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Article

Experimental Study on Failure Mechanisms of Shield Tunnel Segments with Initial Cracks Under Surcharge Loading

by
Pengfei Xiang
1,2,
Gang Wei
3,
Haibo Jiang
1,4,*,
Yongjie Qi
5 and
Yangyang Liu
6
1
College of Water Conservancy & Architectural Engineering, Shihezi University, Shihezi 832003, China
2
Department of Architectural Engineering, Zhejiang Tongji Vocational College of Science and Technology, Hangzhou 311200, China
3
Department of Civil Engineering, Hangzhou City University, Hangzhou 310015, China
4
College of Hydraulic and Civil Engineering, Xinjiang Agriculture University, Urumqi 830052, China
5
College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, China
6
School of Civil Engineering and Architecture, Anhui University of Science and Technology, Huainan 232001, China
*
Author to whom correspondence should be addressed.
Symmetry 2025, 17(7), 1036; https://doi.org/10.3390/sym17071036
Submission received: 4 June 2025 / Revised: 19 June 2025 / Accepted: 26 June 2025 / Published: 1 July 2025
(This article belongs to the Section Engineering and Materials)
Browse Figures
Versions Notes

Abstract

Accidental ground surcharge loads can induce adverse effects such as segment cracking in underlying shield tunnel structures, with particularly pronounced impacts on pre-damaged tunnel segments. Cracks represent one of the most common initial damage forms in shield tunnel structures. To investigate through-crack failure mechanisms in shield tunnel segments with initial cracks under surcharge loading, this study conducted 1:8 scaled indoor model tests, considering factors including initial crack length, quantity, morphology, and surcharge position. Research findings demonstrate that increased initial crack length and quantity significantly reduce the critical load required for through-crack formation. Specifically, segments with 9 cm longitudinal initial cracks required 50.9% less load to develop through-cracks compared to intact segments. Similarly, segments containing two 9 cm circumferential initial cracks exhibited a 22.1% reduction in critical load relative to those with single circumferential cracks. Initial cracks in pre-damaged segments substantially influence the propagation path of new cracks during subsequent loading failures. The detrimental effects of staggered longitudinal-circumferential initial cracks exceed those of purely longitudinal cracks, which themselves pose greater risks than circumferential cracks alone. Bilateral surcharge loading significantly increases the critical load threshold for through-crack formation compared to unilateral loading. This highlights the severe structural risks associated with uneven load distribution.

1. Introduction

As of the end of 2024, eight major cities including Shanghai, Beijing, and Hangzhou have each achieved operational urban rail transit mileage exceeding 500 km. Shanghai has the longest mileage at 896 km. The total nationwide operational urban rail transit mileage now surpasses 12,000 km. Metro systems dominate urban rail transit and have undeniably become one of the most critical transportation modes in Chinese cities. In recent years, accidental surface surcharges near metro shield tunnels have frequently occurred. These events have led to adverse effects, such as bolt fractures, segment cracking, and localized water leakage in shield tunnels. This compromises the safety of metro operations. Consequently, research on the impact of accidental surface surcharges on underlying shield tunnels is of significant importance.
Numerous domestic and international scholars have conducted research on the impact of accidental surface surcharges on underlying shield tunnels. These studies can be categorized into four primary methodologies: theoretical calculations [1,2,3,4,5], field measurements [6,7,8,9,10], finite element simulations [11,12,13,14,15,16,17,18], and model testing [19,20,21,22,23]. Among these approaches, model testing offers advantages of lower costs and reliable results. Liu Xian et al. [19] investigated the failure mechanisms of double-circle shield tunnels through model testing. Their experiments revealed that the failure process under surcharge loading progresses through three stages, namely, the initial linear behavior, rapid accumulation of plastic damage, and overall instability. Zhang Yanming et al. [20] conducted model testing to examine the influence of surcharge loads on shield tunnels in strata with varying proportions of hard rock. They found that the proportion of hard rock in the surrounding stratum significantly affects tunnel displacement and deformation under accidental surcharge. Higher hard-rock proportions correspond to greater critical failure loads. Liang Rongzhu et al. [21] fabricated a refined shield tunnel model using 3D printing technology and employed model testing to investigate stress-deformation mechanisms under accidental surcharge. Wei et al. [22] conducted a 1:15.5 geometrically scaled indoor model test, systematically analyzing factors such as surcharge magnitude, tunnel burial depth, load position, and soil properties. This approach enabled them to study tunnel convergence deformation, settlement, and deep soil displacement induced by surface surcharges. Huang Dawei et al. [23] performed a 1:10 scaled model test to explore deformation mechanisms and soil–tunnel interaction relationships in soft-soil shield tunnels subjected to accidental surcharges. Current research on destructive testing of model shield tunnels remains limited. Existing studies primarily focus on intact segments, yet they overlook potential pre-existing damage from construction or operational phases. However, such pre-damaged segments exhibit significantly higher vulnerability to failure under accidental surcharges. Among various damage forms, cracks represent one of the most common initial defects in shield tunnel segments. This highlights the necessity to investigate failure patterns of shield tunnel segments with pre-existing cracks under accidental surcharge conditions through model testing.
This study employed a 1:8 scaled model testing approach, incorporating variables such as initial crack length, quantity, morphology, and surcharge position. By experimentally investigating failure mechanisms of cracked shield tunnel segments under surcharge loading, it generates reference data critical for assessing potential failure modes in tunnels with diverse crack configurations subjected to accidental surface loads. There are many engineering symmetry and asymmetry phenomena in this study.

