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Construction practice of landslide during tunneling in hilly topography
Engineering Failure Analysis 104 (2019) 1234–1241
Contents lists available at ScienceDirect
Engineering Failure Analysis journal homepage: www.elsevier.com/locate/engfailanal
Construction practice of landslide during tunneling in hilly topography
T
⁎
Pan Lia,b, Cheng Liua, Yongxing Zhanga,c, , Jian Zhangd, Junsheng Yange, Tugen Fengd a
School of Civil Engineering, Nanjing Forestry University, Nanjing 210037, Jiangsu, China School of Rail Transportation, Soochow University, Suzhou 215137, China National Engineering Laboratory of Highway Maintenance Technology, Changsha University of Science & Technology, Changsha 410114, China d College of Civil and Transportation Engineering, Hohai University, No.1 Xikang Road, Nanjing 210098, China e School of Civil Engineering, Central South University, Changsha 410075, China b c
A R T IC LE I N F O
ABS TRA CT
Keywords: Tunneling Landslide Field investigation Numerical analysis Treating countermeasure
This paper presents a case study of landslide during tunneling period in hilly topography, and a practical treating countermeasure is also proposed in the study. The field investigation and numerical analysis demonstrate that tunneling in hilly topography with sloping stratification has risk of landslide while heavy rainfall permeates into ground, and a treating countermeasure of anti-slide piles combined with in-layer compacted backfilling is adopted in the practical implementation. Moreover, the implemented treating work demonstrates that the employed countermeasure is capable of treating landslide during tunneling with heavy rain water permeating into ground, which can provide the design basis for similar treating work.
1. Introduction Tunnel has been widely used in highway engineering due to obvious advantages of traversing obstacle with mountains and rivers [1], the construction of which inevitably encounters terrible geological condition [2–4]. Many published studies have demonstrate that landslide is easily induced during tunneling [5–7]. However, the cause of the aforementioned landslide is not easy to be identified due to very complex influencing factors, such as not only construction method or support system but also harsh geological condition [6,8]. Therefore, the effective treating countermeasure of landslide during tunneling is difficult to determine and further study is urgently required. In this paper, a case study of treating landslide during tunneling period in hilly topography is presented by field investigation and numerical analysis, in which the sloping stratification with heavy rain water permeating into ground is field observed. The study focuses on the effectiveness of the adopted countermeasure for treating landslide during tunneling. 2. Profile of the tunnel 2.1. Landform and geological condition around tunnel site The tunnel is located in denudated hilly topography and buried with quaternary strata, which is 10,743 m long with 515 m
⁎ Corresponding author at: School of Civil Engineering, Nanjing Forestry University, Nanjing 210037, Jiangsu, China; National Engineering Laboratory of Highway Maintenance Technology, Changsha University of Science & Technology, Changsha 410114, China. E-mail address: [email protected] (Y. Zhang).
https://doi.org/10.1016/j.engfailanal.2019.07.064 Received 15 March 2019; Received in revised form 21 July 2019; Accepted 28 July 2019 Available online 29 July 2019 1350-6307/ © 2019 Published by Elsevier Ltd.
Engineering Failure Analysis 104 (2019) 1234–1241
P. Li, et al.
(a) Schematic geology
(b) Location of supplementary geological drillings Fig. 1. Geological condition investigation of the tunnel.
maximum buried depth. Fig. 1 demonstrate the schematic geological condition with steep slope and V-shaped valley. The major rock strata of tunnel entrance are hard-soft heterogeneous ground with sloping stratification, in which there is no visible water in the fissures. The surrounding rocks are respectively constituted of fully-weathered, strongly-weathered and weakly-weathered micaquartzose schist, in which 9 geological drillings are implemented for supplementary survey as marked in Fig. 1(b).
Fig. 2. Construction sequences of the tunnel. 1235
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Fig. 3. Observed ground movement of tunnel entrance during tunneling.
