土压平衡盾构渣土膏体制备与管输特性试验研究

Experimental Study on Paste Production and Pipeline Transportation Characteristics of Earth Pressure Balance Shield Muck

土压平衡盾构掘进效率高、地层适用性强,在城市隧道建设中应用广泛。传统土压平衡盾构一般采用皮带机+电瓶车+门式起重机的出渣方式,容易造成泥水飞溅,工作环境恶劣。稀相管输功耗巨大、后处理繁琐,盾构渣土膏状管输可以实现盾构渣土全过程全封闭输送,并可以简化后期处理程序。分析了典型盾构渣土的基本物性和改良特性,搭建了膏体泵送管输试验装置,进行了环管试验。试验研究发现,盾构渣土试样坍落度在15~25.2cm时呈现膏体状态,坍落度19~25cm的膏体可以泵送,坍落度越大管输阻力损失越小,进一步测得了管输阻力经验模型,并证实了泡沫剂的改良效果。固化试验表明,微风化渣土膏体23h不固结,强风化渣土膏体超过33h不固结,泵送管输系统工程维护时间较充裕。

Earth pressure balance shield is widely used in urban tunnel construction due to its high excavation efficiency and strong geological applicability.Traditional earth pressure balance shield generally uses the slag tapping method with the belt conveyor and the battery truck and the gantry crane,which is easy to cause mud and water splashing and harsh working conditions.The power consumption of the dilute phase pipeline transportation is huge,and the post-processing is cumbersome.The shield muck paste can be transported by pipeline full enclosed throughout the entire process with simple post-processing procedures.The basic physical properties and improvement characteristics of the typical shield muck was analyzed,and a loop pipe experimental unit was built for paste pipeline transportation using pump.The experimental study shows that the shield muck sample belongs to paste state when its slump is between 15cm and 25.2cm,and the shield muck paste with a slump of 19cm to 25cm could be pumped by pipeline.The greater the slump of the shield muck paste,the smaller the pipeline transmission resistance.The empirical model of pipeline transmission resistance was further obtained,and the improvement effect of foam agent was confirmed.The solidification experiment shows that the slightly weathered soil paste does not solidify for 23hours,and the strongly weathered soil paste does not solidify for more than 33hours.The maintenance time for the pipeline transportation system is relatively sufficient.The research results provide a reference for the development of the pipeline transportation technology of shield muck paste.