超大直径泥水盾构掘进对土体的扰动研究

 依托南京长江超大直径泥水盾构隧道工程，通过在始发试验段埋设地表沉降观测点、测斜管、土压计力及孔隙水压力计，进行相应项目的试验。研究泥水平衡盾构掘进各阶段对土体的扰动机制、扰动规律、影响范围以及影响程度。分析得出应力扰动度与距离之间的相关关系，在此基础上计算出盾构推进对土体的显著应力扰动区域(应力扰动度≥5%)为盾构外侧16 m(约一倍洞径)。建立切口压力、同步注浆压力与地表沉降之间的数学模型，进一步修正Peck公式，使之能更好地预估泥水盾构掘进引起的地表沉降。最后结合盾构掘进参数，探究减小土体扰动的措施。

STUDY OF SOIL DISTURBANCE CAUSED BY SUPER-LARGE DIAMETER SLURRY SHIELD TUNNELLING

Based on the Nanjing Yangtze River slurry shield tunnelling project，the investigations on the subsidence，horizontal displacement of soil，earth pressure and pore water pressure are conducted by setting up corresponding equipments. Then，the underlying laws，influential range，and influence degree for soil disturbance exerted by different stages of slurry shield tunnelling are analyzed. In addition，according to the stress variation in soil，the relevant mathematical relations between stress disturbances degree and distances are proposed；and it is found that the shield driving can affect stress disturbance of soil(disturbance degree is larger than 5%) at a range of 16 m from shield(approximately the hole diameter). After that，based on field test data，the Peck formulae are improved by establishing the mathematical model of hydraulic pressure on kerf，the synchronous grouting pressure，and ground subsidence. The model gives better prediction on subsidence caused by slurry shield tunnelling. Finally，with careful consideration on shield tunnelling data，some measures to reduce soil disturbance are also presented.