2.2. Construction procedures Fig. 2 demonstrates the tunnel construction sequences for reducing the disturbance of unstable surrounding rock, in which the construction steps are annotated from 1 to 8. As shown in Fig. 2, the tunnel is excavated and supported with the following procedures: step 1 and 2: excavating upper bench and constructing primary lining around upper bench→ step 3 and 4: excavating middle bench and constructing primary lining around middle bench→ step 5 and 6: excavating lower bench and constructing primary lining around lower bench→ step 7: excavating invert arch and backfilling invert arch with concrete→ step 8: constructing secondary lining. 3. Field investigation of damages during tunneling Field investigation are implemented to obtain the damages during tunneling. Fig. 3 demonstrates the observed typical transfixion cracks and sliding behavior occurred in ground surface, the longitudinal length of which is greater than 200 m and the maximum crack width is almost 0.25 m. Moreover, serious cracks are also observed in the front and side slopes of the tunnel entrance as shown in Fig. 4. Especially, heavy rainfall is observed before slide in ground surface. Fig. 5 demonstrates that cracks occur in concrete lining during excavating the tunnel entrance, in which several longitudinal cracks are observed with 6 mm maximum width, ranged from position B to C as marked in Fig. 2. Moreover, the deviations of tunnel lining are investigated using total station scanning system, and the maximum deviations at both sides of concrete lining are 0.194 m and 0.239 m as shown in Fig. 6. 4. Numerical investigation of landslide during tunneling 4.1. Numerical model The numerical analysis of aforementioned landslide during tunneling is also implemented for investigating the cause of landslide during tunneling using ABAQUS software [9], the numerical model of which is shown in aforementioned Fig. 1. The longitudinal calculation range of the numerical model is 229.4 m, and the vertical calculation ranges of both lateral sides are 111.6 m and 20 m respectively, including vertical range of 17.6 m from tunnel bottom to the lower boundary. Moreover, some assumptions are adopted for the boundary conditions of the numerical model. The displacements of lower boundary are constrained in longitudinal and vertical directions, those of both lateral boundaries are restricted in longitudinal direction, and those of upper boundary are free in both longitudinal and vertical directions.
Fig. 4. Observed cracks in front and side slopes of tunnel entrance. 1236
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Fig. 5. Typical crack in concrete lining of the tunnel.
Fig. 6. Deviations of tunnel lining (unit: m).
4.2. Material property The physical properties of lining concrete and surrounding rocks are listed in Table 1, obtained from aforementioned supplementary geological survey and laboratory test with 25 grouped specimens, in which E is elastic modulus, γ is bulk density, fc’ is compressive strength of concrete, μ is Poisson's ratio, φ is friction angle, and c is cohesive force. The effect of steel arch is converted to that of shotcrete in primary lining, and the surrounding rocks are considered as ideal elastic-plastic material met with Mohr Coulomb yield criterion, which also can reflect the behavior of surrounding rocks during tunneling [10–12]. Fig. 7 demonstrates the numerical model and boundary condition, the longitudinal calculation range is 229.4 m, that of lateral side to the tunnel is 30.4 m, and the vertical calculation ranges of both lateral sides are 111.6 m and 20 m from top surface to lower boundary respectively. The bottom boundary is fixed in both longitudinal and vertical directions, and both lateral boundaries are restricted in longitudinal direction, whereas upper boundary is free in both longitudinal and vertical directions. Moreover, the calculation of ground stress balance is executed and the calculated displacement is returned to zero for removing the adverse influence on sliding surface. Table 1 Physical properties of surrounding rocks. Material
Physical and mechanical parameter
Fully-weathered mica-quartzose schist Strongly-weathered mica-quartzose schist Weakly-weathered mica-quartzose schist Concrete lining
E = 0.1 GPa, γ = 22 kN/m3, μ = 0.4, c = 0.05 MPa,=28.6° E = 3 GPa, γ = 23 kN/m3, μ = 0.3, c = 0.4 MPa,φ=30° E = 20 GPa, γ = 25 kN/m3, μ = 0.25, c = 1.0 MPa,φ=45° E = 31.5 GPa, μ = 0.2
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P. Li, et al.
Fig. 7. Numerical model and boundary condition (unit: m).
