Performance of Super-Large-Span Tunnel Portal Excavated by Upper Bench CD Method Based on Field Monitoring and Numerical Modeling

<table class="table-group" id="tab1"><tr><td><table class="table"><tr><td class="thead-hr" colspan="2"><hr/></td></tr><tr><td class="align_left">Temporary support</td><td class="align_center"><i>φ</i>50 × 5 pregrouting pipe: first row <i>L</i> = 6 m, angle = 6°; second row <i>L</i> = 3m, angle = 15°; circumferential spacing = 40 cm, longitudinal spacing = 1.2 m.</td></tr><tr><td class="align_left" colspan="2"><hr/></td></tr><tr><td class="align_left">Primary support</td><td class="align_center">C25 shotcrete, thickness = 30 cm; <i>φ</i>25 hollow grouting anchor <i>L</i> = 500 cm, spacing = 60 cm; double layer <i>φ</i>8 steel mesh, spacing = 20 × 20 cm; H200 steel rib, spacing = 60 cm; reserved deformation = 20 cm.</td></tr><tr><td class="align_left" colspan="2"><hr/></td></tr><tr><td class="align_left">Secondary lining</td><td class="align_center">C30 concrete, thickness = 70 cm; 40 g/m<sup>2</sup> nonwoven fabrics; EVA waterproof cloth, thickness = 1.5 mm.</td></tr><tr class="table-tr"><td colspan="2"><hr class="tbody-hr"/></td></tr></table></td></tr></table>

<div>The support system of the tunnel portal.</div>

Advances in Civil Engineering

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Table 1

Table 1: Performance of Super-Large-Span Tunnel Portal Excavated by Upper Bench CD Method Based on Field Monitoring and Numerical Modeling 