# Analysis of the Interaction Damage Mechanism and Treatment Measures for an Underpass Landslide Tunnel: A Case from Southwest China

^{*}

## Abstract

**:**

## 1. Introduction

## 2. Project Overview

#### 2.1. Geological Survey

#### 2.2. Theory of Underpass Landslide Tunnels

_{s}is used as an indicator to evaluate the stability of the slope, and its physical meaning is the ratio of the slip resistance of the soil to the sliding force, where F

_{s}< 1 means that the slope has been destabilized and damaged [39]. The maximum disturbance radius R

_{pmax}of the tunnel excavation, the maximum additional load max on the lining corresponding to the thickness H

_{0}, and the minimum safe undercutting distance H

_{min}of the tunnel can be calculated according to the following equations [40,41]:

_{0}is the tunnel radius; θ is the friction angle on both sides of the topsoil column; ρ is the initial rupture angle; φ is the internal friction angle of the surrounding rock; and p

_{i}is the landslide thrust.

## 3. History of the Evolution of Slope Failure in Tunnels

^{3}, forming a 6 m high collapse cavity at the top of the palm face, which extended along the side of the ridge. A photograph of the collapse at the palm face is shown in Figure 5. The lower and middle parts of the palm face are medium-weathered rocks, while the upper part is strongly weathered.

## 4. Numerical Simulation of the Underpass Landslide Tunnel

#### 4.1. Simulation of Slope Stability in the Natural State

#### 4.2. Simulation of Slope Stability after Tunnel Excavation

^{3}, forming a 6 m high collapse cavity at the top of the palm face. After the construction of the third section of the tunnel, the safety coefficient of some slopes was lower than 1. At this time, the surface was prone to tension cracks, and the actual situation was that a section of 90 m long cracks was produced in the similar surface position, which showed that the calculation results were more consistent with the actual situation.

## 5. Analysis of the Interaction Damage Mechanism in Underpass Landslide Tunnels

## 6. On-Site Monitoring and Measurement

^{−1}, the maximum deformation rate was 2.119 cm.d

^{−1}, and the overall deformation was 1 cm.d

^{−1}, which indicated that the horizontal deformation of the slope would continue to increase.

^{−1}, the maximum deformation rate was 2.8 cm.d

^{−1}, and the overall fluctuation in the upper and lower sections was 0.5 cm.d

^{−1}, which indicated that the amount of slope settlement would continue to increase.

## 7. Disposal Options

#### 7.1. Numerical Simulation of Treatment Measures

#### 7.2. Practical Treatment Measures on Site

#### 7.3. Emergency Measures in Tunnel Caverns

- (1)
- The lining type of section ZK142 + 070~080 and section ZK142 + 030~040 of the left cave was adjusted from Sd4-b to Sd4-a for strengthening treatment.
- (2)
- The concrete standard of the lining of section ZK142 + 120–140 of the left cave and section K142 + 100–120 of the right cave was upgraded from C35 to C40, and the lining of section ZK142 + 130–140 of the left cave was changed from XSd5-a to XSd5-c for strengthening treatment.
- (3)
- The lining type of section K142 + 000 to K142 + 030 of the right cave was adjusted from Sd4-b to Sd5-b, and I-beams were added to the elevation arch of section K142 + 030 to K142 + 070 to close the initial support into a ring to improve the integrity of the initial support and strengthen the locking foot of this section.

#### 7.4. Tunnel Slope Treatment

- (1)
- Anti-slip piles: At a 880 m elevation, four square anti-slip piles with a length of 15 m (potential sliding surface depth of approximately 10 m), a pile cross section of 2 m × 4 m, and a pile spacing of 6 m were added to the back edge of the mountain; two square anti-slip piles with a length of 15 m (potential sliding surface depth of approximately 8 m), a pile cross section of 2 m × 4 m, and a pile spacing of 6 m were added to the right side of the left cavern.
- (2)
- Surface grouting: The length of grouting of the disturbed area caused by the collapse of the left tunnel at ZK142 + 140 was from mileage ZK142 + 120 to 130 on the left line and from mileage K142 + 112 to 120 on the right line. The width of grouting was from 30 m outside the outline of the left tunnel to 10 m outside the outline of the right tunnel, and the accumulated grouting area was approximately 600 m
^{2}. The grouting material was P.O.42.5 cement net slurry, cement slurry with a water–cement ratio of (0.6–0.8):1, the initial pressure of grouting was 0.5–1.0 MPa, and the final pressure was 1.0 MPa.

