Evaluation of Pore Size and Distribution Impacts on Uniaxial Compressive Strength of Lithophysal Rock

Abstract

Discrete element method (DEM) has been extensively used for studying the properties of rock mass through numerical simulation, which includes bonded particle (or grain) model method (BPM) and discrete fracture network method. In this paper, utilization of BPM for modeling uniaxial compressive strength (UCS) of lithophysal rock is explored and associated stages are discussed and calibrated including generation of particles, sample scale, loading method, macro- and micro-parameters of BPM. In order to investigate the impacts of pore size and distribution of lithophysal tuff on UCS, various combinations of different pore sizes in one sample and different pore locations with the same pore size are simulated using BPM-DEM. The simulation results show that UCS significantly decreases due to the existence of pores with the same condition of porosity, and when the pore radii increase, the minimum value of UCS slightly declines. Moreover, combinations of different pore sizes in one sample show that greater proportion of small pore radii increases UCS of the sample, while the differences of UCS values decrease. Meanwhile, associated fracture has been observed to develop along the pore and generally tends to develop along the large pores at the edge of the sample in the process of uniaxial compression simulation, with relatively small associated UCS values.