基于PFC离散元混凝土路基填料破碎与压实特性分析

Analysis of crushing and compaction characteristics of concrete subgrade filler based on PFC discrete element method

摘要

为探究废弃混凝土碎块作为路基填料在碾压过程中的破碎以及不同施工工艺对压实度的影响,利用颗粒流离散元软件PFC建立混凝土路基填料模型并进行碾压模拟,系统分析影响填料破碎率的因素(碾压荷载、碾压遍数、摊铺厚度),并从微观角度(接触力链、速度场)分析不同碾压遍数对填料压实度的影响。结果表明:对于摊铺厚度为30、40、50cm的混凝土填料模型,在达到模型内部破碎率与孔隙率相对稳定时所需的最小碾压荷载分别为20、25、30MPa,最少碾压遍数分别为7、11、16次;废弃混凝土碎块经碾压后形成颗粒集合体在单轴抗压等力学强度、孔隙率等结构稳定性方面均满足路基填料的压实质量控制标准;在实际施工中,选择碾压荷载与碾压遍数时应综合考虑不同的摊铺厚度对破碎率、孔隙率、沉降量的影响,以提高施工效率,节省施工成本。

Abstract

To investigate the crushing behavior of waste concrete blocks as subgrade fill material during compaction and the impact of different construction techniques on compaction degree, a discrete element software PFC was used to establish a concrete subgrade fill model and conduct compaction simulations. The factors influencing the crushing rate of the fill material (compaction load, number of passes, and spreading thickness) were systematically analyzed, and the effects of varying compaction passes on the compaction degree were examined from a microscopic perspective based on contact force chains and velocity fields. The results indicate that for concrete fill models with spreading thicknesses of 30, 40, and 50 cm, the minimum compaction loads required to achieve relatively stable internal crushing rates and porosity were 20, 25, and 30 MPa, respectively, with the minimum number of passes being 7, 11, and 16. The mechanical strength (uniaxial compressive strength) and structural stability indicators (porosity) of the particle aggregates formed by waste concrete after compaction meet the requirements of subgrade specification fill materials. In practical engineering, the selection of compaction load and compaction passes should comprehensively consider the effects of different spreading thicknesses on crushing rate, porosity, and settlement to improve construction efficiency and reduce costs.

关键词

路基填料 / 破碎率与压实度 / 离散元 / 废弃混凝土碎块

Key words

subgrade filling / crushing rate and compactness / discrete element / waste concrete fragment

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基金资助

山东省工业和信息化厅2022年山东省企业技术创新项目(202260101480)

山东省自然科学基金面上项目(ZR2024ME056)