Analytical solutions and in-situ measurements on the internal forces of segmental lining produced in the assembling process
Introduction
Shield tunnel lining is formed by assembling the precast segments in the site to form a closed ring to resist the ground pressures. Compared with the cast-in-place concrete lining, the segmental lining could significantly improve the construction efficiency and quality on the presumption that the lining is assembled perfectly. There have been numerous approaches for segmental lining design in the available design guidelines or codes [14], [23]. Most of the general design methods of tunnel lining supposed the external loads as the earth and water pressure at the serviceability stage. However, field measurements showed that loads from the construction stage, especially during the segments assembling, were inherently different from those at the serviceability stage [4], [19]. Still, few of these provide a quantitative justification to the criteria considered for the construction effects or loads on the segment.
The increasing damages of segments during the construction stage indicated that the construction loads were one of the dominant factors for segments [16], which deserved our special attention. Japan Society of Civil Engineers [15] established a technical committee working on the effects of construction loads and found that construction loads were complex with coupling effects. Sugimoto [21] summarized the causes of segments damages of shield tunnel lining during construction. Cavalaro et al. [5] also found frequently occurred cracks caused by the contact deficiencies between the segments. Based on a case study in Shanghai shield tunnel, Yang et al. [25] found that different kinds of segment cracking or damage will occur during the construction stage caused by improper assembling loads. Using a ground-spring model as the joint connector, Chaipanna and Jongpradist [6] investigated the responses of a segmental lining considering the construction loads. Zakhem and Naggar [29] simulated the staged construction sequence of shield tunneling by finite element method (FEM) and found that the earth pressure on the segmental tunnel lining decreased with the grouting consolidation. Several other researchers had employed analytical method [11], [10], [24], FEM [9], [2], [1], [4], [3], [22], [7], [8], model test [4] as well as in-situ measurement [9], [19], [12] to investigate the effects of construction loads on lining behaviours. Most of the research focused on the apparent loads (earth and water pressures, grouting pressures, jack forces, etc.), and interaction forces between shield and tunnel lining, ignoring the actions induced by segment assembly deviations. Although some of the research considered the effects of segment dislocations and pre-deformations in the models [4], [3], they were still assumed as wished in place without considering the assembly process.
Up to date research and design models assumed shield tunnel lining as a perfect ring in place, with various construction loads considered but without special attention to the effects of pre-deformations and the inaccuracies produced in the process. The ignorance and simplification might be reasonable for small diameter tunnels in simple geological conditions. However, with large diameter and deep tunnels emerging around the world, the present design methods are now facing much more difficulties in defining the actual state of tunnel lining imposed by construction uncertainties than before. The new challenges have caused detrimental effects on the tunnel lining.
It is noted that all the effects of the construction-related process should be considered in design; otherwise, the effect of dislocations and inaccuracy of construction will be amplified so much on the design results that the conventional design methods would be no longer applicable in practice. To find a solution to the problem, we contributed an innovative idea, which was to assume appropriately the assembly tolerance of bolt holes and pre-deformations of the lining ring. Then by applying the principle of minimum potential energy, three analytical solutions were established to calculate the internal forces of different boundary conditions induced in the assembly process. Furthermore, the proposed method was verified and validated by an in-situ test on a large underwater tunnel in China.
Section snippets
Basic models and assumptions
As shown in Fig. 1, the basic model consists of the completed lining ring (CLR) and the assembling lining ring (ALR). The ALR includes two kinds of segments, the completed lining segments (CLS) and the assembling lining segment (ALS). Fig. 2 shows the assembling process of the segmental lining, in which the standard segments (B1 ~ B7) are firstly assembled one by one, and then the two adjacent segments (L1 and L2) and lastly, the key segment (K). For simplicity, each segment was assumed to be
In-situ measurement verification
To validate the proposed method, an in-situ measurement was conducted on a large segmental tunnel, and the internal forces of lining produced in the whole process of segments assembly were all successfully measured and recorded for verifications and comparison of the theoretical results with the in-situ measurement.
Conclusions and discussions
This paper developed an analytical method to evaluate the internal forces of segmental lining induced by pre-deformations and assembly inaccuracy. The analytical solutions to the internal forces were obtained for three kinds of segments (ALS) with constraint ALS-FF, ALS-FC, ALS-CC, respectively. Furthermore, an in-situ measurement was conducted to corroborate the proposed method. The main conclusions are summarized as follows:
- (1)
The effect of assembly inaccuracy and pre-deformations on the
CRediT authorship contribution statement
Meng-bo Liu: Investigation, Data curation, Writing - original draft. Shao-ming Liao: Supervision, Conceptualization, Writing - review & editing, Funding acquisition. Jin Xu: Methodology, Validation. Yan-qing Men: Formal analysis, Software.
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments
The authors would like to express their sincere thanks to the supports of the National Basic Research Program of China (973 Program) (Grant No. 2015CB057806) and the projects (Grant No. 17DZ1203804, No. 19511100802) supported by Shanghai Committee of Science and Technology.
References (29)
- et al.
Theoretical and numerical analysis of the three-dimensional response of segmental tunnel linings subjected to localized loads
Tunn Undergr Space Technol
(2015) - et al.
Three dimensional structural response of segmental tunnel linings
Eng Struct
(2012) - et al.
Three-dimensional structural analyses of the shield-driven “Green Heart” tunnel of the high-speed line South
Tunn Undergr Space Technol
(1999) - et al.
Structural analysis of contact deficiencies in segmented lining
Tunn Undergr Space Technol
(2011) - et al.
3D response analysis of a shield tunnel segmental lining during construction and a parametric study using the ground-spring model
Tunn Undergr Space Technol
(2019) - et al.
Analysis of shearing effect on tunnel induced by load transfer along longitudinal direction
Tunn Undergr Space Technol
(2008) - et al.
Study on construction loads during shield tunnelling using a three-dimensional FEM model
Tunn Undergr Space Technol
(2006) - et al.
Longitudinal structural modelling of shield tunnels considering shearing dislocation between segmental rings
Tunn Undergr Space Technol
(2015) - et al.
Effect of the constitutive material model employed on predictions of the behaviour of earth pressure balance (EPB) shield-driven tunnels
Transp Geotech
(2019) - et al.
Three-dimensional structural analyses and design of segmented tunnel lining at construction stage
(1998)
Study on effect of segments erection tolerance and wedge-shaped segment on segment ring in shield tunnel
J Zhejiang Univ SCIENCE A
Mechanical behavior of segment rebar of shield tunnel in construction stage
J Zhejiang Univ SCIENCE A
Stress and strain state in the segmental linings during mechanized tunnelling
Geomech Eng
Structural design models for tunnels in soft soil
Underground Space
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