Deformation–failure and acoustic emission characteristics of tunnels with fracture zones under loading: Analysis of dip angle effects

IF 5.6 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics Pub Date : 2026-03-01 Epub Date: 2025-12-29 DOI:10.1016/j.tafmec.2025.105428

Kexue Wang , Jun Yang , Yanbo Zhang , Wenhui Bian , Xulong Yao

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引用次数: 0

Abstract

Fractured zones are common unfavorable geological structures that pose significant risks to tunnel stability. To investigate the deformation and failure mechanisms of tunnels intersecting fractured zones with different inclinations, a series of rock specimens containing fractured zones at dip angles of 30°, 45°, 60°, 75°, and 90° were prepared based on a shallow-buried metro tunnel project. Biaxial compression tests were conducted using acoustic-emission (AE) monitoring and digital image correlation (DIC). The results indicate that the presence of a fractured zone substantially weakens the mechanical properties of the specimens. Relative to the specimens with no fracture zones (NF), the peak strength of the F-30°, F-45°, F-60°, F-75°, and F-90° specimens was reduced by 56.7 %, 45.1 %, 38.1 %, 14.9 %, and 9.8 %, respectively. The evolution of maximum principal strain exhibits pronounced temporal asynchrony and spatial asymmetry, while tensile cracking dominates the failure behavior, accounting for more than 80 % of all cracks. Prior to peak strength, the AF parameter drops sharply, and the proportion of shear cracking reaches its maximum. Analysis of the AE peak-frequency distributions reveals two distinct failure types. Type-I specimens (F-30° and F-45°), dominated by low-frequency events (>95 %), fail primarily through slow, large-scale slip along the fractured-zone interface. Type-II specimens (F-60°, F-75°, F-90°) exhibit high-frequency AE events that are 2–5 times more abundant than in type-I specimens, reflecting intense microcrack initiation, propagation, and coalescence driven by stress concentration at the fractured-zone tips and the tunnel boundary. Two characteristic failure sequences were identified: F–T, in which deformation and failure initiate in the fractured zone prior to the tunnel, and T–F, in which tunnel deformation and failure develop earlier than those in the fractured zone. The results indicate that the inclination of the fractured zone governs the tunnel failure mode and alters the sequence of damage evolution. The F-30°, F-45°, and F-60° specimens follow the F–T sequence, whereas the F-75° and F-90° specimens follow the T–F sequence. These findings provide theoretical insights and practical guidance for instability assessment and support design in tunnels crossing fractured zones

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荷载作用下裂隙带隧道变形破坏及声发射特征：倾角效应分析

裂缝带是常见的不利地质构造，对隧道的稳定性构成重大威胁。为研究不同倾角下隧道贯通裂隙带的变形破坏机理，以某浅埋地铁隧道为例，在30°、45°、60°、75°和90°倾角下制备了一系列裂隙带岩样。采用声发射（AE）监测和数字图像相关（DIC）进行双轴压缩试验。结果表明，断裂带的存在大大削弱了试样的力学性能。F-30°、F-45°、F-60°、F-75°和F-90°试件的峰值强度分别比无断裂带试件降低56.7%、45.1%、38.1%、14.9%和9.8%。最大主应变演化表现出明显的时间非同时性和空间非对称性，而拉伸裂纹主导破坏行为，占所有裂纹的80%以上。峰值强度之前，AF参数急剧下降，剪切开裂比例达到最大值。对声发射峰频分布的分析揭示了两种不同的破坏类型。i型试件（F-30°和F-45°）主要由低频事件（> 95%）主导，主要通过沿断裂带界面缓慢的大规模滑动破坏。ii型试样（F-60°，F-75°，F-90°）的高频声发射事件比i型试样多2-5倍，反映了在断裂带尖端和隧道边界应力集中驱动下的强烈微裂纹萌生、扩展和合并。确定了两种典型的破坏序列：F-T阶段，裂隙区变形破坏先于巷道发生；T-F阶段，巷道变形破坏先于裂隙区发生。结果表明，裂隙区的倾角决定着隧道的破坏模式，并改变着损伤演化的顺序。F-30°、F-45°和F-60°试样遵循F-T序列，而F-75°和F-90°试样遵循T-F序列。这些研究结果为穿越裂隙带的隧道失稳评估和支护设计提供了理论见解和实践指导

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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.