2. Indoor Model Testing

2.1. Test Overview

The model shield tunnel ring utilized in this study was scaled at 1:8 relative to the typical dimensions of Hangzhou Metro shield tunnels. Specific parameters of the model are detailed in Table 1. The prototype shield tunnel segments for Hangzhou Metro are constructed with C50-grade concrete.
To ensure the mechanical behavior of the model closely approximates that of the prototype, the model was fabricated through four sequential steps, encompassing cutting, thickness grinding, slicing, and assembly. The fabrication process employed Grade II D700 reinforced concrete drainage pipes. A simplified connection method was adopted to focus on self-failure mechanisms of shield tunnel segments with initial cracks under surcharge loading, rather than replicating the prototype’s exact configuration. During assembly, two 127 mm arc-shaped steel angle codes were bolted to the inner surface of the segments for vertical fixation, while steel wire binding secured the outer surface. The resulting model tunnel ring exhibited a reinforcement ratio of approximately 0.3% and a concrete strength grade of C30. The fabrication process is illustrated in Figure 1.
The testing equipment consisted of a loading device, hydraulic pump, resistance strain gauge, and data acquisition system. The loading device incorporated eight loading ports, which were evenly distributed along the model tunnel ring. Figure 2 and Figure 3 depict the experimental setup and equipment, respectively.

2.2. Test Conditions

This study investigated the effects of four key factors, i.e., initial crack length, quantity, morphology, and surcharge position, on damaged shield tunnel segments. A total of 10 failure tests were conducted on shield tunnel segments with pre-existing cracks under surcharge loading. For unilateral eccentric loading, the first loading port was applied to segment 6. For bilateral eccentric loading, the first and third loading ports were simultaneously activated, targeting segments 6 and 2, respectively. Eight displacement transducers were evenly distributed inside the tunnel ring to monitor internal displacements during testing. Pressure sensors integrated into the loading ports captured load data. The failure criterion for the model shield tunnel ring was defined as the formation of through-cracks in segments, following the provisions of the technical code for protection structures of urban rail transit (CJJ/T 202-2013) [24]. In practical engineering, surcharge-induced segment displacements can be easily measured; therefore, each loading increment was controlled by advancing the loading port by 0.5 mm. Detailed test conditions are presented in Table 2.

2.3. Test Procedures

(1) Model Tunnel Ring Fabrication: Model tunnel rings were fabricated according to test specifications. Initial cracks with predefined depths, lengths, and positions were pre-cut into segments based on the designated test conditions.
(2) Pre-Test Preparation: The model tunnel ring was placed into the loading device, and its position was adjusted to align with test specifications. Eight displacement transducers were evenly installed inside the tunnel ring at locations corresponding to the loading ports. Both the displacement transducers and pressure sensors were linked to the strain gauge for data acquisition.
(3) Tunnel Ring Loading: Loading was executed through specified loading ports as per test conditions, while other ports remained fixed. Prior to formal loading, all eight loading ports were adjusted to ensure tight contact with the model tunnel ring, and an initial load of approximately 0.25 kN was applied to each port. During formal loading, the designated loading ports advanced at a rate of 0.005 mm/s for each 0.5 mm increment. After each increment, a 10 min hold period was implemented. Loading concluded after three additional increments following the formation of through-cracks in any segment.
(4) Data Acquisition: Displacement and pressure data were automatically captured at 1 s intervals throughout the entire test duration.