## 8. Conclusions

- (1)
- The interaction effect between the tunnel collapse and the slope instability, as well as the fact that the large amount of mudstone commonly contained in the surrounding rock of this tunnel is rheological, can amplify the interaction effect on the tunnel slopes and lead to greater damage.
- (2)
- Mechanisms of interaction in underpass landslide tunnels: During the excavation process of the tunnel beneath the landslide, a weak sandwich geology was encountered, which resulted in the collapse of the left line tunnel. This collapse created an unloading effect, causing stress concentration on the elevation slope near the left line. A small potential sliding surface slippage occurred within a limited range, accompanied by a surface crack measuring approximately 25 m in length. The sliding force exerted on the elevation slope affected the tunnel, increasing the stress on the tunnel lining. As the excavation progressed, the stress on the elevation slope surged, causing the potential sliding surface slippage range to expand. A large crack, 2–10 cm in width and 91 m in length, appeared on the ground surface. The sliding force exerted on the elevation slope continued to affect the tunnel, resulting in damage and cracking of the lining.
- (3)
- This study adopted the comprehensive treatment plan of “tunnel cave-in rescue + tunnel slope treatment”, where tunnel cave-in includes stopping excavation, shotcrete reinforcement, re-arching, backfill and backpressure, reinforcing the structure, and tunnel slope includes backfill and backpressure, anti-slip piles, surface grouting, drainage, and grass planting. This plan has strong pertinence and effectiveness and solves the problem of tunnel cavity fundamentally and ensures the smooth excavation of the tunnel as well as the safety and stability of the tunnel slope.

