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贯通裂隙注浆体浆岩双介质力学特性及传力机制

Mechanical characteristics and load transfer mechanism of grout-rock dual media in penetrative fracture grouting

  • 摘要: 注浆是提高裂隙岩体稳定性的主要技术之一,而浆岩介质间的传力方式对注浆岩体的破坏具有重要影响。为研究贯通裂隙注浆体浆岩双介质传力承载机制,制备不同角度裂隙类岩石试样,注浆充填后开展单轴压缩试验,并结合离散元数值模拟方法探究了裂隙倾角对试样力学特性、破坏模式、裂纹演化及传力方式的影响规律,从宏细观注浆体结构变化方面揭示了浆岩双介质的传力机制。试验和数值模拟结果表明:贯通裂隙注浆体强度小于完整试样,试样峰值强度随裂隙倾角增加先减小后增大,浆岩接触面处正应力逐渐降低,切应力逐渐增加,45°为试样力学特性转变的临界阈值,此时试样劣化程度最高,且浆岩接触面处正应力与切应力相等,45°~75°时试样峰前应变及峰后延性明显增加。完整试样呈两侧劈裂破坏,裂隙试样破坏模式受角度影响较大,0°~45°时,试样呈弯折型剪切−劈裂破坏,浆岩交界面处出现弯折,且裂纹主要集中在试样中上部;60°~90°时,试样拉剪裂纹逐渐趋于浆液两侧,呈拉剪破坏模式。裂隙倾角与浆岩双介质传力机制存在动态转变规律,以45°裂隙为临界角度,试样以浆液为中心由上下结构转变为左右结构,前者中部浆液强度较高,不利于裂纹向下部扩展,主体承载结构偏上;后者左右结构均可承载,且裂隙倾角越接近90°,试样左右两侧承载传力受浆液影响就越小,裂纹分布越均衡。研究成果可为复杂地质条件下注浆工程设计提供科学依据。

     

    Abstract: Grouting is a primary technique for enhancing the stability of fractured rock masses, and the load-transfer mechanism at the grout-rock interface significantly influences the failure of grouted rock masses. To investigate the load-bearing and load-transfer mechanisms in grouted rock masses with through-going fractures, artificial rock-like specimens containing fractures at various angles were prepared. After grout filling, uniaxial compression tests were conducted. Combined with discrete element numerical simulation, the influence of fracture inclination angle on the mechanical properties, failure modes, crack evolution, and load-transfer behavior of the specimens was studied. The load-transfer mechanism of the grout-rock dual medium was revealed through the analysis of macro-meso-scale structural changes in the grout body. Experimental and numerical results indicate:The strength of specimens with grouted through-going fractures is lower than that of intact specimens. Peak strength initially decreases and then increases with increasing fracture angle. At the grout-rock interface, normal stress progressively declines while shear stress increases. 45° is the critical angle threshold for changes in mechanical behavior, where specimen degradation is most severe, and normal and shear stresses reach equilibrium. Specimens with angles between 45°−75° exhibit significantly increased pre-peak strain and post-peak ductility. Intact specimens fail via splitting along both sides. Failure modes of fractured specimens are highly angle-dependent: For 0°−45°, failure manifests as flexural deformation with combined shear-splitting failure; bending occurs at the grout-rock interface, and cracks concentrate mainly in the upper-middle section. For 60°−90°, tensile-shear cracks in the specimen gradually converge toward both sides of the grout body, exhibiting a tensile-shear failure mode. A dynamic transition in the load-transfer mechanism of the grout-rock dual medium correlates with fracture angle. Taking 45° as the critical angle, the specimen structure shifts from an configuration centered on the grout to a configuration. In the former, the stronger central grout inhibits downward crack propagation, leading to a predominantly upper load-bearing structure. In the latter, both left and right structures contribute to load-bearing. As the angle approaches 90°, the influence of the grout on load transfer diminishes, resulting in more balanced crack distribution.This research provides a scientific basis for the design of grouting engineering under complex geological conditions.

     

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