摘要
针对盾构隧道施工中的被动破坏问题,提出一种基于对数螺旋曲面轮廓的盾构隧道开挖面被动破坏极限支护力计算模型,并通过数值模拟和理论分析对模型的可靠性进行验证。首先,假设盾构隧道的被动破坏机构为三维空间中的对数螺旋曲面轮廓,基于该假设,建立被动极限支护力的理论计算模型,并利用Matlab实现盾构隧道被动破坏机构的三维可视化与支护力的计算。为进一步验证理论模型的可靠性,采用有限差分法软件FLAC3D建立三维数值计算模型,对比分析不同埋深、土体内摩擦角条件下的盾构隧道掌子面的变形与破坏机制。数值模拟结果显示,随着隧道埋深的增加,盾构隧道的被动破坏模式逐渐从突变式“脆性”破坏向渐变式“延性”破坏发展。此外,土体内摩擦角和隧道埋深也是影响被动极限支护力的关键因素。在浅埋和低内摩擦角的地层条件下,盾构支护力对隧道掌子面的稳定性影响显著,当支护力超过极限值时,隧道易发生井喷式破坏。因此,在此类地层条件下的盾构施工中,需特别关注支护力的变化,以避免隧道失稳破坏的发生。通过对比理论计算与数值模拟结果发现,理论模型在埋深较小的情况下与数值模拟结果较为吻合,但在埋深较大的条件下,理论模型对极限支护力的估计存在偏高的问题。因此,在深埋隧道的支护力设计中,建议采用数值模拟的方法进行更为准确的估算。
To address the issue of passive failure during shield tunneling,a calculation model for the passive limit support pressure on the excavation face of a shield tunnel on the basis of a logarithmic spiral surface profile is proposed.The reliability of the model is verified through numerical simulations and theoretical analysis.First,the paper assumes that the passive failure mechanism of the shield tunnel corresponds to a logarithmic spiral surface profile in three-dimensional space.On the basis of this assumption,a theoretical model for calculating the passive limit support pressure is established,and three-dimensional visualization of the passive failure mechanism and support pressure calculation is implemented via MATLAB.To further validate the reliability of the theoretical model,a three-dimensional numerical model is established via the finite difference software FLAC^(3D).A comparative analysis is conducted on the deformation and failure mechanisms of the tunnel face under different burial depths and internal friction angles of the soil.The numerical simulation results reveal that as the burial depth of the tunnel increases,the passive failure mode of the shield tunnel gradually evolves from sudden“brittle”failure to progressive“ductile”failure.Additionally,the internal friction angle of the soil and the burial depth are key factors infuencing the passive limit support pressure.Under conditions of shallow burial and low internal friction angles,the support pressure significantly impacts the stability of the tunnel face.When the support pressure exceeds the limit value,the tunnel is prone to blowout failure.Therefore,during shield construction under such geological conditions,special attention must be given to changes in support pressure to prevent tunnel instability.A comparison of the theoretical calculations with the numerical simulation results reveals that the theoretical model aligns more closely with the numerical simulation results under shallow burial conditions.However,in deeper tunnels,the theoretical model tends to overestimate the limit support pressure.Therefore,in the design of support pressures for deep tunnels,the use of numerical simulation methods is recommended for more accurate estimations.
作者
杨洋
YANG Yang(Guizhou Provincial Transportation Comprehensive Administrative Law Enforcement Direct Subordinate Detachment,Guiyang 550000)
出处
《现代隧道技术》
CSCD
北大核心
2024年第S01期474-484,共11页
Modern Tunnelling Technology
关键词
盾构隧道
开挖面稳定性
三维上限分析
数值模拟
Shield tunnel
Face stability
3D upper limit analysis
Numerical simulation
作者简介
杨洋(1986-),男,高级工程师,主要从事交通运输工程方面的研究工作,E-mail:270844831qq@163.com.
