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AbstractThe kinematic discretisation technique of upper bound limit analysis is adopted in this study to evaluate the limit load of a strip footing located on the soils reinforced with different geosynthetic layers. The reinforcement is assumed to withstand the tension but not bending moment. The failure model of the reinforced foundation soil is generated using the discretisation method, a ‘point by point’ technique. Two failure modes of the reinforcement, the tensile rupture and sliding, are considered in the analysis. This article proposed the formulas for the first time to evaluate the effect of soil friction angle φ on the ultimate bearing capacity and on the failure mechanism of foundation. The calculation results are given considering different reinforcement layers, which describe the impact of different reinforcement depth and length on the ultimate bearing capacity. The optimum positions of different reinforcement layers and the optimum reinforcement length are obtained. The bearing capacity ratios are also presented in figures combing impact of reinforcement depths, soil cohesion and friction angle. The present method was verified by the results reported in literature. The present method can provide a reference for the footing design on the reinforced soils. [ABSTRACT FROM AUTHOR]

Based on the nonlinear failure criterion and modified tangential technique, the upper bound solutions of the critical supporting pressure on the deep tunnel face were obtained under pore water pressure conditions. The influence of parameters on the critical supporting pressure and collapse range was investigated according to the unlimited block failure mechanism. It was found that the upper bound solutions of the critical supporting pressure increase with the growth of the nonlinear coefficient and pore water pressure coefficient. The collapse range of the tunnel face scales out with the increase in the nonlinear coefficient and shrinks with an increasing pore water pressure coefficient. Moreover, with the increase in the nonlinear coefficient, the impact strength on critical supporting pressure and collapse range declines gradually. According to the calculated results, both the pore water pressure and nonlinear criterion factors have negative impacts on the stability of the tunnel face. Thus, more attention should be paid to these parameters to ensure face stability in deep tunnel construction. [ABSTRACT FROM AUTHOR]

A three‐dimensional (3D) collapse mechanism was employed in this work to investigate the roof stability of deep‐buried cylindrical tunnels in soil considering strength nonlinearity. Based on the kinematic approach of limit analysis, three tunnel roof stability measures, namely, the stability number, the required support pressure, and the factor of safety solutions were derived to provide quantitative indicators for evaluating tunnel roof stability. Optimal upper bound solutions for these measures were obtained through optimization. Subsequently, the effects of soil strength nonlinearity and 3D geometry characteristics on roof stability and the profiles of collapsing blocks were investigated: The increase in the nonlinear coefficient m and the tensile strength σt, as well as the decrease in the initial cohesion c0, will lead to a deterioration in the stability of the tunnel roof, and also result in a larger range of collapse blocks of the tunnel roof. A 3D stability analysis of the tunnel roof can provide more reasonable stability estimates than a 2D stability analysis. When the length‐to‐radius ratio L/R → ∞, the 2D solution results. [ABSTRACT FROM AUTHOR]

The active earth pressure of earth-retaining structures (ERSs) is highly dependent on rainfall infiltration. In prior studies, ERS stability was primarily explored based on backfills under unsaturated steady flows or those that were saturated or dry while neglecting the time-dependent properties of the rainfall infiltration procedure. Accordingly, this study assessed the stability of a three-dimensional (3D) unsaturated ERS under diverse modes of rainfall infiltration by exploiting the upper bound theorem of limit analysis. A modified Green–Ampt model was adopted to consider the development of the wetting front; thereafter, an energy equilibrium equation was built to analytically derive the active earth pressure. The effects of the wall friction angle, ERS 3D geometrical characteristics, rainfall infiltration intensity and duration, and rainfall patterns on the active earth pressure coefficient were investigated. According to the results, the wall friction angle and 3D geometrical characteristics lead to a smaller active earth pressure and a superior stability state. The matric suction is a direct determinant of the active earth pressure and stability of the ERS; these exert major effects on the infiltration rate of rainfall into the soil. Furthermore, the rainfall pattern and intensity also have significant impacts on the active earth pressure and the development of the wetting front. [ABSTRACT FROM AUTHOR]

The present study performs a stability analysis of a three-dimensional (3D) rock slope in disturbed rock masses following the Generalized Hoek–Brown (GHB) failure criterion. The factor of safety (FoS) of the slope is derived and the optimal solution is captured combining the limit analysis method and the strength reduction technique. It is indicated by the parametric analysis that the 3D geometric characteristics have a significant impact on slope stability such that FoS decreases sharply with the increase in the width-to-height ratio B / H within 0 < B / H ≤ 2.0 and thereafter reaches a constant value asymptotically. The FoS decreases more than 60% linearly when the disturbance factor D increases from 0 to 1.0. Stability charts and slope angle weight factor fβ_3D for 3D slopes are proposed to provide a convenient and straightforward approach to obtain the FoS solutions of 3D slopes. A case study was carried out to apply the stability charts on practical engineering cases, which showed that slope stability under two-dimensional (2D) plane strain will lead to conservative results, and a 3D stability analysis of slope is more appropriate, especially for a slope with a limited width. [ABSTRACT FROM AUTHOR]