The role of dilatancy in shallow overburden tunneling
The mechanical behavior of sandy ground during shallow circular tunneling is explored for various overburden heights H (=0.5D, 1.0D, 1.5D and 2.0D; D is the diameter of the tunnel) and various dilatancy coefficients (ψ/ϕ = 0, 1/3, 1/2, and 1; ϕ and ψ are the internal friction angle and dilation angl...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
KeAi Communications Co., Ltd.
2019-09-01
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| Series: | Underground Space |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S246796741830014X |
| _version_ | 1827852328714108928 |
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| author | Muhammad Shehzad Khalid Mamoru Kikumoto Ying Cui Kiyoshi Kishida |
| author_facet | Muhammad Shehzad Khalid Mamoru Kikumoto Ying Cui Kiyoshi Kishida |
| author_sort | Muhammad Shehzad Khalid |
| collection | DOAJ |
| description | The mechanical behavior of sandy ground during shallow circular tunneling is explored for various overburden heights H (=0.5D, 1.0D, 1.5D and 2.0D; D is the diameter of the tunnel) and various dilatancy coefficients (ψ/ϕ = 0, 1/3, 1/2, and 1; ϕ and ψ are the internal friction angle and dilation angle, respectively) through finite difference analyses. The ground is modeled as a linear elastic-perfectly plastic material that employs the Mohr–Coulomb yield criterion and obeys the non-associated flow rule. The ground reaction curve is applied in conjunction with the stress path as a conceptual tool for interpreting the mechanical response of the ground to tunneling. It is revealed that, at a certain relaxation value, a yield zone develops during tunneling and extends to the surface. This relaxation value increases with increases in the overburden and ψ/ϕ values for the cases of less shallow tunnels (i.e., H = 1.0D, 1.5D and 2.0D), while for the shallowest case (H = 0.5D), the extent of the yield zone to the ground surface is not sensitive to the ψ/ϕ value. The shear strain due to tunneling also increases with an increase in the ψ/ϕ value. Moreover, the ψ/ϕ value affects the radial displacement and the surface settlement due to tunneling. The magnitudes of the surface settlement and the radial displacement at the tunnel crown both decrease with an increase in the ψ/ϕ value. The relative difference in the displacement at the tunnel crown between the upper bound and lower bound values, ψ/ϕ (at the last computed stage), increases with an increase in the overburden height. It is recommended, therefore, that careful consideration be given to the dilatancy angle in the case of relatively less shallow tunnels. Keywords: Shallow tunnels, Dilatancy, Overburden, Ground reaction curve, Stress path |
| first_indexed | 2024-03-12T10:49:10Z |
| format | Article |
| id | doaj.art-0339ec60b71d496cb4087880c2c45576 |
| institution | Directory Open Access Journal |
| issn | 2467-9674 |
| language | English |
| last_indexed | 2024-03-12T10:49:10Z |
| publishDate | 2019-09-01 |
| publisher | KeAi Communications Co., Ltd. |
| record_format | Article |
| series | Underground Space |
| spelling | doaj.art-0339ec60b71d496cb4087880c2c455762023-09-02T07:10:16ZengKeAi Communications Co., Ltd.Underground Space2467-96742019-09-0143181200The role of dilatancy in shallow overburden tunnelingMuhammad Shehzad Khalid0Mamoru Kikumoto1Ying Cui2Kiyoshi Kishida3Department of Urban Management, Kyoto University, Nishikyo-Ku, Kyoto 615-8540, JapanDepartment of Civil Engineering, Yokohama National University, Yokohama, Kanagawa 240-8501, JapanDepartment of Civil Engineering, Yokohama National University, Yokohama, Kanagawa 240-8501, JapanDepartment of Urban Management, Kyoto University, Nishikyo-Ku, Kyoto 615-8540, Japan; Corresponding author.The mechanical behavior of sandy ground during shallow circular tunneling is explored for various overburden heights H (=0.5D, 1.0D, 1.5D and 2.0D; D is the diameter of the tunnel) and various dilatancy coefficients (ψ/ϕ = 0, 1/3, 1/2, and 1; ϕ and ψ are the internal friction angle and dilation angle, respectively) through finite difference analyses. The ground is modeled as a linear elastic-perfectly plastic material that employs the Mohr–Coulomb yield criterion and obeys the non-associated flow rule. The ground reaction curve is applied in conjunction with the stress path as a conceptual tool for interpreting the mechanical response of the ground to tunneling. It is revealed that, at a certain relaxation value, a yield zone develops during tunneling and extends to the surface. This relaxation value increases with increases in the overburden and ψ/ϕ values for the cases of less shallow tunnels (i.e., H = 1.0D, 1.5D and 2.0D), while for the shallowest case (H = 0.5D), the extent of the yield zone to the ground surface is not sensitive to the ψ/ϕ value. The shear strain due to tunneling also increases with an increase in the ψ/ϕ value. Moreover, the ψ/ϕ value affects the radial displacement and the surface settlement due to tunneling. The magnitudes of the surface settlement and the radial displacement at the tunnel crown both decrease with an increase in the ψ/ϕ value. The relative difference in the displacement at the tunnel crown between the upper bound and lower bound values, ψ/ϕ (at the last computed stage), increases with an increase in the overburden height. It is recommended, therefore, that careful consideration be given to the dilatancy angle in the case of relatively less shallow tunnels. Keywords: Shallow tunnels, Dilatancy, Overburden, Ground reaction curve, Stress pathhttp://www.sciencedirect.com/science/article/pii/S246796741830014X |
| spellingShingle | Muhammad Shehzad Khalid Mamoru Kikumoto Ying Cui Kiyoshi Kishida The role of dilatancy in shallow overburden tunneling Underground Space |
| title | The role of dilatancy in shallow overburden tunneling |
| title_full | The role of dilatancy in shallow overburden tunneling |
| title_fullStr | The role of dilatancy in shallow overburden tunneling |
| title_full_unstemmed | The role of dilatancy in shallow overburden tunneling |
| title_short | The role of dilatancy in shallow overburden tunneling |
| title_sort | role of dilatancy in shallow overburden tunneling |
| url | http://www.sciencedirect.com/science/article/pii/S246796741830014X |
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