Study of Bag Grouting Pile Reinforcing Deep Soft-Soil Foundation with an Interlayer of Hard Materials on High-Speed Railway Ballast Track

High-speed railways are built in deep soft-soil foundations interlayered with hard materials. However, the layers cannot be penetrated by conventional foundation treatment. Moreover, project cost is sometimes prohibitive, which an issue for post-construction subsidence control. The bag grouting pile a special grouting-pile-reinforcement technique treating This paper conducted tests on Ningbo-Taizhou-Wenzhou ballast track passenger railway, combining mixing-pile-foundation (not through layer) processing station and bag-grouting-pile-processing subgrade line. Using field combined numerical calculation, lateral displacement, settlement pile–soil stress were tested to obtain working properties of grouting-pile-composite foundation. variation law settlement, was studied. results showed that bag-grouting-pile- control less than 15 cm 30 cm, respectively, met design requirements. also scheme reasonable (load-sharing ratio bag-pile-foundation soil-based test reasonable). calculation change diameter. It spacing could not improve subsidence-control properties, can promote pore-pressure dissipation accelerate consolidation, increased cut costs incurred pile-bearing capacity.