Especially, the strength reduction finite element method is adopted for numerical simulation, which is expected to reflecting the influence of slope stability from tunneling with heavy rainfall permeating into ground. The reduction of friction angle φ and cohesive force c are obtained by the following equations:
tan φ ⎞ φm = arctan ⎛ ⎝ Fr ⎠ ⎜
cm =
⎟
(1)
c Fr
(2)
where φm and cm are reduced friction angle and cohesive force; Fr is strength reduction coefficient. 4.3. Numerical result Fig. 8 shows the plastic zone distribution of surrounding rocks, in which the transfixion plastic zone represents the numerically
(a) Strength reduction coefficient 0.5
(b) Strength reduction coefficient 0.5711 Fig. 8. Plastic zone distribution of surrounding rocks. 1238
Engineering Failure Analysis 104 (2019) 1234–1241
P. Li, et al.
(a) Tamping transfixion cracks
(b) Anti-slide piles combined with in-layer compacted backfilling Fig. 9. Construction treatment of landslide during tunneling.
obtained main sliding surface and illustrates the instability of surrounding rocks. It can be obviously seen continuous plastic zones are gradually developed with the increased strength reduction coefficient, which means the case of landslide during tunneling in hilly topography with sloping stratification is probably influenced by heavy rainfall permeating into ground. This numerical behavior is similar with that in practical construction. 5. Investigation of treating countermeasure for landslide during tunneling 5.1. Field countermeasure to treat landslide during tunneling The above-discussed investigation demonstrates that the case of landslide during tunneling is affected by heavy rainfall permeating into ground. In the treating practice, the observed transfixion cracks are firstly tamped with clay for preventing rain water from slipping into the sliding body again. Thereafter, the in-layer backfilling with compaction is adopted to exert counter pressure for blocking landslide, implemented from hilly foot to top ground surface of tunnel, and 25 anti-slide piles are finally adopted to block landslide and stabilize the ground as shown in Fig. 9. Moreover, four holes in the aforementioned supplementary geological drillings (positions 1#, 4#, 5# 9# as labeled in Fig. 1) are also adopted for measuring the deep landslide using inclinometer pipe. The relationship curves of horizontal displacement and depth at position 4# are demonstrated in Fig. 10, which can verify that just the treating countermeasure of in-layer compacted backfilling is insufficient for blocking landslide with heavy rainfall, whereas that of anti-slide piles combined with in-layer compacted backfilling is effective in practical implementation. 5.2. Effect confirmation of treating countermeasure using numerical investigation The treating countermeasure is numerically investigated, in which the practical treatment of anti-slide piles combined with inlayer compacted backfilling is considered in the numerical model as demonstrated in Fig. 11(a). Moreover, the boundary condition and material properties are similar with those of investigating landslide during tunneling as shown in aforementioned Fig. 7 and Table 1. Fig. 11(b) shows the plastic zone distribution of surrounding rocks after practical treatment, in which there is no continuous plastic zones as well as transfixion plastic zone. This means the adopted treatment of anti-slide piles combined with in-layer compacted backfilling is capable of treating landslide during tunneling with heavy rain water permeating into ground. 6. Conclusions In this paper, a construction practice of treating landslide during tunneling in hilly topography is studied, and the following conclusions are obtained: (1) Tunneling in hilly topography with sloping stratification has risk of landslide while heavy rainfall permeates into ground, and the 1239
Engineering Failure Analysis 104 (2019) 1234–1241
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Fig. 10. Horizontal displacement versus depth of ground at position #4.
(a) Numerical model and boundary condition (unit: m)
(b) Plastic zone distribution of surrounding rocks Fig. 11. Numerical simulation of practical treating countermeasure.
treating countermeasures with in-time treatment are required. (2) The adopted treating countermeasure of anti-slide piles combined with in-layer compacted backfilling is capable of treating landslide during tunneling with heavy rain water permeating into ground, which can provide the design basis for similar treating work. 1240
