Research on inversion method for stress characteristics of roadway surrounding rock based on real-time weight measurement of drill cuttings

Abstract

The concentration of internal stress and the accumulation of energy within coal bodies are key factors that can trigger catastrophic events, such as rock bursts and gas outbursts. Therefore, understanding the internal stress characteristics of coal is essential. The cuttings method, a commonly used detection technique, is often employed to reflect the degree of stress concentration in coal bodies. However, there is currently insufficient research on the relationship between the weight of cuttings and the stress of the coal body, making it difficult to quantitatively and accurately represent the actual stress state of the surrounding rock in boreholes. This study investigates the relationship between cuttings weight and coal body stress through both theoretical analysis and numerical simulation. Theoretically, a formula for calculating the weight of cuttings under a uniform stress field was derived, based on an analytical solution for the stress and displacement of surrounding rock in boreholes. The sensitivity of cuttings weight to changes in coal body stress is thoroughly analyzed. From a numerical simulation perspective, a discrete element method for coal drilling is developed, revealing the correlation between cuttings weight and coal body stress under both uniform and non-uniform stress conditions, as well as the impact of initial damage on cuttings weight. Additionally, a continuous damage model is constructed of the surrounding rock along the depth dimension, investigating how cuttings weight varies with drilling depth. Based on these findings, an automatic method is proposed for weighing cuttings to locate and estimate the magnitude of lateral stress peaks in roadway-surrounding rock. Field application experiments demonstrate the effectiveness of this method, yielding promising predictive results. The findings of this research provide both technical methods and theoretical support for using cuttings weight to quantitatively characterize coal body stress, which is crucial for accurately assessing coal body stress and for the early detection and warning of dynamic impact hazards.