Numerical study on transient unloading fracture mechanism of deep hard rock under 3D stress path induced by drilling and blasting

IF 4.2 2区工程技术 Q3 ENGINEERING, ENVIRONMENTAL

Bulletin of Engineering Geology and the Environment Pub Date : 2025-10-18 DOI:10.1007/s10064-025-04539-x

Weiqi Wang, Yawei Zhang, Rui Kong, Qihu Wang, Yulong Zhang

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引用次数: 0

Abstract

Transient unloading and rapid stress adjustment of surrounding rock during deep drilling and blasting excavation can easily induce hard rock fracture. Aiming at the dynamic adjustment of the magnitude and direction of the three principal stresses in transient unloading, the proposed spherical discrete element model was used to reveal the influence mechanism of principal stress magnitude, stress rotation and strain rate on transient unloading fracture for the first time. The results show that the transient unloading fracture rate of hard rock is significantly correlated with the magnitude and change trend of principal stress and has obvious inertia. The fracture rate is positively correlated with the maximum differential stress (σ₁-σ₃) and strongly negatively correlated with the minimum principal stress (σ₃). Both transient unloading and stress rotation will induce tensile strain rates with certain inertia and directionality. The stress rotation causes the transient unloading fracture rate significantly related to the strain rate component along the σ₃ axis (effective strain rate) rather than the principal strain rate. The maximum differential stress, minimum principal stress and effective strain rate constitute the stress-strain rate conditions for rapid fracture of rock under transient unloading. Increasing σ₃ will suppress the rate effect of transient unloading fracture, and there is a threshold (8.4 MPa in this study). The mutual influence between the tensile deformation and fracture of rock under transient unloading is weak and is related to the initial maximum unloading direction and the minimum principal stress direction, respectively, which is obviously different from the static mechanical response.

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钻爆三维应力路径下深部硬岩瞬态卸荷断裂机理的数值研究

深钻爆破开挖过程中围岩的瞬态卸载和快速应力调整容易诱发硬岩断裂。针对瞬态卸载过程中三个主应力的大小和方向的动态调整，首次利用所建立的球面离散元模型揭示了主应力大小、应力旋转和应变速率对瞬态卸载断裂的影响机理。结果表明：硬岩瞬态卸荷破裂速率与主应力大小及变化趋势显著相关，且具有明显的惯性；断裂速率与最大差应力（σ1 ~ σ3）呈正相关，与最小主应力（σ3）呈强负相关。瞬态卸载和应力旋转都会产生具有一定惯性和方向性的拉伸应变率。应力旋转导致瞬态卸荷断裂速率与σ3轴应变速率分量（有效应变速率）显著相关，而与主应变速率无关。最大差应力、最小主应力和有效应变率构成暂态卸荷下岩石快速破裂的应力-应变率条件。增大σ3会抑制瞬态卸荷断裂速率效应，且存在一个阈值（8.4 MPa）。瞬态卸荷下岩石拉伸变形与断裂的相互影响较弱，分别与初始最大卸荷方向和最小主应力方向有关，与静态力学响应明显不同。

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来源期刊

Bulletin of Engineering Geology and the Environment 工程技术-地球科学综合

CiteScore

7.10

自引率

11.90%

发文量

445

审稿时长

4.1 months

期刊介绍： Engineering geology is defined in the statutes of the IAEG as the science devoted to the investigation, study and solution of engineering and environmental problems which may arise as the result of the interaction between geology and the works or activities of man, as well as of the prediction of and development of measures for the prevention or remediation of geological hazards. Engineering geology embraces: • the applications/implications of the geomorphology, structural geology, and hydrogeological conditions of geological formations; • the characterisation of the mineralogical, physico-geomechanical, chemical and hydraulic properties of all earth materials involved in construction, resource recovery and environmental change; • the assessment of the mechanical and hydrological behaviour of soil and rock masses; • the prediction of changes to the above properties with time; • the determination of the parameters to be considered in the stability analysis of engineering works and earth masses.