3. Failure Analysis of Shield Tunnel Segments with Initial Cracks Under Surcharge Loading

In the tests, through-cracks occurred in segment 6 of the model tunnel ring across all test conditions (1–10). This study therefore focused on the analysis of load variations applied by loading port 1 to segment 6 under different conditions. Due to differences in crack length, quantity, morphology, and surcharge position, the number of loading stages required to induce through-cracks in segment 6 varied among test conditions. Experimental data from seven loading stages, four stages before and three stages after through-crack formation, were selected for analysis, as through-cracks appeared at Stage 4.

3.1. Failure Analysis of Intact Segments Under Surcharge Loading

To explore mechanical behavior differences in intact segments across tunnel ring configurations, Test Conditions 1 and 10 were selected for comparative analysis. Figure 4 illustrates the load variations before and after the failure of intact segment 6 in different tunnel ring configurations. Figure 5 presents the internal displacement variations of intact segment 6 before and after failure under these configurations.
According to the results of Figure 4 and Figure 5:
(1) In Test Condition 1, the intact segment 6 within the assembled tunnel ring required a load of 5.27 kN to induce through-cracks, accompanied by an internal displacement of 3.30 mm. By contrast, Test Condition 10 (monolithic tunnel ring without slicing) required a higher load of 6.52 kN (123.7% of Condition 1) and exhibited a lower internal displacement of 1.78 mm (53.9% of Condition 1). This indicates that the monolithic tunnel ring exhibits marginally superior load-bearing capacity, whereas the assembled ring shows greater deformation tolerance. This discrepancy can be attributed to the assembled ring’s capacity to accommodate limited dislocation damage between segments.
(2) Across the seven loading stages (four before and three after through-crack formation), the external displacements of intact segment 6 remained consistently at 3.0 mm for both configurations. However, internal displacements diverged; to be specific, 2.67 mm for the assembled ring (Condition 1) and 2.41 mm for the monolithic ring (Condition 10). Notably, external displacements exceeded internal displacements by factors of 1.12–1.24.
(3) Immediately after through-crack formation, the load required for subsequent loading stages dropped significantly (4.7–15.6%) for both configurations. Nevertheless, the load demand gradually increased in later stages. This occurred because continued loading further compressed segment 6 despite through-crack formation, and the intact internal reinforcement retained residual load-bearing capacity.

3.2. Effect of Crack Length

To investigate the influence of initial crack length on segment failure under surcharge loading, Test Conditions 1–4 were selected for comparative analysis. Figure 6 illustrates the load variations before and after failure of segments with different crack lengths, while Figure 7 presents the failure modes of segments with varying crack lengths.
From Figure 6 and Figure 7, in Test Conditions 1–4, the load required for subsequent loading stages after through-crack formation decreased significantly. The maximum reduction (38.6%) occurred in Condition 4. As the initial crack length increased, the critical load required for through-crack formation dropped markedly. Compared to Condition 1 (intact segment), condition 2 showed the most pronounced reduction, while Condition 4 exhibited the largest load reduction (50.9%). These results indicate that the presence of cracks (from no crack to a crack) had a greater impact on load-bearing capacity than incremental increases in crack length.

3.3. Effect of Crack Quantity

To investigate the influence of initial crack quantity on segment failure under surcharge loading, Test Conditions 6 and 8, as well as Conditions 4 and 7, were analyzed comparatively. Figure 8 illustrates the load variations before and after failure of damaged segments in Conditions 6 and 8, while Figure 9 presents the corresponding data for Conditions 4 and 7.
From Figure 8, it is evident that as crack quantity increased, the critical load required for through-crack formation dropped significantly. Compared to Condition 6, Condition 8 exhibited a reduction of 0.81 kN (22.1%). Segment displacement increased after through-crack formation when loading continued. The load growth rate in Condition 6 was notably faster than in Condition 8. This likely resulted from concrete crushing in Condition 8’s multiple-crack segments during and after through-crack formation, which substantially reduced load-bearing capacity.
As shown in Figure 9, despite Condition 7 having two 9 cm longitudinal cracks versus one 9 cm longitudinal crack in Condition 4, the critical loads for through-crack formation were nearly identical (2.62 kN for Condition 7 vs. 2.59 kN for Condition 4). After through-crack formation, the load reduction in Condition 4 was 1.00 kN (38.6%), whereas Condition 7 exhibited a smaller reduction of 0.51 kN (19.5%). This discrepancy arose from differences in crack positions. In Condition 7, the two cracks were located at the one-third and two-thirds positions of the segment; in Condition 4, the single crack aligned with the half-length position, which corresponded to the loading point of Port 1.

