Scholarlink

<p>This study presents a detailed stability assessment of unsupported rectangular tunnels with rounded corners excavated in rock masses, using Adaptive Finite Element Limit Analysis. The analysis investigated the combined influence of geometric parameters that are cover depth-to-height ratio (<i>C/H</i>), edge length-to-width ratio (<i>e/B</i>), curvature radius-to-width ratio (<i>r/B</i>) along with geomechanical properties including the Geological Strength Index (<i>GSI</i>) and the intact rock parameter (<i>m</i><sub><i>i</i></sub>), and the tunnel stability was quantified through a dimensionless stability number (<i>N</i>). Parametric results show that <i>N</i> is highly sensitive to both rock mass quality and tunnel geometry. In high-quality, frictional rocks (<i>GSI</i> ≥ 80, <i>m</i><sub><i>i</i></sub> ≥ 20), <i>N</i> increases significantly with greater curvature and deeper cover, reflecting enhanced shear strength mobilization and confinement effects. Conversely, in low friction dominated rocks (<i>m</i><sub><i>i</i></sub> = 5), the effect of geometric optimization remains limited. The failure plane was analyzed using shear dissipation contours, which reveal a transition from brittle, surface-directed failure at low <i>GSI</i> and shallow cover to ductile, laterally arching mechanisms at higher <i>GSI</i> and greater overburden. Rounded corners (higher <i>r/B</i>) reduce the shear concentration near tunnel corners, promoting more distributed failure.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Stability Analysis of Unsupported Rectangular Tunnels with Rounded Corners in Rock Formations

  • 期刊论文

  • 发表日期：

    2025年8月14日

查看全文
  • Rishabh Kashyap,
  • Vinay Bhushan Chauhan

摘要

This study presents a detailed stability assessment of unsupported rectangular tunnels with rounded corners excavated in rock masses, using Adaptive Finite Element Limit Analysis. The analysis investigated the combined influence of geometric parameters that are cover depth-to-height ratio (C/H), edge length-to-width ratio (e/B), curvature radius-to-width ratio (r/B) along with geomechanical properties including the Geological Strength Index (GSI) and the intact rock parameter (mi), and the tunnel stability was quantified through a dimensionless stability number (N). Parametric results show that N is highly sensitive to both rock mass quality and tunnel geometry. In high-quality, frictional rocks (GSI ≥ 80, mi ≥ 20), N increases significantly with greater curvature and deeper cover, reflecting enhanced shear strength mobilization and confinement effects. Conversely, in low friction dominated rocks (mi = 5), the effect of geometric optimization remains limited. The failure plane was analyzed using shear dissipation contours, which reveal a transition from brittle, surface-directed failure at low GSI and shallow cover to ductile, laterally arching mechanisms at higher GSI and greater overburden. Rounded corners (higher r/B) reduce the shear concentration near tunnel corners, promoting more distributed failure.