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数值模拟研究了马蹄形隧道在不同载荷下从围岩初始损伤至失稳破坏的破坏过程,分析了侧压力系数λ对隧道的初始损伤、拱顶位移、围岩应力分布特征和围岩损伤破坏模式的影响,研究结果表明,损伤机制与λ密切相关,当λ较小时,在空间上初始损伤分布具有较大的离散性,以拱脚、拱肩和拱顶位置为主;当λ较大时,初始损伤以拱顶的拉伸损伤位置为主;拱顶垂直方向的位移随λ的增大而减小,且随埋深的增加而增大;隧道围岩的最大和最小主应力随λ的增大而增大,隧道围岩应力分布和应力集中程度受隧道形状的影响显著,在一定范围内,隧道形状比离自由面的距离作用机制更为强烈;在破裂模式上,当λ较小时,裂纹以垂直方向开裂为主,随着λ的增大转变为以水平方向开裂为主。
Numerical simulation studies the failure process of the horseshoe tunnel from initial damage to instability of surrounding rock under different loads, and analyzes the initial damage of lateral pressure coefficient λ, the dome displacement, the stress distribution characteristics of surrounding rock and the failure damage model of surrounding rock The results show that the damage mechanism is closely related to λ. When λ is small, the distribution of the initial damage in space is more discrete with the positions of arch foot, arch shoulder and vault. When λ is large The initial damage is dominated by the tensile damage of the dome. The displacement in the vertical direction of the dome decreases with the increase of λ, and increases with the increase of the buried depth. The maximum and minimum principal stresses of the surrounding rock of the tunnel vary with λ The stress distribution and stress concentration of the surrounding rock of the tunnel are significantly affected by the shape of the tunnel. Within a certain range, the tunnel shape is stronger than the distance from the free surface. In the rupture mode, when λ is larger Hour, cracks mainly in the vertical direction of cracking, with the increase of λ changes to the horizontal crack-based.