The Research And Application On High-performance Grouting Made By Shield Sediment

Grouting materials which have appropriate early and ultimate strength were filled into the gap in the shield tail while the shield grouting, it can inhibit the deformation of the soil, control land subsidence, to ensure environmental safety。As the first defense line of waterproof lining, it has a waterproof function, and as a lining layer of the structure to strengthen, it can enhance the gap's durability. In a high-pressure water-rich strata the ordinary grouting material of synchronization injection will be diluted by the scouring action of water, leading to structural damage. it only can not play the purpose of filling strata, but also directly affect the structure of lining stability. The mechanism is the slurry flowing into the end of arch segment,it will raise the segment, increase the segment floating, thus undermining the structural stability of the segment. Because cement-based grouting material has defects like easy to be segregated by water dilution, anti-corrosion performance is poor, and early strength is low. Determines it is not enough to meet the large-scale tunnel-projects' engineering requirements. In addition, the development of shield tunneling is often brings a large number of underground sediment, it takes a lot of land due to piling up, and no doubt caused great waste of land in urban subway construction. Disposing of the sediment often spend a lot of manpower and material resources.This article is relying on the topic of Wuhan subway project "High Performance Grout Shield Tunnel Construction materials and technology research and application. "Shield sediment is able to form a card housing structure in slurry to increase the viscosity and impede particles sink due to their own water swelling, to improve the performance of grouting material and increase its stability. Therefore, in this article the author is expected to replace bentonite shield and river sand with sediment,to prepare synchronous grouting material, and combined with the stratigraphic analysis of Wuhan Metro Line tunnel construction area, to optimized a high-performance anti-water dispersion, impermeability synchronization grouting material mixture ratio design.Through the experimental investigation of the composition, content, plasticity index and other properties affect grouting materials of shield sediment, analysis showed that when shield sediment dissolved in water it can reduce the free water and its mobility and increase the viscosity, the surface contains a lot of active groups, which have water absorption, thixotropy, and swelling. It increased both its sliding effect and the stability. The addition of sediment can completely replace the bentonite in traditional synchronous grouting materials in order to reduce costs. Studied the impact to anti-aqueous dispersion properties of grouting material by the two polymers HEC, VAE, the impact to early strength and impermeability of grouting material by the early strength agent Li2CO3 and expansive agent, the mechanism of the slurry properties impact by each component and dosage of shield sediment grouting material. Proposed the control range of the content of each component in common shield sediment grouting materialThe research results applied in Wuhan Metro Line. Engineering practice that:the using of high-performance shield synchronous grouting materials developed with shield sediment, it can not only guarantees the quality, effectively prevent the floating of segment, but also gets excellent work performance and wide application, while saves social resources greatly, reduce the project cost, protects the urban environment and improves the economic and social benefits.