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Conflicts of Interest

## References

- Zhong, T.; Ma, Q. Numerical analysis and research of entrance slope of shallow buried karst tunnel. In IOP Conference Series: Earth and Environmental Science; IOP Publishing: Bristol, UK, 2020; Volume 455, p. 12176. [Google Scholar]
- Ruggeri, P.; Fruzzetti, V.M.E.; Vita, A.; Paternesi, A.; Scarpelli, G.; Segato, D. Deep-seated landslide triggered by tunnel excavation. In Landslides and Engineered Slopes. Experience, Theory and Practice; CRC Press: Boca Raton, FL, USA, 2018; pp. 1759–1766. [Google Scholar]
- Wang, Z.; Yang, J.; Zhang, T.; Yao, C.; Zhang, X.; Gu, P. PPV and Frequency Characteristics of Tunnel Blast-Induced Vibrations on Tunnel Surfaces and Tunnel Entrance Slope Faces. Shock. Vib.
**2021**, 2021, 5527115. [Google Scholar] [CrossRef] - Lee, K.D.; Jung, U.Y.; Lee, J.D. A Case Study of Colluvium Slope Failure On Tunnel Entrance. J. Korean Soc. Hazard Mitig.
**2015**, 15, 345–351. [Google Scholar] [CrossRef] [Green Version] - Song, Y.S.; Yun, J.M. Analysis of the stability and behavior of a calcareous rock slope during construction of a tunnel entrance. J. Eng. Geol.
**2013**, 23, 283–292. [Google Scholar] [CrossRef] - Wang, Z.F.; He, S.M.; Liu, H.D.; Li, D.D. Formation mechanism and risk assessment of unstable rock mass at the Yumenkou tunnel entrance, Shanxi province, China. Bull. Eng. Geol. Environ.
**2021**, 80, 1433–1448. [Google Scholar] [CrossRef] - Song, D.; Chen, J.; Cai, J. Deformation monitoring of rock slope with weak bedding structural plane subject to tunnel excavation. Arab. J. Geosci.
**2018**, 11, 251. [Google Scholar] [CrossRef] - Weng, X.; Sun, Y.; Yan, B.; Niu, H.; Lin, R.; Zhou, S. Centrifuge testing and numerical modeling of tunnel face stability considering longitudinal slope angle and steady state seepage in soft clay. Tunn. Undergr. Space Technol.
**2020**, 101, 103406. [Google Scholar] [CrossRef] - Mahmood, K.; Kim, J.M.; Khan, H.; Safdar, M.; Khan, U. The probabilistic stability analysis of saturated-unsaturated MH and CL soil slope with rainfall infiltration. KSCE J. Civ. Eng.
**2018**, 22, 1742–1749. [Google Scholar] [CrossRef] - Lin, H.; Zhong, W. Influence of rainfall intensity and its pattern on the stability of unsaturated soil slope. Geotech. Geol. Eng.
**2019**, 37, 615–623. [Google Scholar] [CrossRef] - Fan, S.Y.; Song, Z.P.; Zhang, Y.W.; Liu, N.F. Case study of the effect of rainfall infiltration on a tunnel underlying the roadbed slope with weak inter-layer. KSCE J. Civ. Eng.
**2020**, 24, 1607–1619. [Google Scholar] [CrossRef] - Ren, Y.; Li, T.; Lai, L. Centrifugal shaking table test on dynamic response characteristics of tunnel entrance slope in strong earthquake area. Rock Soil Mech.
**2020**, 41, 1605. [Google Scholar] - Niu, J.; Jiang, X.; Yang, H.; Wang, F. Seismic response characteristics of a rock slope with small spacing tunnel using a large-scale shaking table. Geotech. Geol. Eng.
**2018**, 36, 2707–2723. [Google Scholar] [CrossRef] - Xin, C.L.; Wang, Z.Z.; Zhou, J.M.; Gao, B. Shaking table tests on seismic behavior of polypropylene fiber reinforced concrete tunnel lining. Tunn. Undergr. Space Technol.
**2019**, 88, 1–15. [Google Scholar] [CrossRef] - Chen, C.; Nie, Y.; Zhang, Y.; Lei, P.; Fan, C.; Wang, Z. Experimental investigation on the influence of ramp slope on fire behaviors in a bifurcated tunnel. Tunn. Undergr. Space Technol.
**2020**, 104, 103522. [Google Scholar] [CrossRef] - Kim, J.T.; Hong, K.B.; Ryou, H.S. Numerical analysis on the effect of the tunnel slope on the plug-holing phenomena. Energies
**2018**, 12, 59. [Google Scholar] [CrossRef] [Green Version] - Kim, J.T.; Ryou, H.S. Experimental Study on Effect of Tunnel Slope on Heat Release Rate with Heat Feedback Mechanism. Fire Technol.
**2021**, 57, 2661–2681. [Google Scholar] [CrossRef] - Du, X.W.; Gao, Y.T. On the stability and control technology of the side slope of the tunnel entrance. Appl. Mech. Mater.
**2014**, 488, 737–740. [Google Scholar] [CrossRef] - Song, D.; Liu, X.; Chen, Z.; Chen, J.; Cai, J. Influence of tunnel excavation on the stability of a bedded rock slope: A case study on the mountainous area in southern Anhui, China. KSCE J. Civ. Eng.
**2021**, 25, 114–123. [Google Scholar] [CrossRef] - Chiu, Y.C.; Lee, C.H.; Wang, T.T. Lining crack evolution of an operational tunnel influenced by slope instability. Tunn. Undergr. Space Technol.
**2017**, 65, 167–178. [Google Scholar] [CrossRef] - Ren, B.; Shen, Y.; Zhao, T.; Li, X. Deformation monitoring and remote analysis of ultra-deep underground space excavation. Undergr. Space
**2023**, 8, 30–44. [Google Scholar] [CrossRef] - Shen, Y.; Ling, J.; Lu, X.; Zhang, Y.; Yan, Z. Steel wire prestress analysis of large section jacking prestressed concrete cylinder pipe (JPCCP): Site experiment and numerical investigation. Thin-Walled Struct.
