Limited laboratory studies have investigated the cyclic behavior of sands under plane strain state, despite the current extensive applications of the plane strain hypothesis in modeling the behavior of subgrade soils beneath long road embankments. This study aims to explore the traffic-induced deformation behavior of sand under plane strain state and compare it to the conventional triaxial stress state. A series of one-way high-cyclic tests were performed on Fujian sand under both states using a true triaxial apparatus, considering different cyclic stress levels, consolidation stresses, consolidation anisotropies, and relative densities. In the plane strain scenario, the deformation of the specimen in the direction of intermediate principal stress was restricted when the cyclic major principal stress was applied. The test results indicate that during long-term cyclic loading, the sand exhibits substantially lower accumulated axial and volumetric strains when subjected to plane strain state as opposed to the conventional triaxial state. The reduction effect of plane strain state on the accumulated axial strain was found to be distinctively correlated with the strain levels, regardless of the cyclic stress amplitude and relative density. A practical formula was developed to estimate the difference in accumulated axial strain between the plane strain and triaxial states. Additionally, the intermediate principal stress of specimens under plane strain state was observed to oscillate cyclically in accordance with the one-way vertical cyclic stress. The intermediate principal stress coefficient, triggered by vertical cyclic loading, is more pronounced under high deformation, with its magnitude dependent on the specific loading conditions.

Pre-excavation dewatering (PED) can induce centimeter-level movements in the enclosure wall. Current foundation pit design theory only proposes a calculation method for excavation-induced force and deformation of the enclosure wall based on the elastic fulcrum method, which does not address PED-induced wall deflections. To continue using the elastic fulcrum method for calculating PED-induced wall deflections, it is crucial to determine the distribution of earth pressure on both sides of the enclosure wall during PED. This study aims to propose a novel model for calculating the PED-induced earth pressure on both sides of the enclosure wall. First, we analyzed the shape and influence range of disturbed soil on both sides of the enclosure wall during PED. Then, we explored the characteristics of soil strain distribution in the disturbed zone and proposed a distribution mode for the soil strain. Furthermore, we established a mathematical equation presenting the relationship between the soil strain and enclosure wall deflections, and proposed a calculation model of earth pressure considering the wall deflections during PED. The proposed calculation model accurately reflects the nonlinear relationship between wall deflections and earth pressure during PED. The obtained model, with its simple formulation and easily available data, could provide an important reference for predicting PED-induced enclosure wall deflections.

Soil frost deformation significantly influences engineering projects in cold regions. The anisotropic behavior of soil, involving surface and internal deformation in three dimensions (3D), introduces inaccuracies in evaluating freeze-thaw geological hazards. To explore the relationship between internal strain and surface displacement of soil in a 3D space during the freezing -thawing process, a platform for monitoring coupled surface -internal deformation in 3D were developed using binocular recognition technology and a novel 3D strain rosette. Subsequently, a freezing -thawing model test of soil in Dalian Offshore Airport filling is conducted using the platform. The results show that, the internal strain of soil is closely associated with the boundary conditions of the test unit. During freezing test, the vertical strain exhibits a more significant increase in comparison to the horizontal strain. Surface displacements in soil primarily occur during the initial freezing and thawing stages. The variation of surface horizontal displacement in each direction is minimal throughout the freezingthawing process. A surface freezing boundary leads to an increment in internal strain, while the deep frozen stress relief causes the soil surface expand during thawing. This study provides a suggestion for the control of the cold source in cold region engineering. (c) 2023 Production and hosting by Elsevier B.V. on behalf of The Japanese Geotechnical Society. This is an open access article under the CC BYNC -ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

The article presents the stages of numerical modeling of the stress-strain and strength state of a rock mass in the area of a ventilation drift during the mining of flat seams. The problem is solved by the finite element method, taking into account the physical and mechanical properties of coal, host rocks of the roof and soil of the seam and their changes over time of mining. The technique also takes into account the influence of adjacent waste lava. To assess the strength state of the host rocks, the Mohr criterion was used, and to assess the strength state of the coal seam, the criterion of rock strength under volumetric compression was used. The dependences of changes in the values of deformation characteristics of rocks over time were specified by rock creep equations, which made it possible to use the variable modulus method. An example is given of calculating the distribution of the stress-strain state of a rock mass, the convergence of the roof and soil, and soil heaving along the length of a ventilation road. A significant influence of the creep of the immediate soil on the amount of heaving of the roadway soil is shown.

The study delves into the elastoplastic deformation of a frozen wall (FW) with an unrestricted advance height, initially articulated by S.S.Vyalov. It scrutinizes the stress and displacement fields within the FW induced by external loads across various boundary scenarios, notably focusing on the inception and propagation of a plastic deformation zone throughout the FW's thickness. This delineation of the plastic deformation zone aligns with the FW's state of equilibrium, for which S.S.Vyalov derived a formula for FW thickness based on the strength criterion. These findings serve as a pivotal launchpad for the shift from a one-dimensional (1D) to a two-dimensional (2D) exploration of FW system deformation with finite advance height. The numerical simulation of FW deformation employs FreeFEM++ software, adopting a 2D axisymmetric approach and exploring two design schemes with distinct boundary conditions at the FW cylinder's upper base. The initial scheme fixes both vertical and radial displacements at the upper base, while the latter applies a vertical load equivalent to the weight of overlying soil layers. Building upon the research outcomes, a refined version of S.S.Vyalov's formula emerges, integrating the Mohr - Coulomb strength criterion and introducing a novel parameter -the advance height. The study elucidates conditions across various soil layers wherein the ultimate advance height minimally impacts the calculated FW thickness. This enables the pragmatic utilization of S.S. Vyalov's classical formula for FW thickness computation, predicated on the strength criterion and assuming an unrestricted advance height.