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深埋隧道常处于构造应力状态,且水平应力分布并不均匀。采用数值模拟和模型试验方法,研究自重应力场、水平大主应力与洞线平行和垂直、不同围岩级别隧道轴线选择对围岩和衬砌结构稳定性影响。水平大主应力与洞轴平行时,围岩最不利位置发生在边墙;水平大主应力与洞轴垂直时,围岩最不利出现在拱顶。水平地应力使得二次衬砌受力特征发生很大改变,自重应力条件下,衬砌首先发生裂缝部位为拱顶,发生压弯破坏,建议加强衬砌拱顶内侧纵向配筋,提高正截面抗拉能力。当大主水平应力与轴线垂直时,关键控制部位为墙脚,出现压剪破坏,应增设墙脚箍筋,提高抗剪承载力。规范提出隧道轴线宜与水平大主应力方向一致原则,是有适用条件的。研究成果可为深埋隧道设计、施工提供参考。
Deep tunnels are often in tectonic stress state, and the horizontal stress distribution is not uniform. Numerical simulation and model test methods are used to study the effects of self-weight stress field, horizontal principal principal stress and horizontal and vertical cave lines on the stability of surrounding rock and lining. When the horizontal major principal stress is parallel to the hole axis, the most unfavorable position of the surrounding rock occurs at the side wall. When the principal principal stress of the horizontal plane is perpendicular to the hole axis, the most unfavorable surrounding rock appears in the vault. Under horizontal stress, the stress characteristics of the secondary lining greatly changed. Under the conditions of self-weight stress, the crack first occurred in the lining and the bending occurred. It is suggested to strengthen the longitudinal reinforcement inside lining vault and improve the tensile strength of normal section . When the main level of stress perpendicular to the axis, the key control site for the foot of the wall, the emergence of pressure shear damage, wall stirrups should be added to improve the shear capacity. The standard proposes that the tunnel axis should coincide with the principle of horizontal principal stress, which is applicable. The research results can provide reference for the design and construction of deep tunnels.