临海富水砂层盾尾刷更换聚氨酯环试验研究

Experimental study on polyurethane ring in the replacement of shield tail brush in water-rich sand strata at the coast

摘要:

在盾构施工中，注浆法更换盾尾刷需要形成封闭且稳定的止水环，包括聚氨酯环和浆液环。本文结合临海富水砂层盾构施工实例，采集原位地下水对聚氨酯初凝时间、发泡倍率、固体强度等进行室内试验，结果表明：亲水型聚氨酯与地下水反应迅速，形成的固结体密实均匀，发泡率不高，且强度较低，疏水型聚氨酯呈相反状态；现场实际注入可考虑二者同时使用，先注入亲水型聚氨酯，后注入疏水型聚氨酯，并按照5∶1的用量进行控制。现场应用证明，形成的包裹体稳定且质量较佳。

Abstract:

In shield tunneling， the method of replacing the shield tail brushes with grouting needs to forma closed and stable water stop ring， including a polyurethane ring and a slurry ring. This paper combines the example of shield tunneling construction in a water-rich sand strata at the coast， collects the in-situ groundwater to conduct indoor test about the polyurethane including the initial setting time， foaming rate， solid strength， etc. The results show that hydrophilic polyurethane reacts rapidly with groundwater， forming a compact and uniform consolidated body with low foaming rate and low strength， while the hydrophobic polyurethane is in the opposite state. Both can be considered to use on site actual injection at the same time， first injecting hydrophilic polyurethane， then injecting hydrophobic polyurethane with the dosage of 5∶1.The on-site application proves that the formed inclusions are stable and of good quality.