Studying the shear rheological properties of clay is crucial for evaluating slope stability and preventing excessive displacement of roadbeds and retaining walls. In this study, a series of direct simple shear tests were conducted by a novel apparatus to investigate the shear rheological behavior of clay in western China. Test results reveal that both the shear strain-time curve and shear stress-strain curve can be well described by power functions, and the power of shear strain-time curve is independent of the shear stress level. Based on this finding, an empirical shear rheological equation under constant shear stress is built. By assuming the shear stress-strain curves as a series of parallel lines in a double logarithmic coordinate axis, shear equivalent timelines are proposed based on Yin Graham's equivalent timeline theory. The shear equivalent time is then introduced into the proposed empirical shear rheological equation, thereby an equivalent timeline shear rheological model considering the effect of consolidation pressure under varying shear stresses is derived. The shear rheological strains predicted by the model are shown to agree well with test data before clay failure.

This technical note examines the shear distortion of plane strain framed structures resulting from tunnelling- induced surface differential settlements. An equation for calculating the shear stiffness is derived, considering various structural parameters. The effectiveness of the proposed method is validated through both experimental and finite element modeling results, with its accuracy emphasized by comparison with existing methods. Additionally, a method for estimating the redistribution of pressure beneath the foundation of plane strain framed buildings due to tunnelling is proposed and validated through numerical simulations which adopt an advanced soil constitutive model. The parametric study further demonstrates the applicability of the proposed methods for estimating shear stiffness in three-dimensional structures characterized by similar vertical wall and horizontal slab stiffness. The research findings provide tunnelling engineers with a tool for the rapid estimation of shear stiffness in framed structures and a reliable evaluation of pressure redistribution beneath foundations caused by tunnelling.

The shear strength of geocell-reinforced railway roadbeds is influenced by diverse factors. This research aimed to explore the shear deformation performance of the geocell-reinforced railway roadbed under conditions of different reinforcement locations, confining pressures, and numbers of reinforced layers. To this end, large-scale undrained triaxial tests were conducted to measure the mechanical properties of a geocell-reinforced railway roadbed. The results show that geocell reinforcement plays a significant role in improving the peak deviatoric stress of the railway roadbed. The stress-strain relationship of the railway roadbed always exhibits strain-hardening characteristics, and the railway roadbed shows the optimal shear deformation resistance and strength when it is reinforced in its upper part. As the confining pressure increases, the shear strength and stiffness of the railway roadbed both increase while the secant modulus decreases with increasing axial strain. Meanwhile, the shear strength and strength coefficient of reinforcement of the railway roadbed both increase significantly with the increasing number of reinforced layers, along with large increases in the stiffness and energy absorption of the railway roadbed. The research results can provide a reference for the structural design of railway ballast layers to comprehensively control the stability and deformation of existing heavy railway roadbeds.