Experimental DEM Hybrid Approach for Prediction of Landslide in Ughelli Sandstone

Landslide is a rare occurrence in Nigeria; however, in recent time, it has been reported to have occurred. Therefore, it is important to simulate tensile failure and the associated crack number by subjecting the sandstone to compressional stress. The aim is to relate crack number to micro-structural disaggregation which is the degree of isotropic and deviatoric stress in the material. Therefore, the framework for tracking the damage mechanism of Ughelli formation has been provided using strain data. Strain gauges were employed to track the grain slippage during confined compression test, while micro-elastic properties were evaluated as bond stiffness measured from ultrasonic wave velocity. Next the granular assembly of the sandstone was simulated by clumping particles. The granular model was subjected to confined test to reproduce the elastic properties of the natural sandstone. The existing micro-cracks in the rock progress by grain slip and bond breakage of the cementing clay content between the grains. The damage was reached at an observed grain slippage stress of 90 MPa in the natural formation. The systematic crack growth peaks at a stress level of 160 MPa with a straining rate of 10–5(s−1). By shifting away from representing a grain of sandstone with single spherical particles, the significant discrepancies between the elastic properties of observed core sample and the simulated model are improved. The identification of the first grain slippage at possible fracture localized points during a drilling program will suggest injection of plugging pills to maintain wellbore stability. This is because it is often easier and effective to prevent undue landslides than to remedy the occurrence.