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Declaration of Competing Interest The authors declare that there is no conflict of interest in the manuscript. Acknowledgements The author would like to acknowledge the support from National Natural Science Foundation of China (No. 51578292, 51408124, 51508278), Open Fund of National Engineering Laboratory of Highway Maintenance Technology(Changsha University of Science & Technology, Grant No. kfj170101), Six Talent Peak Projects and Qinglan Project. References [1] J.Y. Fu, J.S. Yang, X.M. Zhang, H. Klapperich, S.M. Abbas, Response of the ground and adjacent buildings due to tunnelling in completely weathered granitic soil, Tunn. Undergr. Space Technol. 43 (2014) 377–388. [2] J. Okazaki, A. Ogawa, T. Tamura, A study on cracks of tunnel concrete lining in squeezing ground, J. Tunnel Eng. JSCE 13 (2003) 53–60. [3] Y.X. Zhang, Y.F. Shi, Y.D. Zhao, L.R. Fu, J.S. Yang, Determining the cause of damages in a multiarch tunnel structure through field investigation and numerical analysis, J. Perform. Constr. Facil. 31 (3) (2017). [4] X.Y. Ye, S.Y. Wang, J.S. Yang, D.C. Sheng, C. Xiao, Soil conditioning for EPB shield Tunneling in argillaceous siltstone with high content of clay minerals: case study, Int.l J. Geomech. 17 (4) (2017). [5] M. Inmaculada Alvarez-Fernandez, E. Amor-Herrera, C. Gonzalez-Nicieza, F. Lopez-Gayarre, M. Rodriguez Avial-Llardent, Forensic analysis of the instability of a large-scale slope in a coal mining operation, Eng. Fail. Anal. 33 (2013) 197–211. [6] Y.X. Zhang, J.S. Yang, F. Yang, Field investigation and numerical analysis of landslide induced by tunneling, Eng. Fail. Anal. 47 (2015) 25–33. [7] M. Chatziangelou, B. Christaras, Landslides and tunneling geological failures, during the construction of Thessaloniki-Kavala section of Egnatia highway in N. Greece, Int. J. Geol. 4 (2) (2010) 48–57. [8] M.B. Prendes-Gero, F. Lopez-Gayarre, C. Menendez-Fernandez, M. Rodriguez-Avial Llardent, Forensic analysis of the failure of the foundations of a tunnel built to channel the course of a river, Eng. Fail. Anal. 32 (2013) 152–166. [9] ABAQUS v 6.4, Dassault Simulia International Inc., 2014. [10] Y.D. Zhao, C. Liu, Y.X. Zhang, J.S. Yang, T.G. Feng, Damaging behavior investigation of an operational tunnel structure induced by cavities around surrounding rocks, Eng. Fail. Anal. 99 (2019) 203–209. [11] Y.X. Zhang, Y.F. Shi, Y.D. Zhao, J.S. Yang, Damage in concrete lining of an operational tunnel, J. Perform. Constr. Facil. 31 (4) (2017). [12] X.M. Zhang, J.S. Yang, Y.X. Zhang, Y.F. Gao, Cause investigation of damages in existing building adjacent to foundation pit in construction, Eng. Fail. Anal. 83 (2018) 117–124.
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Contents lists available at ScienceDirect
Engineering Failure Analysis journal homepage: www.elsevier.com/locate/engfailanal
Construction practice of landslide during tunneling in hilly topography
T
⁎
Pan Lia,b, Cheng Liua, Yongxing Zhanga,c, , Jian Zhangd, Junsheng Yange, Tugen Fengd a
School of Civil Engineering, Nanjing Forestry University, Nanjing 210037, Jiangsu, China School of Rail Transportation, Soochow University, Suzhou 215137, China National Engineering Laboratory of Highway Maintenance Technology, Changsha University of Science & Technology, Changsha 410114, China d College of Civil and Transportation Engineering, Hohai University, No.1 Xikang Road, Nanjing 210098, China e School of Civil Engineering, Central South University, Changsha 410075, China b c
A R T IC LE I N F O
ABS TRA CT
Keywords: Tunneling Landslide Field investigation Numerical analysis Treating countermeasure
This paper presents a case study of landslide during tunneling period in hilly topography, and a practical treating countermeasure is also proposed in the study. The field investigation and numerical analysis demonstrate that tunneling in hilly topography with sloping stratification has risk of landslide while heavy rainfall permeates into ground, and a treating countermeasure of anti-slide piles combined with in-layer compacted backfilling is adopted in the practical implementation. Moreover, the implemented treating work demonstrates that the employed countermeasure is capable of treating landslide during tunneling with heavy rain water permeating into ground, which can provide the design basis for similar treating work.
1. Introduction Tunnel has been widely used in highway engineering due to obvious advantages of traversing obstacle with mountains and rivers [1], the construction of which inevitably encounters terrible geological condition [2–4]. Many published studies have demonstrate that landslide is easily induced during tunneling [5–7]. However, the cause of the aforementioned landslide is not easy to be identified due to very complex influencing factors, such as not only construction method or support system but also harsh geological condition [6,8]. Therefore, the effective treating countermeasure of landslide during tunneling is difficult to determine and further study is urgently required. In this paper, a case study of treating landslide during tunneling period in hilly topography is presented by field investigation and numerical analysis, in which the sloping stratification with heavy rain water permeating into ground is field observed. The study focuses on the effectiveness of the adopted countermeasure for treating landslide during tunneling. 2. Profile of the tunnel 2.1. Landform and geological condition around tunnel site The tunnel is located in denudated hilly topography and buried with quaternary strata, which is 10,743 m long with 515 m
⁎ Corresponding author at: School of Civil Engineering, Nanjing Forestry University, Nanjing 210037, Jiangsu, China; National Engineering Laboratory of Highway Maintenance Technology, Changsha University of Science & Technology, Changsha 410114, China. E-mail address: [email protected] (Y. Zhang).
