Proposal on Design of Vertical Pre-Reinforced Bolt Method

在山岭隧道或浅埋隧道洞口段开挖过程中，经常会出现地表沉陷、隧道开挖面坍塌或隧道上方边坡滑坡等问题。应对此类问题的辅助方法称为“垂直预加固螺栓法”，旨在保持自然环境。而竖向预加固法的设计是基于经验的，即考虑了地表移动与锚杆受力的等效性。这不是一种充分评估加固效果以保护地面沉降和滑坡的方法。此外，现场测量的数据还不多。本研究计划通过模型试验验证隧道底部水平以下加固构件穿透深度的有效性，以减少场地面积和施工成本。对竖向预加固锚杆法的设计与施工提出了建议，认为竖向预加固锚杆是一种轴向加固模式，可辅助隧道开挖引起的地表拱度。通过对掌子面的加固，使开挖荷载有效地分布在掌子面的正面和侧面。这项研究已经完成。

During tunnel excavation in the area of the entrance of mountain tunnel or shallow tunnel, such many problems as subsidence of the ground surface and collapse of the cutting face of the tunnel or the land slide of the slope above the tunnel sometimes occur. The auxiliary method of coping with such problems, called "Vertical Pre-Reinforced Bolt Method," is adapted to keep the natural surroundings. However, the design of vertical pre-reinforced method based on the experience in respect of the equivalence force between ground movement and rock bolt. It is not a method for sufficiently evaluating the stiffening effect to protect a ground settlement and a land slide. In addition, there is still few data clarifying the effectiveness of this method from field measurements.This study was planned to verify the effectiveness of penetration depth of reinforce members below the bottom section level of the tunnel using model tests with the aim of reducing the width of site area and construction cost. The proposal of the suggested method on the design and construction of vertical pre-reinforced bolt method was pursued.As the result, the vertical pre-reinforced bolt behaved an axis reinforcement model to assist the ground arch of the ground by tunnel excavation. The load of tunnel excavation is effectively distributed in the front and side of the tunnel face by its reinforcement. This research is completed.