Proposal on Design of Vertical Pre-Reinforced Bolt Method

在山地隧道或浅埋隧道入口区域的隧道开挖中，有时会发生隧道开挖面地面沉降、塌方或隧道上方边坡滑坡等问题。应对此类问题的辅助方法被称为“垂直预加固锚杆法”，该方法适用于保持自然环境。然而，竖向预加固法的设计主要是基于地面运动与锚杆之间的等效力方面的经验。它不是一种充分评价加固效应以保护地面沉降和滑坡的方法。此外，从现场测量中仍然很少有数据阐明该方法的有效性。本研究旨在通过模型试验验证隧道底部断面水平以下加固构件侵彻深度的有效性，以减少场地宽度和施工成本。对竖向预加固锚杆法的设计与施工提出了建议方法。研究结果表明，竖向预加固锚杆是一种轴向加固模式，对隧道开挖后的地面拱起到辅助作用。隧道开挖荷载通过其加固有效地分布在巷道正面和侧面。本研究完成。

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.