Abstract
The tunnel foundations treatment is the key and difficult point of the research of the tunnel in collapsible loess areas. The characteristics and advantages of the common foundations treatment technology for tunnels of loess areas are summarized in this paper, at the same time, the characteristics of a new technology for the non-vibration compaction treatment technology developed by the Northwest Research Institute Co., Ltd. of China Railway Engineering Corporation are introduced, which is suitable for the foundation reinforcement treatment of the tunnel in collapsible loess areas. Through the field experiment of base treatment of high-speed railway tunnel of the Baoji–Lanzhou High-Speed Railway Passenger Dedicated Line, it is demonstrated that the new non-vibration compaction machine has the advantages of convenient movement, controllable treatment effect, miniaturization, low cost and so on. The advancement and maneuverability are verified from the soil compaction coefficient between piles and the change law of collapsibility of the soil between piles under the different pile spacing conditions. The research results can provide new techniques and methods for the foundation reinforcement treatment of the tunnel of small space, strictly controlling construction vibration in collapsible loess areas.
Highlights
With the vigorous construction of Chinese railways and expressways and the rapid promotion of the “the Belt and Road” national strategy, the numbers and the scales of railways and highway tunnels of the project that have been built and under construction in the northwestern loess areas are unprecedented
Many scholars have carried out a lot of research on the reinforcement treatment of collapsible loess tunnel foundations and fruitful results have been achieved
Zhao Yonghu et al.: Research on Present Situation and the New Technology About Reinforcement in Collapsible Loess Foundation Inside Tunnels the tunnel foundation of Baoji–Lanzhou High-Speed Railway Passenger Dedicated Line were systematically summarized such as CFG piles, lime-soil compaction piles, rotary jet grouting piles or powder jetting piles, strong Measures such as ramming method or replacement method by Fu wei [4], the choice of Treatment measures was depended on the thickness of the collapsible soil layer
Summary
With the vigorous construction of Chinese railways and expressways and the rapid promotion of the “the Belt and Road” national strategy, the numbers and the scales of railways and highway tunnels of the project that have been built and under construction in the northwestern loess areas are unprecedented. Zhao Yonghu et al.: Research on Present Situation and the New Technology About Reinforcement in Collapsible Loess Foundation Inside Tunnels the tunnel foundation of Baoji–Lanzhou High-Speed Railway Passenger Dedicated Line were systematically summarized such as CFG piles, lime-soil compaction piles, rotary jet grouting piles or powder jetting piles, strong Measures such as ramming method or replacement method by Fu wei [4], the choice of Treatment measures was depended on the thickness of the collapsible soil layer. Improper water use during the construction period or failure of the waterproof and drainage measures during the operation period may cause significant collapse and deformation of the untreated loess under the foundation, and result in cracks in the lining structure and uneven settlement of the foundations, which indirectly affects the construction and threatening for the safety operation of the loess tunnel. The research results can provide scientific guidance and reference for the application of substrate treatment technology for high-speed railways and highway tunnels in the loess area
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