https://doi.org/10.1016/j.engfailanal.2019.07.064 Received 15 March 2019; Received in revised form 21 July 2019; Accepted 28 July 2019 Available online 29 July 2019 1350-6307/ © 2019 Published by Elsevier Ltd.
Engineering Failure Analysis 104 (2019) 1234–1241
P. Li, et al.
(a) Schematic geology
(b) Location of supplementary geological drillings Fig. 1. Geological condition investigation of the tunnel.
maximum buried depth. Fig. 1 demonstrate the schematic geological condition with steep slope and V-shaped valley. The major rock strata of tunnel entrance are hard-soft heterogeneous ground with sloping stratification, in which there is no visible water in the fissures. The surrounding rocks are respectively constituted of fully-weathered, strongly-weathered and weakly-weathered micaquartzose schist, in which 9 geological drillings are implemented for supplementary survey as marked in Fig. 1(b).
Fig. 2. Construction sequences of the tunnel. 1235
Engineering Failure Analysis 104 (2019) 1234–1241
P. Li, et al.
Fig. 3. Observed ground movement of tunnel entrance during tunneling.
2.2. Construction procedures Fig. 2 demonstrates the tunnel construction sequences for reducing the disturbance of unstable surrounding rock, in which the construction steps are annotated from 1 to 8. As shown in Fig. 2, the tunnel is excavated and supported with the following procedures: step 1 and 2: excavating upper bench and constructing primary lining around upper bench→ step 3 and 4: excavating middle bench and constructing primary lining around middle bench→ step 5 and 6: excavating lower bench and constructing primary lining around lower bench→ step 7: excavating invert arch and backfilling invert arch with concrete→ step 8: constructing secondary lining. 3. Field investigation of damages during tunneling Field investigation are implemented to obtain the damages during tunneling. Fig. 3 demonstrates the observed typical transfixion cracks and sliding behavior occurred in ground surface, the longitudinal length of which is greater than 200 m and the maximum crack width is almost 0.25 m. Moreover, serious cracks are also observed in the front and side slopes of the tunnel entrance as shown in Fig. 4. Especially, heavy rainfall is observed before slide in ground surface. Fig. 5 demonstrates that cracks occur in concrete lining during excavating the tunnel entrance, in which several longitudinal cracks are observed with 6 mm maximum width, ranged from position B to C as marked in Fig. 2. Moreover, the deviations of tunnel lining are investigated using total station scanning system, and the maximum deviations at both sides of concrete lining are 0.194 m and 0.239 m as shown in Fig. 6. 4. Numerical investigation of landslide during tunneling 4.1. Numerical model The numerical analysis of aforementioned landslide during tunneling is also implemented for investigating the cause of landslide during tunneling using ABAQUS software [9], the numerical model of which is shown in aforementioned Fig. 1. The longitudinal calculation range of the numerical model is 229.4 m, and the vertical calculation ranges of both lateral sides are 111.6 m and 20 m respectively, including vertical range of 17.6 m from tunnel bottom to the lower boundary. Moreover, some assumptions are adopted for the boundary conditions of the numerical model. The displacements of lower boundary are constrained in longitudinal and vertical directions, those of both lateral boundaries are restricted in longitudinal direction, and those of upper boundary are free in both longitudinal and vertical directions.
Fig. 4. Observed cracks in front and side slopes of tunnel entrance. 1236
Engineering Failure Analysis 104 (2019) 1234–1241
P. Li, et al.
Fig. 5. Typical crack in concrete lining of the tunnel.
Fig. 6. Deviations of tunnel lining (unit: m).
