameters and surface subsidence, the driving parameters control effect is evaluated. The results show that: In the horizontal direction, there is a significant difference between the two groups of cylinder thrust changes in the curve section and the straight section. The smaller the radius of the line horizontal curve is, the greater the difference is. The thrust difference of the two groups of cylinders in the horizontal direction of the left and right line in curve and straight section is 87.2% and 75.8% respectively. The smaller the horizontal curve radius is, the greater the total thrust and cutterhead torque are, while the tunneling speed is slightly reduced. The average total thrust of the left line and the right line are 1397.6t and 1671.7t, the average cutterhead torque is 3101.1kN·m and 3723.9 kN·m respectively, and the average tunneling speed is 38.8mm/min and 35.1mm/min respectively. As the stratum of the excavation section of the initial section is relatively uniform, the pressure of the soil bin increases linearly with the buried depth of the tunnel, and because the radius of the curve on the right line is smaller, so the dispersion degree of the soil bin pressure is relatively high. The grouting amount of shield tail on the left and right lines has little difference, and the dominant interval is 3m³ ~ 6m³, with an average of about 4m³. The horizontal shield posture overrun rate of the initial section in the left and right line is only 2% and 4%, and the maximum accumulated surface settlement is only 6.25 mm, which indicates that the control effect of driving parameters in the starting 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-enriched sandy stratum, originating along a small radius curve, tunnelling parameters, statistical analysis