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The shield method is commonly employed in the construction of urban subways, and the stability of the excavation surface is extremely important for the safety of tunnel construction. When constructing tunnels in submerged or water-rich strata, the seepage force is a key factor affecting the ultimate support force of excavation faces. Uncertainty of natural geotechnical material hydraulic parameters significantly impacts the seepage force near the face. Based on the classic limit analysis and the random field theory, the principle of effective stress in saturated soil is introduced, and the stochastic numerical limit analysis method considering the influence of pore water pressure is established by combining finite element spatial discretization and second-order cone programming. On this basis, the influence of spatial variability of permeability coefficient on the stability of shield tunnel face in water-rich strata is studied. The results show that the heterogeneity of the permeability coefficient leads to an increase in the pore pressure gradient at the face. The increase in the variation of permeability coefficient and the ratio of vertical to horizontal permeability coefficient significantly increases the support force required to maintain the face stability, and the effect of cross correlation coefficient and autocorrelation distance is relatively small. The present research can provide theoretical guidance for evaluating the face stability of tunnels in water-rich strata.

Background: Small vessel disease (SVD) shares common vascular risk factors with large artery disease (LAD). However, little is known about the relationship between intracranial artery stenosis and SVD burden. Purpose: To investigate whether SVD burden correlates with severity of intracranial LAD. Study Type: Retrospective. Population: Five hundred and sixteen patients with LAD of arterial circulation were enrolled from one hospital, including 384 males (59 ± 11 years) and 132 females (60 ± 12 years). Field Strength/Sequence: 3 T. T1‐weighted fast spin echo (T1W FSE), T2W FSE, T2 fluid attenuated inversion recovery, diffusion‐weighted imaging, susceptibility‐weight imaging, and time‐of‐flight magnetic resonance angiography. Assessment: The LAD was divided into mild stenosis (<30%), moderate stenosis (30%–69%), and severe stenosis (≥70%). The Standard for Reporting Vascular Changes on Neuroimaging criteria was used to rate the SVD burden according to the level of white matter hyperintensity (WMH), perivascular space (PVS), cerebral microbleed (CMB), and lacunes. Statistical Tests: Lilliefors test, ANOVA, chi‐squared test, Mann–Whitney U test, Wilcoxon signed rank test, Bonferroni test, Spearman's correlation, logistic regression, and Cohen's kappa test. Results: The grade scores for centrum semiovale PVS (CS‐PVS) were positively correlated with the degree of stenosis (R = 0.413), whereas the presence of severe basal ganglia PVS (BG‐PVS) was associated with CMB (R = 0.508), lacunes (R = 0.365), and severe WMH (R = 0.478). In multivariate analysis, severe CS‐PVS (adjusted odds ratio [aOR], 3.1; 95% confidence interval [CI], 1.9–4.8) and lacunes (aOR, 2.1; 95% CI, 1.3–3.4) were associated with severe stenosis of LAD. In addition, CS‐PVS was related to severe stenosis in a dose‐dependent manner: when CS‐PVS score was 3 and 4, the aORs of severe stenosis were 1.9 and 7.7, respectively. Data Conclusion: The severity of LAD in anterior circulation is associated with SVD burden, which suggests that different SVD burden may be used for risk stratification in LAD. Evidence Level: 3 Technical Efficacy: Stage 3 [ABSTRACT FROM AUTHOR]