盾构隧道实测土压力分布规律及影响因素研究

以大量现场实测土压力为基础,分析了影响盾构隧道衬砌土压力的一些主要因素,总结出不同地层地铁盾构隧道长期稳定土压力的分布规律,并探讨了盾构施工期土压力随时空的变化情况。研究得出,地下水位高低对稳定土压力大小及分布影响较大;作用在管片上的长期土压力大小与地层衬砌刚度系数有关,当地层衬砌刚度系数为1.5时,管片竖向及水平土压力都较小;盾构施工期临时荷载对管片土压力影响不可忽视,无论是黏土地层还是砂土地层,大的注浆压力及注浆率将导致作用在管片上的稳定土压力分布不均;管片土压力可按时空分为4个阶段,拼装阶段、同步注浆阶段、浆液凝固阶段及后期稳定阶段,其中同步注浆阶段管片周边最大土压力为稳定阶段的2³倍。

Study of distribution law of earth pressure acting on shield tunnel lining based on in-situ data

Based on a series of field monitoring data of earth pressures acting on the shield tunneling segments, the earth pressures for both long-term and construction period are analyzed respectively. The results show that the depth of the ground water level plays an important role on the distribution of earth pressures in the circumferential direction. The earth pressure upon shield tunnel lining will be influenced by the stiffness ratio of ground to lining; the reasonable value of stiffness ratio is 1.5 since the soil reaction acting on segments will be relative smaller. The loads during construction can not be ignored in various strata, the segments are considered to receive larger loads if the backfill grouting pressure or the grouting ratio are larger than design. The earth pressure distribution can be divided into four stages. i.e. segments assemble stage, the backfill grouting stage, grout solidification stage and the stabilization stage. The distribution of earth pressure in the circumferential direction is uneven during construction, the earth pressure in the backfill grouting stage is 2-3 times as much as in the stabilization stage. The insights obtained from this study can contribute to an improvement of load considerations in shield lining design.