Dams are mainly constructed of earth and rock-fill materials and hence they are generally referred to as embankment dams or fill-type dams. Earth-fill dams are simple structures which are able to prevent the sliding and overturning because of their self weight. Due to lack of suitable clay materials, sometimes the dams are designed as zoned core that is composed of three vertical zones including central impermeable core and two permeable shells on either sides of the core. A failure of earth dam is attributed to the following: hydraulic failure, seepage failure, piping through dam body and structural failure due to earthquake. The design and construction of an earth-fill dam is one of the key challenges in the field of geotechnical engineering, because of the unavoidable variation in foundation condition and the properties of the available construction materials. A homogeneous earth-fill dam should be designed with relatively flat slopes to reduce the risk of failure. The practical seepage problems are not easily convertible into an equivalent numerical counterpart because of the heterogeneity of the natural soils and the varying boundary conditions. The role of drainage system is also vital as it shifts the phreatic surface ensuring the safety of downstream toe. This paper presents the results of seepage and stability analyses of the considered earth dam using finite element method. The seepage analysis is divided into two categories viz. Steady state and Transient analyses. Based on the parametric sensitivity analysis, both the seepage and stability studies have brought out the importance of considering the coupled effects on the overall stability of the earth dam. It is concluded that the coupled analysis is a prerequisite for the design and performance evaluation of the earth dam under all conditions of seepage and stability. The study shows that increase in the Young's modulus of core and shell resulted in the decrease of the maximum crest displacement and the variation in angle of internal friction plays a vital role in the fulfilment of the overall stability criteria. The slope of 1V:2.5H was adopted for both the downstream and the upstream sides. The factor of safety (FS) was greater than 1.6 for both the full (high) reservoir condition and low reservoir condition whereas, the FS values were found to be less than the stipulated values for the other stability considerations.

This letter investigates the uplift capacity of plate anchors in granular soils. Simulations based on a discrete-element method are used to measure the uplift capacity of anchors of differing widths to embedment B/H and width to grain-size B/d ratios. Results confirm that the uplift capacity of anchors with a large B/d ratio is well described by existing models developed from continuum mechanics, with no grain-size effect. In contrast, results reveal a strong deviation from these models for anchors with relatively small B/d ratios. A semi-empirical model is introduced that captures this strong grain-size effect. This model is further supported by a micro-mechanical analysis, indicating that anchor uplift capacities are not only governed by a frustum mechanism predicted by continuum mechanics but also involve the mobilisation of grains surrounding this frustum. These results and model are particularly important to rationalise uplift capacities measured in small-scale experiments, typically involving small B/d ratios, and to safely upscale them to larger anchor size relevant to field applications.

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Like in liquids, objects moving in granular materials experience a drag force. We investigate here whether and how the object acceleration affect this drag force. The study is based on simulations of a canonical drag test, which involves vertically uplifting a plate through a granular packing with a prescribed acceleration pattern. Depending on the plate size, plate depth and acceleration pattern, results evidence a rate-independent regime and an inertial regime where the object acceleration strongly enhances the drag force. We introduce an elasto-inertial drag force model that captures the measured drag forces in these two regimes. The model is based on observed physical processes including a gradual, elasto-inertial mobilisation of grains located above the plate. These results and analysis point out fundamental differences between mobility in granular materials upon steady and unsteady loadings. arXiv:1907.05613v1 [cond-mat.soft]

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This paper presents the strain profiles obtained along the height of the seepage barriers of the earth dam. The seepage barriers are employed in the permeable dam section in order to obstruct the seepage of water from upstream to downstream and thereby reducing the risk of piping. A total of 36 finite-element simulations were carried out in the study, wherein the combination and placement of the cut-off walls in the earth dam section were varied. The results include the horizontal, vertical and shear strain profiles and their variation along the height of barriers with respect to its position for different reservoir conditions, such as high reservoir and 5 d drawdown conditions. By the adoption of single barrier in the dam section, the strain values were found to be on the higher side when compared with the near-end barrier in double-configuration system under high reservoir conditions, whereas for the drawdown conditions, the magnitude of the strains in the barrier were more or less the same. The higher strain levels induced in the barrier could cause cracking of the barrier, thereby impairing the function of the barrier.