Abstract: In layered soft rock stratum,the asymmetric failure characteristic of surrounding rock and asymmetric stress feature of supporting system are remarkable after tunnel excavation, resulting in a great challenge for stability control of surrounding rock. Based on this background, an anisotropic constitutive model of layered rock was established to analyze the influence of inclination angle and dip angle of foliation on the failure pattern of surrounding. Finally, the asymmetric support mode of rock bolt for deformation control of surrounding rock was put forward. The research results show that: ①When the inclination angle is 0° and the dip angle is 0°~180°or the dip angle is 0° and the inclination angle is 0°~90°,the plastic failure area and significant deformation area of surrounding rock under different combinations are symmetrically distributed along the vertical axis of the tunnel. When the dip angle is between 0 ° and 90 °, the plastic zone and deformation significant zone of surrounding rock show obvious asymmetric distribution characteristics. When the inclination angle is 90° and the dip angle is 90°,the plastic area and significant deformation area of surrounding rock are symmetrically distributed along the vertical axis of the tunnel.Under the conditions with other dip angles, the plastic zone and significant deformation zone of surrounding rock are asymmetrically distributed along the vertical axis of the tunnel.②For layered rock mass, the characteristic of foliation is the most important factor to influence the failure mode of surrounding rock, and the dinection of geo-stress field is a secondary factor.③The asymmetric bolt support scheme,which is to firstly strengthen the bolt support in the area with large plastic failure of surrounding rock and secondly strengthen the bolt support in the area with large displacement of surrounding rock,can effectively control the large deformation of surrounding rock and the development of plastic area.Key words： tunnel engineering; layered rock mass; anisotropy; deformation controlling; asymmetric supporting

Key words: tunnel engineering, layered rock mass, anisotropy, deformation controlling, asymmetric supporting

摘要： 层状软岩地层中，隧道开挖后围岩的非对称破坏特征与支护结构的非对称受力特征显著，围岩的稳定性控制面临着较大的挑战。基于该背景，建立了层状岩体各向异性本构模型，并采用该模型分析了层理面的倾向与倾角对隧道破坏模式的影响，最终提出了围岩形变控制的锚杆非对称支护模式。研究结果表明：①当岩层倾角为0°，倾向为0°~180°或倾向为0°，倾角为0°~90°时，不同组合下围岩的塑性破坏区及形变显著区域均沿着隧道竖向轴线对称分布；倾角在0°~90°之间时，围岩的塑性区及形变显著区域呈现明显的非对称分布特征；倾角为90°，倾向为90°时，围岩塑性区及形变显著区域沿着隧道竖向轴线对称分布，其余倾向条件下，围岩的塑性区及形变显著区域沿着隧道竖向轴线非对称分布；②对于层状岩体而言，层理面特征是影响围岩破坏模式的最关键因素，而地应力场的方向是次要因素；③锚杆非对称支护方案，即首先加强围岩塑性破坏较大区域内的锚杆支护，其次加强围岩位移较大区域内的锚杆支护，可以有效的控制围岩的大变形与塑性区的发展。

关键词: 隧道工程, 层状岩体, 各向异性, 形变控制, 非对称支护