关于土的空间变异性对盾构隧道施工影响的探讨

The Impact of Spatial Variability of Soils on Shield Tunnelling

为探讨土的强度参数的空间变异性对盾构隧道开挖引起的地表变形的影响,选取黏聚力和内摩擦角作为随机变量,采用Karhunen-Loève方法对随机场进行离散,利用Matlab软件将土性参数随机场与FLAC 3D模型单元一一映射,并使用FLAC 3D进行分析计算。结果表明:土强度参数的空间变异性对地表变形的影响明显;竖直方向相关长度的影响大于水平方向相关长度的影响;地表水平位移受到的影响比地表沉降受到的影响更大;竖向相关长度小于1倍隧道直径时,多次模拟得到的地表沉降值符合正态分布,据此可利用确定性分析结果估算地表沉降变形超限概率或确定控制沉降量。

To investigate the impact of spatial variability of soil strength parameters on the ground surface deforma⁃tion caused by shield tunnelling,the cohesion and internal friction angle are selected as the random variables,the random fields are discretized through the Karhunen-Loève expansion method,the soil parameters random fields are mapped respectively to FLAC 3D model elements by using the Matlab software,and analytical calculations are per⁃formed by using FLAC 3D software.The results show that the spatial variability of the soil strength parameters has a significant impact on ground surface deformation.Specifically,the impact of the scale of fluctuation in vertical direc⁃tion is greater than that of the scale of fluctuation in horizontal direction,and the horizontal displacement of the ground surface is more affected than the ground surface settlement.Furthermore,when the scale of fluctuation in ver⁃tical direction is less than 1 times the tunnel diameter,the values of ground settlement obtained from multiple simu⁃lations conform to a normal distribution,allowing to estimate the exceeding probability or the specified limit of the ground surface settlement by deterministic analysis method.