为研究渝昆高铁斜向超前系统锚杆支护体系的力学特性，在乐业隧道开展了斜向超前系统锚杆现场试验，结合有限差分数值模拟，基于支护应力场的概念，实现斜向超前系统锚杆有效支护范围的定量描述，采用多指标（隧道位移差、围岩塑性区、围岩最小主应力）对斜向超前系统锚杆的支护效果进行定量评价。通过分析锚杆轴力、钢拱架轴力的分布特征，确定斜向超前支护体系的承载规律，并与现场试验结果进行验证和对比分析。结果表明： 1)隧道开挖后，锚杆支护会形成支护应力场，即在开挖面附近形成了最大主应力增大区，而最大主应力的增大提高了岩体抵抗变形的能力； 2)随着掌子面空间效应的减弱，斜向锚杆需要承担的围岩荷载逐渐增大，其有效支护的范围也逐渐增大； 3)在掌子面附近，斜向锚杆支护提高了围岩的自承载能力，降低了拱顶、拱肩和拱腰处钢拱架的轴力，改善了钢拱架的受力特征。
To investigate the
mechanical properties of inclined and advance rockbolts on the Chongqing-Kunming high-speed railway, a field test is
conducted in the Leye tunnel. Utilizing the support stress field concept,
finite difference numerical simulations provide a quantitative description of
the effective support range for these rockbolts. A multi-index method-considering tunnel displacement
differences, surrounding rock plastic zones, and minimum principal stress in
the surrounding rock-is employed to quantitatively
evaluate the support effectiveness of the rockbolts. By analyzing the axial
force distribution in the rockbolts and steel arch, the bearing pattern of the
inclined and advance support system is determined and validated through field
test results. The results reveal that: (1) After tunnel excavation, the
rockbolt support creates a stress field with increased maximum principal stress
near the excavation face, enhancing the anti-deformation
ability of rock mass. (2) As the spatial effect of the tunnel face weakens, the
load on the surrounding rock supported by the rockbolts increases, resulting in
a larger effective support range. (3) Near the tunnel face, inclined and
advance support improves the self-bearing capacity of
the surrounding rock, reduces axial forces in the steel arch at the crown,
shoulder, and haunch, and improves the stress characteristics of the steel
arch.
