软弱地层中既有明洞的基底处理及沉降控制

富水、积水条件下的全风化花岗岩地层往往呈现出膨胀及软化特征,继而导致该地层下明洞基础发生不均匀沉降及衬砌开裂。通过裂缝素描确定合理的注浆孔布置方案,先期注浆小导管对明洞基础进行加固,后续设计钢管树根桩补强方案。监控量测表明该方案有效地控制和缓解了明洞衬砌开裂发展及地基沉降变形,可为类似工程提供借鉴和参考。

Study of the Base Treatment and the Settlement Control of Open-Cut Tunnel in Weak Strata

Fully-weathered granite in rich-watered and water-accumulated strata usually has the characteristics of swelling and softening,which often result in the uneven settlement and cracks of the lining in the foundation of the open-cut tunnel.The layout of grouting holes is determined in the light of the crack sketch.The foundation of the open-cut tunnel is consolidated with initial small-slip-casting guide tubes,which later will be replaced with steel-tube root piles to further consolidate the foundation.Monitoring and surveying show that the steel-tube root piles can effectively control and alleviate the development of lining cracks and the settlement or deformation of the foundation.The paper may serve as a useful reference for other similar projects.