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Advances in Civil Engineering
Volume 2018, Article ID 2352174, 16 pages
https://doi.org/10.1155/2018/2352174
Research Article

Displacement and Stress Characteristics of Tunnel Foundation in Collapsible Loess Ground Reinforced by Jet Grouting Columns

1School of Highway, Chang’an University, Xi’an 710064, China
2China Railway Siyuan Survey and Design Group Co., Ltd., Wuhan 430063, China
3State Key Laboratory of Rail Transit Engineering Informatization, China Railway First Survey and Design Institute Group Co., Ltd., Xi’an 710043, China

Correspondence should be addressed to Houquan Liu; nc.ude.dhc@nauquohuil

Received 25 May 2018; Revised 1 August 2018; Accepted 6 August 2018; Published 16 September 2018

Academic Editor: Lukasz Sadowski

Copyright © 2018 Youyun Li et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Collapsible loess tunnel foundation reinforcement is a new challenge in the construction process of tunnel engineering. According to the field displacement and stress monitoring of the Fujiayao loess tunnel, this paper investigates the reinforcing effect of a high-pressure jet grouting pile on a collapsible loess tunnel foundation in the deep large-span tunnel. The field monitoring method was employed to address the performance of tunnel foundation settlement, additional stress, earth pressure, rock pressure, etc. The results indicate that the stress on the pile tops and the earth pressure between piles increase gradually over time in two stages: stress increases rapidly in the first 45 days and, after this period, stress tends to gradually stabilize. Further, stress increases uniformly with the distance from the centerline of the tunnel, and the rock pressure of the tunnel sidewalls tends to be stable within two months of being constructed. Additional stress on the tunnel foundation increases linearly with time, and it is uniformly distributed in the vertical and horizontal directions of the tunnel section. Settlement of the tunnel foundation also gradually increases with time, and it tends to be stable at 50 days from the time of construction. Additionally, the settlements of different monitoring points are similar at the same depth. The research results will further improve the theoretical knowledge of tunnel bottom reinforcement in the loess tunnel, which not only can effectively guide the design and construction of the loess tunnel and reduce disease treatment cost but also can provide the necessary basic research data and scientific theoretical basis for revision of the corresponding specifications of highway tunnels and railway tunnels.