Finite Element Modeling for Consolidation and Settlement of Lateritic Soils Subject to Heap Leach Pad Loading

Ma. Jhonnie Z. Villareal and Arnulfo B. Santiago MSc.

Earth and Material Science and Engineering Department
Mapua Institute of Technology

Abstract

In anticipation of the impending construction of a pilot heap leach pad in Acoje, Zambales, an evaluation of the competency of the liner material composed of lateritic clays was undertaken. A numerical simulation of the consolidation and settlement behavior as well as the characteristic of the nickeliferrous lateritic clay mass found in ultramafic ophiolitic complexes in response to static loads imposed by the heap leach pad is modeled using PLAXIS 2D version 8.2 finite element modeling (FEM) software assuming plane strain conditions and anisotropy. FEM modeling means require that the soil properties are appropriately defined and its basic engineering parameters known such as moisture content, unit weight, atterberg limits, permeability, cohesion, angle of internal friction, unconfined compressive strength and dilatancy [8]. These parameters were gathered and determined from in-situ observations and laboratory tests which were keyed in to the FEM software for the foundation analyses.

A certain amount of vertical displacement is expected to occur due to the load that the heap will impose on the clay layer. The rate and amount of settlement were determined thru timed/staged construction followed by bearing capacity and factor of safety determination for recommendation of the appropriate heap leach provisions. Results of the finite element modeling analyses were compared with that obtained by manual calculations. A premier and relatively new approach, this paper focuses on the settlement behavior of lateritic clays under various loading conditions.

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