To elucidate the size effect laws governing the mechanical characteristics of basalt rockfill materials under loading, a combined methodology incorporating particle flow numerical simulation and laboratory testing was employed, and by introducing size-dependent patterns of particle strength and elastic modulus derived from single-particle compression tests, mesoscopic parameters of graded aggregates were calibrated based on triaxial compression test results, and numerical simulations of triaxial tests were subsequently conducted for both prototype and scaled gradation rockfill materials. The research resultes demonstrate that increasing particle size promotes stress concentration within specimens, leading to structural failure predominantly manifested as shear shrinkage volumetric deformation; modified formulas were proposed for the Duncan-Chang E-B model parameters , , and to account for particle size effects, revealing that parameters , and exhibit decreasing trends with increasing particle size, while parameter shows an inverse correlation. These research outcomes provide valuable references for predicting stress-deformation behavior in dam structures.
上述研究成果从加载速率、颗粒形状、堆石料缩尺方法、建立特定数值模型及宏细观本构关系模拟等方向,分析了堆石料力学性能的尺寸效应,虽然取得了较多成果,但仍缺乏具体且宏观的堆石料工程力学参数修正方法。目前,工程界广泛采用邓肯-张E-B模型进行土石坝的应力变形预测[10]。然而,室内试验受尺寸限制,无法准确获取原型级配堆石料的力学参数,如何确定原型级配料力学特性的尺寸效应公式以及强度、变形参数的尺寸效应公式,成为目前亟待解决的问题。本文克服传统连续介质分析方法在研究岩石类非均质材料时的局限性,采用颗粒流数值分析方法[13],从细观层面揭示岩石的力学行为。通过三轴数值模拟与室内单粒压缩试验、三轴试验相结合,反演符合堆石料原型级配力学性能的大尺寸颗粒流数值模型,并选择适于模拟岩石材料的平行黏结模型(parallel bond model,PBM)作为细观本构模型,采用离散元碎片替代法(fragment replacement method,FRM)模拟颗粒破碎过程。根据模拟结果,基于邓肯-张E-B模型建立强度、变形参数及颗粒粒径的联系,提出考虑尺寸效应的堆石料宏观本构模型参数的修正方法,为坝体应力变形分析提供理论参考。
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