3.4. Effect of Crack Morphology

To investigate the influence of initial crack morphology on segment failure under surcharge loading, Test Conditions 4 and 6, as well as Conditions 7–9, were comparatively analyzed. Figure 10 displays the load variations before and after failure of damaged segments in Conditions 4 and 6, while Figure 11 presents the corresponding data for Conditions 7–9.
From Figure 10, despite identical initial crack lengths and central positions in Conditions 4 (longitudinal crack) and 6 (circumferential crack), the critical loads for through-crack formation differed significantly. Condition 4 required 2.59 kN, whereas Condition 6 required 3.67 kN. The failure load in Condition 4 was only 70.6% of that in Condition 6, indicating that longitudinal cracks pose significantly greater risks compared to circumferential cracks.
As shown in Figure 11:
(1) Although Condition 7’s two longitudinal cracks were located at the one-third and two-thirds positions (not the center), the critical load for through-crack formation (2.62 kN) remained lower than Condition 8’s 2.86 kN (double circumferential cracks). This confirms that longitudinal cracks are more detrimental than circumferential cracks.
(2) In Condition 9, the segment contained a 9 cm circumferential crack and a 6 cm longitudinal crack. The critical load for through-crack formation was 1.20 kN, only 42.0% of Condition 8’s value. This suggests that staggered longitudinal-circumferential cracks cause far greater damage than double circumferential cracks.
(3) The critical load in Condition 7 (2.62 kN) was 2.18 times that of Condition 9, implying that staggered longitudinal-circumferential cracks are more hazardous than pure longitudinal cracks. However, differences in initial crack positions between these conditions may affect comparability, necessitating further investigation.
(4) No load reduction occurred in Condition 9 after through-crack formation. This may be attributed to rapid load recovery during crack propagation, where minor load reductions were masked by subsequent sharp increases.

3.5. Effect of Surcharge Position

To evaluate the influence of unilateral versus bilateral surcharge loading on segment failure, Test Conditions 1, 3, and 5 were selected for comparative analysis. Figure 12 illustrates the load variations before and after failure of segments in these conditions.
The sole difference between Conditions 3 and 5 lies in the loading configuration. Specifically, Condition 3 applied unilateral loading via Port 1, while Condition 5 implemented bilateral loading through Ports 1 and 3. From Figure 12, it is evident that the critical loads for through-crack formation were 5.27 kN (Condition 1), 3.21 kN (Condition 3), and 4.92 kN (Condition 5). Notably, Condition 5 required 93.4% of Condition 1’s load and 153.3% of Condition 3’s load. Additionally, bilateral loading significantly increased the critical load compared to unilateral loading. This occurred because bilateral loading (Condition 5) led to a more uniform increase in confining pressure across the tunnel ring, thereby enhancing the load threshold for through-crack formation. Similar phenomena were observed in experimental studies by Guo Wenqi et al. [25]. The confining pressure distribution differences under unilateral and bilateral loading are shown in Figure 13.

4. Discussion

(1) Variations in the horizontal distance between surcharge and tunnel, tunnel burial depth, and soil pressure diffusion angle (θsoil) lead to significant differences in the forces acting on shield tunnel segments under accidental surcharge loading. The method employed in this study is particularly applicable when the surcharge force primarily concentrates on segment 6, given specific combinations of these parameters. For different configurations of surcharge–tunnel horizontal distance, burial depth, and θsoil, the impact of accidental surcharge on underlying shield tunnels was visualized, as shown in Figure 14.
(2) Initial crack length, quantity, and morphology of shield tunnel segments significantly influence the propagation path of through-cracks under surcharge loading. In Conditions 2, 3, 4, 5, and 9, where segments initially contained longitudinal cracks, through-cracks developed along the orientation of the initial cracks regardless of their length. In Condition 7, two initial longitudinal cracks located at one-third and two-thirds positions of segment 6 (not the center) led to vertical through-crack propagation along one of the initial cracks. In Conditions 6 and 8, where only circumferential cracks existed, through-cracks initiated from the middle of the initial cracks and propagated vertically. Final through-crack patterns for Conditions 1, 2, 6, and 7 are illustrated in Figure 15.

