基于三维统一解结合类随机介质理论的理论方法，建立适用于复合地层条件下的双线水平盾构隧道施工引起土体变形的计算模型，并推导土体竖向和水平变形的计算公式。公式利用三维统一解考虑不同土质条件对盾构施工引起土体变形的影响，利用类随机介质理论将土体损失区域按照地层进行分割，考虑土体损失区域内不同土层的土质条件对土体变形的影响。本文公式不仅可用于复合地层条件下的盾构施工，还可以解决开挖面上存在多种地层的工况，并且考虑施工顺序和双线相互作用对土体变形的影响。研究结果表明： 1）经过多组工程案例验算，验证了本文方法的可行性；本文方法广泛适用于各类双线水平盾构施工工程。2）通过计算发现，随着土体深度的增大，土体的水平变形量先增大后减小，最大水平变形量发生在隧道顶部埋深处，且由于双线隧道的相互作用，土体的竖向和水平变形均发生了偏移。3）通过对上硬下软与上软下硬2种工况下开挖面内土层分布变化的单因素分析发现，随着较硬土层在开挖面内的占比提高，土体变形量呈非线性变化，占土体损失区域面积越大的土体对变形的影响越大，且双线盾构隧道施工引起的沉降槽曲线呈现更窄长的“W”形；软土的占比增加时，则“W”形趋向于扁平。
To address the challenges
of calculating soil deformation caused by the construction of a double-track horizontal shield tunnel under composite geological
conditions, a model tailored for such tunneling operations is established. This
model integrates a three-dimensional unified solution
combined with the theory of quasi-random medium to
derive calculation formulas for vertical and horizontal soil deformations.
These formulas assess the impact of different geological conditions on
tunneling-caused soil deformation. Soil-loss areas are divided using quasi-random medium according to geology, considering the influence of various geology on soil-loss areas and soil deformation. The prop-osed
formulas are applicable to shield tunneling in composite strata, accounting for
the effects of construction sequence and double-track
interactions on soil deformation. The research results are summarized as
follows: (1) The proposed formulas are feasible and applicable to double-track horizontal shield tunnels. (2) Horizontal soil deformation
initially increases with soil depth and then decreases, with the maximum
deformation occurring at the tunnel crown. The interaction between the double
tracks leads to deviations in vertical and horizontal soil deformations. (3)
Single-factor analysis of soil layer distribution at
the excavation face, considering both upper-hard/lower-soft and upper-soft/lower-hard strata, reveals the following: As the proportion of hard soil
increases, soil deformation exhibits a nonlinear change. Soil types with a
larger proportion of soil-loss areas have a more
significant effect on soil deformation. The settlement groove curve caused by
double-track shield tunneling exhibits an extended
vertical W shape that tends to flatten as the proportion of soft soil
increases.
