崩坡积体浅埋偏压隧道超前支护体系受力变形特征研究

Study on Stress and Deformation Characteristics of Advanced Support System in Shallow-Buried Bias Tunnel under Colluvial Deposit

摘要: 以黄河岸索同坡崩坡积体浅埋偏压隧道为背景，为探究在崩坡积体松散、偏压及浅埋等复杂地质条件下，超前支护体系在动态开挖过程中的受力变形特征，采用ABAQUS有限元软件建立三维精细化数值模型，模拟了单侧壁导坑法施工全过程，对超前管棚和超前小导管进行了受力及变形分析。结果表明：(1) 管棚轴力在空间上呈“左凹右凸”分布，随开挖深度增加，受力趋势由拉力逐渐转变为压力，下导坑开挖是管棚轴力变化的主要控制因素；(2) 小导管轴力同样呈“左凹右凸”形态，其轴力受施工阶段和断面位置控制，轴力响应表现为“激增–阶梯递减–稳定”三阶段演化规律，且对上导坑开挖敏感性较强；(3) 在量值上，小导管所受轴力较管棚小一个数量级，支护效果远不及管棚。研究揭示了浅埋偏压崩坡积体隧道超前支护体系的受力演化机制，可为同类工程设计与施工提供参考。

Abstract: Taking the Suotongpo Tunnel, a shallow-buried bias tunnel located in a colluvial deposit on the bank of the Yellow River, as the engineering background, this study aims to investigate the stress and deformation characteristics of the advanced support system during dynamic excavation under complex geological conditions, including loose colluvial deposit, bias pressure, and shallow overburden. A three dimensional refined numerical model was established using the ABAQUS finite element software to simulate the entire construction process using the single side heading method, and the stress and deformation of the advanced pipe roofs and advanced small pipes were analyzed. The results show that: (1) The axial force of the pipe roofs exhibits a spatial distribution of “concave left and convex right” (i.e., compression on the left and tension on the right). As excavation depth increases, the axial force gradually transitions from tension to compression, with the lower side heading excavation being the dominant controlling factor of the axial force variation. (2) The axial force of the small pipes also exhibits a “concave left and convex right” pattern; it is governed by the construction stage and cross section location, and its evolution follows a three stage trend of “sharp increase-stepwise decrease-stabilization”, with strong sensitivity to upper side heading excavation. (3) In terms of magnitude, the axial force of the small pipes is one order of magnitude smaller than that of the pipe roofs, indicating that the support effectiveness of the small pipes is far inferior to that of the pipe roofs. This study reveals the mechanical evolution mechanism of the advanced support system in shallow-buried bias tunnels under colluvial deposits, which can provide a reference for the design and construction of similar projects.