Analysis of Loose Surrounding Rock Deformation and Slope Stability at Shallow Double-Track Tunnel Portal: A Case Study
Source abstract
Abstract
A low-clearance tunnel portal in the shallow-buried, joint-developed, broken, and loose surrounding rock slope deposit may cause safety issues during construction. In this study, the Guanyin Mountain Tunnel of the Chong-Ai expressway was taken as a case study, and the characteristics of the loose and broken surrounding rocks, their low clearance, and shallow buried bias were comprehensively studied. The three-dimensional numerical model of the Guanyin Mountain tunnel portal section was constructed by the Rhino, AutoCAD, and FLAC 3D software, and the whole construction process of the tunnel portal was simulated. Under the conditions of loose and broken surrounding rocks, the surrounding rock deformation, surface settlement, and slope stability at the portal of the shallow buried tunnel with a small clear distance during the construction of the center diaphragm (CD) method and circular reserved core soil method were studied. The following conclusions are drawn. During the simulated excavation of the tunnel, the maximum surface settlement is 10.74 mm, which meets the requirement of the specification. When the left tunnel is excavated, the surrounding rock deformation of the right arch shoulder should be carefully considered. The maximum deformation value can reach 14.314 mm. After excavation, the deformation rate of the right tunnel is large, and initial support should be installed in time. Since the stratum rock at the portal of the tunnel is strongly weathered, the uplift value of the arch bottom is large and gradually decreases along the axial direction. The tunnel arch bottom and arch foot are plastic areas prone to tensile damage. Therefore, it is imperative to strengthen the inverted arch support of the tunnel in the strongly weathered rock stratum. The excavation sequence of the tunnel portal section adopts the method of excavating the left tunnel first and then excavating the right tunnel, which is more conducive to ensuring the slope stability.
Source: crossref · Quality: baseline
Research context
OpenAlex topics: Geotechnical Engineering and Analysis · Landslides and related hazards · Geotechnical Engineering and Underground Structures
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
Affiliations
Guangxi Road Construction Engineering Group Co., Ltd., Nanning 530001, China
Key Laboratory of Disaster Prevention and Structural Safety, School of Civil Engineering and Architecture, Guangxi University, Nanning 530004, China
References (29)
Show source-provided references
1. Numerical modelling of in situ stress conditions as an aid in route selection for rail tunnels in complex geological formations in South Germany10.1016/S0266-352X(01)00009-X ↗
2. Reinforcement design and control of rock slopes above tunnel portals in northern Italy10.1016/j.ijrmms.2003.12.094 ↗
3. Risk evaluation model of highway tunnel portal construction based on BP fuzzy neural network10.1155/2018/8547313 ↗
4. Seismic damage classification and risk assessment of mountain tunnels with a validation for the 2008 Wenchuan earthquake10.1016/j.soildyn.2012.11.002 ↗
5. Attribute recognition model and its application of risk assessment for slope stability at tunnel portal10.21595/jve.2017.17869 ↗
6. Model test to investigate failure mechanism and loading characteristics of shallow-bias tunnels with small clear distance10.1007/s11771-016-3397-1 ↗
7. Distribution of Surrounding Rock Pressure of Shallow Highway Tunnels with Small Spacing
8. Cracking characteristics and mechanism of entrance section in asymmetrically-load tunnel with bedded rock mass: A case study of a highway tunnel in southwest China10.1016/j.engfailanal.2021.105221 ↗
9. Deformation mechanism and collapse treatment of the rock surrounding a shallow tunnel based on on-site monitoring10.1007/s11629-020-6026-2 ↗
10. Failure mechanism of primary support for a shallow and asymmetrically loaded tunnel portal and treatment measures10.1061/(ASCE)CF.1943-5509.0001385 ↗
11. Construction stability analysis of large section highway tunnel portal section based on numerical analysis
12. Analysis of mechanical behavior in a pipe roof during excavation of a shallow bias tunnel in loose deposits10.1007/s12665-015-5176-y ↗
13. Influence of tunnel excavation on the stability of a bedded rock slope: A case study on the mountainous area in southern Anhui, China10.1007/s12205-020-0831-6 ↗
14. Understanding the mechanism of slope failure on a nearby highway tunnel route by different slope stability analysis methods: A case from NE Turkey10.1007/s10064-015-0770-5 ↗
15. Laboratory investigations into the failure mechanisms of new yielding and inflatable rockbolts under axial and shearing loading conditions10.1007/s00603-022-03086-1 ↗
16. Analytical modelling of load–displacement performance of cable bolts incorporating cracking propagation10.1007/s00603-020-02123-1 ↗
17. Collapse mechanism of shallow tunnel based on nonlinear Hoek–Brown failure criterion10.1016/j.tust.2011.05.008 ↗
18. Tunnel face stability in heavily fractured rock masses that follow the Hoek–Brown failure criterion10.1016/j.ijrmms.2013.01.004 ↗
19. Strength of rock and rock masses
20. Hoek, E., Kaiser, P., and Bawden, W. (2000). Support of Underground Excavations in Hard Rock, CRC Press.10.1201/b16978 ↗
21. Estimation of rock mass deformation modulus and strength of jointed hard rock masses using the GSI system10.1016/S1365-1609(03)00025-X ↗
22. Improving the GSI Hoek-Brown criterion relationships10.1016/j.ijrmms.2016.09.008 ↗
23. Practical estimates of tensile strength and Hoek–Brown strength parameter mi of brittle rocks10.1007/s00603-009-0053-1 ↗
24. The Hoek–Brown failure criterion and GSI–2018 edition10.1016/j.jrmge.2018.08.001 ↗
25. Empirical Estimation of Rock Mass Modulus10.1016/j.ijrmms.2005.06.005 ↗
26. Ministry of Transport of the People’s Republic of China (2019). JTG 3370.1-2018, Highway Tunnel Design Code.
27. Study on the Disaster Mechanism of Steep Melanite Tunnel Based on Improvement Model
28. St John, C.M., and Van Dillen, D.E. (1983, January 12–16). Rockbolts: A new numerical representation and its application in tunnel design. Proceedings of the 24th US Symposium on Rock Mechanics (USRMS), College Station, TX, USA.
29. Illeditsch, M., Preh, A., and Sausgruber, J.T. (2022). Challenges Assessing Rock Slope Stability Using the Strength Reduction Method with the Hoek–Brown Criterion on the Example of Vals (Tyrol/Austria). Geosciences, 12.10.3390/geosciences12070255 ↗