膨胀作用下板岩隧道支护结构力学响应数值模拟研究

Numerical Simulation Research on Mechanical Response of Slate Tunnel Supporting Structures under Action of Swelling

富水板岩地层的膨胀问题一直是地下工程领域亟待解决的难点问题.以沪昆客运专线长昆湖南段姚家隧道出现的膨胀问题为出发点,利用MIDAS/GTS软件建立二维平面应变非线性对称计算模型,将已取得的基于时间效应的富水板岩隧道围岩膨胀本构模型导入至MIDAS/GTS软件中,研究膨胀作用下板岩隧道支护结构力学响应机制.结果表明:板岩在膨胀作用过程中,围岩膨胀力成为影响支护结构内力的主要荷载,由于膨胀力的存在,拱脚处的轴力、剪力、弯矩和仰拱跨中弯矩、轴力均会显著增加;围岩在膨胀过程中,与支护结构密贴的围岩附近会产生明显的塑性区,塑性区主要集中在隧道仰拱以下区域和拱顶附近环形区域内,仰拱以下塑性区层次明显;塑性区的分布范围和隧道支护结构的位移之间呈正相关性.

The swelling problem of water-rich slate stratum has been a difficult problem urgently to be solved in underground engineering field. Based on the swelling problem of Yaojia tunnel at Changsha to Kunming Section in Shanghai to Kunming High-speed railway of China, MIDAS/GTS is used to establish the two-dimensional plane strain calculation model. In order to study the mechanical response mechanism of slate rock tunnel supporting structure under swelling effect, a time-dependent constitutive model for swelling surround- ing rock of tunnel in water-rich slate is imported to the calculation model. The results show that the swelling force of surrounding rock is the main load that influences the internal force of supporting structure in the swelling process of slate. P cause of the existence of swelling force, the axial force, shear force, bending mo- ment and axial force of the arch foot and mid-span bending moment and axial force of the invert significantly increase. In the process of swelling of the surrounding rock, obvious plastic zone will be produced near the surrounding rock closed to the supporting structure. Moreover, the plastic zone is mainly concentrated in the region under the inverted arch of the tunnel and circular area near the vault. Besides, the level of the plastic zone under the inverted arch is obvious. The relationship between the distribution of plastic zone and displace- ment of tunnel supporting structure presents the positive correlation.