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Recent interpretations of wetting-induced compaction revealed that water sensitivity can cause a loss of controllability in samples subjected to fluid injection. This paper elaborates these findings by focusing on fabric anisotropy, i.e., a feature of unsaturated clays not encompassed by previous studies. For this purpose, a hydromechanical elastoplastic model with rotational hardening is developed to capture fabric effects. The model performance has been validated under both saturated and unsaturated conditions with reference to laboratory tests on Lower Cromer Till (LCT). To inspect the role of the material properties, parametric analyses have been conducted, thus identifying the parameters which govern the transition from stable to unstable conditions upon wetting. The results show that fabric anisotropy affects only the deformations prior to wetting-collapse, without changing the value of suction at the onset of volumetric instability. By contrast, it is found that the model parameter governing the intensity of suction-hardening is able to alter the value of critical suction at the loss of control regardless of the intensity of fabric evolution. These results corroborate previous findings obtained through isotropic constitutive laws and emphasize the crucial role of hydromechanical constitutive couplings on the inelasticity of unsaturated porous media. [ABSTRACT FROM AUTHOR]

Cemented paste backfill (CPB) is widely applied in undergroundmines around the world. Prior to stope backfilling, barricades need to be built in drifts near drawpoints to retain the flowable fill. A number of reported barricade failures have shown that barricade stability is critical for ensuring successful and safe application of backfill. The barricades are usually made of high-strength materials such as bricks, concrete blocks, or reinforced shotcrete. Alternatively, barricades made of waste rocks are becoming popular because of their simple and low-cost construction. A simple solution was proposed for sizing waste rock barricades (WRBs) by considering the limit equilibrium of a three-dimensional (3D)-rectangular block. More recently, the authors modified this solution by considering the global stability of trapezoidal barricades, but the local stability was not taken into account. Consequently, the size of the crest can be underestimated, leading to a nonconservative design. In this paper, a more complete solution is proposed, considering both the global and local stabilities of trapezoidal WRBs. The analytical solution was calibrated and validated using numerical modeling. The flexibility and validity of the proposed solution were further tested with complementary simulations. Sample calculations are also performed here to show the application of this solution and to illustrate the effect of key influencing factors on barricade design. [ABSTRACT FROM AUTHOR]

This paper evaluates the significance of basal reinforcement and the presence of the surface sand layer in the stability. This evaluation is carried out by means of field measurements and stability analyses of three test embankments on soft clay taken to failure. Two of the test embankments were reinforced and one was unreinforced. Stability analyses were carried out taking into account measured values of reinforcement tension forces during construction. The set of analyses have shown that the top sand layer was more important to the stability of the embankments than the basal reinforcement. The cases studied have also shown that the conventional design practice that assumes for the reinforcement a fixed tension contribution may lead to unrealistic higher factor of safety. [ABSTRACT FROM AUTHOR]