Freeze-thaw induced structural deterioration of fractured rock: A coupled NMR–CT study on pore network evolution

IF 5.6 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics Pub Date : 2025-10-03 DOI:10.1016/j.tafmec.2025.105274

Yongxin Che, Yongjun Song, Huimin Yang, Hao Tan, Leitao Zhang

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Abstract

Freeze-thaw cycling is one of the main drivers of rock-mass deterioration in cold regions, markedly altering pore structure and permeability. In this study, intact sandstone and pre-fabricated fractured sandstone were examined with a combined nuclear magnetic resonance (NMR) and X-ray computed tomography (CT) program to track multiscale pore-structure evolution. The results show that freeze-thaw action shifts the pore-size toward larger pores: (1) In fractured and intact specimens, the fraction of micropores fell by 22 %, while the fraction of macropores (or microcracks) rose by 114 % and 60 %, respectively; mesopores changed little. The meso-to-macropore fractal dimension measured by NMR decreased in tandem. (2) CT reconstructions revealed a pronounced rise in microcrack volume fraction (intact: from 82.7 % to 88.8 %; fractured: from 79.7 % to 90.1 %), along with total-porosity increases of 21 % and 30 %. The proportion of connected pores climbed from 51 % to 77 % in fractured sandstone and from 56 % to 71 % in intact sandstone. (3) Pre-fabricated fractures, as structural weak planes, strongly magnify freeze-induced pore enlargement, reorganization, and connectivity, driving the pore network from a disordered toward a more ordered, interconnected architecture. These findings furnish multiscale experimental evidence and mechanistic insight for assessing the stability of cold-region rock masses and designing protective measures.

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冻融诱导裂隙岩石结构劣化：核磁共振- ct耦合孔隙网络演化研究

冻融循环是寒区岩体退化的主要驱动因素之一，显著改变了孔隙结构和渗透率。在这项研究中，研究人员使用核磁共振（NMR）和x射线计算机断层扫描（CT）程序对完整砂岩和预制裂缝砂岩进行了检查，以跟踪多尺度孔隙结构的演化。结果表明：冻融作用使孔隙尺寸向大孔隙方向转变：(1)在断裂和完好的试样中，微孔隙的比例分别下降了22%，而大孔隙（或微裂纹）的比例分别上升了114%和60%；中孔变化不大。核磁共振测量的中、大孔分形维数依次下降。(2) CT重建显示，微裂纹体积分数显著增加（完整：从82.7%增加到88.8%；破裂：从79.7%增加到90.1%），总孔隙度分别增加21%和30%。裂缝砂岩中连通孔隙的比例从51%上升到77%，完整砂岩中连通孔隙的比例从56%上升到71%。(3)预制裂缝作为结构薄弱面，强烈放大了冻胀引起的孔隙扩张、重组和连通性，推动孔隙网络从无序走向有序、互联的结构。这些发现为评估寒区岩体的稳定性和设计保护措施提供了多尺度的实验证据和机理见解。

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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.