This study investigates the long-term settlement behaviour induced by shield tunnelling in soft ground, employing a case study and numerical modelling to achieve a comprehensive understanding. Soil consolidation plays a critical role in long-term surface settlement, necessitating precise calibration of essential tunnelling parameters such as face pressure and grouting pressure. The findings indicate that soil settlement progressively increases with increasing face pressure Pf and grouting pressure Pg during the excavation of a shield tunnel. Furthermore, for long-term consolidation settlement, it has been established that setting Pf at 90% of the lateral earth pressure σxx consistently minimizes settlement across all cover depths. This phenomenon is attributed to the soil arching mechanism, which also reduces the height of the loosened zone at this specific Pf level. Similarly, the optimal Pg is identified to be within the range of 130% to 150% of the vertical earth pressure σzz. For cover depths within the loosened zone, the smallest consolidation settlement and loosened zone height are observed at Pg of 150% of σzz. Conversely, for shallower cover depths, beyond the loosened zone but within the arching zone, the smallest consolidation settlement and loosened zone height occur at Pg of 130% of σzz. This study reveals that adjusting the cover depth significantly influences the reduction in vertical stress and the resulting settlement, demonstrating the importance of tailored grouting pressure calibration for varying depths to limit consolidation settlement.

中文翻译：

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关键隧道参数对软土地基盾构隧道固结相关长期绿地沉降的影响


本研究调查了盾构隧道在软土地基中引起的长期沉降行为，采用案例研究和数值建模来实现全面理解。土体固结在长期地表沉降中起着关键作用，因此需要精确校准基本的隧道参数，如掌子面压力和注浆压力。结果表明，在盾构隧道开挖过程中，随着工作面压力 Pf 和注浆压力 Pg 的增加，土体沉降逐渐增加。此外，对于长期固结沉降，已经确定将 Pf 设置为侧向土压力 σxx 的 90% 可以始终减少所有覆盖层深度的沉降。这种现象归因于土壤拱起机制，它也降低了该特定 Pf 水平的松散区的高度。同样，最佳 Pg 被确定为在垂直土压力 σzz 的 130% 至 150% 范围内。对于疏松区内的覆盖深度，在 σzz 的 150% 的 Pg 处观察到最小的固结沉降和疏松区高度。相反，对于较浅的覆盖深度，超出松散区但在拱形带内，最小的固结沉降和松散区高度出现在 σzz 的 130% 的 Pg 处。这项研究表明，调整覆盖层深度会显著影响垂直应力的减少和由此产生的沉降，证明了针对不同深度定制灌浆压力校准以限制固结沉降的重要性。