5. Conclusions

(1) Regardless of the initial damage status, the load required for through-crack formation dropped significantly in the loading stage immediately after crack initiation but gradually increased in subsequent stages. This phenomenon occurred because continued segment compression and intact internal reinforcement after through-crack formation restored partial load-bearing capacity.
(2) Longer initial crack length and higher crack quantities markedly reduced the critical load for through-crack formation. The presence of cracks (from no crack to a crack) had a greater impact on load-bearing capacity than incremental increases in crack length. Initial cracks strongly influenced the propagation path of through-cracks under surcharge loading. Staggered longitudinal-circumferential cracks caused the most severe damage, followed by pure longitudinal cracks, while circumferential cracks exhibited the least detrimental effects.
(3) The critical load for through-crack formation in monolithic (uncut) intact segments exceeded that of assembled segments by 23.7% (123.7% of Condition 1), with internal displacements reduced to 53.9% of the latter. This indicates that monolithic rings exhibit marginally superior load-bearing capacity but significantly lower deformation tolerance compared to assembled rings.
(4) Bilateral loading substantially increased the critical load for through-crack formation by 53.3% compared to unilateral loading. This occurred because bilateral loading induced a more uniform confining pressure distribution across the tunnel ring, thereby enhancing structural resistance. These findings highlight the severe risks posed by uneven confining pressure to shield tunnels.
In the future, the same test method can be used to further simulate the failure law of shield tunnel segments with block falling damage under surcharge loading. However, the current test method hardly simulates the influence of soil conditions on the surcharge failure of shield tunnels.

Author Contributions

Conceptualization, P.X. and H.J.; methodology, P.X., Y.Q. and Y.L.; validation, P.X., G.W. and H.J.; formal analysis, P.X., Y.Q. and Y.L.; resources, G.W.; data curation, P.X., Y.Q. and Y.L.; writing—original draft preparation, P.X.; writing—review and editing, P.X., Y.Q. and Y.L.; supervision, G.W.; project administration, P.X., G.W. and H.J.; funding acquisition, P.X., G.W. and H.J. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the “Tianshan Talent” Youth Top-Notch Talent Cultivation Program, grant number 2024TSYCCX0037; the Zhejiang Provincial Department of Education 2024 Domestic Visiting Engineer Program for University-Enterprise Cooperation Projects, grant number FG2024375; and the National Natural Science Foundation of China, grant numbers 52369021 and 52178399.

Data Availability Statement

The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.

Conflicts of Interest

The authors declare no conflicts of interest.

