隧道超前小导管-拱锚支护体系的力学响应分析

Mechanical response analysis of tunnel overhead small conduit-arch-anchor support system in loose enclosed rock section

摘要

【目的】为探究超前小导管-拱锚支护体系在破碎围岩段施工中的力学响应规律，以桐梓隧道为工程背景，构建了“超前小导管-钢拱架-锁脚锚杆”协同作用力学模型。【方法】基于结构力学理论，结合辛普森数值积分法与虚功原理，分步解析荷载传递路径，并采用隧道实测数据动态校准参数。【结果】研究结果表明：建立的模型可精准预测不同开挖步距下的拱脚传递荷载(剪力、弯矩、轴力)、拱脚变位及拱顶沉降，与现场监测数据对比误差小于9%,验证了模型的可靠性；超前小导管注浆显著提升了围岩稳定性，其锚固体分担约6%的围岩荷载，且钢拱架间距缩小可有效抑制沉降，但需兼顾经济性，建议Ⅳ级围岩段间距取80 cm。【结论】提出的三维协同力学模型，首次实现了超前支护体系从注浆锚固体至锁脚锚杆的全路径荷载解析，为超前小导管动态支护设计提供了兼具理论严谨性与工程实用性的参考依据。

Abstract

[Objective] In order to investigate the mechanical response law of the overreach small conduit-arch anchor support system in the construction of fractured perimeter rock section, Tongzi Tunnel was taken as the engineering background, and constructs the synergistic mechanical model of “overreach small conduit-steel arch-anchor”[Methods] Based on the theory of structural mechanics, combining Simpson's numerical integration method with the principle of virtual work, the load transfer path is analyzed step by step, and the parameters are dynamically calibrated by using the actual tunnel measurement data. [Results] The result show that the model can accurately predict the transfer loads(shear force, bending moment, axial force), arch foot displacement and arch settlement under different excavation steps, and the error is less than 9% compared with the on-site monitoring data, which verifies the reliability of the model; the overtopping small conduit grouting improves the stability of the surrounding rock significantly, and its anchors share about 6% of the surrounding rock load, and the reduction in the spacing of the steel arch frame can inhibit the settlement effectively, but it needs to take into account the economy. The spacing of steel arch can effectively inhibit the settlement, but need to take into account the economy, it is recommended that the spacing of Ⅳ perimeter rock section take 80 cm. [Conclusion] The three-dimensional cooperative mechanical model proposed in this study realizes for the first time the load analysis of the whole path of the overrun support system from the grouting anchor solid to the locking foot anchor, which provides a reference basis of both theoretical rigor and engineering practicability for the design of the dynamic support of overrun small catheters.

关键词

隧道开挖 / 超前小导管 / 拱锚 / 开挖步距 / 力学传递 / 沉降预测 / 影响因素 / 破碎围岩

Key words

tunnel excavation / overhead small conduit / arch anchor / excavation step spacing / mechanical transfer / settlement prediction / influence factor / fractured perimeter

基金资助

国家自然科学基金项目(52464004)

贵州省自然科学基金项目(黔科合基础—ZK[2022]一般082)

贵州省重大科技专项(黔科合重大专项字[2018]3011)

贵阳城市轨道交通科研项目(GD3-FW-YJ-05-2020-13-ZB)

贵州省自然科学基金项目(黔科合基础[2019]1057 号)