富水砂卵石地层EPB盾构衡盾泥辅助施工关键技术研究

Key Techniques of EPB Shield Auxiliary Construction with Paste HND in Water-rich Sand and Pebble Strata

以长沙市某电力盾构隧道为背景,针对富水砂卵石地层中传统泥膜护壁工艺和地表沉降控制技术的不足,通过室内试验和现场实践的方法,进行了富水砂卵石地层衡盾泥辅(HDN)助带压换刀和盾构掘进地表沉降控制关键技术研究。现场实践表明:在衡盾泥辅助带压换刀施工中,注入衡盾泥后在富水砂卵石地层的开挖面形成的泥膜质量好,泥膜护壁效果非常明显,有效解决了渗水透气问题;在衡盾泥辅助盾构掘进中,衡盾泥可有效填充盾体与土体之间的开挖间隙,显著提高了同步注浆及二次注浆效果,累计地表沉降最大值仅为5.75 mm,达到了盾构推进时的沉降控制目标。

Based on the construction of a power shield tunnel in Changsha,focusing on the shortcomings of traditional mud film wall protection technology and surface settlement control technology in water-rich sand and pebble formations,the key technology of water-rich sand and pebble formation paste HDN-assisted tool change under pressure and shield tunneling surface settlement control is carried out based on indoor tests and field practice.Field practice shows that in the construction of paste HDN-assisted tool change under pressure,the mud film formed on the excavation surface of the water-rich sand and pebble stratum after injecting paste HDN is of good quality,and the wall protection effect of the mud film is very obvious,which could effectively solve the problem of water seepage and ventilation;while in the paste HDN-assisted tunnel excavation,paste HDN can effectively fill the excavation gap between the shield and the soil,thus significantly improve the effects of simultaneous grouting and secondary grouting.The maximum cumulative surface settlement is only 5.75 mm and which can meet the settlement control target during the construction.