# Experimental study on fracture and fragmentation characteristics of laminated rocks under impact loading

## TL;DR

This study examines how the orientation of rock layers affects how rocks break and release energy when impacted, which is important for engineering safety.

## Contribution

The study reveals how lamination orientation influences energy dissipation, crack propagation, and fragmentation in laminated rocks under impact loading.

## Key findings

- Lamination angle significantly affects energy dissipation characteristics of rocks.
- Oblique lamination orientations lead to complex damage modes and large-scale crack propagation.
- AE b-values confirm that diagonal laminations increase structural instability and damage.

## Abstract

Laminated rock bodies are prevalent in engineering applications, making the investigation of their damage characteristics and evolution patterns under impact loading critical for ensuring engineering safety. Despite this importance, the relationship between energy dissipation and the crushing mode of laminated rock bodies remains underexplored, particularly regarding the influence of lamination orientation on their dynamic response. To bridge this scientific gap, this study conducts rock impact tests in the presence of various lamination angles (0°, 30°, 60°, and 90°) and employs digital image correlation (DIC) technology alongside acoustic emission (AE) monitoring and fracture sieve analysis to systematically examine how lamination orientation affects energy dissipation patterns, crack propagation behavior, and fragmentation characteristics in rocks. The results indicate that the lamination angle has a significant influence on the energy dissipation characteristics of rocks. When the lamination orientation is parallel or perpendicular to the direction of shock wave propagation, the rocks exhibit a low intensity of energy dissipation, a singular crushing mode, restricted crack propagation, and a relatively stable fragmentation process. Conversely, laminated rocks with oblique intersections demonstrate complex damage modes due to the combined effects of shear and tension, wherein significant large-scale crack propagation occurs, exacerbating structural instability. Analysis of AE b-values corroborates these observations, revealing that the development of microcracks in rocks with diagonally interbedded laminations along the impact direction is more prone to result in large-scale destabilization and damage. This study elucidates the damage mechanisms and directional characteristics of laminated rocks subjected to impact loading, thereby providing a vital theoretical foundation and technical support for the safe design of engineering structures and related construction practices.