4.2. Material property The physical properties of lining concrete and surrounding rocks are listed in Table 1, obtained from aforementioned supplementary geological survey and laboratory test with 25 grouped specimens, in which E is elastic modulus, γ is bulk density, fc’ is compressive strength of concrete, μ is Poisson's ratio, φ is friction angle, and c is cohesive force. The effect of steel arch is converted to that of shotcrete in primary lining, and the surrounding rocks are considered as ideal elastic-plastic material met with Mohr Coulomb yield criterion, which also can reflect the behavior of surrounding rocks during tunneling [10–12]. Fig. 7 demonstrates the numerical model and boundary condition, the longitudinal calculation range is 229.4 m, that of lateral side to the tunnel is 30.4 m, and the vertical calculation ranges of both lateral sides are 111.6 m and 20 m from top surface to lower boundary respectively. The bottom boundary is fixed in both longitudinal and vertical directions, and both lateral boundaries are restricted in longitudinal direction, whereas upper boundary is free in both longitudinal and vertical directions. Moreover, the calculation of ground stress balance is executed and the calculated displacement is returned to zero for removing the adverse influence on sliding surface. Table 1 Physical properties of surrounding rocks. Material
Physical and mechanical parameter
Fully-weathered mica-quartzose schist Strongly-weathered mica-quartzose schist Weakly-weathered mica-quartzose schist Concrete lining
E = 0.1 GPa, γ = 22 kN/m3, μ = 0.4, c = 0.05 MPa,=28.6° E = 3 GPa, γ = 23 kN/m3, μ = 0.3, c = 0.4 MPa,φ=30° E = 20 GPa, γ = 25 kN/m3, μ = 0.25, c = 1.0 MPa,φ=45° E = 31.5 GPa, μ = 0.2
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Fig. 7. Numerical model and boundary condition (unit: m).
Especially, the strength reduction finite element method is adopted for numerical simulation, which is expected to reflecting the influence of slope stability from tunneling with heavy rainfall permeating into ground. The reduction of friction angle φ and cohesive force c are obtained by the following equations:
tan φ ⎞ φm = arctan ⎛ ⎝ Fr ⎠ ⎜
cm =
⎟
(1)
c Fr
(2)
where φm and cm are reduced friction angle and cohesive force; Fr is strength reduction coefficient. 4.3. Numerical result Fig. 8 shows the plastic zone distribution of surrounding rocks, in which the transfixion plastic zone represents the numerically
(a) Strength reduction coefficient 0.5
(b) Strength reduction coefficient 0.5711 Fig. 8. Plastic zone distribution of surrounding rocks. 1238
Engineering Failure Analysis 104 (2019) 1234–1241
P. Li, et al.
(a) Tamping transfixion cracks
(b) Anti-slide piles combined with in-layer compacted backfilling Fig. 9. Construction treatment of landslide during tunneling.
obtained main sliding surface and illustrates the instability of surrounding rocks. It can be obviously seen continuous plastic zones are gradually developed with the increased strength reduction coefficient, which means the case of landslide during tunneling in hilly topography with sloping stratification is probably influenced by heavy rainfall permeating into ground. This numerical behavior is similar with that in practical construction. 5. Investigation of treating countermeasure for landslide during tunneling 5.1. Field countermeasure to treat landslide during tunneling The above-discussed investigation demonstrates that the case of landslide during tunneling is affected by heavy rainfall permeating into ground. In the treating practice, the observed transfixion cracks are firstly tamped with clay for preventing rain water from slipping into the sliding body again. Thereafter, the in-layer backfilling with compaction is adopted to exert counter pressure for blocking landslide, implemented from hilly foot to top ground surface of tunnel, and 25 anti-slide piles are finally adopted to block landslide and stabilize the ground as shown in Fig. 9. Moreover, four holes in the aforementioned supplementary geological drillings (positions 1#, 4#, 5# 9# as labeled in Fig. 1) are also adopted for measuring the deep landslide using inclinometer pipe. The relationship curves of horizontal displacement and depth at position 4# are demonstrated in Fig. 10, which can verify that just the treating countermeasure of in-layer compacted backfilling is insufficient for blocking landslide with heavy rainfall, whereas that of anti-slide piles combined with in-layer compacted backfilling is effective in practical implementation. 5.2. Effect confirmation of treating countermeasure using numerical investigation The treating countermeasure is numerically investigated, in which the practical treatment of anti-slide piles combined with inlayer compacted backfilling is considered in the numerical model as demonstrated in Fig. 11(a). Moreover, the boundary condition and material properties are similar with those of investigating landslide during tunneling as shown in aforementioned Fig. 7 and Table 1. Fig. 11(b) shows the plastic zone distribution of surrounding rocks after practical treatment, in which there is no continuous plastic zones as well as transfixion plastic zone. This means the adopted treatment of anti-slide piles combined with in-layer compacted backfilling is capable of treating landslide during tunneling with heavy rain water permeating into ground. 6. Conclusions In this paper, a construction practice of treating landslide during tunneling in hilly topography is studied, and the following conclusions are obtained: (1) Tunneling in hilly topography with sloping stratification has risk of landslide while heavy rainfall permeates into ground, and the 1239
