论文速览 | Comput.Geotech.:多尺度分析新视角“透视”高堆石坝变形机理

原文摘要

Dams are among the most critical structures in hydraulic engineering, where stability and deformation analysis are essential for ensuring structural safety. For rockfill dams, especially those exceeding 200 m, accurately predicting deformation and settlement remains a significant challenge. This limitation arises from the shortage of conventional constitutive models to fully capture the complex mechanical behavior of rockfill materials, including nonlinear stress–strain response, scale effect and particle breakage, etc. In this study, a hierarchical multiscale approach is introduced to address these challenges. The proposed method significantly improves upon the limitations of earlier multiscale simulations by utilizing high-performance parallel computing. A three- dimensional numerical model of a 233-meter-high prototype dam is developed, which can simulate at the scale of hundreds of millions of particles and provide valuable insights into the deformation mechanism of dams at the particle scale. The micromechanical parameters of RVEs are calibrated using results from laboratory triaxial tests. The simulated deformations from the multiscale model are closely consistent with the monitoring data, validating the accuracy of the proposed method. Through comparative analysis with FEM simulations using the Duncan-Chang constitutive model, new insights were gained, revealing the critical need to account for true triaxial stress states at the dam crest and the upstream and downstream slopes. Additionally, the multiscale simulation quantified the spatial extent and magnitude of deformation caused by particle breakage, providing a more comprehensive understanding of the role of particle-scale mechanical evolution in the macro-scale behavior of rockfill dams. These findings underscore the importance of considering both macro and micro- mechanical behaviors for accurate safety assessments and deformation predictions in rockfill dams.

译文

大坝是水利工程中最核心的构筑物之一，其稳定性与变形分析是保障结构安全的关键。对于堆石坝，尤其是坝高超200米的高堆石坝，精准预测变形与沉降仍是一项重大挑战。这一局限源于传统本构模型难以充分表征堆石料的复杂力学行为，包括非线性应力-应变响应、缩尺效应及颗粒破碎等。本研究提出一种分层多尺度方法以解决上述问题，该方法通过采用高性能并行计算，显著突破了早期多尺度模拟的局限性。研究构建了坝高233米的原型坝三维数值模型，可实现数亿颗粒尺度的模拟，为从颗粒层面揭示大坝变形机理提供重要认知。基于室内三轴试验结果，完成了代表性体积单元（RVE）的细观力学参数率定。多尺度模型的模拟变形与监测数据高度吻合，验证了所提方法的准确性。通过与采用邓肯-张本构模型的有限元模拟进行对比分析，本研究获得了新的认知：坝顶及上下游坝坡区域需重点考虑真三轴应力状态。此外，多尺度模拟量化了颗粒破碎引发的变形空间范围与量级，使人们对颗粒尺度力学演化在堆石坝宏观力学行为中的作用有了更全面的理解。这些研究结果凸显了：要实现堆石坝精准的安全评估与变形预测，需同时考虑其宏观与细观力学行为。

   当一座坝高超200m的高堆石坝横跨峡谷，它不仅承载着水资源调控与防洪减灾的重任，更牵动着下游千万人的安全。然而，在水利工程领域，这类“巨无霸”结构的变形非线性强烈，且在生命周期内不断发展，如果准确预测其变形规律是长期困扰工程师的难题。传统变形预测通过室内三轴试验获取堆石料力学数据，校准邓肯-张等本构模型后，再用有限元法模拟坝体变形。但实际工程中，堆石料并非均匀介质，应力-应变响应非线性，并存在颗粒破碎、历史效应、长期流变等复杂力学机理，还受到常规三轴试验与堆石料粒径差异大导致的缩尺效应问题等制约，导致变形预测方法精度不足；