The development of the subway system in Shenyang City, China, plays a vital role in alleviating traffic congestion and promoting sustainable societal growth. However, the deformation of the surface caused by the tunneling of the shield presents a significant threat to the structural integrity of Shenyang Subway Line 2 and adjacent geotechnical structures. To tackle this challenge, a set of FEA (finite element analysis) simulations were carried out to examine surface deformation under various construction scenarios for Line 2. These simulations were compared with empirical formulas and numerical analyses conducted using Midas GTS NX 2019 software, in addition to actual site measurements. The outcomes of the finite element analysis (FEA) demonstrated a closer alignment with the empirical data than with traditional formulas. The maximum deformation was observed to be approximately twice as large as the equivalent diameter at the back of the excavation face. The analysis indicated that surface deformation is inversely correlated with overburden thickness (H), soil elasticity (E), and the grout filling rate of the shield tail (ψ), while it is directly proportional to the shield’s outer diameter (D). This study provides important methods used in the shield tunneling process employed in the Shenyang subway and suggests that the developed methodologies may be applicable to similar subway projects.

The shear strength parameters of loess samples are determined from conventional triaxial shear test results and used in the rational design of sustainable geotechnical infrastructures. However, the rubber membrane that is used in the triaxial shear apparatus for applying the all-around pressure to the test specimen has a significant influence on the measured shear strength parameters. In this paper, remolded and undisturbed unsaturated loess samples from northwest China are used in a comprehensive testing program to determine the shear strength from triaxial tests and understand the influence of a rubber membrane. The results show that the measured undrained cohesion from unconsolidated undrained triaxial tests on unsaturated soil specimens with and without a rubber membrane are significantly different. In this study, differences in the shear strength with and without a rubber membrane are assessed from shear strength index values that can be determined from undrained cohesion and the internal friction angle derived from conventional triaxial tests. Experimental results suggest that predominant changes arise mainly in the undrained cohesion values. The change rate of shear strength indices values of undisturbed loess shows a strong correlation with its water content; however, it is weak for remolded loess. The correlation coefficient between error and measured values of all shear strength indices is more than 0.8. Empirical correction relationships for triaxial shear tests with a rubber membrane for three different types of loess were established from the investigations. The simple approach used in this study can be used as a reference to apply corrections to the measured undrained cohesion values of unsaturated loess samples from northwest China.