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Stability Evaluation of Unlined Circular Tunnels in Sloping Rock Terrain Using Adaptive Finite Element Limit Analysis
https://orcid.org/http://orcid.org/0000-0002-6939-885X
https://orcid.org/http://orcid.org/0000-0002-9004-7165
Tunnels play a pivotal role in challenging terrains marked by undulations and slopes, where the construction of tunnels is notably more intricate than in flat terrain. This study employs numerical simulation techniques, specifically upper bound (UB) and lower bound (LB), adaptive finite element limit analysis (AFELA), to assess the stability of an unlined circular tunnel under surcharge loading conditions. This study delves into the complex relationship between various factors and the stability of circular shaped tunnel (Nc) in challenging undulating ground. These parameters include geometrical factors such as cover depth ratio (δ/dt), inclination of slope (β), and material properties like uniaxial compressive strength (σci), geological strength index (GSI), and material constant (mi) of the rock formation. Moreover, this investigation explicates potential failure mechanisms in tunnels situated within inclined rock formations, aiming to acquire a comprehensive understanding of their behavior and discern diverse failure zones that may arise during tunnel collapse. The findings demonstrate that a slope with β ≤ 10° affects Nc, while β > 10° considerably diminishes tunnel stability when compared to a tunnel in a levelled rock formation. A linear correlation between cover depth ratio (δ/dt) and Nc is observed, whereas GSI and Nc exhibit an exponentially increasing relationship. An empirical equation was derived using ANN and MLR methods to predict the stability factor Nc, with R2 values of 0.999 and 0.9545, respectively. This study holds practical significance for tunnel designers, providing valuable insights into the assessment of unlined circular tunnels in sloping rock formations, along with potential failure mechanisms.
Stability Evaluation of Unlined Circular Tunnels in Sloping Rock Terrain Using Adaptive Finite Element Limit Analysis
https://orcid.org/http://orcid.org/0000-0002-6939-885X
https://orcid.org/http://orcid.org/0000-0002-9004-7165
Tunnels play a pivotal role in challenging terrains marked by undulations and slopes, where the construction of tunnels is notably more intricate than in flat terrain. This study employs numerical simulation techniques, specifically upper bound (UB) and lower bound (LB), adaptive finite element limit analysis (AFELA), to assess the stability of an unlined circular tunnel under surcharge loading conditions. This study delves into the complex relationship between various factors and the stability of circular shaped tunnel (Nc) in challenging undulating ground. These parameters include geometrical factors such as cover depth ratio (δ/dt), inclination of slope (β), and material properties like uniaxial compressive strength (σci), geological strength index (GSI), and material constant (mi) of the rock formation. Moreover, this investigation explicates potential failure mechanisms in tunnels situated within inclined rock formations, aiming to acquire a comprehensive understanding of their behavior and discern diverse failure zones that may arise during tunnel collapse. The findings demonstrate that a slope with β ≤ 10° affects Nc, while β > 10° considerably diminishes tunnel stability when compared to a tunnel in a levelled rock formation. A linear correlation between cover depth ratio (δ/dt) and Nc is observed, whereas GSI and Nc exhibit an exponentially increasing relationship. An empirical equation was derived using ANN and MLR methods to predict the stability factor Nc, with R2 values of 0.999 and 0.9545, respectively. This study holds practical significance for tunnel designers, providing valuable insights into the assessment of unlined circular tunnels in sloping rock formations, along with potential failure mechanisms.
Stability Evaluation of Unlined Circular Tunnels in Sloping Rock Terrain Using Adaptive Finite Element Limit Analysis
https://orcid.org/http://orcid.org/0000-0002-6939-885X
https://orcid.org/http://orcid.org/0000-0002-9004-7165
Tunnels play a pivotal role in challenging terrains marked by undulations and slopes, where the construction of tunnels is notably more intricate than in flat terrain. This study employs numerical simulation techniques, specifically upper bound (UB) and lower bound (LB), adaptive finite element limit analysis (AFELA), to assess the stability of an unlined circular tunnel under surcharge loading conditions. This study delves into the complex relationship between various factors and the stability of circular shaped tunnel (Nc) in challenging undulating ground. These parameters include geometrical factors such as cover depth ratio (δ/dt), inclination of slope (β), and material properties like uniaxial compressive strength (σci), geological strength index (GSI), and material constant (mi) of the rock formation. Moreover, this investigation explicates potential failure mechanisms in tunnels situated within inclined rock formations, aiming to acquire a comprehensive understanding of their behavior and discern diverse failure zones that may arise during tunnel collapse. The findings demonstrate that a slope with β ≤ 10° affects Nc, while β > 10° considerably diminishes tunnel stability when compared to a tunnel in a levelled rock formation. A linear correlation between cover depth ratio (δ/dt) and Nc is observed, whereas GSI and Nc exhibit an exponentially increasing relationship. An empirical equation was derived using ANN and MLR methods to predict the stability factor Nc, with R2 values of 0.999 and 0.9545, respectively. This study holds practical significance for tunnel designers, providing valuable insights into the assessment of unlined circular tunnels in sloping rock formations, along with potential failure mechanisms.
Stability Evaluation of Unlined Circular Tunnels in Sloping Rock Terrain Using Adaptive Finite Element Limit Analysis
Indian Geotech J
Kumar, Aayush (author) / Chauhan, Vinay Bhushan (author)
Indian Geotechnical Journal ; 55 ; 1-29
2025-02-01
29 pages
Article (Journal)
Electronic Resource
English
Hydraulic Design of Unlined Rock Tunnels
| ASCE | 2021
Head losses in unlined rock tunnels
| UB Braunschweig | 1970
Hydraulic design of unlined rock tunnels
| Engineering Index Backfile | 1969