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Figure 1. Fabrication process of the model tunnel ring. (a) Preliminary cutting. (b) Thickness grinding. (c) Slicing. (d) Assembly.
Figure 1. Fabrication process of the model tunnel ring. (a) Preliminary cutting. (b) Thickness grinding. (c) Slicing. (d) Assembly.
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Figure 2. Experimental setup. (a) Field photo. (b) Schematic diagram.
Figure 2. Experimental setup. (a) Field photo. (b) Schematic diagram.
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Figure 3. Testing equipment.
Figure 3. Testing equipment.
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Figure 4. Load variation before and after failure of intact segment 6 in different tunnel ring configurations.
Figure 4. Load variation before and after failure of intact segment 6 in different tunnel ring configurations.
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Figure 5. Internal displacement variation before and after failure of intact segment 6 in different tunnel ring configurations.
Figure 5. Internal displacement variation before and after failure of intact segment 6 in different tunnel ring configurations.
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Figure 6. Load variation before and after failure of segments with different crack lengths.
Figure 6. Load variation before and after failure of segments with different crack lengths.
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Figure 7. Failure analysis of segments with varying crack lengths.
Figure 7. Failure analysis of segments with varying crack lengths.
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Figure 8. Load variation before and after failure of damaged segments in Test Conditions 6 and 8.
Figure 8. Load variation before and after failure of damaged segments in Test Conditions 6 and 8.
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Figure 9. Load variation before and after failure of damaged segments in Test Conditions 4 and 7.
Figure 9. Load variation before and after failure of damaged segments in Test Conditions 4 and 7.
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Figure 10. Load variation before and after failure of damaged segments in Test Conditions 4 and 6.
Figure 10. Load variation before and after failure of damaged segments in Test Conditions 4 and 6.
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Figure 11. Load variation before and after failure of damaged segments in Test Conditions 7–9.
Figure 11. Load variation before and after failure of damaged segments in Test Conditions 7–9.
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Figure 12. Load variation before and after failure of segments in Test Conditions 1, 3, and 5.
Figure 12. Load variation before and after failure of segments in Test Conditions 1, 3, and 5.
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Figure 13. Schematic of confining pressure distribution under different loading configurations. (a) Unilateral loading. (b) Bilateral loading.
Figure 13. Schematic of confining pressure distribution under different loading configurations. (a) Unilateral loading. (b) Bilateral loading.
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Figure 14. Schematic of surcharge impact on shield tunnels under different parameters. (a) Varying horizontal distance between surcharge and tunnel. (b) Varying tunnel burial depth. (c) Varying soil pressure diffusion angle θsoil.
Figure 14. Schematic of surcharge impact on shield tunnels under different parameters. (a) Varying horizontal distance between surcharge and tunnel. (b) Varying tunnel burial depth. (c) Varying soil pressure diffusion angle θsoil.
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Figure 15. Photographs of final through-cracks under different test conditions. (a) Condition 1. (b) Condition 2. (c) Condition 6. (d) Condition 7.
Figure 15. Photographs of final through-cracks under different test conditions. (a) Condition 1. (b) Condition 2. (c) Condition 6. (d) Condition 7.
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Table 1. Specific parameters of the model tunnel ring.
Table 1. Specific parameters of the model tunnel ring.
External Diameter
(mm)		Internal Diameter
(mm)		Ring Width
(mm)		Wall Thickness
(mm)
Prototype620055001200350
Model775.0687.5150.043.8
Table 2. Test conditions.
Table 2. Test conditions.
Test
Condition		Initial Damage
Forms of Segments		Crack DepthCrack LengthLocation of Damaged SegmentsLoading MethodsSchematic Diagram of Cracks in Segment 6
1Intact segment
(Control group)		///Unilateral eccentric loading/
21 longitudinal crack3 cm3 cmSegment 6Unilateral eccentric loading Symmetry 17 01036 i001
31 longitudinal crack3 cm6 cmSegment 6Unilateral eccentric loadingSymmetry 17 01036 i002
41 longitudinal crack3 cm9 cmSegment 6Unilateral eccentric loadingSymmetry 17 01036 i003
51 longitudinal crack3 cm6 cmSegment 6Bilateral surcharge loadingSymmetry 17 01036 i004
61 circumferential crack3 cm9 cmSegment 6Unilateral eccentric loadingSymmetry 17 01036 i005
72 longitudinal cracks3 cm9 cmSegment 6Unilateral eccentric loadingSymmetry 17 01036 i006
82 circumferential cracks3 cm9 cmSegment 6Unilateral eccentric loadingSymmetry 17 01036 i007
91 longitudinal and
circumferential crack		3 cm6 + 9 cmSegment 6Unilateral eccentric loadingSymmetry 17 01036 i008
10Intact and uncut segment///Unilateral eccentric loading/
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MDPI and ACS Style

Xiang, P.; Wei, G.; Jiang, H.; Qi, Y.; Liu, Y. Experimental Study on Failure Mechanisms of Shield Tunnel Segments with Initial Cracks Under Surcharge Loading. Symmetry 2025, 17, 1036. https://doi.org/10.3390/sym17071036

AMA Style

Xiang P, Wei G, Jiang H, Qi Y, Liu Y. Experimental Study on Failure Mechanisms of Shield Tunnel Segments with Initial Cracks Under Surcharge Loading. Symmetry. 2025; 17(7):1036. https://doi.org/10.3390/sym17071036

Chicago/Turabian Style

Xiang, Pengfei, Gang Wei, Haibo Jiang, Yongjie Qi, and Yangyang Liu. 2025. "Experimental Study on Failure Mechanisms of Shield Tunnel Segments with Initial Cracks Under Surcharge Loading" Symmetry 17, no. 7: 1036. https://doi.org/10.3390/sym17071036

APA Style

Xiang, P., Wei, G., Jiang, H., Qi, Y., & Liu, Y. (2025). Experimental Study on Failure Mechanisms of Shield Tunnel Segments with Initial Cracks Under Surcharge Loading. Symmetry, 17(7), 1036. https://doi.org/10.3390/sym17071036

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