**2023**, 184, 110420. [Google Scholar] [CrossRef] - Jiang, X.; Zhang, X.; Wang, S.; Bai, Y.; Huang, B. Case study of the largest concrete earth pressure balance pipe-jacking project in the world. Transp. Res. Rec.
**2022**, 2676, 92–105. [Google Scholar] [CrossRef] - Causse, L.; Cojean, R.; Fleurisson, J.A. Interaction between tunnel and unstable slope–Influence of time-dependent behavior of a tunnel excavation in a deep-seated gravitational slope deformation. Tunn. Undergr. Space Technol.
**2015**, 50, 270–281. [Google Scholar] [CrossRef] - Lu, L.; Liang, S.; Luo, S.; Li, J.; Zhang, B.; Hu, H. Optimization of the construction technology of shallow-buried tunnel entrance constructed in residual slope accumulation of gravelly soil. Geotech. Geol. Eng.
**2018**, 36, 2391–2401. [Google Scholar] [CrossRef] - Koçkar, M.K.; Akgün, H. Methodology for tunnel and portal support design in mixed limestone, schist and phyllite conditions: A case study in Turkey. Int. J. Rock Mech. Min. Sci.
**2003**, 40, 173–196. [Google Scholar] [CrossRef] - Kong, F.; Lu, D.; Du, X.; Shen, C. Displacement analytical prediction of shallow tunnel based on unified displacement function under slope boundary. Int. J. Numer. Anal. Methods Geomech.
**2019**, 43, 183–211. [Google Scholar] [CrossRef] [Green Version] - Kaya, A.; Akgün, A.; Karaman, K.; Bulut, F. Understanding the mechanism of slope failure on a nearby highway tunnel route by different slope stability analysis methods: A case from NE Turkey. Bull. Eng. Geol. Environ.
**2016**, 75, 945–958. [Google Scholar] [CrossRef] - Lei, M.F.; Lin, D.Y.; Yang, W.C.; Shi, C.H.; Peng, L.M.; Huang, J. Model test to investigate failure mechanism and loading characteristics of shallow-bias tunnels with small clear distance. J. Cent. S. Univ.
**2016**, 23, 3312–3321. [Google Scholar] [CrossRef] - Hu, Z.; Shen, J.; Wang, Y.; Guo, T.; Liu, Z.; Gao, X. Cracking characteristics and mechanism of entrance section in asymmetrically-load tunnel with bedded rock mass: A case study of a highway tunnel in southwest China. Eng. Fail. Anal.
**2021**, 122, 105221. [Google Scholar] [CrossRef] - Deng, X.; Xu, T.; Wang, R. Risk evaluation model of highway tunnel portal construction based on BP fuzzy neural network. Comput. Intell. Neurosci.
**2018**, 2018, 8547313. [Google Scholar] [CrossRef] [Green Version] - Sun, T.; Yue, Z.; Gao, B.; Li, Q.; Zhang, Y. Model test study on the dynamic response of the portal section of two parallel tunnels in a seismically active area. Tunn. Undergr. Space Technol.
**2011**, 26, 391–397. [Google Scholar] [CrossRef] - Zhao, J.; Lan, W.; Wang, G. Analysis of seismic Response and Slope Stability for Intake Tunnel Entrance of Hongyan River Nuclear Project. In IOP Conference Series: Earth and Environmental Scienc; IOP Publishing: Bristol, UK, 2019; Volume 304, p. 42047. [Google Scholar]
- Wang, J.; Zeng, Y.; Xu, Y.; Feng, K. Analysis of the influence of tunnel portal section construction on slope stability. GeoloGy Ecol. Landsc.
**2017**, 1, 56–65. [Google Scholar] [CrossRef] [Green Version] - Chen, L.L.; Wang, Z.F.; Wang, Y.Q. Failure analysis and treatments of tunnel entrance collapse due to sustained rainfall: A case study. Water
**2022**, 14, 2486. [Google Scholar] [CrossRef] - Hou, T.; Duan, X.; Liu, H. Study on stability of exit slope of Chenjiapo tunnel under condition of long-term rainfall. Environ. Earth Sci.
**2021**, 80, 590. [Google Scholar] [CrossRef] - Wu, H. Research on the Deformation Mechanism and Control Technology of Tunnel-Landslide System. Chin. J. Rock Mech. Eng.
**2012**, 31, 3632–3642. (In Chinese) [Google Scholar] - Tao, Z.; Zhang, Q.; Yang, X.J.; Zhao, F.; Cao, S.; Li, S. Experimental study on physical modeling of the effect of underpass tunnel excavation on the stability of loose-packed slopes. J. Coal
**2022**, 47, 61–76. (In Chinese) [Google Scholar] - Shao, Z.; Cui, F.; Li, C.; Ding, B. Research on factors influencing slope stability and treatment technology of powder clay tunnels. J. Railw. Sci. Eng.
**2020**, 17, 2055–2064. (In Chinese) [Google Scholar] - Ma, H.; Wu, H.; Yang, T. Research on Deformation Mechanism and Control Technology of Landslide System in Land Traffic Tunnel; Science Press: Beijing, China, 2020; pp. 118–128. (In Chinese) [Google Scholar]
- Wu, H.G.; Zhao, J.; Li, Y.R.; Chen, S.Y. Research on additional load calculation method for tunnel underpassing landslide. J. Rock Mech. Eng.
**2018**, 37, 4375–4383. [Google Scholar] - GB 50330-2002; Technical Specifications for Construction Slope Works. China Construction Industry Press: Beijing, China, 2002. (In Chinese)

