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Influence of seepage and tunnel face opening on face support pressure of EPB shield
Computers and Geotechnics ( IF 5.3 ) Pub Date : 2021-05-06 , DOI: 10.1016/j.compgeo.2021.104198
Xinsheng Yin , Renpeng Chen , Fanyan Meng

The hydraulic head on the tunnel face is smaller than that in the far-field ground when the earth pressure balance shield excavates in a saturated stratum. The seepage force could thus drag the soil to the tunnel face. However, the effect of the seepage on the tunnel face stability is not yet thoroughly understood. A series of centrifuge tests and numerical back-analyses by the Finite Difference Method were performed to investigate the influence of the ground anisotropic permeability and the tunnel face opening on the tunnel face stability under the seepage condition. The results show that the pore-water pressure in front of the tunnel face decreases with the increasing opening area on the tunnel face and the increasing kv/kh (the ratio of vertical hydraulic conductivity to horizontal hydraulic conductivity) as well. A higher support pressure is required for a higher kv/kh to keep the tunnel face stable. When the tunnel face is sealed, the minimum support pressure to keep stable is 1.92 times that in the condition with the fully permeable tunnel face. It indicates that seepage induced by the water ingress could benefit the tunnel face stability.



中文翻译:

渗流和隧道工作面开口对EPB盾构工作面支撑压力的影响

当土压平衡护罩在饱和地层中开挖时,隧道面上的液压头小于远场地面上的液压头。因此,渗透力可能将土壤拖到隧道工作面。然而,渗流对隧道工作面稳定性的影响尚未完全了解。进行了一系列的离心试验和有限差分法的数值反分析,研究了渗流条件下地层各向异性渗透率和巷道开口对巷道稳定性的影响。结果表明,随着工作面开口面积的增加和k v / k h的增加,洞面前部的孔隙水压力逐渐减小。(垂直水力传导率与水平水力传导率之比)。较高的k v / k h需要较高的支撑压力,以保持隧道面稳定。密封隧道面时,保持稳定的最小支撑压力是在具有完全渗透性的隧道面条件下的最小支撑压力的1.92倍。这表明入水引起的渗流有利于隧道工作面的稳定性。

更新日期:2021-05-07
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