Effect of non-persistent joint on strength and deformation characteristics of soft rock sample

Abstract

This study investigates the effects of displacement rates and joint orientations on the strength and deformation behavior of soft, rock-like materials, focusing on pre-existing non-persistent joints. The motivation stems from the need to understand how these factors influence material stability in geotechnical applications. Experiments were conducted on gypsum samples with intact sample and joints oriented at various angles (0ْ, 15°, 30°, 45°, 60°, and 75°) and subjected to different displacement rates (1.25 mm/min, 1.5 mm/min, and 2.5 mm/min). Results reveal that higher displacement rates generally enhance the material's strength, with the effect being more pronounced in intact and favorably oriented jointed samples. The study found that samples with joints aligned parallel to the loading direction (0° and 30°) exhibited higher peak strengths than those with perpendicular orientations. Elastic modulus, stress-strain behavior, and failure patterns varied with both strain rate and joint orientation, indicating a significant influence on the material's stiffness, ductility, and fracture mechanisms. These findings provide a valuable basis for predicting the behavior of jointed rock-like materials in engineering applications where displacement rate and joint orientation are critical factors.