**Figure 1.**Schematic diagram of the damage to the underpass landslide tunnel. (

**a**) Schematic diagram of the overall damage to the underpass landslide tunnel. (

**b**) Schematic diagram of the damage to the longitudinal section of the underpass landslide tunnel.

**Figure 7.**Deformation and crack diagram of the slope at the rear edge of the tunnel. (

**a**) Slope of the rear edge and (

**b**) the maximum deformation crack.

**Figure 8.**Cracking diagram of the lining of the right hole of the tunnel: (

**a**) Peeling phenomenon of the primary support at the left vault of the right hole K142 + 115; (

**b**) peeling of the initial branch at the left arch waist of the right hole K142 + 115.

**Figure 9.**Cracking diagram of the lining of the left hole of the tunnel: (

**a**) Cracks in the arch waist on the right side of the left hole ZK142 + 130–140; (

**b**) cracks in the arch wall on the right side of the left hole ZK142 + 130–140.

**Figure 10.**Model drawing of the underpass landslide tunnel. (

**a**) Slopes in their natural state and (

**b**) slopes after tunnel excavation. (

**c**) Lined structural body.

**Figure 14.**Distribution of slope safety factors: (

**a**) First paragraph, (

**b**) second paragraph, (

**c**) third paragraph.

Surrounding Rock Level | Severe γ (kN/m ^{3}) | Modulus of Deformation E (GPa) | Poisson’s Ratio μ | Cohesion C (MPa) | Angle of Internal Friction φ (°) | Uniaxial Compressive Strength Ra (MPa) |
---|---|---|---|---|---|---|

Mesothermal rock masses | 23.7 | 1.0 | 0.32 | 0.1 | 25 | 0.002 |

Strongly weathered rock masses | 21.6 | 1.0 | 0.42 | 0.06 | 20 | 0.0012 |

Planting soil | 22.5 | 0.05 | 0.3 | 0.05 | 20 | 0.0001 |

Moderately weathered rock masses (considering dominant joints) | N/A | N/A | N/A | 0.03 | 25 | 0.0006 |

Strongly weathered rock masses (consider dominant joints) | N/A | N/A | N/A | 0.012 | 20 | 0.0004 |

Profile/Tunnel | Maximum Compressive Stress (MPa) | Maximum Tensile Stress (MPa) |
---|---|---|

