考虑参数空间变异性的盾构隧道施工地层变形综合可靠度分析

依托厦门地区典型风化花岗岩地层的盾构隧道工程,针对多层土双线盾构隧道施工地层变形问题,以岩土体参数的空间变异性为切入点,基于随机场理论,采用蒙特卡洛法与有限差分法模拟计算相结合的方法,开展盾构隧道施工地层变形响应的可靠度分析。以土体弹性模量E的空间变异性为研究重点,系统研究土体弹性模量的竖向、水平波动距离(θ_z,θ_x)对地层变形可靠度指标的影响。结果表明:随机分析所得最大地层变形(地表沉降、拱顶沉降、围岩收敛)的可靠度指标随着土体弹性模量波动距离的增大而降低;随着最大地层变形允许值的增大,地层变形可靠度指标也相应提高。在此基础上,借助熵理论客观确定各地层变形指标(地表沉降、拱顶沉降、围岩收敛)的权重系数,结合可靠度设计方法和工程风险分析理论,开展地层变形综合可靠度分析及控制指标体系的研究,提出适合厦门地区的盾构隧道施工地层变形控制指标体系。

Comprehensive Reliability Analysis of Deformation Induced by Shield Tunneling Considering Spatial Variability of Soil Parameters

Stochastic calculations, by combining the random field theory with the finite difference analysis and Monte Carlo simulation, are used to conduct reliability analysis on the surrounding soil deformation induced by twin tunneling in multi-layer soils considering the spatial variability of soil parameters. The effects of scales of fluctuation (SOF) of Young’s modulus in both vertical and horizontal directions on deformation reliability index are investigated and discussed in detail. Results demonstrate that the reliability index of maximum deformation (surface settlement, vault settlement, and surrounding rock convergence) obtained by stochastic analysis decreases with the increase of SOF, and the comprehensive reliability index of deformation increases with the increase of allowable value of deformation. Additionally, the entropy weight coefficients of deformation indices are objectively determined by using the entropy theory. Combining the reliability design method and the engineering risk analysis theory, the comprehensive reliability of deformation is analyzed, and the deformation control index system of shield tunnel suitable for Xiamen area is put forward.