Arching effect

Piled embankments provide an economic solution to the problem of constructing embankments over soft soils. The piles and geosynthetic combination can alleviate the uneven surface settlements that sometimes occur in embankments supported by piles without reinforcement. The main focus of this paper is to present a new method for analysis of an embankment of granular fill on soft ground supported by a rectangular grid of piles and geosynthetic. This method is based on consideration of the arching effect in granular soil and similar to the method proposed by Low, B.. The main refinements are: inclusion of a uniform surcharge load on the embankment fill, individual square caps were used, and taking into account the skin friction mechanism, which contributes to soil–geosynthetic interface resistance. Using this method, the influence of embankment height, soft ground depth, soft ground elastic modulus, and geosynthetic tensile stiffness on efficiency, stress concentration ratio, settlement ratio, tension of geosynthetic, and axial strain of geosynthetic are investigated. The results show that inclusion of a geosynthetic membrane can increase the fill load carried by piles. As a result, both the total and differential settlements of the embankment can be reduced. The new design method was verified against several current design methods. Theoretical solution showed that BS8006 [1995. Code of Practice for Strengthened/Reinforced Soils and other Fills. British Standards Institution, London, p. 162] and Guido, V.A., Kneuppel, J.D., Sweeny, M.A. [1987. Plate loading tests on geogrid-reinforced earth slabs. In: Proceedings of the Geosynthetics '87, New Orleans, USA, IFAI, pp. 216–225] methods overpredict the vertical stress acting on the geosynthetic due to that the reaction of the soft ground on the geosynthetic is not considered in their methods. It also showed that the present method is in good agreement with Low, B.

To retain fresh cemented paste backfill (CPB) (a large fill mass made of man-made fine soils that undergo cementation) in a stope (underground mining excavations), a retaining structure or wall (called a barricade) must be constructed at the base of the stope. Due to the coupled thermo-hydro-mechanical-chemical (THMC) processes that occur in CPB, changes in the total horizontal stress and pore water pressure (PWP) take place with backfilling operations that are flexible, which directly affects the stability of the barricade. Hence, an investigation of the changes and distribution of barricade pressure is crucial for the assessment of the stability of CPB and the barricade. In this paper, an integrated multiphysics model composed of a fully coupled THMC model, a fully coupled multiphysics model that analyzes the consolidation process in CPB and an elastoplastic model that analyzes changes in the interface behavior during the interaction of rock mass/backfill is adopted. The predictive ability of the model is validated by the good agreement between the simulation results and in-situ measurements from a series of field monitoring programs. Then, the validated multiphysics model is used to numerically investigate the changes and spatial distribution of barricade pressure under various conditions (including elapsed time, barricade location and shape, initial temperature, and drainage conditions). The obtained results can provide practical insight into the factors that affect the geotechnical stability of barricade structures.