Profile at 0 m/left line tunnel | 2.01 | 0.24 |

Profile at 20 m/left line tunnel | 3.36 | 0 |

Profile at 0 m/right line tunnel | 2.65 | 0.18 |

Left line tunnel longitudinal section | 1.79 | 0.14 |

Right line tunnel longitudinal section | 1.61 | 0.18 |

Profile/Tunnel | Maximum Compressive Stress (MPa) | Maximum Tensile Stress (MPa) |
---|---|---|

Profile at 0 m/left line tunnel | 3.14 | 0.74 |

Profile at 20 m/left line tunnel | 7.82 | 1.59 |

Profile at 0 m/right line tunnel | 3.32 | 0.85 |

Profile at 60 m/left line tunnel | 11.17 | 0.93 |

Profile at 40 m/right line tunnel | 5.4 | 0.91 |

Left line tunnel longitudinal section | 3.97 | 1.31 |

Right line tunnel longitudinal section | 2.83 | 1.03 |

Profile/Tunnel | Maximum Compressive Stress (MPa) | Maximum Tensile Stress (MPa) |
---|---|---|

Profile at 0 m/left line tunnel | 6.5 | 0.95 |

Profile at 20 m/left line tunnel | 7.03 | 1.72 |

Profile at 0 m/right line tunnel | 3.51 | 1.08 |

Profile at 60 m/left line tunnel | 11.4 | 1.55 |

Profile at 40 m/right line tunnel | 6.9 | 1.55 |

Profile at 70 m/left line tunnel | 6.69 | 1.18 |

Profile at 60 m/right line tunnel | 9.24 | 2.54 |

Profile at 80 m/left line tunnel | 6.23 | 1.23 |

Profile at 70 m/right line tunnel | 6.11 | 1.03 |

Profile at 88.4 m/left line tunnel | 8.23 | 1.03 |

Profile at 78.4 m/right line tunnel | 8.03 | 1.58 |

Left line tunnel longitudinal section | 6.61 | 1.58 |

Right line tunnel longitudinal section | 6.46 | 2.52 |

Profile/Tunnel | Maximum Compressive Stress (MPa) | Maximum Tensile Stress (MPa) |
---|---|---|

Profile at 0 m/left line tunnel | 2.85 | 0.65 |

Profile at 20 m/left line tunnel | 6.03 | 1.02 |

Profile at 0 m/right line tunnel | 2.51 | 0.68 |

Profile at 60 m/left line tunnel | 10.4 | 0.65 |

Profile at 40 m/right line tunnel | 4.9 | 0.63 |

Profile at 70 m/left line tunnel | 4.99 | 0.78 |

Profile at 60 m/right line tunnel | 4.34 | 0.84 |

Profile at 80 m/left line tunnel | 4.33 | 1.05 |

Profile at 70 m/right line tunnel | 4.11 | 0.73 |

Profile at 88.4 m/left line tunnel | 6.33 | 0.83 |

Profile at 78.4 m/right line tunnel | 6.03 | 1.28 |

Left line tunnel longitudinal section | 4.71 | 0.88 |

Right line tunnel longitudinal section | 4.66 | 1.04 |

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## Share and Cite

**MDPI and ACS Style**

Zhou, W.; Xu, X.; Li, X.; Li, S.
Analysis of the Interaction Damage Mechanism and Treatment Measures for an Underpass Landslide Tunnel: A Case from Southwest China. *Sustainability* **2023**, *15*, 11398.
https://doi.org/10.3390/su151411398

**AMA Style**

Zhou W, Xu X, Li X, Li S.
Analysis of the Interaction Damage Mechanism and Treatment Measures for an Underpass Landslide Tunnel: A Case from Southwest China. *Sustainability*. 2023; 15(14):11398.
https://doi.org/10.3390/su151411398

**Chicago/Turabian Style**

Zhou, Wangwang, Xulin Xu, Xiaoqing Li, and Shiyun Li.
2023. "Analysis of the Interaction Damage Mechanism and Treatment Measures for an Underpass Landslide Tunnel: A Case from Southwest China" *Sustainability* 15, no. 14: 11398.
https://doi.org/10.3390/su151411398