Study on the dynamic fracture behavior of anisotropic CCNBD shale specimens under different impact angles

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics Pub Date : 2024-08-12 DOI:10.1016/j.tafmec.2024.104616

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引用次数: 0

Abstract

Drilling and fracturing are the key technologies for shale gas extraction, while most of the loads generated during rock drilling or fracturing are dynamic. In this study, dynamic impact experiments were conducted on the cracked chevron-notched Brazilian disc shale specimens with different chevron-notched crack (CNC) inclinations (β) and layer inclinations (α) by the split Hopkinson pressure bar. The results show that the dynamic peak load and dissipated energy increases with the increase of β, α, and strain rate, but their changing trends are different. The generation and expansion of cracks during the specimen failure process are mainly affected by β. As β increases, the failure type of the specimen can be divided into pure mode I fracture, mode I-II mixed fracture, pure mode II fracture, mixed tension-shear failure, and Brazilian splitting failure. The increase in strain rate will lead to a decrease in the time for crack initiation and propagation as well as an increase in secondary cracks. In addition, the mode I fracture toughness (K_Ⅰ_C) and mode II fracture toughness (K_Ⅱ_C) both grow with the increase of α and strain rate. The K_Ⅱ_C predicted by the generalized maximum tangential stress criterion (GMST) exhibits more accurate.

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各向异性 CCNBD 页岩试样在不同冲击角度下的动态断裂行为研究

钻探和压裂是页岩气开采的关键技术，而岩石钻探或压裂过程中产生的大部分载荷都是动态载荷。本研究采用分体式霍普金森压力棒对不同楔形缺口裂纹（CNC）倾角（β）和层倾角（α）的开裂楔形缺口巴西圆盘页岩试样进行了动态冲击实验。结果表明，动峰值载荷和耗散能量随 β、α 和应变速率的增加而增加，但其变化趋势不同。试样破坏过程中裂纹的产生和扩展主要受 β 的影响，随着 β 的增加，试样的破坏类型可分为纯模式 I 断裂、模式 I-II 混合断裂、纯模式 II 断裂、拉剪混合破坏和巴西劈裂破坏。应变速率的增加会导致裂纹萌发和扩展时间的缩短以及次生裂纹的增加。此外，模式 I 断裂韧度（KⅠC）和模式 II 断裂韧度（KⅡC）都随着 α 和应变速率的增加而增加。广义最大切向应力准则（GMST）预测的 KⅡC 更为精确。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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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.