Engineering Failure Analysis 104 (2019) 1234–1241
P. Li, et al.
Fig. 10. Horizontal displacement versus depth of ground at position #4.
(a) Numerical model and boundary condition (unit: m)
(b) Plastic zone distribution of surrounding rocks Fig. 11. Numerical simulation of practical treating countermeasure.
treating countermeasures with in-time treatment are required. (2) The adopted treating countermeasure of anti-slide piles combined with in-layer compacted backfilling is capable of treating landslide during tunneling with heavy rain water permeating into ground, which can provide the design basis for similar treating work. 1240
Engineering Failure Analysis 104 (2019) 1234–1241
P. Li, et al.
Declaration of Competing Interest The authors declare that there is no conflict of interest in the manuscript. Acknowledgements The author would like to acknowledge the support from National Natural Science Foundation of China (No. 51578292, 51408124, 51508278), Open Fund of National Engineering Laboratory of Highway Maintenance Technology(Changsha University of Science & Technology, Grant No. kfj170101), Six Talent Peak Projects and Qinglan Project. References [1] J.Y. Fu, J.S. Yang, X.M. Zhang, H. Klapperich, S.M. Abbas, Response of the ground and adjacent buildings due to tunnelling in completely weathered granitic soil, Tunn. Undergr. Space Technol. 43 (2014) 377–388. [2] J. Okazaki, A. Ogawa, T. Tamura, A study on cracks of tunnel concrete lining in squeezing ground, J. Tunnel Eng. JSCE 13 (2003) 53–60. [3] Y.X. Zhang, Y.F. Shi, Y.D. Zhao, L.R. Fu, J.S. Yang, Determining the cause of damages in a multiarch tunnel structure through field investigation and numerical analysis, J. Perform. Constr. Facil. 31 (3) (2017). [4] X.Y. Ye, S.Y. Wang, J.S. Yang, D.C. Sheng, C. Xiao, Soil conditioning for EPB shield Tunneling in argillaceous siltstone with high content of clay minerals: case study, Int.l J. Geomech. 17 (4) (2017). [5] M. Inmaculada Alvarez-Fernandez, E. Amor-Herrera, C. Gonzalez-Nicieza, F. Lopez-Gayarre, M. Rodriguez Avial-Llardent, Forensic analysis of the instability of a large-scale slope in a coal mining operation, Eng. Fail. Anal. 33 (2013) 197–211. [6] Y.X. Zhang, J.S. Yang, F. Yang, Field investigation and numerical analysis of landslide induced by tunneling, Eng. Fail. Anal. 47 (2015) 25–33. [7] M. Chatziangelou, B. Christaras, Landslides and tunneling geological failures, during the construction of Thessaloniki-Kavala section of Egnatia highway in N. Greece, Int. J. Geol. 4 (2) (2010) 48–57. [8] M.B. Prendes-Gero, F. Lopez-Gayarre, C. Menendez-Fernandez, M. Rodriguez-Avial Llardent, Forensic analysis of the failure of the foundations of a tunnel built to channel the course of a river, Eng. Fail. Anal. 32 (2013) 152–166. [9] ABAQUS v 6.4, Dassault Simulia International Inc., 2014. [10] Y.D. Zhao, C. Liu, Y.X. Zhang, J.S. Yang, T.G. Feng, Damaging behavior investigation of an operational tunnel structure induced by cavities around surrounding rocks, Eng. Fail. Anal. 99 (2019) 203–209. [11] Y.X. Zhang, Y.F. Shi, Y.D. Zhao, J.S. Yang, Damage in concrete lining of an operational tunnel, J. Perform. Constr. Facil. 31 (4) (2017). [12] X.M. Zhang, J.S. Yang, Y.X. Zhang, Y.F. Gao, Cause investigation of damages in existing building adjacent to foundation pit in construction, Eng. Fail. Anal. 83 (2018) 117–124.
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