The influence of horizontal borehole spacing on the interaction of two dynamic cracks propagating towards each other under unequal biaxial confining pressure

IF 5.6 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics Pub Date : 2025-08-19 DOI:10.1016/j.tafmec.2025.105181

Shengnan Xu , Zhongwen Yue , Xingyuan Zhou , Jun Zhou , Peng Wang , Kejun Xue

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引用次数: 0

Abstract

As resource extraction depth increases, deep rock engineering often encounters geostress environments where horizontal stress significantly exceeds vertical stress, sometimes by factors up to three. This distinctive stress state critically impacts the propagation paths and interaction mechanisms of blasting cracks. This study establishes an experimental system for blasting photoelasticity under unequal biaxial confining pressure (9 MPa horizontal, 3 MPa vertical). It investigates the propagation behavior of opposing cracks and the effects of explosive stress waves and crack-tip stress fields on nearby cracks at various horizontal spacings (8–14 cm). Results indicate that under unequal biaxial confining pressure, the shaped charge shows a marked directional effect, with the optimal horizontal spacing between boreholes being 11 cm. At this spacing, the main cracks between the two boreholes have longer propagation lengths and better connectivity. As horizontal spacing increases, both wave-crack and crack-crack interactions weaken, with crack-crack interactions attenuating faster than wave-crack interactions. When the spacing exceeds 11 cm, the influence of crack-crack interactions on the mode II stress intensity factor at the crack tip rapidly diminishes. Under dynamic-static loading, predictions of crack deflection angle prediction using the Maximum Tangential Stress (MTS) and Generalized Maximum Tangential Stress (GMTS) criteria align closely with experimental trends, particularly regarding the timing of inflection points. However, predictions are consistently larger than actual values, and T-stress has minimal effect on crack deflection. Thus, the simpler MTS criterion is preferable for practical applications. These findings provide key insights into the interaction of opposing dynamic cracks at varying horizontal spacings and strengthen the theoretical foundation for optimizing perimeter-hole blasting parameters in horizontal stress-dominated environments.

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水平钻孔间距对不等双轴围压条件下动态裂缝相互作用的影响

随着资源开采深度的增加，深部岩石工程经常会遇到水平应力明显超过垂直应力的地应力环境，有时会达到3倍。这种特殊的应力状态对爆破裂纹的扩展路径和相互作用机制有重要影响。本研究建立了不等双轴围压（水平9 MPa，垂直3 MPa）下的爆破光弹性实验系统。研究了不同水平间距（8 ~ 14 cm）下相对裂纹的扩展行为以及爆炸应力波和裂纹尖端应力场对相邻裂纹的影响。结果表明：在不等双轴围压条件下，聚能药具有明显的定向效应，最佳井眼水平间距为11 cm；在此间距下，两个井眼之间的主裂缝具有更长的扩展长度和更好的连通性。随着水平间距的增大，波-裂纹和裂纹-裂纹相互作用减弱，且裂纹-裂纹相互作用衰减速度快于波-裂纹相互作用。当裂纹间距超过11 cm时，裂纹-裂纹相互作用对裂纹尖端II型应力强度因子的影响迅速减小。在动静载荷下，使用最大切向应力（MTS）和广义最大切向应力（GMTS）准则预测裂纹挠度角的预测与实验趋势密切相关，特别是关于拐点的时间。然而，预测值始终大于实际值，t应力对裂纹挠度的影响最小。因此，更简单的MTS准则更适合实际应用。这些发现为研究不同水平间距下对立动态裂缝的相互作用提供了关键见解，并为优化水平应力主导环境下的周孔爆破参数提供了理论基础。

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来源期刊

Theoretical and Applied Fracture Mechanics 工程技术-工程：机械

CiteScore

8.40

自引率

18.90%

发文量

435

审稿时长

37 days

期刊介绍： Theoretical and Applied Fracture Mechanics'' aims & scopes have been re-designed to cover both the theoretical, applied, and numerical aspects associated with those cracking related phenomena taking place, at a micro-, meso-, and macroscopic level, in materials/components/structures of any kind. The journal aims to cover the cracking/mechanical behaviour of materials/components/structures in those situations involving both time-independent and time-dependent system of external forces/moments (such as, for instance, quasi-static, impulsive, impact, blasting, creep, contact, and fatigue loading). Since, under the above circumstances, the mechanical behaviour of cracked materials/components/structures is also affected by the environmental conditions, the journal would consider also those theoretical/experimental research works investigating the effect of external variables such as, for instance, the effect of corrosive environments as well as of high/low-temperature.