基底围岩膨胀对泥岩隧道受力特性的影响

Impact of base surrounding rock expansion on the mechanical characteristics of mudstone tunnel

为研究泥岩地区基底膨胀作用下隧道的受力特性及仰拱变形规律,运用非线性有限元数值模拟方法,开展不同含水量条件的基底湿胀特性对泥岩隧道结构的影响分析,获取隧道围岩位移的变化规律,以及衬砌、仰拱、回填层的应变和应力特征.结果表明:隧底围岩吸水膨胀对仰拱底鼓影响较大,对拱顶沉降有一定的抑制作用;随着基底围岩膨胀作用的增强,仰拱的最大主应力表现出减小趋势,最小主应力表现出不断增大趋势;回填层的应力、应变均表现出增加趋势;回填层的最大主应力和最大主应变均呈钟形对称分布,最小主应力呈M形对称分布;回填层中心及一定范围是控制泥岩隧道仰拱底鼓的关键部位.研究结果可为类似的泥岩地区隧道设计及仰拱底鼓控制提供理论参考.

To study the force characteristics and inverted arch deformation laws of the tunnel under the action of base expansion in mudstone area,a non-linear finite element numerical simulation method was used to analyze the influence of the base expansion characteristics on the mudstone tunnel under different water content conditions.The displacement change laws of the tunnel surrounding rock,the strain and stress characteristics of lining,inverted arch and backfill were obtained.The research results show that the water-absorbing expansion of the surrounding rock under the tunnel bottom has great impact on the heave of inverted arch,and has a certain inhibitory effect on the settlement of vault.With the increase of the expansive action of base surrounding rock,the maximum principal stress of inverted arch shows a decreasing trend,and the minimum principal stress shows an increasing trend;the stress and strain of backfill layer show an increasing trend.The maximum principal stress and maximum principal strain of the backfill layer are symmetrically distributed in a bell shape,and the minimum principal stress is symmetrically distributed in an M shape.The center and a certain range of the backfill layer are key parts for control ling the inverted arch heave of the mudstone tunnel.The research results can provide theoretical references for tunnel design and heave control of inverted arch in similar mudstone areas.