土压平衡盾构刀盘开口率对土舱压力的影响

土舱压力与刀盘开口处的土压力并不相等,两者之间存在压力差,该压力差是开挖面土体正常进入土舱的保证。试验及现场监测数据表明,刀盘开口率是影响该压力差的重要因素之一;其它条件相同时,刀盘开口率越小,土舱压力差越大,反之,则越小。采用流体力学理论推导了近似的土舱压力及刀盘开口处压力差计算方法,通过通过现场监测数据和离散元分析结果对公式进行了验证和修正。研究成果使定量分析开口率对盾构推进的影响成为可能,对土压平衡盾构的土舱压力管理及开口率选型有重要意义。

Influence of Aperture Ratio of Cutterhead of EPB Shield on Earth Pressure in the Chamber

Earth pressure in the chamber for EPB shield is not equal to earth pressure at the aperture of the cutterhead,resulting in the pressure difference which makes flowing of the soil on tunnel face into the chamber.Tests and site monitoring data indicate that the aperture ratio of cutterhead is one of important factors that affect the pressure difference.It is illustrated that under the same condition,a smaller aperture ratio will result in a bigger pressure difference in the chamber,on the contrary,a bigger aperture ratio will result in a smaller pressure difference.Based on the theory of fluid mechanics,this paper deduces a calculation formula of the pressure difference,which is verified by the site monitoring data and modified by the results of discrete element method.The research achievements make the quantitative analysis of the influence of aperture ratio on shield driving possible,which is significant for the management of earth pressure in the chamber and selecting of aperture ratio for EPB Shield.